2024/12/03 更新

お知らせ

 

写真a

タカハシ コウジ
髙橋 厚史
TAKAHASHI KOJI
所属
工学研究院 航空宇宙工学部門 教授
カーボンニュートラル・エネルギー国際研究所 (併任)
工学部 航空宇宙工学科(併任)
工学府 航空宇宙工学専攻(併任)
職名
教授
連絡先
メールアドレス
プロフィール
ナノ・マイクロスケールでの伝熱や物質輸送に関する教育と研究を行っている。たとえば、カーボンナノチューブなどのナノ材料や薄膜の熱物性をMEMS技術によって計測したり、液体/固体あるいは気体/固体の界面での相変化をナノのオーダーで観測したり、それらの実験結果を数値シミュレーションや理論モデルから評価している。実験的研究において鍵となる微細加工技術と分析技術は必要に応じて自ら開発している。ナノテクノロジーを社会に役立てるために、ナノとマクロの境界における熱と流れを解明し体系的知見を構築したいと考えている。
ホームページ
外部リンク

学位

  • 博士(工学)

経歴

  • 日本学術振興会特別研究員PD(1992年)   

    日本学術振興会特別研究員PD(1992年)

研究テーマ・研究キーワード

  • 研究テーマ: 界面での相変化現象のナノスケールからの探究

    研究キーワード: ナノバブル、凝縮、蒸発、固気液三相界線

    研究期間: 2010年4月 - 2026年3月

  • 研究テーマ: 熱工学とナノ材料

    研究キーワード: マイクロナノ伝熱、熱物性、輸送現象、低次元材料、フォノン

    研究期間: 2003年4月 - 2025年3月

  • 研究テーマ: マイクロ航空宇宙工学

    研究キーワード: MEMS、ナノテクノロジー

    研究期間: 2000年1月 - 2012年3月

受賞

  • 日本伝熱学会学術賞

    2021年5月   日本伝熱学会学   非定常ラマン分光法によるマイクロ・ナノスケール熱物性計測

  • 業績賞

    2016年10月   日本機械学会熱工学部門   熱工学、とりわけMEMSセンサを用いたナノ材料の熱物性および伝熱機構に関する研究業績が顕著である。

     詳細を見る

    「熱工学、とりわけ独自のセンサを用いた先進的実験手法によるナノ材料の熱物性およびナノマイクロスケールでの伝熱機構に関する研究業績が顕著である」ため日本機械学会熱工学部門業績賞を授与された。

  • 日本機械学会賞(論文)

    2012年4月   日本機械学会   カーボンナノチューブ-固体間の界面熱抵抗に関する実験的研究

  • 日本伝熱学会学術賞

    2008年5月   日本伝熱学会学   ナノ加工技術を用いた金属薄膜およびカーボンナノチューブの熱物性計測

  • 日本機械学会熱工学部門講演論文表彰

    2008年3月   日本機械学会   ナノ熱ダイオード素子の計測方法の開発

論文

  • Precursor-film-driven ultra-early depinning of the three-phase contact line

    Teshima, H; Fukunaga, T; Li, QY; Takahashi, K

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   678 ( Pt C )   1230 - 1238   2025年1月   ISSN:0021-9797 eISSN:1095-7103

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Colloid and Interface Science  

    Hypothesis: Despite its importance in colloid and interface science, contact line pinning remains poorly understood, especially in the presence of a precursor film. We hypothesized that this is due to a lack of an experimental method capable of directly observing their physics at the nanoscale. Methods: Using coherence scanning interferometry, we visualized the three-dimensional behavior of contact lines with a precursor film near a nanogroove structure composed of flat terrace surfaces and steps with an inclination angle of 30° while achieving nanoscale vertical resolution. Findings: We found that even when the contact line is pinned at the edge of the step, the precursor film is not and advances beyond the edge. Furthermore, we discovered that the precursor film has two distinct effects on contact line motion. Specifically, the precursor film facilitates depinning when the contact line descends the step — a contact angle change was 0.9°, only 3.0% of the value predicted by a classical theory of contact angle at a solid edge. This ultra-early depinning is attributed to the formation of a new liquid film past the edge, driven by the progression of the precursor film that overcomes the pinning effect. In contrast, when the contact line ascends the step, the precursor film acts as a resistance to movement due to steric interaction.

    DOI: 10.1016/j.jcis.2024.09.170

    Web of Science

    Scopus

    PubMed

    researchmap

  • Measuring interfacial thermal resistance across carbon nanotubes with in-situ electron microscopy: Unexpected reduction upon detachment and two orders of magnitude variations across diverse morphologies

    Li, DW; Takahashi, K; Li, QY

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   233   2024年11月   ISSN:0017-9310 eISSN:1879-2189

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:International Journal of Heat and Mass Transfer  

    The dynamic mechanical processes can notably impact the van der Waals (vdW) interaction at nanoscale contact interface and further interfacial thermal transport, but the experimental study is challenging. Here, by integrating a movable nanoprobe within an electron microscope, we dynamically adjusted the contact and detachment processes of vdW contact between two carbon nanotubes (CNTs), while measuring the thermal contact resistance (TCR) in situ with a nanofabricated thermal sensor. The TCR was found to span approximately two orders of magnitude at the moments when two CNTs just came into contact or detached. Surprisingly, during the initial stage of detachment, we observed that TCR unexpectedly further decreased by 65% instead of increasing. This decrease is attributed to the subtle alteration of exact contact interface in the circumferential direction, induced by the real-time observed rotation during the detachment process. A two-order magnitude difference in TCR for the diverse morphologies in static equilibrium between the same pair of CNTs due to the non-uniformity of the CNT surface structures can also support it. Our work provides valuable insights for dynamically modulating nanoscale interfacial thermal transport in various applications.

    DOI: 10.1016/j.ijheatmasstransfer.2024.126047

    Web of Science

    Scopus

    researchmap

  • Ultrahigh Subcooling Dropwise Condensation Heat Transfer on Slippery Liquid-like Monolayer Grafted Surfaces

    Huang, TE; Lu, YS; Wei, ZZ; Li, DW; Li, QY; Wang, ZY; Takahashi, K; Orejon, D; Zhang, P

    ACS APPLIED MATERIALS & INTERFACES   16 ( 39 )   53285 - 53298   2024年9月   ISSN:1944-8244 eISSN:1944-8252

     詳細を見る

    記述言語:英語   出版者・発行元:ACS Applied Materials and Interfaces  

    Rapid and continuous droplet shedding is crucial for many applications, including thermal management, water harvesting, and microfluidics, among others. Superhydrophobic surfaces, though effective, suffer from droplet pinning at high subcooling temperature (Tsub). Conversely, slippery liquid-like surfaces covalently bonded with flexible hydrophobic molecules show high stability and low droplet adhesion attributed to their dense and ultrasmooth water repellent polymer chains, enhancing dropwise condensation and rapid shedding. In this work, linear poly(dimethylsiloxane) chains of various viscosities are covalently bonded onto silicon substrates to form thin and smooth monolayer coated surfaces. The formation of the monolayer is characterized by cryogenic transmission electron microscopy. On these surfaces a very low contact angle hysteresis is reported within wide surface temperature ranges as well as continuous dropwise condensation at ultrahigh Tsub of 60 K. In particular, one of the highest condensation heat fluxes of 1392.60 kW·m-2 and a heat transfer coefficient of 23.21 kW·m-2·K-1 at ultrahigh Tsub of 60 K is reported. The experimental heat transfer performance is further compared to the theoretical heat transfer via the individual droplets with the droplet distribution elucidated via both macroscopic observations as well as environmental scanning electron microscopy. Finally, only a mild decrease in the heat transfer coefficient of 20.3% after 100 h of condensation test at Tsub of 60 K is reported. Slippery liquid-like surfaces promote droplet shedding and sustain dropwise condensation at high Tsub without flooding empowered by the lower frictional forces, addressing challenges in heat transfer performance and durability.

    DOI: 10.1021/acsami.4c12220

    Web of Science

    Scopus

    PubMed

  • Temperature-dependent water slip flow combined with capillary evaporation in graphene nanochannels

    Kun Cheng, Qin-Yi Li, Zhenying Wang, Takanobu Fukunaga, Hideaki Teshima, Koji Takahashi

    International Journal of Heat and Mass Transfer   225   125451 - 125451   2024年6月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.ijheatmasstransfer.2024.125451

  • Mastering thermal transport across carbon nanotube contacts through morphological control

    Li, DW; Takahashi, K; Li, QY

    COMMUNICATIONS MATERIALS   5 ( 1 )   2024年5月   eISSN:2662-4443

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Communications Materials  

    Thermally conductive nanomaterials hold great promise for applications in thermal management. However, the interfaces between nanomaterials can significantly impede heat flow, and a comprehensive understanding of thermal transport across nanoscale contacts is highly desired. Here, by integrating a movable nano-manipulator within an electron microscope with a nanofabricated thermal sensor, we adjusted the contact positions, overlapping length, and crossing angles between two carbon nanotubes (CNTs) as desired, while concurrently measuring the thermal contact resistance (TCR) at the van der Waals junction. The TCR far surpassed that of the studied 6 μm-long CNTs, particularly in contacts affected by inevitable nanoscale surface contamination. The TCR per unit area exhibited significant variations across different contact morphologies, spanning two orders of magnitude even for identical pairs of samples, attributable to structural non-uniformity within the CNTs. This in-situ approach and the notable morphology effects can guide the control of heat at the nanoscale.

    DOI: 10.1038/s43246-024-00524-1

    Web of Science

    Scopus

    researchmap

  • Optimizing the methodology for accurate and accessible slip length measurement with atomic force microscopy

    Haruya Ishida, Hideaki Teshima, Qin-Yi Li, Koji Takahashi

    International Journal of Thermofluids   22   100634 - 100634   2024年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.ijft.2024.100634

  • Crack expansion dynamics of freeze-dried soybean curd during rehydration

    Hirakawa Mai, Teshima Hideaki, Ikuta Tatsuya, Takahashi Koji

    Food Science and Technology Research   30 ( 3 )   295 - 303   2024年3月   ISSN:13446606 eISSN:18813984

     詳細を見る

    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本食品科学工学会  

    In contrast to the freeze-drying process, the rehydration process of freeze-dried foods remains unclear. This study investigated the rehydration of freeze-dried soybean curd, also known as tofu, and elucidated its breakage mechanism during rehydration, which impairs texture. The rehydration of freeze-dried tofu was observed at different water temperatures (20, 40, 70, and 100 °C), with the required rehydration time found to decrease with increasing water temperature. Furthermore, tofu was found to absorb water faster in cracks formed during production than in the porous body. Crack expansion was observed only in high-temperature water, leading to breakage of the tofu. Environmental scanning electron microscopy revealed that tofu expanded when a sufficient amount of water was absorbed. Accordingly, crack expansion in high-temperature water is attributed to the stress concentration at the tip of the crack, which is caused by differences in the rehydration rate and resulting stiffness between the porous body and cracks.

    DOI: 10.3136/fstr.fstr-d-23-00230

    Scopus

    CiNii Research

    researchmap

  • Nano-captured water affects the wettability of cellulose nanofiber films

    Masumi Misaka, Hideaki Teshima, Sota Hirokawa, Qin-Yi Li, Koji Takahashi

    Surfaces and Interfaces   46   103923 - 103923   2024年1月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.surfin.2024.103923

  • In situ annealing of nanoporous silicon thin films with transmission electron microscopy

    Qin-Yi Li, Fabian Javier Medina, Kosuke Kokura, Zheyu Jin, Koji Takahashi, Qing Hao

    Applied Physics Letters   123 ( 24 )   2023年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Nanoporous films have potential applications in thermoelectric cooling on a chip, sensors, solar cells, and desalination. For phonon transport, amorphization and other pore-edge defects introduced by the nanofabrication processes can eliminate wave effects by diffusively scattering short-wavelength phonons and thus destroying the phonon phase coherence. As a result, phononic effects can only be observed at 10 K or below, when long-wavelength phonons become dominant for thermal transport. In this work, a 70-nm-thick silicon thin film with approximately 100-nm-diameter nanopores was annealed under a high vacuum, and the change of pore-edge defects was observed with in situ transmission electron microscopy. It was found that the pore-edge defects can be minimized to a sub-1-nm layer by annealing between 773 and 873 K for 30 min, without changing the pore sizes. The largely reduced pore-edge defects are critical to the desired phonon wave effects within a periodic nanoporous structure.

    DOI: 10.1063/5.0181143

  • Nanoscale Contact Line Pinning Boosted by Ångström-Scale Surface Heterogeneity 査読

    Yuta Heima, Hideaki Teshima, Koji Takahashi

    Journal of Physical Chemistry Letters   14 ( 14 )   3561 - 3566   2023年4月

     詳細を見る

    担当区分:最終著者   記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.jpclett.3c00428

  • Random but limited pressure of graphene liquid cells 査読

    Sota Hirokawa, Hideaki Teshima, Pablo Solís-Fernández, Hiroki Ago, Qin-Yi Li, Koji Takahashi

    Ultramicroscopy   250   113747   2023年4月

     詳細を見る

    担当区分:最終著者, 責任著者   記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.ultramic.2023.113747

    リポジトリ公開URL: https://hdl.handle.net/2324/6786359

  • Thermal resistance mapping along a single cup-stacked carbon nanotube with focused electron beam heating 査読

    Dawei Li, Qin-Yi Li, Koji Takahashi

    International Journal of Heat and Mass Transfer   198   123418   2022年9月

     詳細を見る

    記述言語:その他  

    DOI: 10.1016/j.ijheatmasstransfer.2022.123418

  • Slip Flow on Graphene: Current Status and Perspective 査読

    Kuan-Ting Chen, Qin-Yi Li, Koji Takahashi

    Journal of Thermal Science   31 ( 4 )   1115 - 1134   2022年7月

     詳細を見る

    記述言語:その他  

    DOI: 10.1007/s11630-022-1668-8

  • Round Robin Study on the Thermal Conductivity/Diffusivity of a Gold Wire with a Diameter of 30 μm Tested via Five Measurement Methods 査読

    Ryo Abe, Yuki Sekimoto, Shirkant Saini, Koji Miyazaki, Qinyi Li, Dawei Li, Koji Takahashi, Takashi Yagi, Masakazu Nakamura

    Journal of Thermal Science   31 ( 4 )   1037 - 1051   2022年5月

     詳細を見る

    記述言語:その他  

    DOI: 10.1007/s11630-022-1594-9

  • Slip length measurement in rectangular graphene nanochannels with a 3D flow analysis

    Kuan-Ting Chen, Qin-Yi Li, Takeshi Omori, Yasutaka Yamaguchi, Tatsuya Ikuta, Koji Takahashi

    Carbon   189   162 - 172   2022年4月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.carbon.2021.12.048

  • Concurrent thermal conductivity measurement and internal structure observation of individual one-dimensional materials using scanning transmission electron microscopy

    Dawei Li, Qin-Yi Li, Tatsuya Ikuta, Koji Takahashi

    Applied Physics Letters   2022年1月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/5.0079153

  • Dynamic interplay between interfacial nanobubbles: Oversaturation promotes anisotropic depinning and bubble coalescence

    Sarthak Nag, Yoko Tomo, Hideaki Teshima, Koji Takahashi, Masamichi Kohno

    Physical Chemistry Chemical Physics   23 ( 43 )   24652 - 24660   2021年10月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    A dynamics study of surface nanobubbles using liquid phase electron microscopy showcases their unique push–push behavior.

    DOI: 10.1039/d1cp03451k

  • Thermally induced mass transfer between nanobubbles and micropancakes

    Ryota Kimura, Hideaki Teshima, Qin-Yi Li, Koji Takahashi

    International Journal of Heat and Mass Transfer   181   122001   2021年10月

     詳細を見る

    記述言語:その他  

    The response of nanoscopic gas phases at solid-liquid interfaces to temperature changes remains unclear. We investigated the interactions between surface nanobubbles and underlying micropancakes upon heat- ing. By atomic force microscopy imaging of the same area before and after heating, we found that the surface nanobubbles exhibited various behaviors upon heating: nucleation, growth, and disappearance. The differences in behavior are attributable to the existence of underlying gas phases, such as micropan- cakes and adsorbed layers. The nucleation sites of the nanobubbles depend on the positions of the mi- cropancakes. The size of the underlying micropancakes is central to the manner of gas transport between the micropancakes and overlying nanobubbles. We propose that the strongly adsorbed gas layers attract dissolved gas molecules and thereby lead to irreversible growth before and after heating.

  • Pinning in a Contact and Noncontact Manner: Direct Observation of a Three-Phase Contact Line Using Graphene Liquid Cells

    Sota Hirokawa, Hideaki Teshima, Pablo Solis-Fernandez, Hiroki Ago, Qin-Yi Li, Koji Takahashi

    Langmuir 2021   37 ( 42 )   12271 - 12277   2021年10月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.langmuir.1c01589

  • Limited enhancement of subatmospheric boiling on treated structured surfaces with biphilic pattern

    Biao Shen, Naoki Iwata, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata

    Journal of Heat Transfer   143 ( 10 )   101601   2021年9月

     詳細を見る

    記述言語:その他  

  • Persistent Reduction of Boiling of Boiling Incipience of Ethanol on Biphilic Porous Textured Surfaces

    Biao Shen, Takeshi Hamazaki, Kohei Kamiya, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata, Junji Nunomura, Akihiro Fukatsu, Yoichiro Betsuki

    International Journal of Multiphase Flow   142   103739   2021年9月

     詳細を見る

    記述言語:その他  

  • Reflected Laser Interferometry: A Versatile Tool to Probe Condensation of Low-Surface-Tension Droplets

    Sirshendu Misra, Hideaki Teshima, Koji Takahashi, Sushanta K. Mitra

    Langmuir   37 ( 27 )   8073 - 8082   2021年7月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.langmuir.1c00145

  • Thermal conductivity measurement of an individual millimeter-long expanded graphite ribbon using a variable-length T-type method

    Si Wu, Qin Yi Li, Tatsuya Ikuta, Kazuhiko Morishita, Koji Takahashi, Ruzhu Wang, Tingxian Li

    International Journal of Heat and Mass Transfer   171   2021年6月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2021 Expanded graphite (EG) is a well-known carbon derivative and widely used as the thermally conductive enhancer for thermal management composites. However, the investigation on thermal conductivity measurement of an individual EG particle is still unexploited, which prevents the exploration of the coupling mechanism between EG and matrices and further measures for thermal conductivity enhancement. Herein, using a variable-length T-type method, we measure the thermal conductivity of an individual expanded graphite ribbon (EGR) obtained by mechanically compressing a separate EG particle. The EGR has a micrometer-sized thickness and a millimeter-sized length. By changing the sample length while maintaining the contact junction, we simultaneously obtained the thermal conductivity of the EGR and the thermal contact resistance between the sample and the probe. The longitudinal thermal conductivity of the EGR reaches up to 335.6±27.4 W m−1 K−1 at room temperature and decreases to 254.8±20.8 W m−1 K−1 as the temperature rises from 300 K to 380 K. With a higher thermal conductivity than most graphene paper products and some carbon fibers, this low-cost nanocarbon-based material exhibits a great advantage in the development of thermally conductive composites, and the presented accurate thermal conductivity provides indispensable data for the rational design of composites.

    DOI: 10.1016/j.ijheatmasstransfer.2021.121115

  • Mechanistic Insights into Nanobubble Merging Studied Using In Situ Liquid-Phase Electron Microscopy

    Sarthak Nag, Yoko Tomo, Koji Takahashi, Masamichi Kohno

    LANGMUIR   37 ( 2 )   874 - 881   2021年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Nanobubbles have attracted great interest in recent times because of their application in water treatment, surface cleaning, and targeted drug delivery, yet the challenge remains to gain thorough understanding of their unique behavior and dynamics for their utilization in numerous potential applications. In this work, we have used a liquid-phase electron microscopy technique to gain insights into the quasistatic merging of surface nanobubbles. The electron beam environment was controlled in order to suppress any new nucleation and slow down the merging process. The transmission electron microscopy study reveals that merging of closely positioned surface nanobubbles is initiated by gradual localized changes in the physical properties of the region between the adjoining nanobubble boundary. The observed phenomenon is then analyzed and discussed based on the different perceptions: localized liquid density gradient and bridge formation for gas exchange. In this study, it is estimated that the merging of the stable nanobubbles is initiated by the formation of a thin gas layer. This work not only enhances our understanding of the merging process of stable surface nanobubbles but will also lead to exploration of new domains for nanobubble applications.

    DOI: 10.1021/acs.langmuir.0c03208

  • Zigzag gas phases on holey adsorbed layers

    Hideaki Teshima, Naoto Nakamura, Qin Yi Li, Yasuyuki Takata, Koji Takahashi

    RSC Advances   10 ( 73 )   44854 - 44859   2020年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © The Royal Society of Chemistry. We report for the first time a zigzag-shaped gas phase at a highly-ordered pyrolytic graphite/water interface. The novel shape of the gaseous domain is triggered by the holes of the underlying solid-like layers, which are composed of air molecules. Specifically, many holes were created by heating in the thin solid-like layers, which roughened them. The gas domains that formed on these layers deformed from circular to zigzag-shaped as the contact lines expanded while avoiding the holes of the underlying layers. We explained the formation and growth processes of these gas structures in terms of thin film growth, which varies with the mobility of the constituent molecules. This journal is

    DOI: 10.1039/d0ra08861g

  • Ultra-strong stability of double-sided fluorinated monolayer graphene and its electrical property characterization

    Haidong Wang, Masahiro Narasaki, Zhongwei Zhang, Koji Takahashi, Jie Chen, Xing Zhang

    SCIENTIFIC REPORTS   10 ( 1 )   2020年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Fluorinated graphene has a tunable band gap that is useful in making flexible graphene electronics. But the carbon-fluorine (C-F) bonds in fluorinated graphene can be easily broken by increased temperature or electron beam irradiation. Here, we demonstrate that the stability of fluorinated graphene is mainly determined by its C-F configuration. The double-sided fluorinated graphene has a much stronger stability than the single-sided fluorinated graphene under the same irradiation dose. Density functional theory calculations show that the configuration of double-sided fluorinated graphene has a negative and low formation energy, indicating to be an energetically stable structure. On the contrary, the formation energy of single-sided fluorinated graphene is positive, leading to an unstable C-F bonding that is easily broken by the irradiation. Our findings make a new step towards a more stable and efficient design of graphene electronic devices.

    DOI: 10.1038/s41598-020-74618-4

  • Nanostructured and Heterostructured 2D Materials for Thermoelectrics 査読

    Qin-Yi Li, Qing Hao, Tianhui Zhu, Mona Zebarjadi, Mona Zebarjadi, Koji Takahashi

    Engineered Science   13   24 - 50   2020年9月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.30919/es8d1136

  • Gas molecules sandwiched in hydration layers at graphite/water interfaces

    Hideaki Teshima, Qin Yi Li, Yasuyuki Takata, Koji Takahashi

    Physical Chemistry Chemical Physics   22 ( 24 )   13629 - 13636   2020年6月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © the Owner Societies. Hydration structures are ubiquitous at solid/liquid interfaces and play a key role in various physicochemical and biological phenomena. Recently, it has been reported that dissolved gas molecules attracted to hydrophobic surfaces form adsorbed gas layers. Although a hydration structure and adsorbed gas layers coexist on the surface, the relationships between them remain unknown. In this study, we investigated a highly ordered pyrolytic graphite/pure water interface with and without adsorbed gas layers using frequency-modulation atomic force microscopy. We penetrated the adsorbed gas layers with the strong load force of the AFM tip and thereby obtained the frequency shift curves inside them. By comparing the curves with those measured on a bare HOPG surface, we found that the adsorbed gas layers were located at regions where the molecular density of water was low and were sandwiched between hydration layers with high water density. Moreover, the distance between adjacent hydration layers was larger than that predicted by simulations and was the same with and without the adsorbed gas layers. We propose that gas molecules on the hydrophobic surface interact with the hydration structure before forming the adsorbed gas layers, and extend the distance between hydration layers. This journal is

    DOI: 10.1039/d0cp01719a

  • Deterioration of boiling heat transfer on biphilic surfaces under very low pressures

    Biao Shen, Tomosuke Mine, Naoki Iwata, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata

    Experimental Thermal and Fluid Science   113   2020年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2019 Elsevier Inc. Surface wettability engineering has attracted growing attention in recent years as an effective tool to enhance boiling heat transfer. On wettability-patterned (so-called biphilic) surfaces in particular, subatmospheric boiling has been shown to be nearly free of the severe degradation of heat transfer rate that tends otherwise to prevail on plain surfaces. The surprisingly consistent performance under reduced-pressure conditions can be attributed to the rather strong pinning of the three-phase contact line (TPCL) at the border between the hydrophobic and hydrophilic surfaces, which essentially eliminates the waiting period between bubble cycles. Only when the pressure is decreased sufficiently low does the transition to the undesired mode of intermittent boiling eventually occur on the biphilic surface. The purpose of the present study is to investigate the physical mechanism for the heat transfer deterioration on a mixed-wettability surface at very low pressures. To that end, we performed high-speed visualization experiments of the process of bubble nucleation and growth on a smooth copper surface coated with a single hydrophobic polytetrafluoroethylene (PTFE) spot, under different surface superheats and system pressures. The results show an interesting correlation between the TPCL behavior and the bubble growth dynamics. Specifically, under some certain threshold of pressure, it would become increasingly likely for the TPCL to be dislodged from its pinned position on the biphilic surface under a particularly rapid bubble expansion. As a result, full flooding of the hydrophobic surface might ensue, which is deemed responsible for temporary deactivation of the hydrophobic spot as a viable nucleation site. Furthermore, based on the diffuse-interface simulations of TPCL propagation across heterogeneous wettabilities, a comparison of cases with different bubble expansion rates offered qualitative evidence supporting the critical role of such accelerated bubble growth rate in driving the TPCL to overcome the energy barrier raised at the wettability divide.

    DOI: 10.1016/j.expthermflusci.2019.110026

  • Precursor-Film-Mediated Thermocapillary Motion of Low-Surface-Tension Microdroplets

    Hideaki Teshima, Sirshendu Misra, Koji Takahashi, Sushanta K. Mitra

    Langmuir   36 ( 19 )   5096 - 5105   2020年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2020 American Chemical Society. In contrast to microdroplet condensation with high contact angles, the one with low contact angles remains unclear. In this study, we investigated dynamics of microdroplet condensation of low-surface-tension liquids on two flat substrate surfaces by using reflection interference confocal microscopy. Spontaneous migration toward relatively larger droplets was first observed for the microdroplets nucleated on the hydrophilic quartz surface. The moving microdroplets showed a contact angle hysteresis of a0.5°, which is much lower than the values observed on typical flat substrates and is within the range observed on slippery lubricant-infused porous surfaces. Because the microdroplets on the hydrophobic polydimethylsiloxane surface did not move, we concluded that the ultrathin precursor film is formed only on the hydrophilic surface, which reduces a resistive force to migration. Also, reduced size of droplets promotes the thermocapillary motion, which is induced by a gradient in local temperature inside a small microdroplet arising due to the difference in size of adjacent droplets.

    DOI: 10.1021/acs.langmuir.0c00148

  • Nanoscale Bubble Dynamics Induced by Damage of Graphene Liquid Cells

    Sota Hirokawa, Hideaki Teshima, Pablo Solís-Fernández, Hiroki Ago, Yoko Tomo, Qin Yi Li, Koji Takahashi

    ACS Omega   5 ( 19 )   11180 - 11185   2020年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2020 American Chemical Society. Graphene liquid cells provide the highest possible spatial resolution for liquid-phase transmission electron microscopy. Here, in graphene liquid cells (GLCs), we studied the nanoscale dynamics of bubbles induced by controllable damage in graphene. The extent of damage depended on the electron dose rate and the presence of bubbles in the cell. After graphene was damaged, air leaked from the bubbles into the water. We also observed the unexpected directional nucleation of new bubbles, which is beyond the explanation of conventional diffusion theory. We attributed this to the effect of nanoscale confinement. These findings provide new insights into complex fluid phenomena under nanoscale confinement.

    DOI: 10.1021/acsomega.0c01207

  • Contact-line behavior in boiling on a heterogeneous surface Physical insights from diffuse-interface modeling 査読

    Biao Shen, Jiewei Liu, Gustav Amberg, Minh Do-Quang, Junichiro Shiomi, Koji Takahashi, Yasuyuki Takata

    Physical Review Fluids   5 ( 3 )   2020年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Enhancement of boiling heat transfer on biphilic (mixed-wettability) surfaces faces a sudden reversal at low pressures, which is brought about by excessive contact-line spreading across the wetting heterogeneities. We employ the diffuse-interface approach to numerically study bubble expansion on a heating surface that consists of opposing wettabilities. The results show a dramatic shift in the dynamics of a traversing contact line across the wettability divide under different gravities, which correspond to variable bubble growth rates. Specifically, it is found that the contact-line propagation tends to follow closely the rapidly expanding bubble at low gravity, with only a brief interruption at the border between the hydrophobic and hydrophilic sections of the surface. Only when the bubble growth becomes sufficiently weakened at high gravity does the contact line get slowed down drastically to the point of being nearly immobilized at the edge of the hydrophilic surface. The following bubble expansion, which faces strong limitations in the direction parallel to the surface, features a consistent apparent contact angle at around 66.4°, regardless of the wettability combination. A simple theoretical model based on the force-balance analysis is proposed to describe the physical mechanism behind such a dramatic transition in the contact-line behavior.

    DOI: 10.1103/PhysRevFluids.5.033603

  • Contact-line behavior in boiling on a heterogeneous surface: Physical insights from diffuse-interface modeling

    Biao Shen, Jiewei Liu, Gustav Amberg, Minh Do-Quang, Junichiro Shiomi, Koji Takahashi, Yasuyuki Takata

    Physical Review Fluids   5 ( 3 )   2020年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2020 American Physical Society. Enhancement of boiling heat transfer on biphilic (mixed-wettability) surfaces faces a sudden reversal at low pressures, which is brought about by excessive contact-line spreading across the wetting heterogeneities. We employ the diffuse-interface approach to numerically study bubble expansion on a heating surface that consists of opposing wettabilities. The results show a dramatic shift in the dynamics of a traversing contact line across the wettability divide under different gravities, which correspond to variable bubble growth rates. Specifically, it is found that the contact-line propagation tends to follow closely the rapidly expanding bubble at low gravity, with only a brief interruption at the border between the hydrophobic and hydrophilic sections of the surface. Only when the bubble growth becomes sufficiently weakened at high gravity does the contact line get slowed down drastically to the point of being nearly immobilized at the edge of the hydrophilic surface. The following bubble expansion, which faces strong limitations in the direction parallel to the surface, features a consistent apparent contact angle at around 66.4°, regardless of the wettability combination. A simple theoretical model based on the force-balance analysis is proposed to describe the physical mechanism behind such a dramatic transition in the contact-line behavior.

    DOI: 10.1103/PhysRevFluids.5.033603

  • Modification of thermal transport in an individual carbon nanofiber by focused ion beam irradiation

    Masahiro Narasaki, Qin Yi Li, Tatsuya Ikuta, Jin Miyawaki, Koji Takahashi

    Carbon   153   539 - 544   2019年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2019 We report on the in situ thermal measurement of a carbon nanofiber (CNF) modified by focused ion beam (FIB) irradiation. The FIB irradiation led to local amorphization of the crystalline structure of the CNF. The in situ measurement was improved by correcting for the effect of the scattered ions on the sensor. The low effective thermal conductivity of the pristine CNF (∼39 W/mK) resulted from the anisotropic structure made of many individual graphitic fibers. The first FIB irradiation decreased the thermal conductivity by approximately 3.2%. This relatively small decrease is attributed to the structure of the CNF consisting of many individual fibers, with some fibers remaining pristine even after the FIB irradiation. Analysis using a thermal-circuit model suggested that the thermal transport in the CNF could include a ballistic feature of phonons in the micrometer range. Our proposed in situ thermal measurement method can be extended to the study of thermal transport in various structurally modified nanomaterials.

    DOI: 10.1016/j.carbon.2019.07.056

    リポジトリ公開URL: https://hdl.handle.net/2324/7162464

  • Adsorbed gas layers limit the mobility of micropancakes 査読

    Hideaki Teshima, Yasuyuki Takata, Koji Takahashi

    Applied Physics Letters   115 ( 7 )   2019年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In contrast to surface nanobubbles, the properties of atomically flat gas phases such as micropancakes remain unclear. In this study, we investigated nanoscopic gas phases existing at the interface between highly ordered pyrolytic graphite and air-supersaturated pure water using high-sensitivity frequency-modulation atomic force microscopy (AFM). Micropancakes appeared on a disordered gas layer overlying an ordered gas layer and moved in the direction of AFM scanning. Their movement stopped at the edge of the disordered gas layers, whereas the two gas layers did not move at all. The limited mobility of micropancakes is explained by assuming that the disordered and ordered gas layers, which are composed of strongly adsorbed gas molecules, behave like solid surfaces, and that the surface heterogeneity between them results in a pinning effect.

    DOI: 10.1063/1.5113810

  • Enhanced Thermoelectric Performance of As-Grown Suspended Graphene Nanoribbons

    Qin Yi Li, Tianli Feng, Wakana Okita, Yohei Komori, Hiroo Suzuki, Toshiaki Kato, Toshiro Kaneko, Tatsuya Ikuta, Xiulin Ruan, Koji Takahashi

    ACS Nano   13 ( 8 )   9182 - 9189   2019年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2019 American Chemical Society. Conventionally, graphene is a poor thermoelectric material with a low figure of merit (ZT) of 10-4-10-3. Although nanostructuring was proposed to improve the thermoelectric performance of graphene, little experimental progress has been accomplished. Here, we carefully fabricated as-grown suspended graphene nanoribbons with quarter-micron length and â40 nm width. The ratio of electrical to thermal conductivity was enhanced by 1-2 orders of magnitude, and the Seebeck coefficient was several times larger than bulk graphene, which yielded record-high ZT values up to â0.1. Moreover, we observed a record-high electronic contribution of â20% to the total thermal conductivity in the nanoribbon. Concurrent phonon Boltzmann transport simulations reveal that the reduction of lattice thermal conductivity is mainly attributed to quasi-ballistic phonon transport. The record-high ratio of electrical to thermal conductivity was enabled by the disparate electron and phonon mean free paths as well as the clean samples, and the enhanced Seebeck coefficient was attributed to the band gap opening. Our work not only demonstrates that electron and phonon transport can be fundamentally tuned and decoupled in graphene but also indicates that graphene with appropriate nanostructures can be very promising thermoelectric materials.

    DOI: 10.1021/acsnano.9b03521

  • Adsorbed gas layers limit the mobility of micropancakes

    Hideaki Teshima, Yasuyuki Takata, Koji Takahashi

    Applied Physics Letters   115 ( 7 )   2019年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2019 Author(s). In contrast to surface nanobubbles, the properties of atomically flat gas phases such as micropancakes remain unclear. In this study, we investigated nanoscopic gas phases existing at the interface between highly ordered pyrolytic graphite and air-supersaturated pure water using high-sensitivity frequency-modulation atomic force microscopy (AFM). Micropancakes appeared on a disordered gas layer overlying an ordered gas layer and moved in the direction of AFM scanning. Their movement stopped at the edge of the disordered gas layers, whereas the two gas layers did not move at all. The limited mobility of micropancakes is explained by assuming that the disordered and ordered gas layers, which are composed of strongly adsorbed gas molecules, behave like solid surfaces, and that the surface heterogeneity between them results in a pinning effect.

    DOI: 10.1063/1.5113810

  • Enhanced Thermoelectric Performance of As-Grown Suspended Graphene Nanoribbons 査読

    Qin Yi Li, Tianli Feng, Wakana Okita, Yohei Komori, Hiroo Suzuki, Toshiaki Kato, Toshiro Kaneko, Tatsuya Ikuta, Xiulin Ruan, Koji Takahashi

    ACS nano   13 ( 8 )   9182 - 9189   2019年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Conventionally, graphene is a poor thermoelectric material with a low figure of merit (ZT) of 10-4-10-3. Although nanostructuring was proposed to improve the thermoelectric performance of graphene, little experimental progress has been accomplished. Here, we carefully fabricated as-grown suspended graphene nanoribbons with quarter-micron length and â40 nm width. The ratio of electrical to thermal conductivity was enhanced by 1-2 orders of magnitude, and the Seebeck coefficient was several times larger than bulk graphene, which yielded record-high ZT values up to â0.1. Moreover, we observed a record-high electronic contribution of â20% to the total thermal conductivity in the nanoribbon. Concurrent phonon Boltzmann transport simulations reveal that the reduction of lattice thermal conductivity is mainly attributed to quasi-ballistic phonon transport. The record-high ratio of electrical to thermal conductivity was enabled by the disparate electron and phonon mean free paths as well as the clean samples, and the enhanced Seebeck coefficient was attributed to the band gap opening. Our work not only demonstrates that electron and phonon transport can be fundamentally tuned and decoupled in graphene but also indicates that graphene with appropriate nanostructures can be very promising thermoelectric materials.

    DOI: 10.1021/acsnano.9b03521

  • Water Confined in Hydrophobic Cup-Stacked Carbon Nanotubes beyond Surface-Tension Dominance

    Qin Yi Li, Ryo Matsushita, Yoko Tomo, Tatsuya Ikuta, Koji Takahashi

    Journal of Physical Chemistry Letters   10 ( 13 )   3744 - 3749   2019年7月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2019 American Chemical Society. Water confined in carbon nanotubes (CNTs) can exhibit distinctly different behaviors from the bulk. We report transmission electron microscopy (TEM) observation of water phases inside hydrophobic cup-stacked CNTs exposed to high vacuum. Unexpectedly, we observed stable water morphologies beyond surface-tension dominance, including nanometer thin free water films, complex water-bubble structures, and zigzag-shaped liquid-gas interface. The menisci of the water phases are complex and inflected, where we measured the contact angles on the CNT inner wall to be 68-104°. The superstability of the suspended ultrathin water films is attributed to the strong hydrogen-bonded network among water molecules and adsorption of water molecules on the cup-structured inner wall. The complex water-bubble structure is a result of the stability of free water films and interfacial nanobubbles, and the zigzag edge of the liquid-gas interface is explained by the pinning effect. These experimental findings provide valuable knowledge for the research on fluids under nanoscale confinement.

    DOI: 10.1021/acs.jpclett.9b00718

  • Frequency-domain Raman method to measure thermal diffusivity of one-dimensional microfibers and nanowires

    Qin Yi Li, Koji Takahashi, Xing Zhang

    International Journal of Heat and Mass Transfer   134   539 - 546   2019年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2019 Thermal property measurement of individual micro- and nano-materials has been very challenging and the development of measurement methods is crucial for the experimental investigation of microscale and nanoscale heat transfer. Here we present a noncontact frequency-domain Raman method to measure thermal diffusivity of individual 1D microfibers and nanowires without the need of knowing laser absorptivity. Cosine-wave modulated laser is used to heat the sample, while the laser-intensity-weighted spatiotemporal average temperature is simultaneously detected from the sample's Raman band shift. Transient heat conduction models under periodic heating are established and analytically solved in the frequency domain with considerations of the Gaussian laser distribution and thermal contact resistance. By varying the laser modulation frequency as well as the laser spot size, we can eliminate the laser absorptivity by a normalization technique and extract the thermal diffusivity with high sensitivity. Typically, if the thermal diffusivity is on the order of 10−4 m2/s, we need to use the modulation frequencies on the order of 10 Hz to measure millimeter long microfibers, and ∼MHz frequencies to measure micrometer long nanowires. We also demonstrate that any kind of periodic laser modulation can be decomposed to a series of cosine modes and readily analyzed by this frequency-domain approach, which can greatly broaden the applications of transient Raman techniques.

    DOI: 10.1016/j.ijheatmasstransfer.2019.01.057

  • Enhanced pool boiling of ethanol on wettability-patterned surfaces

    Biao Shen, Takeshi Hamazaki, Wei Ma, Naoki Iwata, Sumitomo Hidaka, Atsushi Takahara, Koji Takahashi, Yasuyuki Takata

    Applied Thermal Engineering   149   325 - 331   2019年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2018 Due to the considerably reduced boiling point, organic fluids such as ethanol provide an attractive alternative to water as the working fluid in two-phase thermal management systems for high-heat-flux applications. The state-of-the-art enhancement methods for ethanol boiling normally involve surface structure engineering. Here we report, for the first time, enhancement of nucleate boiling of ethanol using wettability-patterned surfaces. By depositing onto a polished copper surface an array of circular spots of superamphiphobic coating of modified halloysite nanotubes (HNT) with fluoropolymer, which was shown to repel low-surface-tension fluids, we managed to create a meaningful biphilic pattern of alternating hydrophobicity (with ethanol contact angle exceeding 100°) and hydrophilicity (with contact angle close to 0°) on the surface. Boiling heat transfer was found to be improved dramatically on the coated surface. Specifically, the onset of nucleate boiling was found to drop by more than 35%. Moreover, at 20 K surface superheat (above the boiling point), a maximum heat transfer enhancement over 300% compared with a plain copper surface occurred on the surface with a pitch-to-spot ratio close to 2.5. The significantly increased heat transfer rate of the biphilic surfaces could be attributed to facilitated bubble nucleation and stronger agitation effect.

    DOI: 10.1016/j.applthermaleng.2018.12.049

  • Water Confined in Hydrophobic Cup-Stacked Carbon Nanotubes beyond Surface-Tension Dominance 査読

    Qin Yi Li, Ryo Matsushita, Yoko Tomo, Tatsuya Ikuta, Koji Takahashi

    Journal of Physical Chemistry Letters   10 ( 13 )   3744 - 3749   2019年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Water confined in carbon nanotubes (CNTs) can exhibit distinctly different behaviors from the bulk. We report transmission electron microscopy (TEM) observation of water phases inside hydrophobic cup-stacked CNTs exposed to high vacuum. Unexpectedly, we observed stable water morphologies beyond surface-tension dominance, including nanometer thin free water films, complex water-bubble structures, and zigzag-shaped liquid-gas interface. The menisci of the water phases are complex and inflected, where we measured the contact angles on the CNT inner wall to be 68-104°. The superstability of the suspended ultrathin water films is attributed to the strong hydrogen-bonded network among water molecules and adsorption of water molecules on the cup-structured inner wall. The complex water-bubble structure is a result of the stability of free water films and interfacial nanobubbles, and the zigzag edge of the liquid-gas interface is explained by the pinning effect. These experimental findings provide valuable knowledge for the research on fluids under nanoscale confinement.

    DOI: 10.1021/acs.jpclett.9b00718

  • Measurement of thermal contact resistance between individual carbon fibers using a laser-flash Raman mapping method

    Qin Yi Li, Koki Katakami, Tatsuya Ikuta, Masamichi Kohno, Xing Zhang, Koji Takahashi

    Carbon   141   92 - 98   2019年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2018 Elsevier Ltd Thermal contact resistance (TCR) between individual carbon fibers (CFs) can dominate heat dissipation rates in CF-based composite materials. Here, we develop a totally non-contact “laser-flash Raman mapping” method to simultaneously measure the TCR at the CF-CF junction and their thermal conductivities. Laser power is used to heat the sample and the laser absorptivity is experimentally determined by a transient laser-flash Raman technique. The laser heating positions are changed along two connected CFs, and the change of temperature rise with varying positions is in-situ measured from the temperature dependent Raman band shifts. The high spatial resolution of the micro-Raman mapping allows direct observation of the abrupt jump of thermal resistance at the CF-CF junction, from which we extracted the TCR as well as the thermal conductivity. The laser absorptivity of the 11 μm-diameter CFs is measured to be 0.12 ± 0.03, the thermal conductivities of the individual CFs are around 200 W/mK, and the TCR of the CF-CF junction is (2.98 ± 0.92) × 105 K/W. This work provides indispensable knowledge for the design of CF-based composite for thermal management, and the novel non-contact measurement method can stimulate characterization and manipulation of contact/interface heat conduction between various micro- and nano-materials.

    DOI: 10.1016/j.carbon.2018.09.034

  • Unexpected Homogeneous Bubble Nucleation near a Solid-Liquid Interface

    Yoko Tomo, Qin Yi Li, Tatsuya Ikuta, Yasuyuki Takata, Koji Takahashi

    Journal of Physical Chemistry C   122 ( 50 )   28712 - 28716   2018年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © Copyright 2018 American Chemical Society. We report a quasi-three-dimensional observation of electron-beam-induced nanobubbles inside a 1000 nm thick layer of water using the liquid cell electron microscopy. In the early stage of observation, heterogeneous bubble nucleation occurred, and small bubbles coalesced with the adjacent bubbles when they come in contact with each other. However, for the first time, we found that after prolonged electron beam irradiation heterogeneous nucleation did not occur more, and then homogeneous nucleation started even though a solid surface was available for heterogeneous nucleation. We conclude that the Ostwald ripening effect prevents heterogeneous nucleation from occurring and that the lower surface tension due to the generation of ions and radicals boosts the homogeneous nucleation. It was also discovered that the generation sites of homogeneous nucleation are beneath the three-phase contact lines of existing interfacial bubbles.

    DOI: 10.1021/acs.jpcc.8b09200

  • Depinning of bubble contact line on a biphilic surface in subatmospheric boiling: Revisiting the theories of bubble departure

    Biao Shen, Masayuki Yamada, Tomosuke Mine, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    International Journal of Heat and Mass Transfer   126   715 - 720   2018年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2018 Elsevier Ltd Boiling suffers from inefficient intermittent cycles of bubble generation under subatmospheric conditions. Such deterioration in heat transfer rates can be alleviated but not completely eliminated by use of mixed-wettability (biphilic) surfaces. Here we study bubble dynamics on a single hydrophobic spot in low-pressure pool boiling. The results reveal an interesting transition in bubble departure behavior from the surface-driven mode to the drag-driven mode, which correlates closely with the dynamic state of the three-phase contact line on the surface. Based on the force-balance argument, a simple model is derived to map the contact-line mobility during bubble growth. It is found that below a certain threshold pressure, the bubble base expansion is increasingly likely to overcome the strong pinning of the contact line at the interface between the hydrophobic and hydrophilic regions. That could lead to total removal of vapor residues from the surface and cause deactivation of the nucleation site, which portends the eventual takeover of intermittent boiling on the biphilic surface.

    DOI: 10.1016/j.ijheatmasstransfer.2018.06.030

  • Effect of dissolved gas on bubble growth on a biphilic surface: A diffuse-interface simulation approach

    Biao Shen, Jiewei Liu, Junichiro Shiomi, Gustav Amberg, Minh Do-Quang, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    International Journal of Heat and Mass Transfer   126   816 - 829   2018年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2018 Elsevier Ltd In this paper, we numerically study pool boiling of a binary (water and nitrogen) mixture on a surface endowed with a combination of hydrophobicity and hydrophilicity (i.e., the so called biphilic surface). Here we adopt a numerical approach based on the phase field theory, where the vapor-liquid interface is assumed to be of a finite thickness (hence diffusive in nature) and requires no explicit tracking schemes. The theoretical modeling of two-phase heat and mass transfer in water diluted with nitrogen demonstrates the significant impact of impurities on bubble dynamics. The simulations show that locally high concentrations of nitrogen gas within the vapor bubble is essential to weakening the condensation effect, which results in sustained bubble growth and ultimately (partial) departure from the surface under the artificially enlarged gravity. Simply increasing the solubility of nitrogen in water, however, turns out to be counterproductive because possible re-dissolution of the aggregated nitrogen by the bulk water could deprive the bubble of vital gas contents, leading instead to continuous bubble shrinkage and collapse. Additionally, it is found that with the significant accumulation of nitrogen, the bubble interface is increasingly dominated by a strong interfacial thermocapillary flow due to the Marangoni effect.

    DOI: 10.1016/j.ijheatmasstransfer.2018.06.043

  • Variable-spot-size laser-flash Raman method to measure in-plane and interfacial thermal properties of 2D van der Waals heterostructures 査読

    Qin Yi Li, Xing Zhang, Koji Takahashi

    International Journal of Heat and Mass Transfer   125   1230 - 1239   2018年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2018 Elsevier Ltd Stacked layers of different atomically thin 2D materials is called the van der Waals (vdW) heterostructure, which has become a rapidly developing research field due to its extraordinary and tunable properties. In this paper, we develop a variable-spot-size laser-flash Raman method to in-situ measure the thermal properties as well as the laser absorption in the supported 2D vdW heterostructure with arbitrary layers. The extracted thermal properties include the in-plane thermal conductivity and diffusivity of each layer, and interfacial thermal conductance between every two adjacent layers. A three-dimensional transient heat conduction model is developed and analytically solved to describe the process of pulsed Gaussian laser heating supported n-layer heterostructure. The temperature of each atomic layer can be simultaneously non-contact detected from their distinct Raman peaks whose positions are temperature dependent. The laser spot sizes and pulse durations are varied to generate multiple temperature curves. The multiple thermal properties as well as the laser absorption can be extracted by simultaneously fitting these temperature curves into the analytical solutions at multiple spot sizes or/and pulse durations. We also establish the approach of sensitivity and uncertainty analysis for the multi-response multi-parameter least-square fitting in our proposed measurement methods. Case studies show that the transient temperature curves are generally more sensitive to the thermal properties than the steady-state temperatures at variable spot sizes. All the unknown thermal properties and laser absorption can be extracted with sufficiently high accuracy if multiple transient temperature curves at multiple spot sizes are simultaneously fitted into the analytical solution. The measurement method and uncertainty analysis approach presented here are useful for investigating the thermal transport in the emerging 2D materials and vdW heterostructures.

    DOI: 10.1016/j.ijheatmasstransfer.2018.05.011

  • Meniscus Motion and Void Generation Inside Carbon Nanotubes

    Yutaka Yamada, Kanoko Taguchi, Tatsuya Ikuta, Akihiko Horibe, Koji Takahashi

    Journal of Physical Chemistry C   122 ( 38 )   21910 - 21918   2018年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Copyright © 2018 American Chemical Society. The hollow inside of a carbon nanotube (CNT) has great potential not only for flow rate enhancement of nanocapillary, but also for a material container which can be applied for drug delivery and nanoparticle infusion. However, these applications focus on after liquid infusion into CNTs, whereas the understanding of the filling process is still limited. We conducted capillary filling experiments using individual open-ended CNTs, which were stuck into an ionic liquid and visualized by scanning transmission electron microscopy. The results showed that the meniscus stopped inside the CNT, which is not predicted by the Lucas-Washburn equation. To explain this discrepancy, the intermolecular force between the liquid and CNT inner wall was proposed to provide an additional friction force. In addition, voids were observed in the liquid inside the CNT. The generation mechanism of voids was proposed to be induced by the instability of the thin liquid layer along the CNT inner surface caused by the advance of the three-phase contact line. The results of the present study increase our understanding of nanoscale capillary action.

    DOI: 10.1021/acs.jpcc.8b06406

  • A loop thermosyphon with hydrophobic spots evaporator surface

    Hongbin He, Biao Shen, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata

    ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2018   2018年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Copyright © 2018 ASME. Heat transfer characteristic of a closed two-phase thermosyphon with enhanced boiling surface is studied and compared with that of a copper mirror surface. Two-phase cooling improves heat transfer coefficient (HTC) a lot compared to single-phase liquid cooling. The evaporator surfaces, coated with a pattern of hydrophobic circle spots (non-electroplating Ni-PTFE, 0.5~2 mm in diameter and 1.5-3 mm in pitch) on Cu substrates, achieve very high heat transfer coefficient and lower the incipience temperature overshoot using water as the working fluid. Sub-atmospheric boiling on the hydrophobic spot-coated surface shows a much better heat transfer performance. Tests with heat loads (30 W to 260 W) reveals the coated surfaces enhance nucleate boiling performance by increasing the bubbles nucleation sites density. Hydrophobic circle spots coated surface with diameter 1 mm, pitch 1.5 mm achieves the maximal heat transfer enhancement with the minimum boiling thermal resistance as low as 0.03 K/W. The comparison of three evaporator surfaces with same spot parameters but different coating materials is carried out experimentally. Ni-PTFE coated surface with immersion method performs the optimal performance of the thermosyphon.

    DOI: 10.1115/icnmm2018-7623

  • Study on liquid-gas interface at nanoscale using transmission electron microscopy

    Yoko Tomo, Alexandros Askounis, Khellil Sefiane, Yasuyuki Takata, Koji Takahashi

    International Heat Transfer Conference   2018-August   1169 - 1174   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Control for the bubble nucleation at the onset of nucleate boiling (ONB) ensures the stable start of boiling heat transfer. However, the bubble nucleation mechanism at the ONB remains unclear, because of the difficulty of in-situ observation, which is due to the small size of nucleation. Thus, in order to break through the current technological barrier of boiling heat transfer, a new experimental technique enabling the investigation of the dynamics of bubbles near the solid-liquid interface is highly desirable. Liquid cell electron microscopy is the most useful method for the in-situ observation of liquid samples at the nanoscale. We prepared a closed liquid cell fabricated using MEMS technology and observed the generation and growth of bubbles at the nanoscale and in real time using transmission electron microscopy (TEM). In the growing process, the water meniscus between smaller bubbles becomes thinner and thinner and eventually ruptures. However, when the bubbles grow, the meniscus between larger bubbles do not rupture and the bubble overlaps with others, suggesting that thin meniscus can be stable only in the case of larger bubbles because of the difference of the curvature of their liquid-gas interfaces between smaller bubbles and larger bubbles. Our experimental results lead to the insight of the mechanism of the stability and the phase change phenomena at the liquid-gas interface at the nanoscale.

    DOI: 10.1615/ihtc16.bae.023136

  • Influence of surface wettability and nanostructure on the generation of interfacial nanobubbles

    Hideaki Teshima, Takashi Nishiyama, Yasuyuki Takata, Koji Takahashi

    International Heat Transfer Conference   2018-August   6909 - 6914   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Interfacial nanobubbles were first speculated in 1994 and experimentally confirmed in 2000 by atomic force microscopy (AFM) measurements. It was recently proposed that the onset of boiling with the very low superheat on hydrophobic surface could be explained by assuming the existence of interfacial nanobubbles. To reduce the superheat and enhance the reliability of boiling heat transfer, the control of the generation of interfacial nanobubbles is indispensable. In this study, we measured the interfacial nanobubbles by AFM and examined the influence of surface wettability and nanostructure on their generation. First, we measured the spherical-cap shaped nanobubbles generated on the HOPG surface. It was observed that the nanobubbles only generate on the hydrophobic terraced area and do not cross the nanosized hydrophilic steps. Next, we prepared the hydrophilic-hydrophobic hybrid surfaces and generated the nanobubbles on those. As a result, the range of nanobubble generation clearly changed by the difference of wettability between adjacent surfaces. These results show that the generation of interfacial nanobubbles can be controlled by the surface processing of the substrate and can be expected to be applied to boiling heat transfer.

    DOI: 10.1615/ihtc16.nmt.022210

  • Heater assisted raman method to measure interfacial thermal conductance in van der waals heterostructures

    Qin Yi Li, Koji Takahashi, Xing Zhang

    International Heat Transfer Conference   2018-August   7137 - 7143   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Two-dimensional (2D) layered materials have been the focus of materials research for more than a decade. Stacking different 2D nanosheets and 3D substrates with van der Waals interactions in between has opened up new ways to sophisticated design of novel device functionalities and platforms for new physics. The performance of van der Waals heterostructure (vdWH) devices can be most often limited by the heat dissipation issue, but the thermal transport in vdWHs has rarely been studied yet. This paper presents a novel heater assisted Raman method to accurately measure interfacial thermal conductance between every two layers in the vdWH, which is suitable to detect interfacial thermal transport between all kinds of nanosheets no matter whether the neighboring layer is electrical conductor or insulator. In this method, a transparent insulating thin layer and a patterned transparent conducting indium-tin-oxide (ITO) layer are successively sputtered on top of the vdWH. The ITO layer is electrically heated to provide vertical heat flux, while the temperatures of each atomic layer and the substrate surface are simultaneously detected from their temperature dependent Raman band shifts, thus the interfacial thermal conductance between every two layers can be accurately determined from the ITO's Joule heating power and the Raman-measured temperatures. With high sensitivity and accuracy, the measurement method proposed here provides a general way to experimentally investigate interfacial thermal transport across both electrically conducting and insulating van der Waals interfaces in 2D-material-based devices.

    DOI: 10.1615/ihtc16.nmt.021756

  • Enhanced boiling heat transfer on surfaces patterned with mixed wettability

    Biao Shen, Masayuki Yamada, Tomosuke Mine, Sumitomo Hidaka, Junichiro Shiomi, Gustav Amberg, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    International Heat Transfer Conference   2018-August   1379 - 1386   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Amongst an extensive collection of surface characteristics that could affect boiling performance, surface wettability (as measured by the contact angle with water) proves to play a unique role in potentially manipulating bubble behavior to the advantage of higher heat transfer rates. In this study, we show experimentally that controlled bubble behavior be realized under the surface design incorporating these two characteristics (namely, by coating an array of hydrophobic spots on a hydrophilic substrate), which leads to a great enhancement in boiling heat transfer under various conditions. In reduced-pressure pool boiling, the strong pinning of the bubble contact line at the border between the hydrophilic and hydrophobic regions manages to prevent total deactivation of nucleation sites. As a result, the deleterious transition to intermittent boiling is effectively delayed, whereby no heat transfer deterioration occurs until a very low pressure of about 8 kPa is reached. Moreover, in subcooled boiling, bubble growth on a patterned surface is found to be facilitated by a pronounced presence of dissolved gas in defiance of exhaustive degassing efforts through continuous boiling, thanks to an unusually strong retention of gas contents by the hydrophobic surface. As experimental and numerical evidence show, only bubbles with sufficiently high concentrations of gas components (i.e., causing weakened condensation) are able to grow large enough on the hydrophobic surface such that periodic pinch-offs might take place, which is responsible for most of the initial heat transfer enhancement before large-scale bubble nucleation starts on the hydrophilic surface as well.

    DOI: 10.1615/ihtc16.bae.023482

  • Effective thermal rectification in suspended monolayer graphene

    Haidong Wang, Xing Zhang, Hiroshi Takamatsu, Koji Takahashi

    International Heat Transfer Conference   2018-August   6903 - 6908   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Thermal rectification is a phenomenon that the heat flow changes by reversing the direction of temperature gradient. This is a fundamental behavior of the thermal rectifiers, which can be used for the active heat flow control, thermally driven computer, efficient energy harvesting, etc. The key challenge is how to increase the thermal rectification ratio, which is defined as the relative change of thermal conductivities in different heat flow directions. Due to the significant size effect and unique heat transfer mechanisms, nanomaterials (such as carbon nanotubes, nanowires, graphene, etc.) are suggested to have high thermal rectification ratio. However, the experiment result showed that the ratio of the single carbon nanotube thermal rectifier was only 7%. In the past decade, many theoretical researches and molecular dynamics simulations have shown that the monolayer graphene may have high thermal rectification ratio due to its unique two-dimensional heat transfer mechanism. But the experimental work is still a blank because of the difficult fabrication process of suspended graphene electronic device. In this work, we report the experimental demonstration of a suspended monolayer graphene thermal rectifier. Three different types of graphene thermal rectifiers have been fabricated with different asymmetric nanostructures. The focused ion beam manufacturing, electron beam induced deposition and precise electron beam lithography were used to design and create asymmetric nanostructures on the monolayer graphene. The thermal rectification ratios were measured by using a precise H-type sensor method. The highest rectification ratio reaches 28% for the graphene with asymmetric nanopores. The asymmetric dependence of thermal conductivity on temperature and space is known to be the physical reason. For the other two kinds of thermal rectifiers, the rectification ratios are about 10%. The asymmetric phonon scattering is known to be the physical reason, which has been proved by using large-scale molecular dynamics simulation.

    DOI: 10.1615/ihtc16.nmt.022118

  • Bubbles and droplets at the initial stage of nucleation: Recent advances in experimental techniques

    Koji Takahashi

    International Heat Transfer Conference   2018-August   359 - 367   2018年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 2018 International Heat Transfer Conference. All rights reserved. Recent microfabrication techniques have exhibited tremendous opportunities to improve the phase-change heat transfer by tailoring the surface structure and wettability, which indicates that microscopic understanding of liquid-gas phase change is vital for further improvement of heat transfer devices. Boiling and condensation have been studied by numerous researchers for more than a half century and are known to be a successive process of nucleation, growth and departure of bubbles and droplets. Fluid dynamical modeling has been extensively developed for their growth and departure but the nucleation is still incompletely understood because of the lack of imaging techniques of two-phase phenomena smaller than the resolution limit of optical microscopy. This paper introduces new trends to investigate nanoscale bubbles and droplets experimentally, using AFM, SEM and TEM. AFM is of the highest spatial resolution and its feedback control of tip tapping enables us to obtain the accurate shape of nanobubbles at the solid-liquid interface. A new mode of AFM gives force data of approaching and retracting tips, which unveils the strong interaction between nanobubble and AFM tip. Environmental SEM is a useful tool for observing water condensation with droplets of micrometer-order diameter but there are several concerns including the contamination due to the electron beam irradiation. TEM requires ultra-high vacuum environment but utilization of nano liquid cell enables us to image the liquid-gas interface in nanoscale. By using these techniques, some key issues for generation and stability of interfacial nanobubbles and condensed nanodroplets have been understood, which should result in novel techniques to control the initial stage of phase change heat transfer.

    DOI: 10.1615/ihtc16.kn.000017

  • Effects of hydrogenation on thermal conductivity of ultrananocrystalline diamond/amorphous carbon composite films prepared via coaxial arc plasma deposition

    Satoshi Takeichi, Takashi Nishiyama, Mitsuru Tabara, Shuichi Kawawaki, Masamichi Kohno, Koji Takahashi, Tsuyoshi Yoshitake

    Applied Physics Express   11 ( 6 )   2018年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2018 The Japan Society of Applied Physics. Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) and UNCD/non-hydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were prepared via coaxial arc plasma deposition, and their thermal conductivity and interfacial conductance in grain boundaries were measured using a time-domain thermoreflectance method. The interfacial conductance was estimated to be 1,010 and 4,892MW/(m2&K) for UNCD/a-C:H and UNCD/a-C films, respectively. The reasons for the hydrogenated film having lower interfacial conductance than the non-hydrogenated film are 1) the reduced number of carriers that contribute to heat transport and 2) the hydrogen atoms, which are preferentially located at the grain boundaries and enhance phonon scattering.

    DOI: 10.7567/APEX.11.065101

  • Heat transfer enhancement of a loop thermosyphon with a hydrophobic spot-coated surface

    Hongbin He, Biao Shen, Liangyu Chen, Sumitomo Hidaka, Koji Takahashi, Masamichi Kohno, Yasuyuki Takata

    Journal of Thermal Science and Technology   13 ( 1 )   2018年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2018 The Japan Society of Mechanical Engineers. Heat transfer characteristic of a closed two-phase thermosyphon with enhanced boiling surface is studied and compared with that of a copper mirror surface. Two-phase cooling is widely used in application of thermal engineering and considerably more efficient than single-phase liquid cooling. The evaporator surfaces, coated with a pattern of hydrophobic circular spots (0.5 - 2 mm in diameter and 1.5 - 3 mm in pitch) on Cu substrates, achieve very high heat transfer coefficient and low incipience temperature overshoot with water as working fluid. Sub-atmospheric boiling on the hydrophobic spot-coated surface shows a much better heat transfer performance. Tests under heat loads 30 W to 260 W reveal the coated surfaces enhance nucleate boiling performance by increasing the bubbles nucleation-site density. The surface with hydrophobic spots with diameter 1 mm and pitch 1.5 mm achieves the maximal heat transfer enhancement with the minimum boiling thermal resistance as low as 0.03 K/W. A comparison of three evaporator surfaces with identical wettability patterns but with different surface topographies and coating thicknesses is carried out experimentally. The results show superior heat transfer rates and wear resistance on the surface coated with HNTs spots thanks to the large contact angle, great thickness, and durability of the coating layer.

    DOI: 10.1299/jtst.2018jtst0011

  • Superstable Ultrathin Water Film Confined in a Hydrophilized Carbon Nanotube 査読

    Yoko Tomo, Alexandros Askounis, Tatsuya Ikuta, Yasuyuki Takata, Khellil Sefiane, Koji Takahashi

    Nano Letters   18 ( 3 )   1869 - 1874   2018年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2018 American Chemical Society. Fluids confined in a nanoscale space behave differently than in the bulk due to strong interactions between fluid molecules and solid atoms. Here, we observed water confined inside "open" hydrophilized carbon nanotubes (CNT), with diameter of tens of nanometers, using transmission electron microscopy (TEM). A 1-7 nm water film adhering to most of the inner wall surface was observed and remained stable in the high vacuum (order of 10-5 Pa) of the TEM. The superstability of this film was attributed to a combination of curvature, nanoroughness, and confinement resulting in a lower vapor pressure for water and hence inhibiting its vaporization. Occasional, suspended ultrathin water film with thickness of 3-20 nm were found and remained stable inside the CNT. This film thickness is 1 order of magnitude smaller than the critical film thickness (about 40 nm) reported by the Derjaguin-Landau-Verwey-Overbeek theory and previous experimental investigations. The stability of the suspended ultrathin water film is attributed to the additional molecular interactions due to the extended water meniscus, which balances the rest of the disjoining pressures.

    DOI: 10.1021/acs.nanolett.7b05169

  • Wettability of AFM tip influences the profile of interfacial nanobubbles 査読

    Hideaki Teshima, Koji Takahashi, Yasuyuki Takata, Takashi Nishiyama

    Journal of Applied Physics   123 ( 5 )   054303   2018年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2018 Author(s). To accurately characterize the shape of interfacial nanobubbles using atomic force microscopy (AFM), we investigated the effect of wettability of the AFM tip while operating in the peak force tapping (PFT) mode. The AFM tips were made hydrophobic and hydrophilic by Teflon AF coating and oxygen plasma treatment, respectively. It was found that the measured base radius of nanobubbles differed between AFM height images and adhesion images, and that this difference depended on the tip wettability. The force curves obtained during the measurements were also different depending on the wettability, especially in the range of the tip/nanobubble interaction and in the magnitude of the maximum attractive force in the retraction period. The difference suggests that hydrophobic tips penetrate the gas/liquid interface of the nanobubbles, with the three phase contact line being pinned on the tip surface; hydrophilic tips on the other hand do not penetrate the interface. We then quantitatively estimated the pinning position and recalculated the true profiles of the nanobubbles by comparing the height images and adhesion images. As the AFM tip was made more hydrophilic, the penetration depth decreased and eventually approached zero. This result suggests that the PFT measurement using a hydrophilic tip is vital for the acquisition of reliable nanobubble profiles.

    DOI: 10.1063/1.5010131

  • Bubbles and droplets at the initial stage of nucleation Recent advances in experimental techniques 査読

    Koji Takahashi

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   359 - 367   2018年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Recent microfabrication techniques have exhibited tremendous opportunities to improve the phase-change heat transfer by tailoring the surface structure and wettability, which indicates that microscopic understanding of liquid-gas phase change is vital for further improvement of heat transfer devices. Boiling and condensation have been studied by numerous researchers for more than a half century and are known to be a successive process of nucleation, growth and departure of bubbles and droplets. Fluid dynamical modeling has been extensively developed for their growth and departure but the nucleation is still incompletely understood because of the lack of imaging techniques of two-phase phenomena smaller than the resolution limit of optical microscopy. This paper introduces new trends to investigate nanoscale bubbles and droplets experimentally, using AFM, SEM and TEM. AFM is of the highest spatial resolution and its feedback control of tip tapping enables us to obtain the accurate shape of nanobubbles at the solid-liquid interface. A new mode of AFM gives force data of approaching and retracting tips, which unveils the strong interaction between nanobubble and AFM tip. Environmental SEM is a useful tool for observing water condensation with droplets of micrometer-order diameter but there are several concerns including the contamination due to the electron beam irradiation. TEM requires ultra-high vacuum environment but utilization of nano liquid cell enables us to image the liquid-gas interface in nanoscale. By using these techniques, some key issues for generation and stability of interfacial nanobubbles and condensed nanodroplets have been understood, which should result in novel techniques to control the initial stage of phase change heat transfer.

  • Study on liquid-gas interface at nanoscale using transmission electron microscopy 査読

    Yoko Tomo, Alexandros Askounis, Khellil Sefiane, Yasuyuki Takata, Koji Takahashi

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   1169 - 1174   2018年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Control for the bubble nucleation at the onset of nucleate boiling (ONB) ensures the stable start of boiling heat transfer. However, the bubble nucleation mechanism at the ONB remains unclear, because of the difficulty of in-situ observation, which is due to the small size of nucleation. Thus, in order to break through the current technological barrier of boiling heat transfer, a new experimental technique enabling the investigation of the dynamics of bubbles near the solid-liquid interface is highly desirable. Liquid cell electron microscopy is the most useful method for the in-situ observation of liquid samples at the nanoscale. We prepared a closed liquid cell fabricated using MEMS technology and observed the generation and growth of bubbles at the nanoscale and in real time using transmission electron microscopy (TEM). In the growing process, the water meniscus between smaller bubbles becomes thinner and thinner and eventually ruptures. However, when the bubbles grow, the meniscus between larger bubbles do not rupture and the bubble overlaps with others, suggesting that thin meniscus can be stable only in the case of larger bubbles because of the difference of the curvature of their liquid-gas interfaces between smaller bubbles and larger bubbles. Our experimental results lead to the insight of the mechanism of the stability and the phase change phenomena at the liquid-gas interface at the nanoscale.

  • Heater assisted raman method to measure interfacial thermal conductance in van der waals heterostructures 査読

    Qin Yi Li, Koji Takahashi, Xing Zhang

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   7137 - 7143   2018年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Two-dimensional (2D) layered materials have been the focus of materials research for more than a decade. Stacking different 2D nanosheets and 3D substrates with van der Waals interactions in between has opened up new ways to sophisticated design of novel device functionalities and platforms for new physics. The performance of van der Waals heterostructure (vdWH) devices can be most often limited by the heat dissipation issue, but the thermal transport in vdWHs has rarely been studied yet. This paper presents a novel heater assisted Raman method to accurately measure interfacial thermal conductance between every two layers in the vdWH, which is suitable to detect interfacial thermal transport between all kinds of nanosheets no matter whether the neighboring layer is electrical conductor or insulator. In this method, a transparent insulating thin layer and a patterned transparent conducting indium-tin-oxide (ITO) layer are successively sputtered on top of the vdWH. The ITO layer is electrically heated to provide vertical heat flux, while the temperatures of each atomic layer and the substrate surface are simultaneously detected from their temperature dependent Raman band shifts, thus the interfacial thermal conductance between every two layers can be accurately determined from the ITO's Joule heating power and the Raman-measured temperatures. With high sensitivity and accuracy, the measurement method proposed here provides a general way to experimentally investigate interfacial thermal transport across both electrically conducting and insulating van der Waals interfaces in 2D-material-based devices.

    DOI: 10.1615/ihtc16.nmt.021756

  • A loop thermosyphon with hydrophobic spots evaporator surface

    Hongbin He, Biao Shen, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata

    ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2018 ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2018   2018年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Heat transfer characteristic of a closed two-phase thermosyphon with enhanced boiling surface is studied and compared with that of a copper mirror surface. Two-phase cooling improves heat transfer coefficient (HTC) a lot compared to single-phase liquid cooling. The evaporator surfaces, coated with a pattern of hydrophobic circle spots (non-electroplating Ni-PTFE, 0.5~2 mm in diameter and 1.5-3 mm in pitch) on Cu substrates, achieve very high heat transfer coefficient and lower the incipience temperature overshoot using water as the working fluid. Sub-atmospheric boiling on the hydrophobic spot-coated surface shows a much better heat transfer performance. Tests with heat loads (30 W to 260 W) reveals the coated surfaces enhance nucleate boiling performance by increasing the bubbles nucleation sites density. Hydrophobic circle spots coated surface with diameter 1 mm, pitch 1.5 mm achieves the maximal heat transfer enhancement with the minimum boiling thermal resistance as low as 0.03 K/W. The comparison of three evaporator surfaces with same spot parameters but different coating materials is carried out experimentally. Ni-PTFE coated surface with immersion method performs the optimal performance of the thermosyphon.

  • Variable-spot-size laser-flash Raman method to measure in-plane and interfacial thermal properties of 2D van der Waals heterostructures 査読

    Qinyi Li, Xing Zhang, Koji Takahashi

    International Journal of Heat and Mass Transfer   125   1230 - 1239   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Stacked layers of different atomically thin 2D materials is called the van der Waals (vdW) heterostructure, which has become a rapidly developing research field due to its extraordinary and tunable properties. In this paper, we develop a variable-spot-size laser-flash Raman method to in-situ measure the thermal properties as well as the laser absorption in the supported 2D vdW heterostructure with arbitrary layers. The extracted thermal properties include the in-plane thermal conductivity and diffusivity of each layer, and interfacial thermal conductance between every two adjacent layers. A three-dimensional transient heat conduction model is developed and analytically solved to describe the process of pulsed Gaussian laser heating supported n-layer heterostructure. The temperature of each atomic layer can be simultaneously non-contact detected from their distinct Raman peaks whose positions are temperature dependent. The laser spot sizes and pulse durations are varied to generate multiple temperature curves. The multiple thermal properties as well as the laser absorption can be extracted by simultaneously fitting these temperature curves into the analytical solutions at multiple spot sizes or/and pulse durations. We also establish the approach of sensitivity and uncertainty analysis for the multi-response multi-parameter least-square fitting in our proposed measurement methods. Case studies show that the transient temperature curves are generally more sensitive to the thermal properties than the steady-state temperatures at variable spot sizes. All the unknown thermal properties and laser absorption can be extracted with sufficiently high accuracy if multiple transient temperature curves at multiple spot sizes are simultaneously fitted into the analytical solution. The measurement method and uncertainty analysis approach presented here are useful for investigating the thermal transport in the emerging 2D materials and vdW heterostructures.

    DOI: 10.1016/j.ijheatmasstransfer.2018.05.011

  • Influence of surface wettability and nanostructure on the generation of interfacial nanobubbles 査読

    Hideaki Teshima, Takashi Nishiyama, Yasuyuki Takata, Koji Takahashi

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   6909 - 6914   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Interfacial nanobubbles were first speculated in 1994 and experimentally confirmed in 2000 by atomic force microscopy (AFM) measurements. It was recently proposed that the onset of boiling with the very low superheat on hydrophobic surface could be explained by assuming the existence of interfacial nanobubbles. To reduce the superheat and enhance the reliability of boiling heat transfer, the control of the generation of interfacial nanobubbles is indispensable. In this study, we measured the interfacial nanobubbles by AFM and examined the influence of surface wettability and nanostructure on their generation. First, we measured the spherical-cap shaped nanobubbles generated on the HOPG surface. It was observed that the nanobubbles only generate on the hydrophobic terraced area and do not cross the nanosized hydrophilic steps. Next, we prepared the hydrophilic-hydrophobic hybrid surfaces and generated the nanobubbles on those. As a result, the range of nanobubble generation clearly changed by the difference of wettability between adjacent surfaces. These results show that the generation of interfacial nanobubbles can be controlled by the surface processing of the substrate and can be expected to be applied to boiling heat transfer.

    DOI: 10.1615/ihtc16.nmt.022210

  • Enhanced boiling heat transfer on surfaces patterned with mixed wettability 査読

    Biao Shen, Masayuki Yamada, Tomosuke Mine, Sumitomo Hidaka, Junichiro Shiomi, Gustav Amberg, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   1379 - 1386   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Amongst an extensive collection of surface characteristics that could affect boiling performance, surface wettability (as measured by the contact angle with water) proves to play a unique role in potentially manipulating bubble behavior to the advantage of higher heat transfer rates. In this study, we show experimentally that controlled bubble behavior be realized under the surface design incorporating these two characteristics (namely, by coating an array of hydrophobic spots on a hydrophilic substrate), which leads to a great enhancement in boiling heat transfer under various conditions. In reduced-pressure pool boiling, the strong pinning of the bubble contact line at the border between the hydrophilic and hydrophobic regions manages to prevent total deactivation of nucleation sites. As a result, the deleterious transition to intermittent boiling is effectively delayed, whereby no heat transfer deterioration occurs until a very low pressure of about 8 kPa is reached. Moreover, in subcooled boiling, bubble growth on a patterned surface is found to be facilitated by a pronounced presence of dissolved gas in defiance of exhaustive degassing efforts through continuous boiling, thanks to an unusually strong retention of gas contents by the hydrophobic surface. As experimental and numerical evidence show, only bubbles with sufficiently high concentrations of gas components (i.e., causing weakened condensation) are able to grow large enough on the hydrophobic surface such that periodic pinch-offs might take place, which is responsible for most of the initial heat transfer enhancement before large-scale bubble nucleation starts on the hydrophilic surface as well.

    DOI: 10.1615/ihtc16.bae.023482

  • Effective thermal rectification in suspended monolayer graphene 査読

    Haidong Wang, Xing Zhang, Hiroshi Takamatsu, Koji Takahashi

    16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference   2018-August   6903 - 6908   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Thermal rectification is a phenomenon that the heat flow changes by reversing the direction of temperature gradient. This is a fundamental behavior of the thermal rectifiers, which can be used for the active heat flow control, thermally driven computer, efficient energy harvesting, etc. The key challenge is how to increase the thermal rectification ratio, which is defined as the relative change of thermal conductivities in different heat flow directions. Due to the significant size effect and unique heat transfer mechanisms, nanomaterials (such as carbon nanotubes, nanowires, graphene, etc.) are suggested to have high thermal rectification ratio. However, the experiment result showed that the ratio of the single carbon nanotube thermal rectifier was only 7%. In the past decade, many theoretical researches and molecular dynamics simulations have shown that the monolayer graphene may have high thermal rectification ratio due to its unique two-dimensional heat transfer mechanism. But the experimental work is still a blank because of the difficult fabrication process of suspended graphene electronic device. In this work, we report the experimental demonstration of a suspended monolayer graphene thermal rectifier. Three different types of graphene thermal rectifiers have been fabricated with different asymmetric nanostructures. The focused ion beam manufacturing, electron beam induced deposition and precise electron beam lithography were used to design and create asymmetric nanostructures on the monolayer graphene. The thermal rectification ratios were measured by using a precise H-type sensor method. The highest rectification ratio reaches 28% for the graphene with asymmetric nanopores. The asymmetric dependence of thermal conductivity on temperature and space is known to be the physical reason. For the other two kinds of thermal rectifiers, the rectification ratios are about 10%. The asymmetric phonon scattering is known to be the physical reason, which has been proved by using large-scale molecular dynamics simulation.

    DOI: 10.1615/ihtc16.nmt.022118

  • Early Onset of Nucleate Boiling on Gas-covered Biphilic Surfaces 査読

    Biao Shen, Masayuki Yamada, Sumitomo Hidaka, Jiewei Liu, Junichiro Shiomi, Gustav Amberg, Minh Do-Quang, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Scientific Reports   7 ( 1 )   2017年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s41598-017-02163-8

  • Early Onset of Nucleate Boiling on Gas-covered Biphilic Surfaces 査読

    Biao Shen, Masayuki Yamada, Sumitomo Hidaka, Jiewei Liu, Junichiro Shiomi, Gustav Amberg, Minh Do-Quang, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Scientific Reports   7 ( 1 )   2036   2017年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 The Author(s). For phase-change cooling schemes for electronics, quick activation of nucleate boiling helps safeguard the electronics components from thermal shocks associated with undesired surface superheating at boiling incipience, which is of great importance to the long-term system stability and reliability. Previous experimental studies show that bubble nucleation can occur surprisingly early on mixed-wettability surfaces. In this paper, we report unambiguous evidence that such unusual bubble generation at extremely low temperatures-even below the boiling point-is induced by a significant presence of incondensable gas retained by the hydrophobic surface, which exhibits exceptional stability even surviving extensive boiling deaeration. By means of high-speed imaging, it is revealed that the consequently gassy boiling leads to unique bubble behaviour that stands in sharp contrast with that of pure vapour bubbles. Such findings agree qualitatively well with numerical simulations based on a diffuse-interface method. Moreover, the simulations further demonstrate strong thermocapillary flows accompanying growing bubbles with considerable gas contents, which is associated with heat transfer enhancement on the biphilic surface in the low-superheat region.

    DOI: 10.1038/s41598-017-02163-8

  • Enhancement of boiling heat transfer under sub-atmospheric pressures using biphilic surfaces

    M. Yamada, B. Shen, T. Imamura, S. Hidaka, M. Kohno, K. Takahashi, Y. Takata

    International Journal of Heat and Mass Transfer   115   753 - 762   2017年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2017 Elsevier Ltd Surface wettability of a heating surface is one of the most important factors affecting boiling performance. While a biphilic surface (with juxtaposed hydrophilic and hydrophobic regions) is known as a promising technique to enhance water pool boiling at the atmospheric pressure, there is no research regarding its potential for sub-atmospheric applications. In the present study, we have investigated the characteristics of pool nucleate boiling on biphilic surfaces at sub-atmospheric pressures. Biphilic surfaces were made by applying Ni-TFEO (tetrafluoroethylene oligomer) electroplating (with a contact angle of about 140°) on a copper surface. The heat transfer performance of various biphilic surfaces (with different hydrophobic spot diameters and pitches) were measured in the pressure range from atmospheric to 6.9 kPa. At a pressure of 14.0 kPa, the wall superheat at the onset of nucleate boiling was reduced by 12 K on a biphilic surface compared with a mirror-finished copper surface. The experiment with three different biphilic patterns revealed that smaller pitch and diameter of the hydrophobic spots were favorable to heat transfer at 14.0 kPa. The enhancement of HTC over Kutateladze's correlation reached 270%. A sharp transition from continuous to intermittent boiling, resulting in large deterioration of HTC, was observed on a biphilic surface at a much lower pressure than that on a copper surface. Boiling performance was less affected by the pressure level above the transition pressure.

    DOI: 10.1016/j.ijheatmasstransfer.2017.08.078

  • Simultaneous dropwise and filmwise condensation on hydrophilic microstructured surfaces

    Daniel Orejon, Orest Shardt, Naga Siva Kumar Gunda, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, Sushanta K. Mitra

    International Journal of Heat and Mass Transfer   114   187 - 197   2017年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2017 Elsevier Ltd While wicking or spreading of a liquid through microstructures has been found to be promising for applications such as textiles, microelectronics or heat sinks, the effects of such structured surfaces on condensation phase change has received less attention. On a hydrophilic surface and for a fixed micropillar aspect ratio (height/diameter), the spacing between pillars is found to have a strong impact on the dynamics of condensation and on the final morphology of the condensate. In the case of micropillars with a large spacing between pillars, the condensate grows initially dropwise, and thereafter, as condensation develops, the condensate overcomes the pillars’ height flooding the substrate, and condensation continuous in a filmwise condensation (FWC) fashion. In contrast, filmwise condensation and the continuous nucleation, growth, and departure of drops at the pillars’ tops in a dropwise condensation (DWC) fashion occurs when the spacing between pillars is decreased. In this configuration, the geometry of the microstructures constrains the condensate between the pillars and rise of the condensate interface above the micropillars’ height is not thermodynamically favorable, while the top of the pillars act as nucleation sites. We refer to this latter condensation behavior as simultaneous dropwise/filmwise condensation. These observations were enabled by the excellent spatial and temporal resolution of Environmental Scanning Electron Microscopy. A heat transfer model is proposed to demonstrate the greater heat transfer performance of the simultaneous dropwise/filmwise condensation behavior on these surfaces when compared to solely filmwise condensation. The enhanced heat transfer is realizable due to the ability to maintain a thin film within the microstructures and to the active dropwise condensation at the micropillars’ tops. We report for the first time the occurrence of dropwise condensation on a completely hydrophilic wettability configuration without the assistance of a hydrophobic coating. Our findings pave the way to the development of microstructures for enhanced condensation heat transfer.

    DOI: 10.1016/j.ijheatmasstransfer.2017.06.023

  • Comment on "divergent and Ultrahigh Thermal Conductivity in Millimeter-Long Nanotubes" 査読

    Qin Yi Li, Koji Takahashi, Xing Zhang

    Physical Review Letters   119 ( 17 )   2017年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1103/PhysRevLett.119.179601

  • Experimental study on thermal conductivity of free-standing fluorinated single-layer graphene 査読

    Masahiro Narasaki, Haidong Wang, Takashi Nishiyama, Tatsuya Ikuta, Koji Takahashi

    Applied Physics Letters   111 ( 9 )   093103   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 Author(s). We measured the thermal conductivity of free-standing fluorinated single-layer graphene (FSLG) using a precise T-type method. Pristine graphene was fluorinated and suspended above the substrate using xenon difluoride gas. Compared with the thermal conductivity of pristine single-layer graphene (SLG) (∼2000 W/mK) previously measured by the same T-type method for the same original SLG, the FSLG exhibited a much lower thermal conductivity (∼80 W/mK) and a weak dependence of the thermal conductivity on nanohole defects. The experimental results suggest that the fluorine atoms and sp3 bonding in the FSLG strongly contributed to phonon scattering. The phonon scattering by the fluorine atoms and sp3 bonding has a dominant effect on the thermal conductivity decrease over the phonon scattering by nanohole defects. This study lays a foundation for the thermal measurement of 2D fluorinated materials and benefits future applications of fluorinated graphene.

    DOI: 10.1063/1.5001169

  • Efficiency enhancement of a loop thermosyphon on a mixed-wettability evaporator surface

    Hongbin He, Kento Furusato, Masayuki Yamada, Biao Shen, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Applied Thermal Engineering   123   1245 - 1254   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 Elsevier Ltd This study presents an experimental investigation of the heat transfer performance of a two-phase loop thermosyphon with an enhanced mixed-wettability evaporator surface at sub-atmospheric pressures. For central-processing-unit (CPU) cooling applications, a lowering of the saturation temperature (pressure) is essential when water is used as the working fluid. Compared with copper mirror surfaces, up to over 100% enhancement of high heat transfer coefficient (HTC) was observed using surfaces with spotted wettability patterns, which consists of hydrophobic spots with contact angle ranged from 145° to 150°. The results revealed that the boiling behaviors changed drastically with the application of hydrophobic spots coating by artificially increasing the nucleation site density. Parametric tests with a variety of operating conditions, including different filling ratios, condenser temperatures, and heat loads revealed the minimum thermal resistance (i.e., the optimum thermosyphon performance) to be 0.03 K/W on the boiling side.

    DOI: 10.1016/j.applthermaleng.2017.05.145

  • Measurement of specific heat and thermal conductivity of supported and suspended graphene by a comprehensive Raman optothermal method 査読

    Qin Yi Li, Kailun Xia, Ji Zhang, Yingying Zhang, Qunyang Li, Koji Takahashi, Xing Zhang

    Nanoscale   9 ( 30 )   10784 - 10793   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 The Royal Society of Chemistry. The last decade has seen the rapid growth of research on two-dimensional (2D) materials, represented by graphene, but research on their thermophysical properties is still far from sufficient owing to the experimental challenges. Herein, we report the first measurement of the specific heat of multilayer and monolayer graphene in both supported and suspended geometries. Their thermal conductivities were also simultaneously measured using a comprehensive Raman optothermal method without needing to know the laser absorption. Both continuous-wave (CW) and pulsed lasers were used to heat the samples, based on consideration of the variable laser spot radius and pulse duration as well as the heat conduction within the substrate. The error from the laser absorption was eliminated by comparing the Raman-measured temperature rises for different spot radii and pulse durations. The thermal conductivity and specific heat were extracted by analytically fitting the temperature rise ratios as a function of spot size and pulse duration, respectively. The measured specific heat was about 700 J (kg K)-1 at room temperature, which is in accordance with theoretical predictions, and the measured thermal conductivities were in the range of 0.84-1.5 × 103 W (m K)-1. The measurement method demonstrated here can be used to investigate in situ and comprehensively the thermophysical properties of many other emerging 2D materials.

    DOI: 10.1039/c7nr01695f

  • Experimental study of thermal rectification in suspended monolayer graphene 査読

    Haidong Wang, Shiqian Hu, Koji Takahashi, Xing Zhang, Hiroshi Takamatsu, Jie Chen

    Nature Communications   8   15843   2017年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 The Author(s). Thermal rectification is a fundamental phenomenon for active heat flow control. Significant thermal rectification is expected to exist in the asymmetric nanostructures, such as nanowires and thin films. As a one-atom-thick membrane, graphene has attracted much attention for realizing thermal rectification as shown by many molecular dynamics simulations. Here, we experimentally demonstrate thermal rectification in various asymmetric monolayer graphene nanostructures. A large thermal rectification factor of 26% is achieved in a defect-engineered monolayer graphene with nanopores on one side. A thermal rectification factor of 10% is achieved in a pristine monolayer graphene with nanoparticles deposited on one side or with a tapered width. The results indicate that the monolayer graphene has great potential to be used for designing high-performance thermal rectifiers for heat flow control and energy harvesting.

    DOI: 10.1038/ncomms15843

  • Nanobubble nucleation studied using Fresnel fringes in liquid cell electron microscopy 査読

    Yoko Tomo, Koji Takahashi, Takashi Nishiyama, Tatsuya Ikuta, Yasuyuki Takata

    International Journal of Heat and Mass Transfer   108   1460 - 1465   2017年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 Elsevier Ltd Liquid cell electron microscopy is a useful technique for the observation of chemical, biological, and mechanical processes in liquids at nanometer-scale resolution. This study investigated the generation and growth of nanobubbles using the Fresnel fringe method, which enabled us to determine the location of bubble interface; the nanobubbles were induced in the 600-nm-thick water sample in the cell, by the electron beam. Nucleation occurred first at the solid–liquid interface in the upstream side of electron beam, and this was followed by second-group nucleation at the downstream-side interface; all of the stable nucleations occurred on the solid surfaces. The size of the nucleated bubbles at the moment they became visible depended on the magnification used in the electron microscope, and a higher-energy density in the electron beam induced larger bubbles. The underlying mechanism was also considered in this study.

    DOI: 10.1016/j.ijheatmasstransfer.2017.01.013

  • Highly sensitive charge mobility of suspended monolayer graphene

    Hiroshi Takamatsu, Haidong Wang, Koji Takahashi, Zhang Xing

    6th International Symposium on Micro and Nano Technology   2017年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

  • Thermal Conductivity of Liquid/CNT Core-Shell Nanocomposites 査読 国際誌

    Yutaka Yamada, ASKOUNIS ALEXANDROS, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, SEFIANE KHELLIL

    J. Appl. Phys.   121   015104   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.4973488

  • Thermal conductivity of liquid/carbon nanotube core-shell nanocomposites 査読

    Yutaka Yamada, Alexandros Askounis, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, Khellil Sefiane

    Journal of Applied Physics   121 ( 1 )   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 Author(s). Hollow carbon nanotubes (CNTs) were impregnated with an ionic liquid, resulting in a composite core-shell nanostructure. Liquid infusion was verified by transmission electron microscopy and rigorous observations unveiled that the nanocomposite is stable, i.e., liquid did not evaporate owing to its low vapor pressure. A series of individual nanostructures were attached on T-type heat sensors and their thermal behavior was evaluated. The liquid core was found to reduce the thermal conductivity of the base structure, CNT, from ca. 28 W/mK to ca. 15 W/mK. These findings could contribute to a better understanding of nanoscale thermal science and potentially to applications such as nanodevice thermal management and thermoelectric devices.

    DOI: 10.1063/1.4973488

  • Nanoscale pinning effect evaluated from deformed nanobubbles 査読

    Hideaki Teshima, Takashi Nishiyama, Koji Takahashi

    Journal of Chemical Physics   146 ( 1 )   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2017 Author(s). Classical thermodynamics theory predicts that nanosized bubbles should disappear in a few hundred microseconds. The surprisingly long lifetime and stability of nanobubbles are therefore interesting research subjects. It has been proposed that the stability of nanobubbles arises through pinning of the three-phase contact line, which results from intrinsic nanoscale geometrical and chemical heterogeneities of the substrate. However, a definitive explanation of nanobubble stability is still lacking. In this work, we examined the stability mechanism by introducing a "pinning force." We investigated nanobubbles at a highly ordered pyrolytic graphite/pure water interface by peak force quantitative nano-mechanical mapping and estimated the pinning force and determined its maximum value. We then observed the shape of shrinking nanobubbles. Because the diameter of the shrinking nanobubbles was pinned, the height decreased and the contact angle increased. This phenomenon implies that the stability results from the pinning force, which flattens the bubble through the pinned three-phase contact line and prevents the Laplace pressure from increasing. The pinning force can also explain the metastability of coalesced nanobubbles, which have two semispherical parts that are joined to form a dumbbell-like shape. The pinning force of the semispherical parts was stronger than that of the joint region. This result demonstrates that the contact line of the semispherical parts is pinned strongly to keep the dumbbell-like shape. Furthermore, we proposed a nanobubble generation mechanism for the solvent-exchange method and explained why the pinning force of large nanobubbles was not initially at its maximum value, as it was for small nanobubbles.

    DOI: 10.1063/1.4973385

  • Enhancement of boiling heat transfer under sub-atmospheric pressures using biphilic surfaces 査読

    M. Yamada, B. Shen, T. Imamura, S. Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    International Journal of Heat and Mass Transfer   115   753 - 762   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.ijheatmasstransfer.2017.08.078

  • Efficiency enhancement of a loop thermosyphon on a mixed-wettability evaporator surface 査読

    Hongbin He, Kento Furusato, Masayuki Yamada, Biao Shen, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Applied Thermal Engineering   123   1245 - 1254   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.applthermaleng.2017.05.145

  • Bubble activation from a hydrophobic spot at “negative“ surface superheats in subcooled boiling 査読

    Biao Shen, Bambang Joko Suroto, Sana Hirabayashi, Masayuki Yamada, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Applied Thermal Engineering   88   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.applthermaleng.2014.10.054

  • Thermal Conductivity of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition 査読

    Takashi Nishiyama, Masamichi Kohno, Koji Takahashi, Tsuyoshi Yoshitake

    ECS Transactions   75 ( 25 )   27 - 32   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Measurement of specific heat and thermal conductivity of supported and suspended graphene by a comprehensive Raman optothermal method 査読

    Qinyi Li, Koji Takahashi, Zhang Xing

    Nanoscale   9   10784 - 10793   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Influence of ion beam scattering on the electrical resistivity of platinum hot films 査読

    Masahiro Narasaki, Haidong Wang, Yasuyuki Takata, Koji Takahashi

    Microelectronic Engineering   166   15 - 18   2016年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Elsevier B.V. Platinum hot films have been used as precise resistance thermometers to measure the thermal conductivities of carbon nanotubes and graphene. Assisted by focused ion beam (FIB) irradiation, the influence of defects on phonon transport have been examined. However, wide lateral ion beam scattering may affect the electrical properties of hot films and cause uncertainty. In this letter, the effect of FIB irradiation on the electrical resistivity of platinum hot films was evaluated. To investigate this effect qualitatively, electrical resistivity measurement and FIB irradiation were alternated while changing irradiation positions and doses. Irradiated ions were found to travel further than 25 μm away from the directly irradiated area, resulting in an increase of electrical resistivity of the film according to total accumulated dose. The number of scattered ions was found to depend on the irradiated surface. An empirical equation describing the relationship between electrical resistivity and assumed ion density in the hot films was proposed. The obtained results enable us to accurately estimate the thermal or electrical properties of nanomaterials using hot-film sensors combined with nanofabrication techniques using FIB.

    DOI: 10.1016/j.mee.2016.09.008

  • Special Issue of the First Pacific Rim Thermal Engineering Conference (PRTEC2016) Preface

    Kazuhiko Suga, Koji Fukagata, Kaoru Maruta, Akio Miyara, Koji Takahashi

    JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY   11 ( 3 )   2016年12月

     詳細を見る

    記述言語:英語  

    DOI: 10.1299/jtst.2016jtst0034

  • On the linear dependence of a carbon nanofiber thermal conductivity on wall thickness 査読

    Alexandros Askounis, Yutaka Yamada, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, Khellil Sefiane

    AIP Advances   6 ( 11 )   2016年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Author(s). Thermal transport in carbon nanofibers (CNFs) was thoroughly investigated. In particular, individual CNFs were suspended on T-type heat nanosensors and their thermal conductivity was measured over a range of temperatures. Unexpectedly, thermal conductivity was found to be dependent on CNF wall thickness and ranging between ca. 28 and 43 W/(m⋅K). Further investigation of the CNF walls with high resolution electron microscopy allowed us to propose a tentative description of how wall structure affects phonon heat transport inside CNFs. The lower thermal conductivities, compared to other CNTs, was attributed to unique CNF wall structure. Additionally, wall thickness is related to the conducting lattice length of each constituent graphene cone and comparable to the Umklapp length. Hence, as the wall thickness and thus lattice length increases there is a higher probability for phonon scattering to the next layer.

    DOI: 10.1063/1.4968831

  • ナノスケールの気相生成に関する実験的研究

    塘 陽子, 西山 貴史, 生田 竜也, 高田 保之, 高橋 厚史

    熱工学コンファレンス講演論文集   2016 ( 0 )   C122   2016年10月

     詳細を見る

    記述言語:日本語  

    <p>Liquid cell electron microscopy (LCEM) is a useful experimental method of bubble nucleation, which is not understood sufficiently because it is difficult to observe nucleation at nanometer scale in real-time. In our TEM observation, when an electron beam irradiated water, interfacial nanobubbles were generated and grew in a nano liquid cell, whose gap was filled with pure water between two silicon nitride (Si3N4) membranes. In this paper, we introduce Fresnel fringe method, which enable to understand the position of nucleated nanobubbles and the interaction between nanobubbles on the surface of top Si3N4 membrane and the bottom membrane.</p>

    DOI: 10.1299/jsmeted.2016.C122

  • Effect of nanohole defect on the thermal conductivity of free-standing single-layer graphene

    Hiroshi Takamatsu, Haidong Wang, Kosaku Kurata, Takanobu Fukunaga, Koji Takahashi, Zhang Xing

    11th Asian Thermophysical Properties Conference (ATPC 2016)   2016年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

  • Thermal Conductivity of Ultrananocrystalline Diamond/Nonhydrogenated Amorphous Carbon Composite Films Prepared By Coaxial Arc Plasma Deposition

    Satoshi Takeichi, Takashi Nishiyama, Masamichi Kohno, Koji Takahashi, Yuki Katamune, Tsuyoshi Yoshitake

    ECS Meeting Abstracts   MA2016-02 ( 8 )   1060 - 1060   2016年9月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Diamond possesses the highest thermal conductivity (2 × 103 Wm-1K-1) in all bulk materials, owing to low phonon scattering in diamond. Since phonon scattering is drastically enhanced by grain boundaries, the thermal conductivity of polycrystalline diamond films is strongly dependent on the grain size. The thermal conductivity of ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) films comprising a large number of UNCD grains with diameters of less than 10 nm and an a-C:H matrix have been prepared mainly by chemical vapor deposition (CVD). The highest thermal conductivity reported so far is 12 Wm-1K-1, which is comparable with that of sp3-rich non-hydrogenated amorphous carbon (a-C). It has been reported for a-C:H and UNCD/a-C:H films that the thermal conductivity is degraded by the incorporation of H atoms in the films.

    Recently we have realized the formation of UNCD/a-C films comprising UNCD grains and an a-C matrix, by coaxial arc plasma deposition (CAPD). CAPD does not necessarily require a hydrogen atmosphere during the deposition for the formation of diamond grains. So far, the thermal conductivity of hydrogen-free UNCD/a-C films has never been studied because H atoms are unintentionally incorporated into the films from source gases in CVD. In this study, UNCD/a-C films were deposited under a base pressure, and the thermal conductivity of the films were measured for the first time to our knowledge.

    UNCD/a-C films were deposited on n-Si substrates at base pressures of less than 10-4 Pa and the substrate temperature of 550 °C using coaxial arc plasma gun equipped with a graphite target. Mo films with the thickness of 80 nm were deposited on the UNCD/a-C films by sputtering for the TDTR. The thermal conductivity of the UNCD/a-C films was measured by a time-domain thermoreflactance (TDTR) technique.

    The thermal conductivity of the UNCD/a-C films was estimated to be 23.7 Wm-1K-1 by TDTR. The thermal conductivity is evidently higher than that of UNCD/a-C:H prepared by CVD. Two reasons for it are supposed. One is that an a-C in UNCD/a-C is probably advantageous for thermal conduction as compared with an a-C:H in UNCD/a-C:H, since it has been reported for a-C:H that the thermal conductivity decreases with increasing hydrogen content in a-C:H. The other is that UNCD/a-C does not contain hydrogen atoms that prevent from phonon scattering, whereas the preferential existence of hydrogen atoms at grain boundaries between UNCD grains and those between UNCD grains and an a-C:H matrix enhances phonon scattering for UNCD/a-C:H films prepared by CVD, which results in a decrease in the thermal conductivity. Further details will be presented in the conference.

    DOI: 10.1149/ma2016-02/8/1060

  • Temperature-dependent specific heat of suspended platinum nanofilms at 80-380 K 査読

    Qin Yi Li, Masahiro Narasaki, Koji Takahashi, Tatsuya Ikuta, Takashi Nishiyama, Xing Zhang

    Chinese Physics B   25 ( 11 )   2016年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Chinese Physical Society and IOP Publishing Ltd. Metallic nanofilms are important components of nanoscale electronic circuits and nanoscale sensors. The accurate characterization of the thermophysical properties of nanofilms is very important for nanoscience and nanotechnology. Currently, there is very little specific heat data for metallic nanofilms, and the existing measurements indicate distinct differences according to the nanofilm size. The present work reports the specific heats of 40-nm-thick suspended platinum nanofilms at 80-380 K and ∼5×10-4 Pa using the 3ω method. Over 80-380 K, the specific heats of the Pt nanofilms range from 166-304 J/(kg•K), which are 1.65-2.60 times the bulk values, indicating significant size effects. These results are useful for both scientific research in nanoscale thermophysics and evaluating the transient thermal response of nanoscale devices.

    DOI: 10.1088/1674-1056/25/11/114401

  • Integrative characterization of the thermoelectric performance of an individual multiwalled carbon nanotube

    Tingting Miao, Shaoyi Shi, Shen Yan, Weigang Ma, Xing Zhang, Koji Takahashi, Tatsuya Ikuta

    Journal of Applied Physics   120 ( 12 )   2016年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Author(s). Carbon nanotube-based organic composites and carbon nanotube networks are important flexible and lightweight thermoelectric materials. Characterization of the thermoelectric performance of individual carbon nanotubes is of vital importance for exploring the coupling mechanism between carbon nanotubes and organic composites, and proposing further improvement measures. The thermoelectric performance of an individual multiwalled carbon nanotube with a diameter of 66 nm has been comprehensively studied by applying our T-type method from 260 K to 420 K, using the same measurement configuration. The figure of merit increases from 4.84 × 10-8 to 1.32 × 10-6 on increasing the temperature, which is smaller than previous experimental results on carbon nanotube samples. The thermal conductivity increases from 706 W m-1 K-1 at 260 K to 769.3 W m-1 K-1 at 320 K, and then stays nearly constant until 420 K. The phonons dominate the thermal transport. The electrical conductivity exhibits thermally activated carrier generation and transport with an energy barrier of 194.5 meV. The Seebeck coefficient is in the range of 29.4-41.0 μV K-1 and tends to decrease with temperature.

    DOI: 10.1063/1.4962942

  • A general method of fabricating free-standing, monolayer graphene electronic device and its property characterization 査読

    Haidong Wang, Kosaku Kurata, Takanobu Fukunaga, Hiroki Ago, Hiroshi Takamatsu, Xing Zhang, Tatsuya Ikuta, Koji Takahashi, Takashi Nishiyama, Yasuyuki Takata

    Sensors and Actuators, A: Physical   247   24 - 29   2016年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Elsevier B.V. All rights reserved. We demonstrate a general process for fabricating graphene nanoelectronic devices that have next several features: free-standing, micrometer-sized monolayer graphene with high quality, arbitrarily-shaped metallic electrodes or sensors. In contrast to the normal routes, a gas etching process is used to create a deep trench in silicon for suspending the whole graphene device in a much larger area. User-designed electrodes or sensors are fabricated on the suspended graphene at the same time for realizing multiple functions. In this work, a suspended gold nanofilm sensor is designed to measure the intrinsic electrical and thermal properties of graphene on site. The sensor serves as both electrode and precise resistance thermometer at the same time. By simply changing the metallic electrode shape and electrical circuit, the free-standing graphene can be made into different devices, such as single-molecule detector or nano-resonator. In order to test the robustness of graphene device, a high electrical current is applied to heat the graphene in vacuum until it breaks. The breakdown current density is measured to be 1.86 mA/μm. More importantly, this method is not only limited to graphene, but also can be applied to any other two-dimensional materials.

    DOI: 10.1016/j.sna.2016.05.002

  • Experimental Study of Nanobubbles and Nanodroplets on Hydrophilic/Hydrophobic Combined Surfaces 招待 査読 国際誌

    Koji Takahashi, Takashi Nishiyama, 山田 寛, Yasuyuki Takata

    12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT2016), 11 to 13 July 2016, Costa del Sol, Spain   655 - 662   2016年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

  • Wettability on Inner and Outer Surface of Single Carbon Nanotubes 査読

    Yutaka Yamada, Koji Takahashi, Yasuyuki Takata, Khellil Sefiane

    Langmuir   32 ( 28 )   7064 - 7069   2016年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 American Chemical Society. The surface wettability of a liquid on the inner and outer surface of single carbon nanotubes (CNTs) was experimentally investigated. Although these contact angles on both surfaces were previously studied separately, the available data are of limited help to elucidate the effect of curvature orientation (concave or convex) on wettability due to the difference in surface structure. Here, we report on the three-phase contact region and wettability on the outer surface of CNT during the dipping and withdrawing experiment of CNT into an ionic liquid. Furthermore, the wettability on the inner surface was measured using a liquid within the same CNT. Our results show that the contact angle on the outer surface of the CNT is larger than that on the flat surface and that on the inner surface is smaller than that on the flat one. These findings suggest that the surface curvature orientation has a noticeable effect on the contact angle at the nanoscale because both inner and outer surfaces expose the same graphite wall structure and the contact line tension will be negligible in this situation. The presented results are rationalized using the free energy balance of liquid on curved surfaces.

    DOI: 10.1021/acs.langmuir.6b01366

  • Simultaneous measurement of electrical and thermal conductivities of suspended monolayer graphene 査読

    Haidong Wang, Kosaku Kurata, Takanobu Fukunaga, Hiroki Ago, Hiroshi Takamatsu, Xing Zhang, Tatsuya Ikuta, Koji Takahashi, Takashi Nishiyama, Yasuyuki Takata

    Journal of Applied Physics   119 ( 24 )   244306   2016年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 Author(s). We measured both in-plane electrical and thermal properties of the same suspended monolayer graphene using a novel T-type sensor method. At room temperature, the values are about 240 000 Ω-1 m-1 and 2100 W m-1 K-1 for the electrical and thermal conductivities, respectively. Based on the Wiedemann-Franz law, the electrons have negligible contribution to the thermal conductivity of graphene, while the in-plane LA and TA modes phonons are the dominant heat carriers. In monolayer graphene, the absence of layer-layer and layer-substrate interactions enhances the contribution of long wave-length phonons to the heat transport and increases the thermal conductivity accordingly. The reported method and experimental data of suspended monolayer graphene are useful for understanding the basic physics and designing the future graphene electronic devices.

    DOI: 10.1063/1.4954677

  • Hydrophilic Domains Enhance Nanobubble Stability 査読

    Takashi Nishiyama, Koji Takahashi, Tatsuya Ikuta, Yutaka Yamada, Yasuyuki Takata

    ChemPhysChem   17 ( 10 )   1500 - 1504   2016年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Highly stable nanoscale gas states at solid/liquid interfaces, referred to as nanobubbles, have been widely studied for over a decade. In this study, nanobubbles generated on a hydrophobic Teflon amorphous fluoroplastic thin film in the presence and absence of hydrophilic carbon domains are investigated by peak force quantitative nanomechanics. On the hydrophobic surface without hydrophilic domains, a small number of nanobubbles are generated and then rapidly decrease in size. On the hydrophobic surface with hydrophilic domains, the hydrophilic domains have a significant effect on the generation and stability of nanobubbles, with bubbles remaining on the surface for up to three days. Bigger, better bubbles: The enhancement of nanobubble generation and stability by the existence of hydrophilic domains on a surface is shown (see picture). Close to the Ti/Si boundary, many nanobubbles are generated on the relatively hydrophobic Si surface. The hydrophilic-hydrophobic combination is one of the key factors for nanobubble generation and stabilization.

    DOI: 10.1002/cphc.201501181

  • A simple method for fabricating free-standing large area fluorinated single-layer graphene with size-tunable nanopores 査読

    Haidong Wang, Kosaku Kurata, Takanobu Fukunaga, Hiroshi Takamatsu, Xing Zhang, Tatsuya Ikuta, Koji Takahashi, Takashi Nishiyama, Hiroki Ago, Yasuyuki Takata

    Carbon   99   564 - 570   2016年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2015 Elsevier Ltd. All rights reserved. As a solid-state membrane with only one-atom thickness, nano-porous graphene has attracted intense attention in many critical applications. Here, the key challenge is to suspend a single-layer graphene (SLG) and drill nanopores with precise dimensions. Here, we report a simple and reliable route for making suspended fluorinated SLG with size-tunable nanopores. Our method consists of two steps: 1. a free-standing SLG ribbon was created between two gold pads after deep dry etching of silicon substrate by xenon difluoride. The SLG was fluorinated by 5-13%. Superior to the normal wet etching method, the dry etching process is much simpler and results in less hole-defect and edge deformation. A large area fluorinated SLG can be suspended due to the sufficient etch depth. 2. a focused ion beam was introduced to drill nanopores in graphene with an initial diameter around 20 nm. Followed by an electron beam induced carbon deposition, the diameter of nanopore was gradually decreased to sub-10 nm. By changing the deposition time, the size of nanopore can be precisely controlled. High-cost transmission electron microscope is no longer needed. Our method provides a simple and effective way for preparing free-standing fluorinated SLG ribbon suitable for single-molecule detection.

    DOI: 10.1016/j.carbon.2015.12.070

  • In-situ measurement of the heat transport in defect-engineered free-standing single-layer graphene 査読

    Haidong Wang, Kosaku Kurata, Takanobu Fukunaga, Hiroshi Takamatsu, Xing Zhang, Tatsuya Ikuta, Koji Takahashi, Takashi Nishiyama, Hiroki Ago, Yasuyuki Takata

    Scientific Reports   6   21823   2016年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Utilizing nanomachining technologies, it is possible to manipulate the heat transport in graphene by introducing different defects. However, due to the difficulty in suspending large-area single-layer graphene (SLG) and limited temperature sensitivity of the present probing methods, the correlation between the defects and thermal conductivity of SLG is still unclear. In this work, we developed a new method for fabricating micro-sized suspended SLG. Subsequently, a focused ion beam (FIB) was used to create nanohole defects in SLG and tune the heat transport. The thermal conductivity of the same SLG before and after FIB radiation was measured using a novel T-type sensor method on site in a dual-beam system. The nanohole defects decreased the thermal conductivity by about 42%. It was found that the smaller width and edge scrolling also had significant restriction on the thermal conductivity of SLG. Based on the calculation results through a lattice dynamics theory, the increase of edge roughness and stronger scattering on long-wavelength acoustic phonons are the main reasons for the reduction in thermal conductivity. This work provides reliable data for understanding the heat transport in a defective SLG membrane, which could help on the future design of graphene-based electrothermal devices.

    DOI: 10.1038/srep21823

  • A T-type method for characterization of the thermoelectric performance of an individual free-standing single crystal Bi<inf>2</inf>S<inf>3</inf> nanowire

    Weigang Ma, Tingting Miao, Xing Zhang, Koji Takahashi, Tatsuya Ikuta, Boping Zhang, Zhenhua Ge

    Nanoscale   8 ( 5 )   2704 - 2710   2016年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 The Royal Society of Chemistry. A comprehensive method to evaluate the thermoelectric performance of one-dimensional nanostructures, called the T-type method, has been first developed. The thermoelectric properties, including the Seebeck coefficient, thermal conductivity and electrical conductivity, of an individual free-standing single crystal Bi2S3 nanowire have been first characterized by applying the T-type method. The determined figure of merit is far less than the reported values of nanostructured bulk Bi2S3 samples, and the mechanism is that the Seebeck coefficient is nearly zero in the temperature range of 300-420 K and changes its sign at 320 K.

    DOI: 10.1039/c5nr05946a

  • Temperature mapping on a suspended carbon nanotube using electron thermal microscopy

    Koji Takahashi, Kazuma Nomoto, Tatsuya Ikuta

    IEEE-NANO 2015 - 15th International Conference on Nanotechnology   781 - 784   2016年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    © 2015 IEEE. Nanoscale thermal mapping along an individual multi-walled carbon nanotube suspended between two electrodes/heat-sinks was successfully demonstrated by using the solid/liquid phase transition of indium nanoparticles in a transmission electron microscope. The brightness shift of nanoparticles in the dark-field image was clearly recognized according to the DC heating of the nanotube. It was also found that the indium deposition induces defects in the nanotube, resulting in the decrease of thermal conductivity. The temperature distribution along the nanotube obtained from the dark-field images showed good agreement with the simulated data of a defective nanotube with Joule-heating.

    DOI: 10.1109/NANO.2015.7388726

  • Tuning Surface Wettability at the Submicron-Scale: Effect of Focused Ion Beam Irradiation on a Self-Assembled Monolayer 査読

    Yutaka Yamada, Koji Takahashi, Tatsuya Ikuta, Takashi Nishiyama, Yasuyuki Takata, Wei Ma, Atsushi Takahara

    Journal of Physical Chemistry C   120 ( 1 )   274 - 280   2016年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2015 American Chemical Society. Realizing surface wettability tuning at the submicron-scale resolution is expected to enable the fabrication of micro/nano-structured fluidic devices and is particularly important in nanobiotechnology and high-resolution printing. Herein, we propose an approach to modify the wettability of self-assembled monolayer surfaces using focused ion beam (FIB) irradiation. The contact angle of the irradiated region changed from hydrophobic to hydrophilic by increasing the ion dosage. The chemical composition and associated depth profile of the sample surfaces were analyzed by glow discharge-optical emission spectroscopy. The results indicated that the content of fluorine at the surface decreased after FIB irradiation of the samples. A submicron-scale hydrophobic-hydrophilic hybrid surface was then fabricated by forming hydrophilic dots with diameters of ∼110 nm on a hydrophobic surface by FIB irradiation. The difference in wettability of the hydrophobic and hydrophilic areas on the surface was confirmed by microscale condensation and evaporation experiments. Condensed droplets with diameters of ∼300 nm appeared on the surface according to the fabricated pattern, thus suggesting that condensation preferentially occurred on the hydrophilic dots than on the hydrophobic surface. Furthermore, tiny droplets remained on the hydrophilic dots following evaporation of the larger droplets. The current approach provides a means to control wettability-driven phenomena.

    DOI: 10.1021/acs.jpcc.5b09019

  • 集束イオンビーム照射を受けた 多層カーボンナノチューブの熱伝導 査読

    楢﨑将弘, 生田 竜也, 西山 貴史, 髙橋 厚史

    日本熱物性学会   29 ( 4 )   179 - 184   2015年10月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  • Chapter 11: Nanotube thermometry

    Koji Takahashi

    RSC Nanoscience and Nanotechnology   2016-January ( 38 )   339 - 351   2015年10月

     詳細を見る

    記述言語:その他  

    © The Royal Society of Chemistry 2016. Carbon nanotubes (CNTs) have many advantages when used as nanoscale thermal probes, for example, their thin diameter, robustness, and low thermal resistance. However, there are some difficulties in both fabrication and analytical steps for CNT thermometry. In this chapter, recently developed techniques for the fabrication of CNT thermal probes and the current understanding of the thermal properties of CNTs are addressed. An example of quantitative temperature sensing at a nanoscale point contact using a CNT bonded to a Pt hot film is also explained.

    DOI: 10.1039/9781782622031-00339

  • MEASURING THE THERAL CONTACT RESISTANCE WITHOUT SURFACE ROUGHNESS 査読 国際誌

    Koji Takahashi, Yusuke Kuwada, Tatsuya Ikuta

    Proceedings of the 26th International Symposium on Transport Phenomena, 27 Sep. - 1 Oct. 2015, Leoben, Austria   2015年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

  • Temperature Mapping on a Suspended Carbon Nanotube Using Electron Thermal Microscopy 査読 国際誌

    Koji Takahashi, Kazuma Nomoto, Tatsuya Ikuta

    Proceedings of IEEE NANO 2015, 15th INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY, 27-30 JULY 2015, ROME, ITALY   2015年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

  • In-Situ ESEM and EELS Observation of Water Uptake and Ice Formation in Multilayer Graphene Oxide 査読

    Takeshi Daio, Thomas Bayer, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata, Kazunari Sasaki, Stephen Matthew Lyth

    SCIENTIFIC REPORTS   5   2015年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Graphene oxide (GO) is hydrophilic and swells significantly when in contact with water. Here, we investigate the change in thickness of multilayer graphene oxide membranes due to intercalation of water, via humidity-controlled observation in an environmental scanning electron microscope (ESEM). The thickness increases reproducibly with increasing relative humidity. Electron energy loss spectroscopy (EELS) reveals the existence of water ice under cryogenic conditions, even in high vacuum environment. Additionally, we demonstrate that freezing then thawing water trapped in the multilayer graphene oxide membrane leads to the opening up of micron-scale inter-lamellar voids due to the expansion of ice crystals.

    DOI: 10.1038/srep11807

  • ナノスケールの親水部を有する撥水面での凝縮に関する研究 査読

    山田寛, 草場彰, 生田竜也, 西山貴史, 高橋厚史, 高田保之

    日本機械学会論文集   81 ( 823 )   14-00495:1 - 14-00495:7   2015年3月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    Water condensation on a hydrophobic surface with nanoscale hydrophilic regions was investigated to reveal the condensation mechanism of submicron-scale droplets. This feature was found on the graphite step-terrace structured surface; step surfaces are more wettable relative to terrace surfaces, and it was precisely characterized using an atomic force microscope. Condensation experiments were conducted using an environmental scanning electron microscope and droplets were observed to line up on preferentially along the graphite steps. Observed droplets ranged from 150 to 300 nm in diameter and the droplet interval depends on the width of hydrophobic region. The heterogeneous nucleation theory was extended to consider attracted water molecules on hydrophilic step surface, which enable us to explain the current observed result under unsaturated condition. As a result, proposed theory shows qualitatively that narrower hydrophobic region induces short droplet interval. Our suggestion for design the hybrid hydrophilic-hydrophobic surface would enable the development of surface that will perform high heat transfer at dropwise condensation.

    DOI: 10.1299/transjsme.14-00495

  • Temperature dependent thermal conductivity of a suspended submicron graphene ribbon 査読

    Qin Yi Li, Koji Takahashi, Hiroki Ago, Xing Zhang, Tatsuya Ikuta, Takashi Nishiyama, Kenji Kawahara

    Journal of Applied Physics   117 ( 6 )   065102   2015年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2015 AIP Publishing LLC. Thermophysical characterization of graphene is very important for both fundamental and technological research. While most of the existing thermal conductivity measurements are for graphene sheets with sizes larger than 1 μm, the thermal conductivities for suspended submicron graphene ribbons are still very few, although the thermal conductivity of graphene ribbons at the submicron scale is predicted to be much smaller than large graphene and strongly size dependent for both length and width due to the 2D nature of phonon transport. Here, we report the temperature dependent thermal conductivity of a 169-nm wide and 846-nm long graphene ribbon measured by the electrical self-heating method. The measured thermal conductivities range from (12.7 ± 2.95) W/m/K at 80 K to (932 ± 333) W/m/K at 380 K, being (349 ± 63) W/m/K at 300 K, following a ∼ T2.79 law for the full temperature range of 80 K to 380 K and a ∼ T1.23 law at low temperatures. The comparison of the measured thermal conductance with the ballistic transport limit indicates diffusive transport in this narrow and short ribbon due to phonon-edge as well as phonon-defect scattering. The data were also combined with an empirical model to predict possible width dependence of thermal conductivity for suspended graphene ribbons. These results help understand the 2D phonon transport in suspended submicron graphene ribbons and provide knowledge for controlling thermophysical properties of suspended graphene nanoribbons through size manipulation.

    DOI: 10.1063/1.4907699

  • Temperature mapping on a suspended carbon nanotube using electron thermal microscopy

    Koji Takahashi, Kazuma Nomoto, Tatsuya Ikuta

    15th IEEE International Conference on Nanotechnology, IEEE-NANO 2015 IEEE-NANO 2015 - 15th International Conference on Nanotechnology   781 - 784   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Nanoscale thermal mapping along an individual multi-walled carbon nanotube suspended between two electrodes/heat-sinks was successfully demonstrated by using the solid/liquid phase transition of indium nanoparticles in a transmission electron microscope. The brightness shift of nanoparticles in the dark-field image was clearly recognized according to the DC heating of the nanotube. It was also found that the indium deposition induces defects in the nanotube, resulting in the decrease of thermal conductivity. The temperature distribution along the nanotube obtained from the dark-field images showed good agreement with the simulated data of a defective nanotube with Joule-heating.

    DOI: 10.1109/NANO.2015.7388726

  • Metastable nanobubbles at the solid-liquid interface due to contact angle hysteresis 査読

    Takashi Nishiyama, Yutaka Yamada, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata

    Langmuir   31 ( 3 )   982 - 986   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2014 American Chemical Society. Nanobubbles exist at solid-liquid interfaces between pure water and hydrophobic surfaces with very high stability, lasting in certain cases up to several days. Not only semispherical but also other shapes, such as micropancakes, are known to exist at such interfaces. However, doubt has been raised as to whether or not the nanobubbles are gas-phase entities. In this study, surface nanobubbles at a pure water-highly ordered pyrolytic graphite (HOPG) interface were investigated by peak force quantitative nanomechanics (PF-QNM). Multiple isolated nanobubbles generated by the solvent-exchange method were present on the terraced areas, avoiding the steps of the HOPG surface. Adjacent nanobubbles coalesced and formed metastable nanobubbles. Coalescence was enhanced by the PF-QNM measurement. We determined that nanobubbles can exist for a long time because of nanoscale contact angle hysteresis at the water-HOPG interface. Moreover, the hydrophilic steps of HOPG were avoided during coalescence, providing evidence that the nanobubbles are truly gas phase.

    DOI: 10.1021/la5036322

  • Study of condensation on hydrophobic surface with nanoscale hydrophilic regions 査読

    Yutaka Yamada, Koji Takahashi, Yasuyuki Takata

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   81 ( 823 )   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Water condensation on a hydrophobic surface with nanoscale hydrophilic regions was investigated to reveal the condensation mechanism of submicron-scale droplets. This feature was found on the graphite step-terrace structured surface; step surfaces are more wettable relative to terrace surfaces, and it was precisely characterized using an atomic force microscope. Condensation experiments were conducted using an environmental scanning electron microscope and droplets were observed to line up on preferentially along the graphite steps. Observed droplets ranged from 150 to 300 nm in diameter and the droplet interval depends on the width of hydrophobic region. The heterogeneous nucleation theory was extended to consider attracted water molecules on hydrophilic step surface, which enable us to explain the current observed result under unsaturated condition. As a result, proposed theory shows qualitatively that narrower hydrophobic region induces short droplet interval. Our suggestion for design the hybrid hydrophilic-hydrophobic surface would enable the development of surface that will perform high heat transfer at dropwise condensation.

  • Droplet nucleation on a well-defined hydrophilic-hydrophobic surface of 10 nm order resolution 査読

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    Langmuir   30 ( 48 )   14532 - 14537   2014年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2014 American Chemical Society. Water condensation on a hybrid hydrophilic-hydrophobic surface was investigated to reveal nucleation mechanisms at the microscale. Focused ion beam (FIB) irradiation was used to change the wettability of the hydrophobic surface with 10 nm order spatial resolution. Condensation experiments were conducted using environmental scanning electron microscopy; droplets, with a minimum diameter of 800 nm, lined up on the FIB-irradiated hydrophilic lines. The heterogeneous nucleation theory was extended to consider the water molecules attracted to the hydrophilic area, thereby enabling explanation of the nucleation mechanism under unsaturated conditions. Our results showed that the effective surface coverage of the water molecules on the hydrophilic region was 0.1-1.1 at 0.0 °C and 560 Pa and was dependent on the width of the FIB-irradiated hydrophilic lines and hydrophobic area. The droplet nucleation mechanism unveiled in this work would enable the design of new surfaces with enhanced dropwise condensation heat transfer. (Figure Presented).

    DOI: 10.1021/la503615a

  • Characterization of thermal transport in multiwalled carbon nanotube using FIB irradiation

    Koji Takahashi, Hiroyuki Hayashi

    Thermomechanical Phenomena in Electronic Systems -Proceedings of the Intersociety Conference   1375 - 1378   2014年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    © 2014 IEEE. Thermal conductance of an individual multiwalled carbon nanotube was measured as a function of its length. Focused ion beam was used to shorten a 4.8 micrometer-long nanotube to 2.4, 1.2, 0.6, and 0.3-micrometer-long specimens on a hot-film sensor. As the nanotube is shorten, the conductance decreases more than expected by the diffusive thermal conduction theory. We treated two nanotubes of 64nm and 85nm diameters, both of which showed quasi-ballistic phonon transport. This is the first experiment to quantitatively investigate the contribution of phonons with long free paths in multiwalled carbon nanotube. The principle of thermal measurement, amorphous carbon induced by the ion beam, and considerable errors are also explained.

    DOI: 10.1109/ITHERM.2014.6892439

  • Series study on the thermal transport properties of nanofilm by applying transient thermoreflectance method

    Weigang Ma, Xing Zhang, Keisuke Kubo, Masamichi Kohno, Yasuyuki Takata, Tatsuya Ikuta, Koji Takahashi

    Proceedings of the 15th International Heat Transfer Conference, IHTC 2014   2014年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    With the continued size reduction and operation frequency increase in micro/nanoelectromechanical systems, heat accumulation has become more critical. It is crucial to carry out an in-depth investigation on the thermal transport properties of thin metal films, i.e., electron-phonon relaxation, thermal diffusivity and interfacial thermal resistance. In this paper, series study of the thermal transport properties of thin metal films have been performed by applying transient thermoreflectance method, including femtosecond and picosecond laser thermoreflectance systems. The electron-phonon coupling factor of thin gold films with different thickness have been measured by applying femtosecond laser thermoreflectance system. The results show that the electronphonon relaxation is nearly the same as that of bulk gold and independent of film thickness. The cross-plane thermal diffusivity of 95.3 and 200-nm-thick molybdenum film has been studied by applying the picosecond laser thermoreflectance system. The measurement results show that the cross-plane thermal diffusivity of molybdenum thin film decrease significantly compared to the corresponding bulk value and tends to increase as films become thicker.

    DOI: 10.1615/ihtc15.nmm.009179

  • Wettability-driven water condensation at the micron and submicron scale 査読 国際誌

    Yutaka Yamada, Akira Kusaba, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    Proceedings of the 15th International Heat Transfer Conference, IHTC 2014   827 - 834   2014年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    Water condensation on a graphite surface was investigated at the micron and submicron scale by environmental scanning electron microscopy. The graphite comprised a hydrophobic terrace and hydrophilic step edges, of which the nanoscale structure was precisely measured by atomic force microscopy prior to the condensation experiments. The condensed droplets were preferentially aligned parallel to the step edges with a step height of 1 nm. The droplets featured a diameter of 150-300 nm at intervals greater than 150 nm. Shorter droplet intervals were realized by narrower terraces and higher steps. The current findings extend beyond the nucleation theory, whereby the effect of adsorbed water molecules on hydrophilic step edges was considered. The contact angle (i.e., 10°) of the nucleated droplet at its initial stage (with diameter in the nanoscale) was determined from the extended theory, and was consistent with direct observation of slightly grown droplets. The growth mechanism of the submicrometer-sized droplets was also investigated; under this scale regime, the three-phase contact line does not recede during coalescence.

    DOI: 10.1615/ihtc15.cds.009177

  • Bubble activation from a hydrophobic spot at “negative“ surface superheats in subcooled boiling

    Biao Shen, Bambang Joko Suroto, Sana Hirabayashi, Masayuki Yamada, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    Applied Thermal Engineering   88   2014年6月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    © 2014 Elsevier Ltd. We present experimental results on the controlled bubble generation from a single PTFE (polytetrafluoroethylene) spot-with diameter varying from 2mm to 6mm-deposited on a flat polished copper surface that was submersed in subcooled pure water. The static contact angle of the PTFE coating was measured to be over 120°, which conveniently produced a clear contrast with the copper substrate in terms of wettability that ensured controlled bubble nucleation. By making use of a high-speed camera, statistical details about the bubble formation that include the departure frequency and diameter have been obtained at various surface temperatures. An interesting observation was made of repeated cycles of bubble nucleation and detachment at nominally negative surface superheats (i.e., the wall temperature being below the saturation temperature at the system pressure), which featured particularly long bubble growth time and seemingly no waiting time. The vertical temperature distribution inside the bubble, which was measured by a micro-thermocouple of about 250μm in diameter, suggests a relatively stable bubble composition of water vapor and dissolved air. A heat-pipe analogy was drawn to describe the internal heat transfer mechanism of bubble growth on a mixed wettability surface under subcooled conditions.

    DOI: 10.1016/j.applthermaleng.2014.10.054

  • Study on the cross plane thermal transport of polycrystalline molybdenum nanofilms by applying picosecond laser transient thermoreflectance method

    Tingting Miao, Weigang Ma, Xing Zhang, Keisuke Kubo, Masamichi Kohno, Yasuyuki Takata, Tatsuya Ikuta, Koji Takahashi

    Journal of Nanomaterials   2014   2014年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Thin metal films are widely used as interconnecting wires and coatings in electronic devices and optical components. Reliable thermophysical properties of the films are required from the viewpoint of thermal management. The cross plane thermal transport of four polycrystalline molybdenum nanofilms with different thickness deposited on glass substrates has been studied by applying the picosecond laser transient thermoreflectance technique. The measurement is performed by applying both front pump-front probe and rear pump-front probe configurations with high quality signal. The determined cross plane thermal diffusivity of the Mo films greatly decreases compared to the corresponding bulk value and tends to increase as films become thicker, exhibiting significant size effect. The main mechanism responsible for the thermal diffusivity decrease of the present polycrystalline Mo nanofilms is the grain boundary scattering on the free electrons. Comparing the cross plane thermal diffusivity and inplane electrical conductivity indicates the anisotropy of the transport properties of the Mo films. © 2014 Tingting Miao et al.

    DOI: 10.1155/2014/578758

  • Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube 査読

    Hiroyuki Hayashi, Koji Takahashi, Tatsuya Ikuta, Takashi Nishiyama, Yasuyuki Takata, Xing Zhang

    Applied Physics Letters   104 ( 11 )   2014年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated. © 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4869470

  • Micro-beam sensor for detection of thermal conductivity of gases and liquids

    Hiroshi Takamatsu, Takanobu Fukunaga, Yuki Tanaka, Kosaku Kurata, Koji Takahashi

    Sensors and Actuators, A: Physical   206   10 - 16   2014年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A prototype of "micro-beam" MEMS sensor that is made of a thin metallic film suspended across a trench on a silicon substrate was fabricated for examination of the feasibility of detecting thermal conductivity of gases and liquids. Heating the sensor in a sample demonstrated the potential measurement at a steady state because no natural convection took place during heating. The measured temperature rise of the sensor agreed fairly well with the temperature rise estimated by a numerical analysis of heat conduction to a sample fluid from the sensor with given measured dimensions. The temperature of the sensor was significantly higher in the air than FC-72 as well, indicating the feasibility of detecting thermal conductivity by the proposed method. © 2013 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.sna.2013.11.019

  • Nanobubbles on a very flat hydrophobic surface prepared by self-assembled monolayers 査読

    Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2013   2013年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Boiling is one of the most effective heat transfer methods due to its high heat transfer coefficient. Therefore, boiling heat transfer plays a very important role for various applications in many technological and industrial areas. However, a very complex mechanism of boiling, especially bubble nucleation, is still not sufficiently understood. On the other hand, numerous experiments have revealed the existence of soft domains that called nanobubbles at the solid-liquid interface. In this study, to investigate the influence of the solid-liquid interface nanobubbles on the bubble nucleation, an atomic force microscope (AFM) is used to characterize the morphology of nanobubbles. In order to separate the effect of wettability of a solid surface from that of surface structure, a very flat hydrophobic surface was prepared. 1H,1H,2H,2H-Perfluoro-noctylphosphonic acid (FOPA) formed the interface of hydrophobic self-assembled monolayers (SAMs). As the result of AFM measurement, many nanobubbles about 100 nm in diameter and 30 nm thick are observed at the interface of the FOPA surface and the pure water. In addition, to prove the existence of gaseous phase, the heat conductance measurement by time-domain thermoreflectance method (TDTR) was introduced. TDTR is an ultrafast optical pump probe technique well suited for thermal measurement of thin films. It enables to resolve the thermal conductivity of the thin film and the thermal conductance of the interface. If nanobubbles are the gaseous phase, the big change of interface heat thermal resistance will be seen and the TDTR signal should also change. The effectiveness of a TDTR to confirm the existence of nanobubbles is shown by the model simulation of TDTR. A clear difference is seen in TDTR signal by the existence of only 1 nm gaseous phase. After confirming the existence of nanobubbles by AFM measurement, it can be proved that the nanobubbles are truly gaseous phase of the TDTR measurement. Copyright © 2013 by ASME.

    DOI: 10.1115/MNHMT2013-22077

  • Experimental study on thermal contact resistance of multiwalled carbon nanotubes 査読

    Kazunari Tsuru, Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2013   2013年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Heat transfer at solid-solid interface is very fascinating where no one knows the full mechanism which has a huge impact in many applications in engineering and science. In many kinds of interfaces, we treat a van der Waals contact of perfectly-smooth surfaces by using multiwalled carbon nanotubes (CNTs). Their thermal contact resistance (TCR) is estimated by comparing measured thermal conductivity of CNT specimen and numerical simulation result. The TCR per unit area is estimated as 1.58∼3.33×10-8 m 2K/W at room temperature in vacuum, which is much higher than our previous result in air. It was also found that TCR is inversely proportional with the temperature to the 1.92th power different from the simple phonon model represented by the diffuse mismatch model. Copyright © 2013 by ASME.

    DOI: 10.1115/MNHMT2013-22078

  • A photographic study on the effects of hydrophobic-spot size and subcooling on local film boiling

    Bambang Joko Suroto, Masahiro Tashiro, Sana Hirabayashi, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013   2013年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    The effects of hydrophobic circle spot size and subcooling on local film boiling phenomenon from the copper surface with single PTFE (Polytetrafluoroethylene) hydrophobic circle spot at low heat flux has been investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0 and 10K. The heat transfer surfaces are used polished copper block with single PTFE hydrophobic circle spot of diameters 2, 4 and 6 mm, respectively. A high-speed camera was used to capture bubble dynamics and disclosed the sequence of the process leading to local film boiling. The result shows that local films boiling occurs on the PTFE circle spot at low heat flux and was triggered by the merging of neighboring bubbles. The study also showed that transition time required for change from nucleate boiling regime to local film boiling regime depends on the diameter of the hydrophobic circle spot and the subcooling. A stable local film boiling occurs at the smallest diameter of hydrophobic spot. Subcooling cause the local film boiling occur at negative superheat and oscillation of bubble dome. Copyright © 2013 by ASME.

    DOI: 10.1115/ICNMM2013-73069

  • Experimental study on thermal contact resistance at the end of a carbon nanotube

    J. Hirotani, T. Ikuta, K. Takahashi

    International Journal of Thermophysics   34 ( 12 )   2351 - 2360   2013年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    A carbon nanotube (CNT) has a very high intrinsic thermal conductivity and is expected to be used in a variety of thermal applications. However, the thermal contact resistance (TCR) between a CNT and ambient material still remains unclear. Some analytical and molecular dynamics studies have been reported, but there is no reliable experimental method to quantitatively investigate the interface issues. This article reports on a new technique for measuring the TCR at the end of an individual CNT by using a platinum hot film sensor. Two methods are introduced to obtain the TCR between a multi-walled CNT and a SiO2 surface, and both methods were confirmed to give an identical TCR. © 2011 Springer Science+Business Media, LLC.

    DOI: 10.1007/s10765-011-1137-1

  • Submicron-scale condensation on hydrophobic and hydrophilic surfaces 査読

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)   15   2013年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Condensation heat transfer is a widely-used technique for industrial applications represented by heat exchanger because of its high heat transfer coefficient. To enhance its performance, a suitable surface is required, where both condensation and droplet removal smoothly occur. In this study, we compared wettability of a graphene surface and an amorphous carbon surface. The result shows that an amorphous carbon surface is more hydrophilic. Then we prepared a graphite surface which has nanoscale hydrophilic regions in large hydrophobic area. We observed the submicron-scale droplet condensation occurs preferentially on the hydrophilic graphite step by using environmental scanning electron microscope (ESEM). Copyright © 2013 by ASME.

    DOI: 10.1115/IMECE2013-66186

  • Breakdown of Wiedemann-Franz law in individual suspended polycrystalline gold nanofilms down to 3 K

    Haidong Wang, Jinhui Liu, Xing Zhang, Koji Takahashi

    International Journal of Heat and Mass Transfer   66   585 - 591   2013年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Metallic nanofilms are of great importance in integrated circuit design and electronic devices. Understanding energy dissipation and transport in metallic nanofilms is essential to practical thermal management. The Wiedemann-Franz (WF) law states a precisely fixed ratio by which the electrons transport heat and charge, providing a basic rule to determine the thermal properties. Hitherto no bulk material has been known to violate the WF law. We report compelling evidence for the breakdown of the WF law in polycrystalline gold nanofilms at low temperatures, the Lorenz number increases notably with decreasing temperature. Our results show that the electrons dominate in heat transport at high temperatures, leading to a constant Lorenz number. While below 40 K, inelastic electron scattering at grain boundaries becomes significant and part of the electron energy is transferred to phonons. Correspondingly, the phonon thermal conductivity is increased and the WF law is violated. A detailed kinetic theoretical model has been developed to investigate several phonon scattering mechanisms in depth and matches well with the experimental results. © 2013 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijheatmasstransfer.2013.07.066

  • Optical absorptance measurement of an individual multiwall carbon nanotube using a T type thermal probe method

    Qin Yi Li, Jin Hui Liu, Hai Dong Wang, Xing Zhang, Koji Takahashi

    Review of Scientific Instruments   84 ( 10 )   2013年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Optical absorptance is an important property of carbon nanotubes for practical applications but has rarely been accurately measured. We developed a T type thermal probe method to measure the optical absorptance of an individual multiwall carbon nanotube. In this method, one end of the carbon nanotube (CNT) is attached to the center of a platinum nanofilm in a T shape and the Pt nanofilm acts as a thermometer. A laser beam irradiates at the CNT and the absorbed laser power can be determined by measuring the average temperature rise of the Pt nanofilm based on the temperature dependence of the electric resistance. Experimental results showed that a 100-nm-diameter multiwall CNT could absorb 13.2&#37; of the 514-nm-wavelength laser power with the laser spot diameter being 1 μm. This method is useful for determining the optical absorptance of CNTs and other one-dimensional nanostructures such as Si/Ge nanowires for various optical wavelengths in their photovoltaic, photoelectrolysis and other optical applications. © 2013 AIP Publishing LLC.

    DOI: 10.1063/1.4824494

  • Carbon nanotube thermal probe for quantitative temperature sensing

    Jun Hirotani, Juo Amano, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Sensors and Actuators, A: Physical   199   1 - 8   2013年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Quantitative temperature sensing at the nanoscale point contact is developed using a platinum hot film sensor with a carbon nanotube (CNT) as a thermal probe. High spatial resolution and robustness is achieved because of the small tip radius and high stiffness of the CNT. The quantitative local temperature at the CNT probe contact point is determined by bringing the probe in and out of contact and controlling the amount of heat of the Pt hot film in high vacuum environment. Using this method, we overcome the problems of thermal contact resistance (TCR) between the CNT and sample surface. Sensor sensitivity for TCR and thermal conductivity measurement of a CNT is analyzed and the sensor configuration is optimized. © 2013 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.sna.2013.04.038

  • カーボンナノチューブプローブを用いた表面温度計測法 査読

    天野 樹生, 廣谷潤, 生田 竜也, 西山 貴史, 髙橋 厚史

    日本機械学会論文集 079巻799号B編   79 ( 799 )   390 - 398   2013年3月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  • Surface temperature measurement using a carbon nanotube probe

    Juo Amano, Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   79 ( 799 )   390 - 398   2013年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    A new technique of micro/nanoscale temperature measurement is developed using an individual carbon nanotube (CNT) on a platinum hot-film, which can control the heat flow through the CNT probe and sense its own average temperature. A feedback control to extinct the heat flow enables us to neglect the effect of contact thermal resistance and to know the real surface temperature. Spatial resolution of 70 nm, temperature uncertainty of less than 0.5 K and enough robustness are achieved. Using this method, quantitative temperature profiles are obtained around a line heater of 604 nm-width and 9.73 μm-length. ©2013 The Japan Society of Mechanical Engineers.

    DOI: 10.1299/kikaib.79.390

  • Enhanced anisotropic heat conduction in multi-walled carbon nanotubes 査読 国際誌

    Hiroyuki Hayashi, Taysuya Ikuta, Takashi Nishiyama, Koji Takahashi

    J. Appl. Phys.   113   014301   2013年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: DOI: 10.1063/1.4772612

  • Measuring the Thermal Boundary Resistance of van der Waals Contacts Using an Individual Carbon Nanotube 査読 国際誌

    Jun Hirotani, Taysuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Journal of Physics: Condensed Matter   25   025301   2013年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: doi:10.1088/0953-8984/25/2/025301

  • Report on the seventh U.S.-Japan Joint seminar on nanoscale transport phenomena-science and engineering

    B. A. Cola, H. Daiguji, C. Dames, N. Fang, K. Fushinobu, S. Inoue, G. Kikugawa, M. Kohno, S. Kumar, D. Y. Li, J. R. Lukes, J. A. Malen, A. J.H. McGaughey, O. Nakabeppu, K. Pipe, P. Reddy, S. Shen, L. Shi, M. Shibahara, Y. Taguchi, K. Takahashi, T. Yamamoto, T. Zolotoukhina

    Nanoscale and Microscale Thermophysical Engineering   17 ( 1 )   25 - 49   2013年1月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The seventh U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Shima, Japan, from December 11 to 14, 2011. The goals of this joint seminar were to provide a critical assessment of the state of the art and future directions in the field of nanoscale transport phenomena and energy conversion processes, to foster U.S.-Japan collaborations, and to provide international exposure to a new generation of scientists in this field. Issues discussed in the joint seminar were organized in 10 topical sessions, including (1) nanoscale thermophysical measurements; (2) optical characterization; (3) thermal and molecular transport; (4) phonon transport modeling; (5) energy storage and conversion; (6) nanoscale fluidics and phase change phenomena; (7) biological and organic systems; (8) interfacial thermal transport; (9) novel thermoelectric and thermal management materials; and (10) nanocarbon materials and devices. In addition to these topical sessions, the joint seminar featured an opening plenary session and a closing plenary session as well as an expert panel, where leading experts provided critical assessment of the past progress and addressed future directions in the field. In addition, an evening poster session provided opportunities for graduate and postdoc students to present their latest research results. About 35 researchers from Japan and 31 researchers from the United States participated in the meeting. The meeting was organized by S. Maruyama, K. Fushinobu, L. Shi, and J. Lukes together with about 20 other participants who served as session chairs. Summaries of different sessions of the seminar were prepared by the session and conference chairs and are collected into this report. © 2013 Taylor & Francis Group, LLC.

    DOI: 10.1080/15567265.2012.745913

  • Measuring the thermal boundary resistance of van der Waals contacts using an individual carbon nanotube

    Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Journal of Physics Condensed Matter   25 ( 2 )   2013年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Interfacial thermal transport via van der Waals interaction is quantitatively evaluated using an individual multi-walled carbon nanotube bonded on a platinum hot-film sensor. The thermal boundary resistance per unit contact area was obtained at the interface between the closed end or sidewall of the nanotube and platinum, gold, or a silicon dioxide surface. When taking into consideration the surface roughness, the thermal boundary resistance at the sidewall is found to coincide with that at the closed end. A new finding is that the thermal boundary resistance between a carbon nanotube and a solid surface is independent of the materials within the experimental errors, which is inconsistent with a traditional phonon mismatch model, which shows a clear material dependence of the thermal boundary resistance. Our data indicate the inapplicability of existing phonon models when weak van der Waals forces are dominant at the interfaces. © 2013 IOP Publishing Ltd.

    DOI: 10.1088/0953-8984/25/2/025301

  • Enhanced anisotropic heat conduction in multi-walled carbon nanotubes

    Hiroyuki Hayashi, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Journal of Applied Physics   113 ( 1 )   2013年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Anisotropy of heat conduction in multi-walled carbon nanotubes (MWNTs) is investigated by measuring heat flows in a pristine MWNT and in a MWNT with defects. The in- and out-of-shell thermal conductivities of each MWNT graphite shell are determined, and differences of more than four orders of magnitude are obtained because of the inter-shell gaps. This enhanced anisotropy reduces the conductance by 74% compared with that of the pristine MWNT because of the presence of outer shell defects, which comprise only 2.8% volume ratio. Furthermore, the anisotropy-assisted length dependence of thermal conductivity is demonstrated, even though there is no ballistic phonon transport. © 2013 American Institute of Physics.

    DOI: 10.1063/1.4772612

  • Submicron-scale condensation on hydrophobic and hydrophilic surfaces

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    ASME 2013 International Mechanical Engineering Congress and Exposition, IMECE 2013 Safety, Reliability and Risk; Virtual Podium (Posters)   2013年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Condensation heat transfer is a widely-used technique for industrial applications represented by heat exchanger because of its high heat transfer coefficient. To enhance its performance, a suitable surface is required, where both condensation and droplet removal smoothly occur. In this study, we compared wettability of a graphene surface and an amorphous carbon surface. The result shows that an amorphous carbon surface is more hydrophilic. Then we prepared a graphite surface which has nanoscale hydrophilic regions in large hydrophobic area. We observed the submicron-scale droplet condensation occurs preferentially on the hydrophilic graphite step by using environmental scanning electron microscope (ESEM).

    DOI: 10.1115/IMECE2013-66186

  • Report on the seventh U.S.-Japan Joint seminar on nanoscale transport phenomena-science and engineering 査読

    B. A. Cola, H. Daiguji, C. Dames, N. Fang, K. Fushinobu, S. Inoue, G. Kikugawa, M. Kohno, S. Kumar, D. Y. Li, J. R. Lukes, J. A. Malen, A. J.H. McGaughey, O. Nakabeppu, K. Pipe, P. Reddy, S. Shen, L. Shi, M. Shibahara, Y. Taguchi, K. Takahashi, T. Yamamoto, T. Zolotoukhina

    Nanoscale and Microscale Thermophysical Engineering   17 ( 1 )   25 - 49   2013年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The seventh U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Shima, Japan, from December 11 to 14, 2011. The goals of this joint seminar were to provide a critical assessment of the state of the art and future directions in the field of nanoscale transport phenomena and energy conversion processes, to foster U.S.-Japan collaborations, and to provide international exposure to a new generation of scientists in this field. Issues discussed in the joint seminar were organized in 10 topical sessions, including (1) nanoscale thermophysical measurements; (2) optical characterization; (3) thermal and molecular transport; (4) phonon transport modeling; (5) energy storage and conversion; (6) nanoscale fluidics and phase change phenomena; (7) biological and organic systems; (8) interfacial thermal transport; (9) novel thermoelectric and thermal management materials; and (10) nanocarbon materials and devices. In addition to these topical sessions, the joint seminar featured an opening plenary session and a closing plenary session as well as an expert panel, where leading experts provided critical assessment of the past progress and addressed future directions in the field. In addition, an evening poster session provided opportunities for graduate and postdoc students to present their latest research results. About 35 researchers from Japan and 31 researchers from the United States participated in the meeting. The meeting was organized by S. Maruyama, K. Fushinobu, L. Shi, and J. Lukes together with about 20 other participants who served as session chairs. Summaries of different sessions of the seminar were prepared by the session and conference chairs and are collected into this report.

    DOI: 10.1080/15567265.2012.745913

  • Surface temperature measurement using a carbon nanotube probe 査読

    Juo Amano, Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   79 ( 799 )   390 - 398   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A new technique of micro/nanoscale temperature measurement is developed using an individual carbon nanotube (CNT) on a platinum hot-film, which can control the heat flow through the CNT probe and sense its own average temperature. A feedback control to extinct the heat flow enables us to neglect the effect of contact thermal resistance and to know the real surface temperature. Spatial resolution of 70 nm, temperature uncertainty of less than 0.5 K and enough robustness are achieved. Using this method, quantitative temperature profiles are obtained around a line heater of 604 nm-width and 9.73 μm-length.

    DOI: 10.1299/kikaib.79.390

  • Applications of nano hot-film sensor for micro/nanoscale thermal measurement

    Koji Takahashi, Jun Hirotani, Takashi Nishiyama, Tatsuya Ikuta, Hiroshi Takamatsu

    ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012 ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012   677 - 681   2012年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Platinum hot-film sensors, whose typical size is 500nm wide x 10&mu;m long x 40nm thick, are developed for investigating micro and nanoscale thermal events. This paper reports four kinds of applications with measurement principle, sensitivity analysis, and test results. Thermal conductivity of individual nanowire, represented by carbon nanotube, has been measured by bridging the specimen between the sensor and a heat sink. Here a new device is newly developed, which enables us to measure quantitatively both intrinsic thermal conductivity of the specimen and thermal contact resistance between the specimen and a target material. Focused beam-induced deposition is also measured by comparing the thermal conductance of deposited sensor and pristine one. Flow sensor is another application and we investigate the performance of carbon nanotube (CNT) fins deposited on the sensor by using dielectrophoresis technique to enhance the flow signal. The applicability of this sensor for measuring the thermal conductivity of fluid of very limited volume (femto-liter order) is also analytically studied.

    DOI: 10.1115/MNHMT2012-75030

  • Non-Fourier heat conduction study for steady states in metallic nanofilms

    Hai Dong Wang, Jin Hui Liu, Zeng Yuan Guo, Koji Takahashi

    Chinese Science Bulletin   57 ( 24 )   3239 - 3243   2012年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    As a fundamental theory of heat transfer, Fourier's law is valid for most traditional conditions. Research interest in non-Fourier heat conditions is mainly focused on heat wave phenomena in non-steady states. Recently, the thermomass theory posited that, for steady states, non-Fourier heat conduction behavior could also be observed under ultra-high heat flux conditions at low ambient temperatures. Significantly, this is due to thermomass inertia. We report on heat conduction in metallic nanofilms from large currents at low temperatures; heat fluxes of more than 1×1010 W m-2 were used. The measured average temperature of the nanofilm is larger than that based on Fourier's law, with temperature differences increasing as heat flux increased and ambient temperature decreased. Experimental results for different film samples at different ambient temperatures reveal that non-Fourier behavior exists in metallic nanofilms in agreement with predictions from thermomass theory. © 2012 The Author(s).

    DOI: 10.1007/s11434-012-5288-7

  • Preface

    Koji Takahashi, Naoki Shikazono

    Journal of Thermal Science and Technology   7 ( 3 )   405   2012年7月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1299/jtst.7.405

  • Effect of nanoscale structure on thermal contact resistance of carbon nanotubes 査読

    Yutaka Yamada, Takashi Nishiyama, Tatsuya Ikuta, Koji Takahashi

    ASME 2012 Heat Transfer Summer Conf. Collocated with the ASME 2012 Fluids Engineering Div. Summer Meeting and the ASME 2012 10th Int. Conf. on Nanochannels, Microchannels and Minichannels, HT 2012   1   173 - 177   2012年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Carbon nanotube is a promising material for thermal-management of micro devices because of its high intrinsic thermal conductivity. However, most bulk nanotubes show very low thermal conductivity due to the high thermal contact resistance. There are very few reliable experimental data for the contact issue of nanotubes. This paper uses three kinds of multi-walled carbon nanotubes; pristine, thermally-oxidized, and acidized nanotube. Each has unique nanoscale structure in their outermost surface. We measured thermal conductivity of their pellets and simultaneously conducted computational analysis treating random network model of spherocylinders. By comparing both results, thermal contact resistances between nanotubes are estimated and the effect of defected structure is discussed. The reliability of our method is also successfully confirmed compared with reported data using individual nanotubes. Copyright © 2012 by ASME.

    DOI: 10.1115/HT2012-58203

  • Thermal boundary conductance between multi-walled carbon nanotubes 査読

    Yutaka Yamada, Takashi Nishiyama, Takahiro Yasuhara, Koji Takahashi

    Journal of Thermal Science and Technology   7 ( 1 )   190 - 198   2012年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Interfacial thermal transport of multi-walled carbon nanotubes (MWNTs) is investigated by using bulk pellet specimens. Steady-state conduction method gives thermal conductivity of 1 to 4 W/mK for the pellets with mass density from 0.2 to 0.35 g/cm3. This low thermal conductivity is due to the thermal boundary conductance between the nanotubes. Computational analysis is conducted for the pellet modeled as a random network of spherocylinders (SCs) and calculated dependency of thermal conductivity on pellet density shows good agreement with experimental data when we treat non-uniform SCs. By comparing the experimental and computational results, the thermal boundary conductance between two MWNTs can be taken as 1.5×10-8 W/K. This result agrees well with the reported data obtained by individual measurement, which suggests this simple method is applicable to probe the interfacial thermal phenomena of nanomaterials. An improved scaling law, k ∝ ρ2.14, for thermal conductivity of MWNTs aggregations is also proposed and discussed. © 2012 by JSME.

    DOI: 10.1299/jtst.7.190

  • APPLICATIONS OF NANO HOT-FILM SENSOR FOR MICRO/NANOSCALE THERMAL MEASURMENT 査読 国際誌

    Koji Takahashi, Jun Hirotani, Takashi Nishiyama, Tatsuya Ikuta, Hiroshi Takamatsu

    Proceedings of the ASME 2012 3rd Micro/Nanoscale Heat & Mass Transfer International Conference, March 3-6, 2012, Atlanta, Georgia, USA, MNHMT2012-75030   2012年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

  • Applications of nano hot-film sensor for micro/nanoscale thermal measurement

    Koji Takahashi, Jun Hirotani, Takashi Nishiyama, Tatsuya Ikuta, Hiroshi Takamatsu

    ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012   677 - 681   2012年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Platinum hot-film sensors, whose typical size is 500nm wide x 10&mu;m long x 40nm thick, are developed for investigating micro and nanoscale thermal events. This paper reports four kinds of applications with measurement principle, sensitivity analysis, and test results. Thermal conductivity of individual nanowire, represented by carbon nanotube, has been measured by bridging the specimen between the sensor and a heat sink. Here a new device is newly developed, which enables us to measure quantitatively both intrinsic thermal conductivity of the specimen and thermal contact resistance between the specimen and a target material. Focused beam-induced deposition is also measured by comparing the thermal conductance of deposited sensor and pristine one. Flow sensor is another application and we investigate the performance of carbon nanotube (CNT) fins deposited on the sensor by using dielectrophoresis technique to enhance the flow signal. The applicability of this sensor for measuring the thermal conductivity of fluid of very limited volume (femto-liter order) is also analytically studied. Copyright © 2012 by ASME.

    DOI: 10.1115/MNHMT2012-75030

  • Edge effect on phonon transport in suspended and supported graphene nanoribbons 査読

    Masanari Kimura, Takafumi Matsuzaki, Koji Takahashi

    Computational Thermal Sciences   4 ( 3 )   193 - 199   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Heat conduction in a graphene nanoribbon (GNR) is investigated using nonequilibrium molecular dynamics simulation. GNR shows an intriguing dependence of thermal conductivity on its width, length, and edge shape. For example, thermal conductivity of thin armchair GNR is about three times lower than that of zigzag GNR due to the strong phonon scattering at the armchair edge. The substrate interaction is another critical issue for phonon transport. GNR supported on a substrate is analyzed by using the Lennard-Jones potential, and the thermal conductivity of a zigzag ribbon is found to decrease significantly due to phonon scattering by the substrate. However, under the same conditions, that of armchair ribbon is not affected by the substrate or even increases. This phenomenon is caused by the suppression of edge-localized flexural phonons of armchair GNR, which triggers their smaller thermal conductivity than the zigzag one. This anomalous edge-substrate combined effect on thermal transport in supported GNR is discussed.

    DOI: 10.1615/ComputThermalScien.2012004393

  • Defect-induced thermal rectification Numerical study on carbon nanotube and FPU-beta lattice

    Hiroyuki Hayashi, Koji Takahashi

    ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011   2011年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    The thermal properties of a half-defective single-walled carbon nanotube, and one-dimensional (1D) nonlinear lattices were investigated to unveil the mechanism of defect-induced thermal rectification. We propose a model of an asymmetrically defective low-dimensional material to explain the underlying mechanism of thermal rectification obtained in a past experiment in which C 9H 16Pt was asymmetrically deposited on a nanotube. These numerical approaches show the applicability of asymmetrically defective low-dimensional material to solid-state thermal rectification.

  • Thermal boundary resistance between the end of an individual carbon nanotube and a Au surface 査読

    Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    Nanotechnology   22 ( 31 )   2011年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The thermal boundary resistance between an individual carbon nanotube and a Au surface was measured using a microfabricated hot-film sensor. We used both closed and open-ended multi-walled carbon nanotubes and obtained thermal boundary resistance values of 0.947-1.22 × 107KW- 1 and 1.43-1.76 × 107KW- 1, respectively. Considering all uncertainties, including the contact area, the thermal boundary conductances per unit area were calculated to be 8.6 × 107-2.2 × 108Wm- 2K- 1 for c-axis orientation and 4.2 × 108-1.2 × 109Wm- 2K- 1 for the a-axis. The trend in these values agrees with the predicted conductance dependence on the interface orientation of anisotropic carbon-based materials. However, the measured thermal boundary conductances are found to be much larger than the reported results. © 2011 IOP Publishing Ltd.

    DOI: 10.1088/0957-4484/22/31/315702

  • Experimental study on the influences of grain boundary scattering on the charge and heat transport in gold and platinum nanofilms

    Hai Dong Wang, Jin Hui Liu, Xing Zhang, Zeng Yuan Guo, Koji Takahashi

    Heat and Mass Transfer/Waerme- und Stoffuebertragung   47 ( 8 )   893 - 898   2011年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The electrical and thermal conductivities of polycrystalline gold and platinum nanofilms have been measured simultaneously using a direct current heating method from 60 to 300 K. The measured electrical and thermal conductivities are greatly decreased from the corresponding bulk values. And it is found that the reduction increases as the temperature decreases. The deviation from the bulk value is due to the effect of grain boundary scattering. Furthermore, the experimental results indicate that the grain boundary scattering effect imposes greater influence to the charge transport than to the heat transport. Consequentially, the Lorentz number is several times larger than that of bulk materials, leading to the violation of the Wiedemann-Franz law. The reflection coefficient R (0.86 in platinum, 0.42 in gold) at grain boundaries is obtained based on the Mayadas-Shatzkes theory and Matthiessen's rule, which agrees well with the previous experiments. © 2011 Springer-Verlag.

    DOI: 10.1007/s00231-011-0825-5

  • Deposition rate and movement effect of paraffin-based EBID

    Satoshi Kai, Koji Takahashi, Hilmi Norsyazwan, Tatsuya Ikuta, Takashi Nishiyama, Kunihito Nagayama

    Electronics and Communications in Japan   94 ( 5 )   39 - 46   2011年4月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Electron-beam-induced deposition (EBID) is a simple and versatile technique of processing materials for three-dimensional nanoscale structures. A variety of precursor molecules can be used to build a localized solid deposition by the exposure of a substrate to an electron beam. This paper reports nano carbon deposition using solid n-tetracosane as a precursor, because this paraffin-based EBID can be introduced into existing scanning electron microscope (SEM) systems without difficulty. The paraffin is prepared on an aluminum film and operated by a manipulator in the SEM. The effects of the accelerating voltage, beam current, magnification, distance from the paraffin to the exposure point, the amount of paraffin, and the working distance are measured and discussed. It is found that the electron-beam-induced etching and the beam diameter are sometimes the dominant factors influencing the deposition rate, and that the thickness of the paraffin also affects the deposition distribution. Electron-beam bending, which is a critical factor causing degradation of nanofabrication, is treated carefully in order to understand the declination of carbon pillars. The obtained carbon pillar configurations suggest that electrically charged paraffin produced during preliminary irradiation of the electron beam causes a Coulomb force and results in the movement effect of deposition. Copyright © 2011 Wiley Periodicals, Inc.

    DOI: 10.1002/ecj.10192

  • Defect-induced thermal rectification: Numerical study on carbon nanotube and FPU-beta lattice

    Hiroyuki Hayashi, Koji Takahashi

    ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011   283 - 288   2011年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    The thermal properties of a half-defective single-walled carbon nanotube, and one-dimensional (1D) nonlinear lattices were investigated to unveil the mechanism of defect-induced thermal rectification. We propose a model of an asymmetrically defective low-dimensional material to explain the underlying mechanism of thermal rectification obtained in a past experiment in which C 9H16Pt was asymmetrically deposited on a nanotube. These numerical approaches show the applicability of asymmetrically defective low-dimensional material to solid-state thermal rectification. Copyright © 2011 by ASME.

    DOI: 10.1115/ajtec2011-44071

  • Thermal rectification of asymmetrically-defective materials

    Hiroyuki Hayashi, Yohei Ito, Koji Takahashi

    Journal of Mechanical Science and Technology   25 ( 1 )   27 - 32   2011年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We conducted numerical simulations of heat conduction in one-dimensional (1D) nonlinear lattices to reveal the mechanism of thermal rectification of asymmetrically-defective materials. A decreased spring constant simulates the defective lattice and the obtained temperature profile suggests a thermal resistance existing at the interface of two linked segments with different spring constants. Our numerical results suggest that the thermal rectification of two-segment system is dependent on the spring constant and temperature gradient. Introducing the estimated phonon band, most of the rectification mechanisms are clearly explained and performance limit as a thermal rectifier is found for the defective/pristine materials. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

    DOI: 10.1007/s12206-010-1008-x

  • Experimental study on the thermal boundary resistance between an individual carbon nanotube end and a au surface

    Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 Heat and Mass Transport Processes   301 - 302   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    DOI: 10.1115/imece2011-62844

  • Defective carbon nanotube for use as a thermal rectifier 査読

    Koji Takahashi, Masato Inoue, Yohei Ito

    Japanese journal of applied physics   49 ( 2 PART 2 )   2010年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We investigated the thermal properties of a single-walled carbon nanotube with vacancy defects to determine its applicability to solid-state thermal rectification. Nonequilibrium molecular dynamics simulation of a nanotube with randomly located defects only along half the length revealed asymmetric heat conduction at room temperature. The direction of rectification is in good agreement with that obtained in a past experiment in which C9H16Pt was asymmetrically deposited on a nanotube, as far as the local deposition is supposed to cause defects in the nanotube lattice. The mechanism underlying the current thermal rectification effect is discussed considering the temperature dependence of the local thermal conductivity and the phonon filtering effect. The calculated phonon density of states shows larger overlapping when heat flows from the defective part to the pristine part and intermediate-frequency phonons are mainly responsible for rectification.

    DOI: 10.1143/JJAP.49.02BD12

  • A graphene chain acts as a long-distance ballistic heat conductor

    Koji Takahashi, Yohei Ito, Tatsuya Ikuta

    2010 14th International Heat Transfer Conference, IHTC 14 2010 14th International Heat Transfer Conference, IHTC 14   331 - 336   2010年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    A carbon nanofiber material, consisting of bottomless graphene cups inside on each other in a line, like a set of soft-drink cups, has been discovered to have the potential to conduct heat ballistically over a long distance. Its longitudinal heat transport ability had been forecast to be extremely poor due to the weak van der Waals force operating between the graphene cups, but our measurements using nano thermal sensor showed that its thermal conductivity is much higher than that along the c-axis of bulk graphite. This unexpected result can be understood by its similarity to a one-dimensional (1D) harmonic-chain where no phonon is scattered even for an infinite length. The current graphene-based nanofiber resembles this type of "superconductive" chain due to the huge difference between the stiff covalent bonding in each cup and the weak inter-cup interaction. A non-equilibrium molecular dynamics simulation is conducted to explore the phonon transport in this fiber. The simulation results show that the thermal conductivity varies with the fiber length in a power law fashion with an exponent as large as 0.7. The calculated phonon density of states and atomic motions indicate that a low-frequency quasi-1D oscillation occurs there. Our investigations show that treating the current nanofiber as a 1D chain with three-dimensional oscillations explains well why this material has the most effective ballistic phonon transport ever observed.

    DOI: 10.1115/IHTC14-22289

  • Electrical properties and reduced Debye temperature of polycrystalline thin gold films

    Weigang Ma, Xing Zhang, Koji Takahashi

    Journal of Physics D: Applied Physics   43 ( 46 )   2010年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The temperature-dependent electrical properties of four suspended polycrystalline thin gold films with thicknesses of 20.0, 23.0, 36.0 and 54.0 nm have been measured in the temperature range 100-310 K. The measured results show that the electrical resistivity of the films significantly increases while the corresponding temperature dependence decreases compared with bulk gold. The significantly increased electrical resistivity indicates that grain boundary scattering dominates over surface scattering in the studied films. However, fixing the Debye temperature to the bulk value will lead to an erroneous temperature dependence of resistivity. Taking into account the reduced characteristic Debye temperature along with the surface and grain boundary scattering, the electrical properties of the films can be well described in the whole temperature range. The extracted grain boundary reflection coefficient is 0.3 ± 0.03, within the range of the previous reported values, 0.1-0.45. The films' characteristic Debye temperatures decrease from the bulk value of 165 K to between 83 and 121K and tend to increase with increasing film thickness. This tendency coincides with the previous studies on thin gold, copper, platinum, silver films or wires, and cobalt/nickel superlattices. The possible mechanism responsible for the reduced Debye temperature is phonon softening at the surfaces, grain boundaries, disorder, defects and impurities, part of which has been demonstrated in other studies. © 2010 IOP Publishing Ltd.

    DOI: 10.1088/0022-3727/43/46/465301

  • Submicroscale flow sensor employing suspended hot film with carbon nanotube fins 査読

    Yohei Ito, Taku Higuchi, Koji Takahashi

    Journal of Thermal Science and Technology   5 ( 1 )   51 - 60   2010年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A submicroscale flow sensor has been developed that consists of a suspended hot film and carbon nanotube (CNT) fins. Flow measurement experiments, together with a theoretical model, revealed the advantages of the use of CNT fins. The suspended metal film reduces heat loss and the CNT fins enhance the heat transfer to the fluid flow. Herein, the working principle of the CNT fins is presented in detail, together with a description of the micro electro mechanical systems (MEMS)/nano electro mechanical systems (NEMS) techniques used to fabricate the sensor. The CNTs were deposited by a manipulation method that is based on dielectrophoresis.

    DOI: 10.1299/jtst.5.51

  • カーボンナノチューブ-固体間の界面熱抵抗に関する実験的研究 査読

    廣谷潤,甲斐聡, 生田竜也,高橋厚史

    日本機械学会論文集 076巻769号B編   76 ( 769 )   2010年9月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    固体間の熱伝導に関して界面熱抵抗を深く理解するにはナノスケールでの現象の把握が必要不可欠となる.そこで我々は,CNTと固体表面の間の熱抵抗を正確に計測することを目指し,サブミクロンスケールの微細な白金ホットフィルムを用いた独自のセンサを開発した.これを用いることで,CNT 先端とSiO2面の間の界面熱抵抗値を実験的に得ることに初めて成功した.また,CNT 先端での界面熱抵抗は接触圧力に依存しないことも確認することができた.

  • Experimental study on interfacial thermal resistance between carbon nanotube and solid material

    Jun Hirotani, Satoshi Kai, Tatsuya Ikuta, Koji Takahashi

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   76 ( 769 )   1412 - 1419   2010年9月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Measurement method of the interfacial thermal resistance (ITR) between a multi-walled carbon nanotube (MWCNT) and solid surface is developed by using a sub-micrometer Pt hot-film. Thermal application of CNTs is promising due to their very high intrinsic thermal conductivity. However ITR could be dominant in the total thermal resistance when CNT is used for heat dissipation devices. Therefore measuring ITR between CNT and solid material is important in order to determine the total thermal resistance. Though it is fundamental to understand the ITR in nano or atomic scale, there have been reported very few experimental approaches to measure the ITR due to technical difficulties. By using a MWCNT as a probe on the Pt hot-film, it is concluded that the ITR between MWCNT tip and SiO2 surface is 1 × 105 K/W, which is confirmed to be independent of contact pressure.

    DOI: 10.1299/kikaib.76.769_1412

  • A GRAPHENE CHAIN ACTS AS A LONG-DISTANCE BALLISTIC HEAT CONDUCTOR 査読 国際誌

    Koji Takahashi, Yohei Ito, Tatsuya Ikuta

    Proceedings of the International Heat Transfer Conference IHTC14, August 8-13, 2010, Washington, DC, USA,   2010年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

  • Orthogonal growth of horizontally aligned single-walled carbon nanotube arrays

    Hiroki Ago, Tetsushi Nishi, Kenta Imamoto, Naoki Ishigami, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of Physical Chemistry C   114 ( 30 )   12925 - 12930   2010年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Direction-controlled growth of horizontally aligned single-walled carbon nanotubes (SWNTs) on r-plane sapphire substrates and their alignment mechanisms are demonstrated. On a flat r-plane substrate, anisotropic nanotube-substrate interaction is known to align SWNTs parallel to the [11̄01̄] direction of the sapphire. We find that the introduction of a slight miscut (-1° inclined to the [11̄01̄] direction) on the substrate changed the SWNT growth direction by 90°, aligning perpendicular to the [11̄01̄] direction. This dramatic change of the growth direction is explained by the contribution of newly proposed one-dimensional surface atomic rows and/or atomic steps appeared on the r-plane. Annealing the substrate in hydrogen atmosphere prior to SWNT growth recovers the original nanotube growth direction, while annealing in air deteriorates the alignment. The direct growth of an orthogonally aligned SWNT array is achieved through optimized surface treatment. Site-selective directional control of aligned SWNTs is also demonstrated by applying hydrogen annealing to the miscut substrate whose surface is partially covered with SiO2. Our study gives insights into the alignment mechanism on single crystal substrates and offers a new means to assemble SWNTs for advanced integrated structures. © 2010 American Chemical Society.

    DOI: 10.1021/jp1032993

  • Effective patterning of metal nanoparticles on sapphire surface for aligned growth of single-walled carbon nanotubes

    Hiroki Ago, Ryota Ohdo, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of Nanoscience and Nanotechnology   10 ( 6 )   3867 - 3872   2010年6月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    We studied patterning of metal nanoparticle catalyst on sapphire (α-Al 2O 3) substrates to grow horizontally-aligned single-walled carbon nanotubes (SWNTs) from defined positions. Various modifications of sapphire surface were investigated for effective adsorption of iron oxide nanoparticles. We found that phosphoric acids bind to sapphire surface and enhance the adsorption of the nanoparticles. This surface modification enabled effective patterning of nanoparticle via electron beam lithography. The small nanoparticles with a mean diameter of 5 nm tended to diffuse at high temperature during the nanotube growth, while the large particles with 12 nm mean diameter mostly stayed at the same position giving aligned SWNTs grown from the catalyst pattern. Copyright © 2010 American Scientific Publishers All rights reserved.

    DOI: 10.1166/jnn.2010.1977

  • Feasibility study of a novel technique for measurement of liquid thermal conductivity with a micro-beam sensor 査読

    Hiroshi Takamatsu, Kyosuke Inada, Satoru Uchida, Koji Takahashi, Motoo Fujii

    International Journal of Thermophysics   31 ( 4-5 )   888 - 899   2010年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A new method was proposed to measure the thermal conductivity of liquids with infinitesimal samples, which are much smaller than those required in conventional methods. The method utilizes a micro-beam-type MEMS sensor fabricated across a trench on a silicon substrate. Numerical analysis of heat conduction within and around a uniformly heated sensor showed that the temperature of a 10 μm long sensor reached a steady state within approximately 0.1 ms, after the start of heating. It was also revealed that the average temperature of the sensor at the steady state was higher in liquids with lower thermal conductivity. These results demonstrate a new idea of measuring the thermal conductivity of liquids within an extremely short time at a steady state before the onset of natural convection.

    DOI: 10.1007/s10765-009-0700-5

  • Feasibility study of a novel technique for measurement of liquid thermal conductivity with a micro-beam sensor

    Hiroshi Takamatsu, Kyosuke Inada, Satoru Uchida, Koji Takahashi, Motoo Fujii

    International Journal of Thermophysics   31 ( 4-5 )   888 - 899   2010年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    A new method was proposed to measure the thermal conductivity of liquids with infinitesimal samples, which are much smaller than those required in conventional methods. The method utilizes a micro-beam-type MEMS sensor fabricated across a trench on a silicon substrate. Numerical analysis of heat conduction within and around a uniformly heated sensor showed that the temperature of a 10 μm long sensor reached a steady state within approximately 0.1 ms, after the start of heating. It was also revealed that the average temperature of the sensor at the steady state was higher in liquids with lower thermal conductivity. These results demonstrate a new idea of measuring the thermal conductivity of liquids within an extremely short time at a steady state before the onset of natural convection. © Springer Science+Business Media, LLC 2010.

    DOI: 10.1007/s10765-009-0700-5

  • Defective Carbon Nanotube for Use as a Thermal Rectifier 査読 国際誌

    Koji Takahashi, Masato Inoue, and Yohei Ito

    Japanese Journal of Applied Physics   49   2010年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Submicroscale Flow Sensor Employing Suspended Hot Film with Carbon Nanotube Fins 査読 国際誌

    Yohei Ito, Taku Higuchi and Koji Takahashi

    Journal of Thermal Science and Technology   Vol. 5 ( No. 1 )   2010年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Experimental study on interfacial thermal resistance between carbon nanotube and solid material 査読

    Jun Hirotani, Satoshi Kai, Tatsuya Ikuta, Koji Takahashi

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   76 ( 769 )   1412 - 1419   2010年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Measurement method of the interfacial thermal resistance (ITR) between a multi-walled carbon nanotube (MWCNT) and solid surface is developed by using a sub-micrometer Pt hot-film. Thermal application of CNTs is promising due to their very high intrinsic thermal conductivity. However ITR could be dominant in the total thermal resistance when CNT is used for heat dissipation devices. Therefore measuring ITR between CNT and solid material is important in order to determine the total thermal resistance. Though it is fundamental to understand the ITR in nano or atomic scale, there have been reported very few experimental approaches to measure the ITR due to technical difficulties. By using a MWCNT as a probe on the Pt hot-film, it is concluded that the ITR between MWCNT tip and SiO2 surface is 1 × 105 K/W, which is confirmed to be independent of contact pressure.

    DOI: 10.1299/kikaib.76.769_1412

  • One-dimensionality of phonon transport in cup-stacked carbon nanofibers 査読

    Y. Ito, M. Inoue, Koji Takahashi

    Journal of Physics Condensed Matter   22 ( 6 )   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We treat the ballistic heat conduction of cup-stacked carbon nanofibers (CSCNF) by a nonequilibrium molecular dynamics simulation. The CSCNF consist of numerous tiny graphene cups linked in line by weak intermolecular forces. The simulation results show that the thermal conductivity varies with the fiber length in a power law fashion with an exponent as large as 0.7. The calculated phonon density of states revealed that a low frequency oscillation in the radial and axial directions dominates the heat conduction in CSCNF. The atomic motions indicate that these low frequency oscillations are quasi-one-dimensional (1D) where each cup moves axially like a rigid body and radially with a breathing motion. This quasi-1D oscillation occurs due to the unique structure of a CSCNF that resembles a 1D harmonic chain. Our investigations show that treating a CSCNF as a 1D chain with three-dimensional oscillations explains why this material has the highest ballistic phonon transport ever observed.

    DOI: 10.1088/0953-8984/22/6/065403

  • Carbon nanotube thermal probe using platinum nano hot-film

    Koji Takahashi, Jun Hirotani, Satoshi Kai, Tatsuya Ikuta

    ASME 2009 Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT2009 Proceedings of the ASME Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT2009   2   457 - 462   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    This paper reports on a thermal probe using a carbon nanotube (CNT) on a platinum hot-film. CNT probe is expected to breakthrough the limitations of the existing ones owing to its unique characteristics but no practical thermal device has been fabricated yet. In order to explore the mechanisms of heating and measuring the smaller region than 10nm, we applied our recently developed sensor coupled with CNT, which consists of a suspended platinum film of 40nm × 500nm × 10micrometer. The principle of this probe as heater and sensor is explained, based on one dimensional heat conduction. Fabrication process using MEMS technique is also introduced, especially for a couple of critical techniques. One is to fabricate the nano sensor on an edge of the sensor substrate. The other is to bond a CNT on the suspended hot-film sensor. A CNT thermal probe using a multi-walled CNT of 70nm diameter and ca. 10 micrometers length is successfully fabricated. Its performances are tested in vacuum environment as to eliminate the presence of in-air conduction effect and water absorption effect around the contact point, which work for heat transport dominantly in atmospheric condition and degrade the spatial resolution. Our CNT probe showed a clear and reliable signal in vacuum and its sensitivity available for nanoscale thermal sensing and heating is confirmed.

    DOI: 10.1115/MNHMT2009-18356

  • Measurement of the thermal conductivity of nanodeposited material

    Koji Takahashi, Norsyazwan Hilmi, Yohei Ito, Tatsuya Ikuta, Xing Zhang

    International Journal of Thermophysics   30 ( 6 )   1864 - 1874   2009年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The small size of nanomaterials deposited by either focused ions or electron beams has prevented the determination of reliable thermal property data by existing methods. A new method is described that uses a suspended platinum hot film to measure the thermal conductivity of a nanoscale deposition. The cross section of the Pt film needs to be as small as 50 nm × 500 nm to have sufficient sensitivity to detect the effect of the beam-induced nanodeposition. A direct current heating method is used before and after the deposition, and the change in the average temperature increase of the Pt hot film gives the thermal conductivity of the additional deposited material. In order to estimate the error introduced by the one-dimensional analytical model employed, a two-dimensional numerical simulation was conducted. It confirmed the reliability of this method for situations where the deposit extends onto the terminals by (1 μm or more. Measurements of amorphous carbon (a-C) films fabricated by electron beam induced deposition (EBID) produced thermal conductivities of 0.61 W • m -1 • K -1 to 0.73 W • m -1 • K -1 at 100 K to 340 K, values in good agreement with those of a-C thin films reported in the past. © 2009 Springer Science+Business Media, LLC.

    DOI: 10.1007/s10765-009-0666-3

  • Experimental and numerical studies on ballistic phonon transport of cup-stacked carbon nanofiber

    Koji Takahashi, Yohei Ito, Tatsuya Ikuta, Xing Zhang, Motoo Fujii

    Physica B: Condensed Matter   404 ( 16 )   2431 - 2434   2009年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A carbon nanofiber material, consisting of a stacked graphene cups, with the potential to conduct heat ballistically has been discovered and tested. Its unexpected high thermal conductivity can be understood by the similarity to a one-dimensional harmonic chain where no phonon is scattered even for an infinite length. A non-equilibrium molecular dynamics simulation for this fiber validated this hypothesis by revealing a uniform temperature distribution between hot and cold reservoirs. © 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physb.2009.05.001

  • Direct growth of bent carbon nanotubes on surface engineered sapphire

    Hiroki Ago, Kenta Imamoto, Tetsushi Nishi, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi, Munetoshi Fukui

    Journal of Physical Chemistry C   113 ( 30 )   13121 - 13124   2009年7月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Bending of horizontally aligned single-walled carbon nanotubes (SWNTs) was achieved on surface engineered single-crystal sapphire (α-Al 2O3). The SWNTs grown on the r-plane sapphire are aligned along the specific crystallographic [11̄01̄] direction due to the lattice-oriented growth, and we created artificial step structures perpendicular to this SWNT growth direction. These steps changed the nanotube growth direction from the [11̄01̄] to the step direction with the bending angle of nearly 90°. Effects of the bending structure on electron transport property were studied. Our approach to combine the lattice-oriented growth with the step-templated growth will offer a new route toward the growth of two-dimensionally controlled SWNT architectures for future nanoelectronics. © 2009 American Chemical Society.

    DOI: 10.1021/jp902409w

  • Estimating error in measuring thermal conductivity using a T-type nanosensor

    Yohei Ito, Koji Takahashi, Motoo Fujii, Xing Zhang

    Heat Transfer - Asian Research   38 ( 5 )   297 - 312   2009年7月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    We discuss the measurement error caused by fabrication and measurement of a T-type nanosensor with a suspended sub-micrometer Pt hot film that was developed to measure the thermal properties of individual nanowire materials. Comparison of numerical simulation and one-dimensional analysis revealed that the thermal conductivity of nanowire material such as a carbon nanotube is calculated to be 17% lower. As an example, the thermal conductivity measurement result for a SiC nanowire is reported. The error caused by contact thermal resistance is found to depend on the contact length and can be as great as 20%. It can be said that future measuring can have higher reliability by correcting the estimated measurement error. © 2009 Wiley Periodicals, Inc.

    DOI: 10.1002/htj.20228

  • Estimating Error in Measuring Thermal Conductivity Using a T-type Nanosensor 査読 国際誌

    Yohei Ito, Koji Takahashi, Motoo Fujii and Xing Zhang

    Heat Transfer - Asian Research   2009年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Horizontally aligned growth of single-walled carbon nanotubes on a surface-modified silicon wafer

    Naoki Yoshihara, Hiroki Ago, Kenta Imamoto, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of Physical Chemistry C   113 ( 19 )   8030 - 8034   2009年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    For the integration with modern Si-based electronics, it is important to organize single-walled carbon nanotubes (SWNTs) into a rational structure on a Si wafer with a SiO2 oxide layer. In this study, the aligned growth of SWNTs was achieved on the SiO2/Si substrate whose surface was pretreated with CF4 plasma. The plasma treatment gave the radially extended steps which guided the SWNT growth. Back-gate field effect transistors were demonstrated with the aligned SWNTs. Our work presents the possibility of assembling SWNTs on SiO2/Si substrate through the formation of artificial step structures, which is a great step toward fully functional SWNT-on-Si devices. © 2009 American Chemical Society.

    DOI: 10.1021/jp810036t

  • Effect of underetching on thermal conductivity measurement of suspended nanofilm

    Yohei Ito, Koji Takahashi, Tatsuya Ikuta, Xing Zhang

    Japanese Journal of Applied Physics   48 ( 5 PART 3 )   2009年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The measurement of the in-plane thermal conductivity of a nanofilm by the direct-current heating method is examined by a numerical heat transfer simulation to obtain reliable data for nanosensor applications. A platinum film of 500 nm in width and 10 μm in length is fabricated to be suspended between two terminals. An underetched part always exists on the edge of the terminals owing to the isotropic etching process, which causes a temperature jump at the end of the suspended film. As a result, the thermal conductivity measured by the direct- current heating method is found to be underestimated from the intrinsic properties of the suspended nanofilm. Numerical simulations are conducted to calculate the temperature jump and the necessary correction of thermal conductivity is derived, which critically depends on the width of the underetched part. The corrected thermal conductivity is discussed with the simultaneously obtained electrical conductivity in comparison with the bulk data. © 2009 The Japan Society of Applied Physics.

    DOI: 10.1143/JJAP.48.05EB01

  • Different effects of grain boundary scattering on charge and heat transport in polycrystalline platinum and gold nanofilms

    Ma Wei-Gang, Wang Hai-Dong, Zhang Xing, Takahashi Koji

    CHINESE PHYSICS B   18 ( 5 )   2035 - 2040   2009年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thickness and measured in a temperature range between the boiling point of liquid nitrogen (77 K) and room temperature by using the direct current heating method. The result shows that both the electrical and thermal conductivities of the nanofilms reduce greatly compared with their corresponding bulk values. However, the electrical conductivity drop is considerably greater than the thermal conductivity drop, which indicates that the influence of the internal grain boundary on heat transport is different from that of charge transport, hence leading to the violation of the Wiedemann-Franz law. We build an electron relaxation model based on Matthiessen's rule to analyse the thermal conductivity and employ the Mayadsa & Shatzkes theory to analyse the electrical conductivity. Moreover, a modified Wiedemann-Franz law is provided in this paper, the obtained results from which are in good agreement with the experimental data.

    DOI: 10.1088/1674-1056/18/5/051

  • ナノ材料の熱物性計測

    Koji Takahashi, Motoo Fujii

    伝熱 : journal of the Heat Transfer Society of Japan   47 ( 198 )   20 - 25   2009年

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  • Micro oscillation heat pipe fabricated on silicon wafer

    Masamichi Kohno, Takashi Nishizono, Yasunori Onaka, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata

    6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008 Proceedings of the 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008   1343 - 1346   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Heat transport characteristics of micro oscillation heat pipe have been investigated. A single winding flow path consists of 28 turns microchannels fabricated on a silicon wafer the size of which was 31mmx27mm. We used heat pipe with non-uniformed cross section. Equivalent diameters of channels were 0.19 and 0.10mm. Test fluid was R141b and liquid fractions were 0, 75, 85%. It was found that steady pulsating flow occurred by increasing the number of turns and the frequency of vibration has an effect on heat transfer performance.

    DOI: 10.1115/ICNMM2008-62082

  • Unidirectional growth of single-walled carbon nanotubes

    Hiroki Ago, Naoki Ishigami, Tetsushi Nishi, Ken Ichi Ikeda, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of the American Chemical Society   130 ( 51 )   17264 - 17265   2008年12月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Unidirectional growth of single-walled carbon nanotubes (SWNTs) was achieved using the patterned Co-Mo salt catalyst on the r-plane sapphire substrate. This is in marked contrast with the SWNTs grown on an a-plane sapphire and ST-cut quartz, on which the SWNTs grew bidirectionally. This new growth mode is not dependent on the gas flow and attributed to the asymmetric surface atomic arrangement of the sapphire surface. Copyright © 2008 American Chemical Society.

    DOI: 10.1021/ja8080549

  • Horizontally-aligned single-walled carbon nanotubes on sapphire

    Hiroki Ago, Naoki Ishigami, Kenta Imamoto, Tomoko Suzuki, Ken Ichi Ikeda, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of Nanoscience and Nanotechnology   8 ( 11 )   6165 - 6169   2008年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Recently, we discovered the horizontally-aligned growth of single-walled carbon nanotubes (SWCNTs) on R- and A-plane sapphire substrates, which we call "atomic arrangement-programmed growth (AAP growth)." This is a unique method because the growth direction of SWCNTs is determined by the crystallographic direction of the sapphire surface. In this paper, we report on the characterization of the aligned SWCNTs by polarized Raman and electron transport measurements, and on the effect of the step/terrace structure formed on sapphire surface. These results may open up a possibility of creating the artificial SWCNT network, which can be applied to high-performance electronics. Copyright © 2008 American Scientific Publishers. All rights reserved.

    DOI: 10.1166/jnn.2008.SW01

  • Report on 6th U.S.-Japan joint seminar on nanoscale transport phenomena - Science and engineering

    T. Borca-Tasciuc, D. G. Cahill, G. Chen, S. B. Cronin, H. Daiguji, C. Dames, K. Fushinobu, T. Inoue, A. Majumdar, S. Maruyama, K. Miyazaki, M. Matsumoto, P. M. Norris, L. Shi, M. Shibahara, M. Shannon, J. Shiomi, Y. Taguchi, K. Takahashi, T. Tsuruta, S. G. Volz, E. Wang, X. F. Xu, B. Yang, R. G. Yang

    Nanoscale and Microscale Thermophysical Engineering   12 ( 4 )   273 - 293   2008年10月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The objective of this U.S.-Japan joint seminar series is to provide a cross-disciplinary and international forum for discussing and identifying outstanding science and technology issues in the area of nanoscale thermophysics and energy conversion and to foster collaboration among researchers in these areas. The first of this seminar series, championed by the late Professors Chang-Lin Tien and Kunio Hijikata, was held in Kanazawa, Japan, in June of 1993. Subsequent meetings have been held every three years, alternating venues between the United States and Japan. The Sixth U.S.-Japan Joint Seminar on Nanoscale Transport PhenomenaScience and Engineering was held in Boston, Massachusetts, July 13-16, 2008, and was organized by Professors Gang Chen from MIT, Fushinobu Kazuyoshi from Tokyo Institute of Technology, Shigeo Maruyama from Tokyo University, and Pamela Norris from University of Virginia. Nearly 100 scientists participated in the seminar. (The agenda of the seminar is attached at the end at this report[14].) The seminar included keynote sessions and invited sessions, as well as a dedicated poster session of selected presentations from an open call for papers. All papers presented in the regular sessions, the invited sessions, were upon invitation by the organizers. Invited sessions used a mixed form of communication: each speaker gave a 5-minute summary of his work followed by a 30-minute poster session of just the papers summarized orally, and then these speakers came back to the podium, serving as panelists to answer questions regarding their papers and session themes. This format offered good opportunities for the presenters to discuss their work with the participants. Reports for each session were summarized by session chairs. Following is a brief summary of the sessions.

    DOI: 10.1080/15567260802591928

  • Charge and heat transport in polycrystalline metallic nanostructures

    Xing Zhang, Koji Takahashi, Motoo Fujii

    Chinese Physics Letters   25 ( 9 )   3360 - 3363   2008年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Metals are typically good conductors in which the abilities to transport charge and to transport heat can be related through the Wiedemann-Franz law. Here we report on an abnormal charge and heat transport in polycrystalline metallic nanostructures in which the ability to transport charge is weakened more obviously than that to transport heat. We attribute it to the influence of the internal grain boundaries and have formulated a novel relation to predict the thermal conductivity. The Wiedemann-Franz law is then modified to account for the influence of the grain boundaries on the charge and heat transport with the predictions now agreeing well with the measured results. © 2008 Chinese Physical Society and IOP Publishing Ltd.

    DOI: 10.1088/0256-307X/25/9/071

  • Ptホットフィルムを用いたナノ堆積物の熱伝導率計測

    伊藤 洋平, 高橋 厚史, Hilmi Norsyazwan, 張 興

    Thermal science and engineering   16 ( 3 )   105 - 111   2008年7月

     詳細を見る

    記述言語:日本語  

    A novel method to measure the thermal conductivity of nano scale deposition is developed by using platinum hot film suspended between two terminals. The nano-deposition, which can be built by either focused ion or electron beam, is one of the newest fabrication techniques for three dimensional nano-structure, and can be applied to patterning, repairing, bonding, et al. However, its thermal property is still unknown because the size is too small to measure by the existing thermal sensors. The hot film used here is fabricated by NEMS (Nanoelectromechanical Systems) technology and has enough sensitivity to measure nanoscale materials. Direct current heating method is applied before and after the deposition and the change of averaged temperature increase of the platinum film gives the thermal conductivity of additionally-deposited material by using one-dimensional heat conduction model. As an example, amorphous carbon (a-C) with the thickness of 563 nm is deposited by electron beam induced deposition (EBID) method and thermal conductivity of a-C nano-deposition is obtained to be 0.61 W&frasl;(m&middot;K) to 0.73 W&frasl;(m&middot;K) at 100 K to 340 K. In order to confirm the reliability of this method, two-dimensional numerical simulation is conducted and the measuring uncertainty is calculated exactly. The effect of thermal boundary resistance is also treated and discussed. From the comparison of 1D model and 2D simulation, it is found that the deposition extended on the terminals by 1 &mu;m length can decrease the error of 1D model from 5.5 % to 3.1 % but no more extension has little effect to improve the accuracy of this method.

    DOI: 10.11368/tse.16.105

  • パラフィンを用いたEBIDの堆積速度と移動現象 査読

    甲斐聡、高橋厚史、ノルシャズワン、生田竜也、西山貴史、永山邦仁

    電気学会論文誌E センサ・マイクロマシン部門誌   2008年4月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    Deposition Rate and Position Shifting of Paraffin-Based EBID

  • Thermal conductivity of SiC nanowire formed by combustion synthesis 査読 国際誌

    Koji Takahashi, Yohei Ito, Tatsuya Ikuta, Takashi Nishiyama, Motoo Fujii, Xing Zhang and Andrzej Huczko,

    High Temperatures-High Pressures   2008年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Thermal conductivity of SiC nanowire formed by combustion synthesis

  • Ptホットフィルムを用いたナノ堆積物の熱伝導率計測 査読 国際誌

    伊藤洋平、高橋厚史、Norsyazwan Hilmi、張興

    Thermal Science and Engineering   2008年3月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    Measuring Thermal Conductivity of Nano Deposition Usinh Pt Hot Film

  • T字一体型ナノセンサを用いた熱伝導率計測における誤差の推定 査読

    伊藤洋平、高橋厚史、藤井丕夫、張興

    熱物性   2008年2月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    Estimating Error of Measuring Thermal Conductivity Using T-Type Nano Sensor

  • Visualization of horizontally-aligned single-walled carbon nanotube growth with13C/12C isotopes

    Hiroki Ago, Naoki Ishigami, Naoki Yoshihara, Kenta Imamoto, Seiji Akita, Ken Ichi Ikeda, Masaharu Tsuji, Tatsuya Ikuta, Koji Takahashi

    Journal of Physical Chemistry C   112 ( 6 )   1735 - 1738   2008年2月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Horizontally aligned growth of single-walled carbon nanotubes (SWNTs) on single-crystal surfaces has attracted great interest in terms of nanoelectronic applications, but their growth mechanism is not fully understood. We report on the 13C/12C isotope-labeled growth of SWNTs on a sapphire surface to visualize their growth process. Switching carbon feedstock from 13CH4 to 12CH4 during SWNT growth induces a gradient distribution of the carbon isotopes along the tube axis. From the Raman mapping analysis, we succeeded to observe the gradual change in the isotope distribution of individual SWNTs. The results indicate the base-growth mode for the horizontally aligned SWNTs, which suggests that nanotube-sapphire interaction is essential to alignment. This method offers a unique technique to analyze the nanotube growth mechanism and kinetics. © 2008 American Chemical Society.

    DOI: 10.1021/jp709737q

  • Measuring Thermal Conductivity of Nano Deposition Usinh Pt Hot Film 査読

    Yohei Ito, Koji Takahashi, Xing Zhang

    Thermal science and engineering   16 ( 3 )   105 - 111   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Thermal conductivity of SiC nanowire formed by combustion synthesis 査読

    Koji Takahashi, Yohei Ito, Tatsuya Ikuta, Takashi Nishiyama, Motoo Fujii, Xing Zhang, Andrzej Huczko

    High Temperatures - High Pressures   37 ( 2 )   119 - 125   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    This paper reports on the measurement of the thermal conductivity of an individual silicon carbide (SiC) nanowire of 140 nm diameter. T-type nanosensor and high-resolution transmission electron microscopy (HRTEM) are applied to obtain reliable property data. HRTEM images show that this nanowire has highly-crystalline SiC core of 126 nm diameter and surrounding amorphous silicon-dioxide layer of 7 nm thickness. Thermal contact resistance is estimated by using a simple analysis of the amorphous-carbon nanostructure between nanowire and nanosensor. Obtained apparent thermal conductivity of this nanowire suggests the thermal conductivity of SiC core is over 100W·m -1·K-1 at room temperature, which is much greater than the past-reported data of thin film but less than the pure bulk data. Compared with bulk samples, phonon scattering mechanism is also discussed.

  • Experimental study on the in-plane thermal conductivity of Au nanofilms

    Bingyang Cao, Qingguang Zhang, Xing Zhang, Takahashi Koji, Ikuta Tatsuya, Wenming Qiao, Fujii Motoo

    Progress in Natural Science   17 ( 2 )   212 - 216   2007年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The in-plane thermal conductivity of Au nanofilms with thickness of 23 nm, which are fabricated by the electron beam- physical vapor deposition method and a suspension technology, is experimentally measured at 80-300 K by a one-dimensional steady-state electrical heating method. Strong size effects are found on the measured nanofilm thermal conductivity. The Au nanofilm in-plane thermal conductivity is much less than that of the bulk material. With the increasing temperature, the nanofilm thermal conductivity increases. This is opposite to the temperature dependence of the bulk property. The Lorenz number of the Au nanofilms is about three times larger than the bulk value and decreases with the increasing temperature, which indicates the invalidity of the Wiedemann-Franz law for metallic nanofilms.

    DOI: 10.1080/10020070612331343248

  • Thermal and electrical properties of a suspended nanoscale thin film

    X. Zhang, H. Q. Xie, M. Fujii, H. Ago, K. Takahashi, T. Ikuta, H. Abe, T. Shimizu

    International Journal of Thermophysics   28 ( 1 )   33 - 43   2007年2月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    This paper reports on measurements of in-plane thermal conductivities, electrical conductivities, and Lorentz number of two microfabricated, suspended, nanosized thin films with a thickness of 28 nm. The effect of the film thickness on the in-plane thermal conductivity is examined by measuring other nanofilm samples with a thickness of 40 nm. The experimental results show that the electrical conductivity, resistance-temperature coefficient, and in-plane thermal conductivity of the nanofilms are much smaller than the corresponding bulk values from 77 to 330 K. However, the Lorentz number of the nanofilms is about two times that of the bulk value at room temperature, and even up to three times that of the bulk value at 77 K. These results indicate that the relation between the thermal conductivity and electrical conductivity of the nanofilms does not follow the Wiedemann-Franz law for bulk metallic materials. © Springer Science+Business Media, LLC 2007.

    DOI: 10.1007/s10765-006-0135-1

  • Microreactor utilizing a vertically-aligned carbon nanotube array grown inside the channels 査読

    Naoki Ishigami, Hiroki Ago, Koji Takahashi, Masaharu Tsuji

    Chemical Communications   ( 16 )   1626 - 1628   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Grain size and its effect on thermal conductivity of Pt nanofilms

    Bingyang Cao, Qingguang Zhang, Xing Zhang, Koji Takahashi, Tatsuya Ikuta, Wenming Qiao, Motoo Fujii

    Jinshu Xuebao/Acta Metallurgica Sinica   42 ( 11 )   1207 - 1211   2006年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Six Pt films with thicknesses of 15-62 nm have been fabricated by electron beam-physical vapor deposition (EB-PVD). The grain sizes of the Pt nanofilms and its effect on the thermal conductivity have been studied experimentally. It is found that the grain size increases with the nanofilm thickness increasing and goes to a constant about 20 nm. The grain size is nearly comparable with the nanofilm thickness with the thickness less than 30 nm, while becomes much less than the nanofilm thickness with the thickness larger than 30 nm. Influenced by the surface and grain boundary effects, the thermal conductivity of the Pt nanofilms is greatly lower than that of the Pt bulk. It is noted that the thermal conductivity of the studied platinum nanofilms increases with the thickness increasing and runs to 35 W/mK, which is much lower than that of the bulk material.

  • Measurements of thermal conductivity of individual carbon nanotubes

    Motoo Fujii, Xing Zhang, Koji Takahashi

    Physica Status Solidi (B) Basic Research   243 ( 13 )   3385 - 3389   2006年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    This paper describes a novel method to measure the thermal conductivity of individual carbon nanotubes (CNTs) by using a suspended sample-attached T-type nanosensor. The CNTs used were made by an arcdischarge evaporation method. We could successfully measure the thermal conductivity of individual carbon nanotubes in the range of temperature from 77 K to 320 K, and the results show that the thermal conductivity increases with the temperature and approaches an asymptote near 320 K. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.

    DOI: 10.1002/pssb.200669194

  • Influence of Grain Boundary Scattering on the Electrical and Tthermal Conductivities of Polycrystalline Gold Nanofilms

    Q. G. ZHANG, B. Y. CAO, X. ZHANG, M. FUJII, K. TAKAHASHI

    Phys. Rev. B   2006年10月

     詳細を見る

    Influence of Grain Boundary Scattering on the Electrical and Tthermal Conductivities of Polycrystalline Gold Nanofilms

  • Experimental study on thermal characteristics of suspended platinum nanofilm sensors

    Xing Zhang, Huaqing Xie, Motoo Fujii, Koji Takahashi, Tatsuya Ikuta, Hiroki Ago, Hidekazu Abe, Tetsuo Shimizu

    International Journal of Heat and Mass Transfer   49 ( 21-22 )   3879 - 3883   2006年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In this paper, the thermal characteristics of suspended platinum (Pt) nanofilm sensors have been investigated experimentally. The Pt nanofilm sensors with the thickness of 28-40 nm, the width of 260-601 nm, and the length of 5.3-5.7 μm were fabricated by electron beam lithography, electron beam physical vapor deposition and isotropic/anisotropic etching processes. Based on the one-dimensional heat conduction model, the in-plane thermal conductivity of the nanofilm sensors was obtained from the linear relation of the volume-averaged temperature increase and the heating rate measured in vacuum. Furthermore, natural convection heat transfer coefficients of air around the suspended nanofilm sensors at the pressures ranging from 1 × 10-2 Pa to 1 atm were also investigated. The experimental results show that the in-plane thermal conductivities of the nanofilm sensors are much lower than those of the bulk values, the natural convection heat transfer coefficients are, however, very high at the atmospheric pressure. © 2006 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijheatmasstransfer.2006.04.016

  • Size effects on the thermal conductivity of polycrystalline platinum nanofilms

    Q. G. Zhang, B. Y. Cao, X. Zhang, M. Fujii, K. Takahashi

    Journal of Physics Condensed Matter   18 ( 34 )   7937 - 7950   2006年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The surface and grain-boundary effects on the in-plane thermal conductivity of polycrystalline platinum nanofilms have been investigated. The thicknesses of the nanofilms range from 15.0 to 63.0nm and the mean grain sizes measured by x-ray diffraction vary from 9.5 to 26.4nm. The thermal conductivities of the nanofilms measured by a direct electrical heating method are greatly reduced from the bulk values. The measured results are compared with the values predicted by the Qiu and Tien model and the Kumar and Vradis theory. It is found that the reduction in the thermal conductivity is mainly caused by grain-boundary scattering and the reflection coefficient of electrons striking the grain boundaries is around 0.35. The relaxation time model is also applied to study the size effects to check whether the Matthiessen rule is still valid in predicting the in-plane thermal conductivity of polycrystalline metallic nanofilms. The results indicate that by considering only grain-boundary scattering and background scattering the Matthiessen rule is still valid. If surface scattering, however, is included, deviations of the Matthiessen rule from other theories mentioned above have been found. © 2006 IOP Publishing Ltd.

    DOI: 10.1088/0953-8984/18/34/007

  • Experimental studies on thermal and electrical properties of platinum nanofilms

    Xing Zhang, Qing Guang Zhang, Bing Yang Cao, Motoo Fujii, Koji Takahashi, Tatsuya Ikuta

    Chinese Physics Letters   23 ( 4 )   936 - 938   2006年4月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    We experimentally studied the in-plane thermal and electrical properties of a suspended platinum nanofilm in thickness of 15nm. The measured results show that the in-plane thermal conductivity, the electrical conductivity and the resistance-temperature coefficient of the studied nanofilm are much less than those of the bulk material, while the Lorenz number is greater than the bulk value. Comparing with the results reported previously for the platinum nanofilm in thickness of 28nm, we further find that the in-plane thermal conductivity, the electrical conductivity and the resistance-temperature coefficient decrease with the decreasing thickness of the nanofilm, while the Lorenz number increases with the decreasing thickness of the nanofilm. These results indicate that strong size effects exist on the in-plane thermal and electrical properties of platinum nanofilms. ©2006 Chinese Physical Society and IOP Publishing Ltd.

    DOI: 10.1088/0256-307X/23/4/048

  • Influence of grain boundary scattering on the electrical and thermal conductivities of polycrystalline gold nanofilms 査読

    Q. G. Zhang, B. Y. Cao, X. Zhang, M. Fujii, K. Takahashi

    Physical Review B - Condensed Matter and Materials Physics   74 ( 13 )   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The electrical and thermal conductivities of polycrystalline gold nanofilms have been measured simultaneously by a direct current heating method, and the measured results are compared with the Mayadas and Shatzkes theory. It is found that the reduced electrical and thermal conductivities of gold nanofilms are strongly dominated by grain boundary scattering. The reflection coefficient of electrons striking the grain boundaries for charge transport is 0.7, which agrees well with a previous scanning tunneling potentiometry study. The reflection coefficient for thermal transport, however, is only 0.25. The Lorenz numbers for the polycrystalline gold nanofilms, which are calculated from the measured electrical and thermal conductivities, are much greater than the value predicted by the Wiedemann-Franz law for the bulk material. The results indicate that the electron scatterings on the grain boundaries impose different influences on the charge and heat transport in the polycrystalline gold nanofilms. A model of effective density of conduction electrons has been utilized to interpret the violation of the Wiedemann-Franz law in polycrystalline gold nanofilms.

    DOI: 10.1103/PhysRevB.74.134109

  • Influence of grain boundary scattering on the electrical properties of platinum nanofilms 査読

    Q. G. Zhang, X. Zhang, B. Y. Cao, M. Fujii, K. Takahashi, T. Ikuta

    Applied Physics Letters   89 ( 11 )   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The electrical conductivity and temperature coefficient of resistance of polycrystalline platinum nanofilms have been investigated experimentally and theoretically. The results show that these electrical properties have been greatly reduced mainly by grain boundary scattering. By applying the theory of Mayadas and co-workers [Appl. Phys. Lett. 14, 345 (1969); Phys. Rev. B 1, 1382 (1970)] to predict the electrical conductivity and temperature coefficient of resistance with the same reflection coefficient, however, obvious discrepancies have been found. These discrepancies indicate that Drude's relation for bulk metals cannot be applied directly in the nanosized grain interior of polycrystalline metallic films.

    DOI: 10.1063/1.2338885

  • Porous silicon as a proton exchange membrane for micro fuel cells 査読

    Gyoko Nagayama, Naohiro Idera, Takaharu Tsuruta, Jing Rong Yu, Koji Takahashi, Michio Hori

    Electrochemistry   73 ( 11 )   939 - 941   2005年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    The porous silicon wafer filled with acid or Nafion was developed as a proton conduction membrane for micro fuel cells. The pores in size of 3 - 6 μm penetrated through the silicon wafer were prepared by anodic etching with back illumination. When the sulfuric solution or the Nafion solution sank the porous silicon substrate, it was assembled into the H2 / air feed fuel cell test section at ambient conditions using conventional electrodes. For the porous wafer filled with sulfuric solution of 10% and 20%, the open circuit voltages (OCV) of 0.932 V and 0.971 V were obtained and the maximum power density of 12.75 mW/cm2 was achieved. For the Nafion filled porous silicon wafer, an OCV of 0.892 V and a maximum power density of 1.27 mW/cm 2 were achieved.

    DOI: 10.5796/electrochemistry.73.939

  • Measuring the thermal conductivity of a single carbon nanotube

    Motoo Fujii, Xing Zhang, Huaqing Xie, Hiroki Ago, Koji Takahashi, Tatsuya Ikuta, Hidekazu Abe, Tetsuo Shimizu

    Physical Review Letters   95 ( 6 )   2005年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Although the thermal properties of millimeter-sized carbon nanotube mats and packed carbon nanofibers have been readily measured, measurements for a single nanotube are extremely difficult. Here, we report a novel method that can reliably measure the thermal conductivity of a single carbon nanotube using a suspended sample-attached T-type nanosensor. Our experimental results show that the thermal conductivity of a carbon nanotube at room temperature increases as its diameter decreases, and exceeds 2000W/mK for a diameter of 9.8 nm. The temperature dependence of the thermal conductivity for a carbon nanotube with a diameter of 16.1 nm appears to have an asymptote near 320 K. The present method is, in principle, applicable to any kind of a single nanofiber, nanowire, and even single-walled carbon nanotube. © 2005 The American Physical Society.

    DOI: 10.1103/PhysRevLett.95.065502

  • Thermal and electrical conductivity of a suspended platinum nanofilm

    Xing Zhang, Huaqing Xie, Motoo Fujii, Hiroki Ago, Koji Takahashi, Tatsuya Ikuta, Hidekazu Abe, Tetsuo Shimizu

    Applied Physics Letters   86 ( 17 )   1 - 3   2005年4月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    This letter reports on the measurements of the in-plane thermal conductivity and the electrical conductivity of a microfabricated, suspended, nanosized platinum thin film with the width of 260 nm, the thickness of 28 nm, and the length of 5.3 μm. The experimental results show that the electrical conductivity, the resistance-temperature coefficient and the in-plane thermal conductivity of the nanofilm are greatly lower than the corresponding bulk values from 77 to 330 K. The comparison results indicate that the relation between the thermal conductivity and the electrical conductivity of this nanofilm might not follow the Wiedemann-Franz law that describes the relation between the thermal conductivity and the electrical conductivity of a bulk metallic material. © 2005 American Institute of Physics.

    DOI: 10.1063/1.1921350

  • MEMS技術と宇宙用推進機 招待 査読

    高橋厚史

    日本航空宇宙学会誌   2004年10月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    MEMS Technology and Space Propulsion

  • 超小型人工衛星用液体燃料型マイクロスラスタの熱流体現象 査読

    尾崎靖彦、高橋厚史

    電気学会論文誌E   2003年10月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    Microfluidics of liquid propellant microthruster for pico-satellites
    Yasuhiko Osaki, Koji Takahashi
    IEEJ Transactions on Sensors and Micromachines, Vol.123, No.10, pp.436-441, 2003

  • Fabrication of a microevaporator equipped with a piezoelectrically-driven diaphragm pump

    Ken Ichiro Sotowa, Daigo Miyagawa, Guibing Zhao, Katsuki Kusakabe, Shigeharu Morooka, Koji Takahashi

    Journal of Chemical Engineering of Japan   36 ( 1 )   7 - 13   2003年1月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    An evaporator unit for use in microreactor systems was constructed. The unit consisted of a micropump driven by piezoelectricity and a microevaporator heated electrically by means of a Pt wire. The micropump was comprised of two tightly bonded plates; a silicon (100) plate having three diaphragms and a glass plate having valve and pump chambers. These flow conduits were patterned by photolithography and formed by wet-etching. The diaphragms, as well as the valve and pump chambers, were 7 mm in diameter, and were arranged triangularly. The discharge rates of the pumps were found to be dependent on the voltage and frequency applied to the piezo discs, the actuation pattern, the backpressure at the outlet, and the liquid viscosity. The pump assembled with an epoxy adhesive showed high discharge rates, while a similar one, assembled by anodic bonding, showed high discharge pressures. The flow rate of the former pump reached 60 ml/min for water. The microevaporator channel was wet-etched on a 10 mm × 40 mm silicon wafer, and a channel for a Pt wire heater was formed on the reverse side. Both sides of the silicon plate were covered with glass plates. Benzene, when pumped to the microevaporator, was evaporated to give a vapor flow rate of 6.8 cm3/min, which is sufficiently large as a feed rate for a gas-phase catalytic microreactor.

    DOI: 10.1252/jcej.36.7

  • マイクロチャンネル中での気液界面のダイナミクスに関する数値解析 査読

    古賀光、土井原良次、高橋厚史

    日本機械学会論文集B編   2002年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  • Numerical study on gas-liquid interface in a microchannel

    Kou Koga, Ryoji Doihara, Koji Takahashi

    Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   68 ( 669 )   1344 - 1351   2002年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    A bubble or droplet can be driven in a microchannel due to the thermocapillary force controlled by microheaters, which comes from the surface tension imbalance. Though practical optical switches based on this principle have been developed by micromachining technique, there has been no contribution of fluid dynamics both experimentally and analytically. In order to treat gas-liquid interface accurately in a microchannel, it is necessary to improve the models of surface tension and contact angle. A new numerical scheme is developed based on C-CUP and Level-Set function method with CSF model and is able to calculate the surface tension distribution precisely. It is the first time to simulate the thermally-driven bubble in a microchannel and the obtained results show good agreements with experimental results qualitatively. Comparisons with the conventional numerical schemes and fundamental mechanisms of the thermally-driven interfaces are also discussed.

    DOI: 10.1299/kikaib.68.1344

  • 簡易型ピエゾ駆動式マイクロポンプの試作研究 査読

    生田竜也, 高橋厚史

    九州大学工学集報, 第74巻, 第6号   2001年11月

     詳細を見る

    掲載種別:研究論文(大学,研究機関等紀要)  

  • チップ成型とスラスタヘの応用

    高橋 厚史

    日本ガスタービン学会誌   29 ( 4 )   262 - 265   2001年7月

     詳細を見る

    記述言語:日本語  

    MEMS Fabrication and Micro thruster

  • Numerical calculation of laser-produced bubble near a solid boundary until the second collapse

    R. Doihara, K. Takahashi

    JSME International Journal, Series B: Fluids and Thermal Engineering   44 ( 2 )   238 - 246   2001年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The violent motion of cavitation bubble near a solid boundary is treated by a newly developed numerical code based on the CIP (Cubic Interpolated Propagation) method. This is the first study to successfully simulate the repetitive collapses and rebounds of bubbles with the penetration of microjets until the second collapse while maintaining toroidal shape. The obtained gas-liquid interfaces show similar tendency to bubble shapes observed in past experimental studies, although phase change, surface tension and viscosity are neglected. The key factor of this flow field is the density difference between gas and liquid. The velocity of microjet and resulting water hammer pressure are calculated successfully. However no shock wave appears from the collapsed bubbles in the present study, which suggests that an appropriate model for highly-compressed gas is important for tempestuous two-phase flow. This study indicates a high possibility of using the Euler-type numerical code to calculate such complicated two-phase problems and also suggests which factor is dominant in the cavitation bubble dynamics.

    DOI: 10.1299/jsmeb.44.238

  • 気泡を用いたマイクロモーター

    高橋 厚史

    ながれ : 日本流体力学会誌   20 ( 2 )   92 - 98   2001年4月

     詳細を見る

    記述言語:日本語  

    Micro Motor Using Micro Bubbles

    DOI: 10.11426/nagare1982.20.92

  • Micro-isolation valve for fuel tank array

    Koji Takahashi, Kunihito Nagayama, Tetsuo Yasaka, Tanemasa Asano

    2001 ASME International Mechanical Engineering Congress and Exposition ASME International Mechanical Engineering Congress and Exposition, Proceedings   2   2845 - 2850   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(その他学術会議資料等)  

    Isolation valve system for low-cost liquid tank array is designed and demonstrated. This valve is normally closed and opens only once for liquid injection. This array system can supply precise amount of liquid at each operation as many times as the number of tanks. In order to tolerate the ambient high pressure and to accomplish the perfect injection, a large and thick membrane is fabricated and tested as valve. Without any special structure, our valves are found to open just by applying low AC voltage to a pair of electrodes that are apart from each other by tens of micrometers. Dielectric breakdown and pressure increase inside tank are found to work effectively to form a large hole.

  • Molecular Dynamics in Microscale Thermophysical Engineering 査読 国際誌

    Chou, F. C., J. R. Lukes, X. G. Liang, K. Takahashi, and C. L. Tien

    Annual Review of Heat Transfer   1999年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Marangoni effect in microbubble systems

    Koji Takahashi, Jian Gang Weng, Chang Lin Tien

    Microscale Thermophysical Engineering   3 ( 3 )   169 - 182   1999年8月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    This work explores the application of the Marangoni effect in micro systems involving small gas or vapor bubbles in a liquid environment subjected to a temperature gradient. The Marangoni effect characterizes the variation of surface tension along the bubble surface resulting from the temperature gradient around the bubble, thus driving the bubble toward the higher temperature region. This phenomenon is more pronounced as the bubble becomes smaller and the temperature gradient becomes steeper, both of which can be achieved in microbubble systems. Potential applications based on the Marangoni effect include linear bubble actuators, dynamic microvalves, and hot-spot locators. The optimum bubble size for these applications is expected to be of the order of 10 μ m. A smaller bubble may be difficult to introduce into the working system and maintain its size. Presented for illustration is a feasibility analysis for both a noncondensable gas bubble and a vapor bubble situated above a microheater. The analysis yields results for the temperature field around the bubble surface and the Marangoni driving pressure, which is a key element of the performance evaluation for all Marangoni-effect-based applications. The findings demonstrate clearly that the Marangoni effect on microbubbles is very significant and shows great promise for applications in microelectromechanical systems (MEMS). © 1999 Taylor … Francis Group, LLC.

    DOI: 10.1080/108939599199729

  • Marangoni effect in microbubble systems 査読

    Koji Takahashi, Jian Gang Weng, Chang Lin Tien

    Microscale Thermophysical Engineering   3 ( 3 )   169 - 182   1999年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    This work explores the application of the Marangoni effect in micro systems involving small gas or vapor bubbles in a liquid environment subjected to a temperature gradient. The Marangoni effect characterizes the variation of surface tension along the bubble surface resulting from the temperature gradient around the bubble, thus driving the bubble toward the higher temperature region. This phenomenon is more pronounced as the bubble becomes smaller and the temperature gradient becomes steeper, both of which can be achieved in microbubble systems. Potential applications based on the Marangoni effect include linear bubble actuators, dynamic microvalves, and hot-spot locators. The optimum bubble size for these applications is expected to be of the order of 10 μ m. A smaller bubble may be difficult to introduce into the working system and maintain its size. Presented for illustration is a feasibility analysis for both a noncondensable gas bubble and a vapor bubble situated above a microheater. The analysis yields results for the temperature field around the bubble surface and the Marangoni driving pressure, which is a key element of the performance evaluation for all Marangoni-effect-based applications. The findings demonstrate clearly that the Marangoni effect on microbubbles is very significant and shows great promise for applications in microelectromechanical systems (MEMS).

    DOI: 10.1080/108939599199729

  • Atomic force microscope study of carbon thin films prepared by pulsed laser deposition

    Tsuyoshi Yoshitake, Takashi Nishiyama, Hajime Aoki, Koji Suizu, Koji Takahashi, Kunihito Nagayama

    Applied Surface Science   141 ( 1-2 )   129 - 137   1999年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Amorphous carbon films and diamond like carbon films were grown by pulsed laser deposition (PLD) using different laser wavelengths (λ=193 nm, 532 nm, 1064 nm) and substrate temperatures (from room temperature to 500°C). The morphology of the film surface was observed using an atomic force microscope (AFM) and a scanning electron microscope (SEM). Mechanisms for film growth are explained qualitatively using the subplantation model. All films showed the occasional incorporation of spherical particles with a diameter of 1-10 μm ejected from the targets due to surface being melted.

    DOI: 10.1016/S0169-4332(98)00601-1

  • アメリカンドリーム型学長との楽しい日々 : 外国滞在を機に新しい研究を始める方法

    高橋 厚史

    伝熱研究 = News of HTSJ   38 ( 149 )   20 - 21   1999年3月

     詳細を見る

    記述言語:日本語  

    Personal Memory of Stay in Chancellor's Laboratory : How to start new topics in USA

  • The effects of substrate temperature and laser wavelength on the formation of carbon thin films by pulsed laser deposition

    Tsuyoshi Yoshitake, Takashi Nishiyama, Hajime Aoki, Koji Suizu, Koji Takahashi, Kunihito Nagayama

    Diamond and Related Materials   8 ( 2-5 )   463 - 467   1999年3月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Amorphous carbon films and diamond-like carbon films were grown by pulsed laser deposition (PLD) using different laser wavelengths (λ=193, 532 and 1064 nm) and substrate temperatures (ranging from room temperature to 500 °C). The morphology of the film surface was observed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The mechanisms of film growth using laser wavelengths of 1064, 532 and 193 nm are explained qualitatively to be surface growth, subsurface growth accompanied with migration of the penetrating species to the film surface, and subsurface growth, respectively, using the subplantation model.

    DOI: 10.1016/s0925-9635(98)00348-3

  • Molecular Dynamics in Microscale Thermophysical Engineering 査読

    J. R. Lukes, Xingang Liang, Koji Takahashi, Chang Lin Tien

    Annual Review of Heat Transfer   10   141 - 176   1999年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1615/AnnualRevHeatTransfer.v10.60

  • Computational Fluid Dynamics of Collapsing Bubble with Micro-jet 査読

    Koji Takahashi

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   64 ( 625 )   2874 - 2879   1998年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  • Time intervals of the cavitation bubble's collapse near a free surface 査読

    Satoshi Mohri, Ryoji Doihara, Koji Takahashi, Kunihito Nagayama

    Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B   64 ( 625 )   2897 - 2901   1998年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Cavitation bubbles induced by pulsed laser near a free surface have been investigated experimentally and numerically. The successive pressure waves from them and their vertical migrations and volume change were measured by using hydrophone and high-speed streak camera. The characteristics of the first and second rebound times due to the distance from the free surface enable us to guess the mechanisms of bubble collapse with microjet. Because our new scheme by CIP method is successfully applicable for such two-phase flow, the comparison between experimental and numerical results is also very useful to understand the fundamental factor of the complicated phenomena of cavitation bubbles.

    DOI: 10.1299/kikaib.64.2897

  • CIP法によるキャビテーション気泡の非定常流動解析

    土井原 良次, 毛利 哲, 高橋 厚史

    九州大学工学集報   70 ( 6 )   555 - 561   1997年11月

     詳細を見る

    記述言語:その他  

    Numerical Analysis on Unsteady Motion of Cavitation Bubble by CIP Method

  • Analysis of aerodynamic noise by distributed monopole method

    Koji Takahashi, Shojiro Kaji

    JSME International Journal, Series B: Fluids and Thermal Engineering   39 ( 1 )   86 - 100   1996年2月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    Aerodynamic acoustic problems near plate edges are treated by a new method based on the linear theory. For sound radiation and generation problems, we can calculate one of the half acoustic fields divided by semi-infinite plates by determining the distributions of the acoustic monopoles. Some numerical calculations confirm the validity of this distributed monopole method. Applying this method, we can impose the Kutta condition explicitly at the trailing edge and explain the feedback mechanism in terms of sound wave effects on the flow field. The generation of vorticity waves at the trailing edge due to the incident sound wave is calculated and the possibility of self-excited tones between the trailing edge and the leading edge is verified. The relationship obtained is the same as that of the edge tone phenomenon, and the necessary amplification of the vortex during its convection for the sound to become self-excited is quantified.

    DOI: 10.1299/jsmeb.39.86

  • Optical Measurement of Sound Field by Laser Differential Interferometry 査読

    Koji Takahashi

    可視化情報学会誌 = Journal of the Visualization Society of Japan   16   119 - 122   1996年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Laser differential interferometry using two laser beams of perpendicular polarization is applied to sound pressure measurements. The weak density difference due to the sound wave no more than 70dB between the two beams is measurable in proportional to the differential output signal of the two photo detecters. Both steady and transient sound wave signals are obtained by our interferometer as clearly as by microphone. Acoustic vibration of the optical systems and the way of sound visualization in future are also discussed.

  • Observations of bubble motions and distortions by streak camera

    Koji Takahashi, S. Mohri, K. Nishihara, Y. Mori, S. Hatano, K. Nagayama

    Proceedings of SPIE - The International Society for Optical Engineering   2513   35 - 39   1995年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(その他学術会議資料等)  

    © 1995 SPIE. Air bubbles are observed at the moment of there emergence from a vertical nozzle in water. We can classify them into two types by formation process. The bubbles broken off from a large air bulk always emit sound pulses, but those not being split but keeping their initial volume hardly produce any sound. By comparing their motions and distortions not only by means of the sequential series of photographs but also by the streak photographs of the vertical linear portion of the axisymmetric bubble, we obtain the difference of the subtle distortion of their surface which causes the emission of sound pulse.

    DOI: 10.1117/12.209625

  • 分布monopole法による空力騒音の解析

    高橋 厚史, 梶 昭次郎

    日本機械学会論文集 B編   59 ( 567 )   p3466 - 3474   1993年11月

     詳細を見る

    記述言語:日本語  

    Aerodynamic acoustic problems near plate edges are treated by a new method based on the linear theory. For sound radiation and generation problems, we can calculate one of the half acoustic fields divided by semi-infinite plates by determining the distributions of the acoustic monopoles. Some numerical calculations confirm the validity of this distributed monopole method. Applying this method, we can impose the Kutta condition explicitly at the trailing edge and explain the feedback mechanism in terms of sound wave effects on the flow field. The generation of vorticity waves at the trailing edge due to the incident sound wave is calculated and the possibility of self-excited tones between the trailing edge and the leading edge is verified. The relationship obtained is the same as that of the edge tone phenomenon, and the necessary amplification of the vortex during its convection is quantified for the sound to become self-excited.

  • Analytical study on plate edge noise (noise generation from tandemly situated trailing and leading edges)

    Koji Takahashi, Shojiro Kaji

    JSME International Journal, Series B: Fluids and Thermal Engineering   36 ( 2 )   214 - 221   1993年5月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    The problem of noise generation due to the interaction between flows and plate edges is treated analytically. In uniform flow containing vorticity waves, two semi-infinite flat plates are placed with the trailing edge of one plate and leading edge of the other being tandemly situated a finite distance apart. This flow is considered to be a simplified model for self-excited tones such as edge tone and cavity noise. An approximate solution to the sound pressure is obtained by the Wiener-Hopf technique, and the calculated acoustic field shows the characteristics of the trailing edge noise and the leading edge noise. The sound pressure level varies with peaks and troughs as the wave number increases, especially in the region upstream from both edges, and these peaks show a frequency dependence similar to edge tones. Such a selective response mechanism will be explained by the phase relationship between vortex and sound.

    DOI: 10.1299/jsmeb.36.214

  • Analytical study on plate edge noise. (Trailing edge noise caused by vorticity waves)

    Koji Takahashi, Shojiro Kaji

    JSME International Journal, Series 2: Fluids Engineering, Heat Transfer, Power, Combustion, Thermophysical Properties   34 ( 4 )   431 - 438   1991年11月

     詳細を見る

    記述言語:その他   掲載種別:研究論文(学術雑誌)  

    An analysis is performed on the trailing edge noise which is one of the important mechanisms of noise generation in flow machines. An acoustic field is treated where a semi-infinite flat plate is placed parallel to the inviscid uniform flow with incident vorticity waves convected from the upstream direction. Applying the Wiener-Hopf technique, we obtain an exact solution to the sound pressure proportional to the amplitude of the incident vorticity wave without restriction of frequency or velocity. The calculated acoustic field, which varies with flow velocity, exhibits general features of the sound pressure level (SPL) in a cardioid pattern with the constant phase surface distorted by the main flow. The relationship between flow velocity and SPL is ascertained to be dependent on the 5th law at low Mach numbers. However, the results show that such dependence does not hold at higher Mach numbers where the radiated noise level rises progressively as the flow velocity increases.

    DOI: 10.1299/jsmeb1988.34.4_431

  • Analytical study on plate edge noise. (Trailing edge noise caused by vorticity waves) 査読

    Koji Takahashi, Shojiro Kaji

    JSME International Journal, Series 2: Fluids Engineering, Heat Transfer, Power, Combustion, Thermophysical Properties   34 ( 4 )   431 - 438   1991年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    An analysis is performed on the trailing edge noise which is one of the important mechanisms of noise generation in flow machines. An acoustic field is treated where a semi-infinite flat plate is placed parallel to the inviscid uniform flow with incident vorticity waves convected from the upstream direction. Applying the Wiener-Hopf technique, we obtain an exact solution to the sound pressure proportional to the amplitude of the incident vorticity wave without restriction of frequency or velocity. The calculated acoustic field, which varies with flow velocity, exhibits general features of the sound pressure level (SPL) in a cardioid pattern with the constant phase surface distorted by the main flow. The relationship between flow velocity and SPL is ascertained to be dependent on the 5th law at low Mach numbers. However, the results show that such dependence does not hold at higher Mach numbers where the radiated noise level rises progressively as the flow velocity increases.

    DOI: 10.1299/jsmeb1988.34.4_431

▼全件表示

書籍等出版物

  • マイクロ・ナノ熱工学の進展

    高橋厚史・塘陽子(分担執筆)(担当:共著)

    エヌ・ティー・エス  2021年5月 

     詳細を見る

    記述言語:日本語   著書種別:学術書

    Advances in micro/nano thermal engineering

  • Thermometry at the Nanoscale: Techniques and Selected Applications

    Koji Takahashi(担当:共著)

    Royal Society of Chemistry  2015年10月 

     詳細を見る

    担当ページ:Chapter 11: Nanotubes Thermometry   記述言語:英語   著書種別:一般書・啓蒙書

    カーボンナノチューブを用いて表面温度をナノスケールで計測する技術について解説した。

  • ナノ・マイクロスケール熱物性ハンドブック

    髙橋 厚史(担当:共著)

    養賢堂  2014年6月 

     詳細を見る

    記述言語:日本語   著書種別:学術書

  • マイクロ・ナノ熱流体ハンドブック

    高橋厚史(分担執筆)(担当:共著)

    エヌ・ティー・エス  2006年1月 

     詳細を見る

    担当ページ:pp. 412-422   記述言語:日本語   著書種別:学術書

    Handbook of Micro/Nano Scale Thermo Fluids

  • “図解ナノテク活用技術のすべて”微細加工でポンプをつくる

    高橋厚史(担当:共著)

    工業調査会  2002年1月 

     詳細を見る

    担当ページ:p.204-207   記述言語:日本語   著書種別:一般書・啓蒙書

    ZUKAI NANOTECH KATSUYO GIJUTU NO SUBETE

講演・口頭発表等

  • Crack Propagation Mechanism of Freeze-Dried Soybean Curds during the Rehydration Process

    Mai HIRAKAWA, Hideaki TESHIMA, Tatsuya IKUTA, Koji TAKAHASHI

    APS DFD 2023  2023年11月 

     詳細を見る

    開催年月日: 2023年11月

    記述言語:英語  

    国名:その他  

  • Three-Dimensional Observation of Three-Phase Contact Line with Precursor Film on Nanostructured Surfaces

    H. Teshima, T. Ueno, K. Takahashi

    APS DFD 2023  2023年11月 

     詳細を見る

    開催年月日: 2023年11月

    記述言語:英語  

    国名:その他  

  • DEVELOPMENT OF AFM MEASUREMENT METHOD FOR SLIP LENGTH CONSIDERING THE EFFECT OF ELECTRIC DOUBLE LAYER FORCE

    H. Ishida H. Teshima, K. Takahashi

    The 8th International Conference on Micro and Nano Flows  2023年9月 

     詳細を見る

    開催年月日: 2023年9月

    記述言語:英語  

    国名:その他  

  • Thermally induced mass transfer between nanobubbles and micropancakes

    Hideaki Teshima, Qin-Yi Li, Koji Takahashi

    The 8th International Conference on Micro and Nano Flows  2023年9月 

     詳細を見る

    開催年月日: 2023年9月

    記述言語:英語  

    国名:その他  

  • Slip flow and capillary evaporation in graphene nanochannels

    Qin-Yi Li, Kun Cheng, Kuan-Ting Cheng, Koji Takahashi

    6th International Conference on Droplets  2023年8月 

     詳細を見る

    開催年月日: 2023年8月

    記述言語:英語  

    国名:その他  

  • Experimental Investigation of Solid-Liquid Interfacial Phenomena at the Nanoscale 招待

    Hideaki Teshima, Koji Takahashi

    10th US-Japan Joint Seminar on Nanoscale Transport Phenomena  2023年7月 

     詳細を見る

    開催年月日: 2023年7月

    記述言語:英語  

    国名:その他  

  • Nanomaterials for phase change heat transfer 招待 国際会議

    Koji Takahashi

    13th Asian Thermophysical Properties Conference (ATPC2022), September 26-30, 2022, Sendai, Japan  2022年9月 

     詳細を見る

    開催年月日: 2022年9月

    記述言語:英語   会議種別:口頭発表(招待・特別)  

    開催地:Online   国名:その他  

    Nanomaterials are of unique thermophysical properties and have been used in a wide variety of experimental studies aimed at significant enhancement of heat transfer performance. Many successful results have been reported, for example, selective thermal radiation of surface coatings with nanoparticles, high-thermal conductivity composites or coolants with nanoscale fillers. So far, most of their roles are to improve the conduction or radiation heat transfer. On the other hand, their applications to improve mass transfer are still in the stage of trial and error. The most well-known application is to use hydrophilic materials for preventing surface dryout at high heat flux but the underlying mechanisms of capillary motion and evaporation in nanoscale are not clarified yet, thus we have no strategy to precisely control the liquid-vapor phase change by designing artificial nanostructured surfaces. In this talk, a novel approach to enhance the convection in the evaporating meniscus on a hot surface is introduced, where the atomic-scale flatness of two-dimensional materials represented by graphene is used. Its beneficial role is the large slip length of liquid on the surface. In addition to the reviews of past reports, new experimental and theoretical results are presented for evaluating the slip flow on graphene, together with the relationship between wettability and slip length of an identical surface. The gap between ideal thermophysical property of nanomaterials and real performance of heat transfer devices is also discussed. At first, the above-mentioned surface of atomic-scale flatness is mostly dirty with contaminants and nanoparticles, which pin the three-phase contact lines and consequently influence the cooling performance. Newest nanoscale findings on the pinned or unpinned contact lines using AFM and TEM are summarized in this talk. Next, the thermal contact resistance between fibrous materials is treated, which is a difficult research target for thermal application of nanomaterials. An experimental method is presented to quantitatively evaluate the contact resistance using Raman spectroscopy. The last concern is the quality of nanomaterials and a STEM-based experimental study clearly demonstrated that the thermal conductivity of an individual nanotube depends on its structural quality. The history of nanotechnology is over 20 years but these kinds of experimental studies are still needed to increase the reliability of heat transfer devices with nanomaterials and nanostructures.

  • 固液界面の顕微観察の現状と課題 招待

    高橋厚史

    第59回日本伝熱シンポジウム  2022年5月 

     詳細を見る

    開催年月日: 2022年5月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    開催地:岐阜市   国名:日本国  

  • Gas molecules at solid-liquid interfaces 招待 国際会議

    Koji Takahashi

    The 7th International Conference on Micro and Nano Flows (MNF 2021)  2021年5月 

     詳細を見る

    開催年月日: 2021年5月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Online   国名:その他  

    その他リンク: https://www.micronanoflows.com/mnf2021

  • Towards reliable cooling technology from nanoscale transport phenomena 招待 国際会議

    Koji Takahashi

    I2CNER THRUST WORKSHOP: SCIENCE AND TECHNOLOGY FOR CARBON-NEUTRALITY  2021年1月 

     詳細を見る

    開催年月日: 2021年1月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Online   国名:その他  

  • Morphology of Water inside CNTs Depending on Wettability 国際会議

    @Yoko Tomo, #Ryo Matsushita, @Qin-Yi Li, @Tatsuya Ikuta, @Koji Takahashi

    The Second Pacific Rim Thermal Engineering Conference (PRTEC2019)  2019年12月 

     詳細を見る

    開催年月日: 2019年12月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Maui   国名:アメリカ合衆国  

  • Mobility of Micropancakes on Adsorbed Gas Layers 国際会議

    #Hideaki Teshima, #Naoto Nakamura, @Yasuyuki Takata, @Koji Takahashi

    The Second Pacific Rim Thermal Engineering Conference (PRTEC2019)  2019年12月 

     詳細を見る

    開催年月日: 2019年12月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Maui   国名:アメリカ合衆国  

  • Nanoscale observation of three-phase contact line using graphene liquid cells 国際会議

    #Sota Hirokawa, #Hideaki Teshima, @Pablo Solis Fernandez, @Hiroki Ago, @Qinyi Li, @Koji Takahashi

    The 30th International Symposium on Transport Phenomena (ISTP30)  2019年11月 

     詳細を見る

    開催年月日: 2019年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Halong   国名:ベトナム社会主義共和国  

    Revealing nanoscale dynamics of three-phase contact line promotes practical application such as nano-channels and micro heat transfer devices. However, there are still many unexplained phenomena that are obstacles to establish precise models. Thus, in order to expand knowledge of three-phase contact line, further investigation near the phase interfaces are desirable. In this study, we used liquid cell electron microscopy that enables us to investigate in-situ liquid dynamics with nanoscale spatial resolution. We prepared graphene liquid cells that give the highest resolution in liquid cells and observed three-phase contact line consisting of confined water and nanobubbles in real time using transmission electron microscopy (TEM). In our samples, nanobubbles, smaller than a few hundred nanometers in diameter, scattered around and thin water rings surrounded them. During the observation for several tens of seconds, nanobubbles deformed their shapes, which allowed us to see the movements of three-phase contact line. We elucidated the mechanism of this movement by considering the influences of electron beam irradiation on water and the graphene layers.

  • Record-high Thermoelectric Performance of Graphene 国際会議

    @Qinyi Li, Toshiaki Kato, Xiulin Ruan, @Koji Takahashi

    The 12th Asian Thermophysical Properties Conference (ATPC2019)  2019年10月 

     詳細を見る

    開催年月日: 2019年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Xi'an   国名:中華人民共和国  

  • Water confined in hydrophilic and hydrophobic inner spaces of cup-stacked carbon nanotubes 国際会議

    @Koji Takahashi, @Yoko Tomo, #Ryo Matsushita, @Tatsuya Ikuta, @Qin-Yi Li

    30th International Conference on Diamond & Carbon Materials 2019  2019年9月 

     詳細を見る

    開催年月日: 2019年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Seville   国名:スペイン  

  • TEM and AFM studies of bubble nucleation and growth near solid-liquid interfaces 招待 国際会議

    @Koji Takahashi

    2019 Micro and Nanoscale Phase Change Heat Transfer, Gordon Research Conference  2019年2月 

     詳細を見る

    開催年月日: 2019年2月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Lucca   国名:イタリア共和国  

    New experimental techniques to investigate nanoscale bubbles and droplets are explained, using TEM and AFM. AFM is of the highest spatial resolution and its feedback control of tip tapping enables us to obtain the accurate shape of nanobubbles at the solid-liquid interface. TEM requires ultra-high vacuum environment but utilization of nano liquid cell enables us to image the liquid-gas interface in nanoscale. By using these techniques, some key issues for generation and growth of interfacial nanobubbles have been understood.

  • Nanomaterials and Nanobubles for Heat Transfer 招待 国際会議

    @Koji Takahashi

    6th UK Japan Engineering Education League Workshop 2018  2018年9月 

     詳細を見る

    開催年月日: 2018年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Fukuoka   国名:日本国  

  • BUBBLES AND DROPLETS AT THE INITIAL STAGE OF NUCLEATION: RECENT ADVANCES IN EXPERIMENTAL TECHNIQUES 招待 国際会議

    @Koji Takahashi

    16th International Heat Transfer Conference  2018年8月 

     詳細を見る

    開催年月日: 2018年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Beijing   国名:中華人民共和国  

  • Interfacial Nanobubbles on Biphilic Surfaces 招待 国際会議

    @Koji Takahashi

    ASME 2018 16th International Conference on Nanochannels, Microchannels and Minichannels (ICNMM2018)  2018年6月 

     詳細を見る

    開催年月日: 2018年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Dubrovnik   国名:クロアチア共和国  

  • Thermophysical measurement methods for individual nanomaterials and control of nanoscale thermal transport 招待 国際会議

    @Koji Takahashi, @Qinyi Li, Xing Zhang

    2018 I2CNER Annual Symposium: challenges in thermal science towards a sustainable society  2018年1月 

     詳細を見る

    開催年月日: 2018年1月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Fukuoka   国名:日本国  

  • Experimental Approach to Control the Thermal Conductivity of Single-Layer Graphene by Fluorination 国際会議

    #Masahiro Narasaki, Haidong Wang, Yasuyuki Takata, Tatsuya Ikuta, Koji Takahashi

    ASME 2017 International Mechanical Engineering Congress and Exposition  2017年11月 

     詳細を見る

    開催年月日: 2017年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Tampa   国名:アメリカ合衆国  

  • Direct Observation of Heterogeneous Bubble Nucleation in Nanoscale 国際会議

    #Yoko Tomo, Koji Takahashi, Tatsuya Ikuta, Yasuyuki Takata

    ASME International conference on nanochannels, microchannels, and minichannels  2017年8月 

     詳細を見る

    開催年月日: 2017年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Boston   国名:アメリカ合衆国  

  • Dual-mode Raman method to measure thermal transport properties of 2D materials and van der Waals heterostructures 国際会議

    Li Q Y, Zhang X, Takahashi K

    The 9th US-Japan Joint Seminar on Nanoscale Transport Phenomena  2017年7月 

     詳細を見る

    開催年月日: 2017年7月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Tokyo   国名:日本国  

  • AFM and TEM studies on nanobubbles 招待 国際会議

    Koji Takahashi

    The 9th US-Japan Joint Seminar on Nanoscale Transport Phenomena  2017年7月 

     詳細を見る

    開催年月日: 2017年7月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Tokyo   国名:日本国  

  • Thermal Transport of Fluorinated Single-Layer Graphene 国際会議

    #Masahiro Narasaki, Haidong Wang, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    The 9th World Conference on Experimental Heat Tranfer, Fluid Mechanics and Thermodynamics  2017年6月 

     詳細を見る

    開催年月日: 2017年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Foz do Iguacu   国名:ブラジル連邦共和国  

  • EXPERIMENTAL STUDY ON THE COALESCENCE OF INTERFACIAL NANOBUBBLES 国際会議

    Hideaki Teshima, Takashi Nishiyama, Koji Takahashi

    The 27th International Symposium on Transport Phenomena  2016年9月 

     詳細を見る

    開催年月日: 2016年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • THERMAL TRANSPORT IN MULTI-WALLED CARBON NANOTUBE AND CARBON NANOFIBER DEFECTED BY FOCUSED ION BEAM 国際会議

    Masahiro Narasaki, Jin Miyawaki, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    The 27th International Symposium on Transport Phenomena  2016年9月 

     詳細を見る

    開催年月日: 2016年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • TEM Study on Phase Change in a Nano Liquid Cell 国際会議

    Yoko Tomo, Koji Takahashi, Takashi Nishiyama, Tatsuya Ikuta, Yasuyuki Takata

    5th Micro and Nano Flows Conference  2016年9月 

     詳細を見る

    開催年月日: 2016年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Milan   国名:イタリア共和国  

  • Experimental Study of Nanobubbles and Nanodroplets on Hydrophilic/Hydrophobic Combined Surfaces 招待 国際会議

    Koji Takahashi, Yasuyuki Takata, Takashi Nishiyama, 山田 寛

    12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT2016)  2016年7月 

     詳細を見る

    開催年月日: 2016年7月

    記述言語:英語   会議種別:口頭発表(招待・特別)  

    開催地:Costa del Sol   国名:スペイン  

  • IN SITU THERMAL CONDUCTANCE MEASUREMENT OF AN INDIVIDUAL CARBON NANOFIBER DEFECTED BY FOCUSED ION BEAM 国際会議

    Masahiro Narasaki, Koji Takahashi, Jin Miyawaki, Yasuyuki Takata

    7th European Thermal-Sciences Conference, EUROTHERM 2016  2016年6月 

     詳細を見る

    開催年月日: 2016年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Krakow   国名:ポーランド共和国  

  • Boiling Heat Transfer Enhancement with Hydrophobic Islands at Sub-Atmospheric Pressures 国際会議

    #Masayuki Yamada, Biao Shen, #Hongbin He, #Kento Furutsato, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

    The First Pacific Rim Thermal Engineering Conference  2016年3月 

     詳細を見る

    開催年月日: 2016年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • Stability of intefacial nanobubble depends on substrate 国際会議

    #Ayumu Iwanaga, Takashi Nishiyama, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, Yutaka Yamada

    The First Pacific Rim Thermal Engineering Conference  2016年3月 

     詳細を見る

    開催年月日: 2016年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • Electron Thermal Microscopy of Suspended MWCNT 国際会議

    #Seigo Nakajima, #Kazuma Nomoto, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    The First Pacific Rim Thermal Engineering Conference  2016年3月 

     詳細を見る

    開催年月日: 2016年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • Surface Wettability Tuning for Submicron-Scale Condensation and Evaporation 国際会議

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata, @Khellil Sefiane

    The First Pacific Rim Thermal Engineering Conference  2016年3月 

     詳細を見る

    開催年月日: 2016年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • Uncovering the Potential of CNTS as Nano- Heat Pipes 国際会議

    Alexandros Askounis, Yutaka Yamada, Tatsuya Ikuta, Koji Takahashi, Yasuyuki Takata, @Khellil Sefiane

    The First Pacific Rim Thermal Engineering Conference  2016年3月 

     詳細を見る

    開催年月日: 2016年3月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii   国名:アメリカ合衆国  

  • MEASURING THE THERAL CONTACT RESISTANCE WITHOUT SURFACE ROUGHNESS 国際会議

    Koji Takahashi, Yusuke Kuwada, Tatsuya Ikuta

    The 26th International Symposium on Transport Phenomena  2015年9月 

     詳細を見る

    開催年月日: 2015年9月 - 2015年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Leoben   国名:オーストリア共和国  

  • Generation and Metastability of Interfacial Nanobubbles 招待 国際会議

    Koji Takahashi, Takashi Nishiyama, Yasuyuki Takata

    14th UK Heat Transfer Conference 2015  2015年9月 

     詳細を見る

    開催年月日: 2015年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Edinburgh   国名:グレートブリテン・北アイルランド連合王国(英国)  

  • Experimental study on thermal transport of an artificially-defected multi-walled carbon nanotube 国際会議

    Masahiro Narasaki, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    XXIV International Materials Research Congress  2015年8月 

     詳細を見る

    開催年月日: 2015年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Cancun   国名:メキシコ合衆国  

  • Temperature Mapping on a Suspended Carbon Nanotube Using Electron Thermal Microscopy 国際会議

    Koji Takahashi, Kazuma Nomoto, Tatsuya Ikuta

    IEEE NANO 2015, 15th INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY  2015年7月 

     詳細を見る

    開催年月日: 2015年7月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Roma   国名:イタリア共和国  

  • SUBMICRON-SCALE WETTABILITY CONTROL BY USING FOCUSED ION BEAM IRRADIATION TO FOPA-SAM 国際会議

    Koji Takahashi, Yutaka Yamada, Takashi Nishiyama, Tatsuya Ikuta, Yasuyuki Takata

    International Symposium on Micro and Nano Technology, ISMNT-5  2015年5月 

     詳細を見る

    開催年月日: 2015年5月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Calgary   国名:カナダ  

  • HYDROPHOBIC-HYDROPHILIC SURFACE PATTERNED BY FIB TO REVEAL NUCLEATION MECHANISMS 国際会議

    Yutaka Yamada, Koji Takahashi, Yasuyuki Takata

    9th International Conference on Boiling and Condensation Heat Transfer  2015年4月 

     詳細を見る

    開催年月日: 2015年4月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Boulder, Colorado   国名:アメリカ合衆国  

  • Reliability of AFM Measurement of Nanobubbles on Solid Liquid Interface 国際会議

    Koji Takahashi, Takashi Nishiyama, Yutaka Yamada, Yasuyuki Takata

    Gordon Research Conference Micro & Nanoscale Phase Change Heat Transfer  2015年1月 

     詳細を見る

    開催年月日: 2015年1月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Galveston   国名:アメリカ合衆国  

  • Thermal Resistance of van der Waals Contacts for Nanoscale Thermometry 招待 国際会議

    Koji Takahashi, Yutaka Yamada, Takashi Nishiyama, Tatsuya Ikuta

    Material Science and Engineering (MSE 2014)  2014年9月 

     詳細を見る

    開催年月日: 2014年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Darmstadt   国名:ドイツ連邦共和国  

  • Study on heat conduction of defective MWNT using focused ion beam irradiation 国際会議

    Masahiro Narasaki, Hiroyuki Hayashi, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    20th European Conf. Thermophysical Properties (ECTP2014)  2014年9月 

     詳細を見る

    開催年月日: 2014年8月 - 2014年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Porto   国名:ポルトガル共和国  

  • Wettability-driven water condensation in micron- and submicron-scale 国際会議

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    15th International Heat Transfer Conference (IHTC-15)  2014年8月 

     詳細を見る

    開催年月日: 2014年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Kyoto   国名:日本国  

  • Experimental Investigation of Nanodroplets and nanobubbles 招待 国際会議

    Koji Takahashi, Yutaka Yamada, Takashi Nishiyama, Yasuyuki Takata

    8th US-Japan Joint Seminar on Nanoscale Transport Phenomena  2014年6月 

     詳細を見る

    開催年月日: 2014年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Santa Cruz, CA   国名:アメリカ合衆国  

  • Characterization of Thermal Transport in Multiwalled Carbon Nanotube Using FIB Irradiation 国際会議

    Koji Takahashi, Hiroyuki Hayashi

    Fourteenth InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 201  2014年5月 

     詳細を見る

    開催年月日: 2014年5月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Florida   国名:アメリカ合衆国  

  • Growth and Coalescence of Condensed Microdroplets on Graphite Surface 国際会議

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    5th International Conference on HEAT TRANSFER AND FLUID FLOW IN MICROSCALE  2014年4月 

     詳細を見る

    開催年月日: 2014年4月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Marseille   国名:フランス共和国  

  • Experimental Study on Thermal Contact Resistance of Multi-Walled Carbon Nanotubes 国際会議

    Kazunari Tsuru, Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass  2013年12月 

     詳細を見る

    開催年月日: 2013年12月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Hong Kong   国名:中華人民共和国  

  • Submicron Scale Condensation on Hydrophobic and Hydrophilic Surfaces 国際会議

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

    ASME 2013 International Mechanical Engineering Congress & Exposition (IMECE2013)  2013年11月 

     詳細を見る

    開催年月日: 2013年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:San Diego   国名:アメリカ合衆国  

  • Microfabrication techniques for nanoscale heat transfer 招待 国際会議

    Koji Takahashi

    The 4th International Symposium on Micro and Nano Technology (ISMNT-4)  2013年10月 

     詳細を見る

    開催年月日: 2013年10月

    記述言語:英語   会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:Shanghai   国名:中華人民共和国  

  • Anisotropic Thermal Transport and Metrological Application of Multiwalled Carbon Nanotube 招待 国際会議

    Koji Takahashi

    The 10th Asian Thermophysical Properties Conference (ATPC2013)  2013年10月 

     詳細を見る

    開催年月日: 2013年9月 - 2013年10月

    記述言語:英語   会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:Jeju   国名:大韓民国  

  • Fluctuating Electromagnetics for Thermal Contact Conductance 国際会議

    Juo Amano, Koji Takahashi

    8th International Conference on Surfaces, Coatings and NanoStructured Materials (NANOSMAT)  2013年9月 

     詳細を見る

    開催年月日: 2013年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Granada   国名:スペイン  

  • Experimental Study on Heat Conduction in a Defected Multi-walled Carbon Nanotube 国際会議

    Koji Takahashi, Hiroyuki Hayashi, Masahiro Narasaki, Tatsuya Ikuta, Takashi Nishiyama

    8th International Conference on Surfaces, Coatings and NanoStructured Materials (NANOSMAT)  2013年9月 

     詳細を見る

    開催年月日: 2013年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Granada   国名:スペイン  

  • Experimental Techniques using Nano Hot-film for Micro/Nanoscale Heat Transfer 招待 国際会議

    Koji Takahashi

    ASME 11th Int. Conf Nanochannels, Microchannels, Minichannels  2013年6月 

     詳細を見る

    開催年月日: 2013年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Sapporo   国名:日本国  

  • Experimental characterization of heat conduction in multi-walled carbonnanotubes 国際会議

    Hiroyuki Hayashi, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    2013 MRS Spring Meeting & Exhibit  2013年4月 

     詳細を見る

    開催年月日: 2013年4月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:San Francisco   国名:アメリカ合衆国  

  • Quantitative Evaluation of Carbon Nanotube Fin for Chip Cooling 国際会議

    Yutaka Yamada, Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    23rd International Symposium on Transport Phenomena  2012年11月 

     詳細を見る

    開催年月日: 2012年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Auckland   国名:ニュージーランド  

  • Carbon Nanotube Temperature Profiler using Platinum Hot Film 国際会議

    Juo Amano, Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    23rd International Symposium on Transport Phenomena  2012年11月 

     詳細を見る

    開催年月日: 2012年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Auckland   国名:ニュージーランド  

  • Individual Measurement of Thermal Conductivity of Damaged MWCNT 国際会議

    Hiroyuki Hayashi, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    3rd International Forum on Heat Transfer  2012年11月 

     詳細を見る

    開催年月日: 2012年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Nagasaki   国名:日本国  

  • Thermal Boundary Resistance of Nanoscale van der Waals Contacts between a Carbon Nanotube End and Solid Surfaces 国際会議

    Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    3rd International Forum on Heat Transfer  2012年11月 

     詳細を見る

    開催年月日: 2012年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Nagasaki   国名:日本国  

  • Thermal Contact Resistance Between Defective Multi-Walled Carbon Nanotubes 国際会議

    Koji Takahashi, Yutaka Yamada, Takashi Nishiyama

    International Conference on Diamond and Carbon Materials  2012年9月 

     詳細を見る

    開催年月日: 2012年9月

    会議種別:口頭発表(一般)  

    開催地:Granada   国名:スペイン  

  • Effect of Nanoscale Stracture on Thermal Contact Resistance of Carbon Nanotubes 国際会議

    Yutaka Yamada, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    ASME 2012 Summer Heat Transfer Conference  2012年7月 

     詳細を見る

    開催年月日: 2012年7月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Rio Grande, Puerto Rico   国名:アメリカ合衆国  

  • Thermal Conductivity of Partially-Amorphized Individual Carbon Nanotube 国際会議

    Hiroyuki Hayashi, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    EIGHTEENTH SYMPOSIUM ON THERMOPHYSICAL PROPERTIES  2012年6月 

     詳細を見る

    開催年月日: 2012年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Boulder, CO   国名:アメリカ合衆国  

  • APPLICATIONS OF NANO HOT-FILM SENSOR FOR MICRO/NANOSCALE THERMAL MEASURMENT 国際会議

    Koji Takahashi, Jun Hirotani, Takashi Nishiyama, Tatsuya Ikuta, Hiroshi Takamatsu

    ASME 2012 3rd Micro/Nanoscale Heat & Mass Transfer International Conference  2012年3月 

     詳細を見る

    開催年月日: 2012年3月

    会議種別:口頭発表(一般)  

    開催地:Atlanta   国名:アメリカ合衆国  

  • Carbon nanotube thermal probe 招待 国際会議

    Koji Takahashi

    7th US-Japan Joint Seminar on Nanoscale Transport Phenomena - Science and Engineering -  2011年12月 

     詳細を見る

    開催年月日: 2011年12月

    会議種別:口頭発表(一般)  

    開催地:Shima   国名:日本国  

  • EXPERIMENTAL STUDY ON THE THERMAL BOUNDARY RESISTANCE BETWEEN AN INDIVIDUAL CARBON NANOTUBE END AND A AU SURFACE 国際会議

    Jun Hirotani, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi

    ASME 2011 International Mechanical Engineering Congress and Exposition (IMECE2011)  2011年11月 

     詳細を見る

    開催年月日: 2011年11月

    会議種別:口頭発表(一般)  

    開催地:Denver   国名:アメリカ合衆国  

  • ナノ熱ダイオード素子の計測方法の開発

    伊藤洋平、高橋厚史、藤井丕夫、張興

    日本機械学会熱工学コンファレンス2007  2007年11月 

     詳細を見る

    開催年月日: 2007年11月

    国名:日本国  

  • 単一のSiCナノワイヤの熱伝導率測定

    高橋厚史、伊藤洋平、生田竜也、西山貴史、張興、藤井丕夫

    日本機械学会熱工学コンファレンス2007  2007年11月 

     詳細を見る

    開催年月日: 2007年11月

    国名:日本国  

  • ナノ材料の熱物性測定のためのNEMS技術

    高橋厚史、伊藤洋平、生田竜也、永山邦仁、藤井丕夫、張興

    第28回日本熱物性シンポジウム  2007年10月 

     詳細を見る

    開催年月日: 2007年10月

    開催地:札幌   国名:日本国  

  • 単一SiCナノワイヤの熱伝導率計測

    伊藤洋平、高橋厚史、生田竜也、西山貴史、永山邦仁、藤井丕夫

    第68回応用物理学会秋季学術講演会  2007年9月 

     詳細を見る

    開催年月日: 2007年9月

    開催地:札幌   国名:日本国  

  • カーボンナノチューブによるNEMS流体センサーの高感度化

    樋口琢、伊藤洋平、山田陽一、生田竜也、高橋厚史

    第44回日本伝熱シンポジウム  2007年5月 

     詳細を見る

    開催年月日: 2007年5月

    会議種別:口頭発表(一般)  

    開催地:長崎   国名:日本国  

    Study on NEMS fluidic sensor using carbon nanotubes

  • アモルファスカーボンナノ構造体に関する実験的研究

    高橋厚史、ノルシャズワン、甲斐聡、生田竜也、西山貴史、永山邦仁、藤井丕夫

    第44回日本伝熱シンポジウム  2007年5月 

     詳細を見る

    開催年月日: 2007年5月

    会議種別:口頭発表(一般)  

    開催地:長崎   国名:日本国  

    Experimental Study on Amorphous Carbon Nanostructure

  • SILICON-FREE MICRO RESITOR ARRAY FOR SMART HOT FILM 国際会議

    Koji Takahashi

    The 1st International Symposium on Micro & Nano Technology  2004年3月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:ハワイ   国名:アメリカ合衆国  

    SILICON-FREE MICRO RESITOR ARRAY FOR SMART HOT FILM Koji Takahashi The 1st International Symposium on Micro & Nano Technology, 14-17 March, 2004, Honolulu, Hawaii, USA, 2004

  • HEAT CONDUCTION OF SILICON DIOXIDE THIN FILM LAYERS FOR MEMS THRUSTER 国際会議

    Hideyo Ebisuzaki, Xing Zhang, Motoo Fujii and Koji Takahashi

    The 1st International Symposium on Micro & Nano Technology  2004年3月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:ハワイ   国名:アメリカ合衆国  

    HEAT CONDUCTION OF SILICON DIOXIDE THIN FILM LAYERS FOR MEMS THRUSTER Hideyo Ebisuzaki, Xing Zhang, Motoo Fujii and Koji Takahashi The 1st International Symposium on Micro & Nano Technology, 14-17 March, 2004, Honolulu, Hawaii, USA, 2004

  • POROUS SILICON AS A SUPERHYDROPHOBIC MICROCHANNEL SURFACE 国際会議

    Koji Takahashi

    The 1st International Symposium on Micro & Nano Technology  2004年3月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:ハワイ   国名:アメリカ合衆国  

    POROUS SILICON AS A SUPERHYDROPHOBIC MICROCHANNEL SURFACE Koji Takahashi The 1st International Symposium on Micro & Nano Technology, 14-17 March, 2004, Honolulu, Hawaii, USA, 2004

  • DDNPのマイクロ燃焼に関する実験的研究

    岡田貴洋 山田吉徳 生田竜也 永山邦仁 高橋厚史

    第十回日本機械学会動力エネルギーシンポジウム  2005年6月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:長崎   国名:日本国  

  • マイクロチャンネルに適した気体加熱システムに関する研究

    梶原勇人 高橋厚史

    日本機械学会動力エネルギーシンポジウム  2005年6月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:長崎  

  • マイクロ流体デバイス用ナノ熱線センサの開発

    伊藤洋平、高橋厚史

    第22回「センサ・マイクロマシンと応用システム」シンポジウム  2005年10月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:東京  

  • 自励振動型マイクロヒートパイプの熱輸送特性

    西薗 崇,大仲 泰憲,日高 澄具,河野 正道,高橋 厚史,高田 保之

    第43回日本伝熱シンポジウム  2006年5月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:名古屋   国名:日本国  

  • ジュール・トムソン型マイクロ冷凍機の基礎研究

    藤井 智明,須加原 光喜,立川 孝幸,久保田 裕己,河野 正道,高橋 厚史,高田 保之

    第43回日本伝熱シンポジウム  2006年5月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:名古屋   国名:日本国  

  • ナノ流体センサの製作とDSMC解析

    伊藤洋平, 高橋厚史

    第43回日本伝熱シンポジウム  2006年5月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:名古屋   国名:日本国  

  • 金ナノ薄膜面方向の熱伝導率および電気伝導度の測定

    田中 秀治,高橋 厚史,生田 竜也,張 清光,曹 炳陽,張 興,藤井 丕夫

    第43回日本伝熱シンポジウム  2006年5月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:名古屋   国名:日本国  

  • Optical study of the SWNT dispersion after dielectrophoresis 国際会議

    M. Shinagawa, H. Ago, N. Ishigami, M. Tsuji, T. Ikuta, K. Takahashi

    Nanotube 2006  2006年6月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:Nagano   国名:日本国  

    Optical study of the SWNT dispersion after dielectrophoresis

  • サファイア基板上における単層カーボンナノチューブの位置と方向の同時制御に関する研究

    大堂良太,吾郷浩樹,品川 直嗣,上原 直保,辻正治,生田 竜也,高橋 厚史

    第43回化学関連支部 合同九州大会  2006年7月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:北九州   国名:日本国  

  • 垂直配向カーボンナノチューブを組み込んだマイクロリアクター

    石神直樹,吾郷浩樹,本山幸弘,高崎幹大,品川直嗣,高橋厚史,辻正治

    第43回化学関連支部 合同九州大会  2006年7月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:北九州   国名:日本国  

  • CONTEMPORARY TECHNOLOGY AND APPLICATION OF MEMS ROCKET 招待 国際会議

    Koji Takahashi

    CANEUS 2006 Conference on Micro-Nano-Technologies for Aerospace Applications  2006年8月 

     詳細を見る

    会議種別:口頭発表(一般)  

    開催地:Toulouse   国名:フランス共和国  

    CONTEMPORARY TECHNOLOGY AND APPLICATION OF MEMS ROCKET

  • 超微細フィンを持つナノ熱線センサーの数値解析

    樋口琢、高橋厚史

    日本機械学会 2006年度年次大会  2006年9月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:熊本市   国名:日本国  

    Numerical Study on Nano Thermal Sensor with Ultra Fine Fins

  • Catalytic Porous Microchannel for hydrogen Peroxide MEMS Thruster 招待

    K. Takahashi, T. Ikuta, Y. Dan, K. Nagayama, M. Kishida

    The 23rd Sensor Symposium  2006年10月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:takamatsu   国名:日本国  

    Catalytic Porous Microchannel for hydrogen Peroxide MEMS Thruster

  • Study on Local Heat Transfer of Nano Fluidic Sensor

    K. Takahashi, T. Higuchi, Y. Ito, T. Ikuta, K. Nagayama

    The 23rd Sensor Symposium  2006年10月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:takamatsu   国名:日本国  

    Study on Local Heat Transfer of Nano Fluidic Sensor

  • Development Study of 100?m-order Solid Rocket for Pico Satellite Application 国際会議

    K. Takahashi, T. Ikuta, T. Okada, K. Nagayama

    PowerMEMS 2006  2006年11月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:Berkeley   国名:アメリカ合衆国  

    Development Study of 100?m-order Solid Rocket for Pico Satellite Application

  • カーボンナノチューブをフィンとする超高感度熱式センサーに関する研究

    樋口琢、山田陽一、高橋厚史

    日本航空宇宙学会西部支部講演会(2006)  2006年11月 

     詳細を見る

    会議種別:シンポジウム・ワークショップ パネル(公募)  

    開催地:福岡市   国名:日本国  

    Research for Ultrasensitive Thermal Sensor with CNT Fins

  • ナノ空間における気泡の変形と核生成の観察

    廣川颯汰, 手嶋秀彰, Pablo Solís Fernández, 吾郷弘樹, 塘陽子, 李秦宜, 生田竜也, 高橋厚史

    第57回日本伝熱シンポジウム  2020年6月 

     詳細を見る

    記述言語:その他  

    国名:その他  

  • その場TEM観察によるナノバブル生成における温度依存性の研究

    ナグ サルタック, 正覚雄善, 用正大地, 李秦宜, 生田竜也, 高橋厚史, 河野正道

    第57回 日本伝熱シンポジウム  2020年6月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    In-situ electron microscopic study of effect of temperature on nanobubble generation

  • Nanobubble dynamics studied using in-situ liquid cell electron microscopy

    Sarthak Nag, Yuzen Masame, Tatsuya Ikuta, Qin-Yi Li, Koji Takahashi, Masamichi Kohno

    2020年7月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    Nanobubble dynamics studied using in-situ liquid cell electron microscopy

  • 純水中の高配向性グラファイト表面に吸着した気体分子について

    手嶋秀彰, 高田保之, 高橋厚史

    混相流シンポジウム2020  2020年8月 

     詳細を見る

    記述言語:その他  

    国名:その他  

  • Raman optothermal methods to measure interfacial thermal conductance of low-dimensional materials

    Qin-Yi Li, Koji Takahashi

    2020年9月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    Raman optothermal methods to measure interfacial thermal conductance of low-dimensional materials

  • Raman optothermal methods to measure interfacial thermal conductance of low-dimensional materials

    Qin-Yi Li, Koji Takahashi

    2020年9月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    Raman optothermal methods to measure interfacial thermal conductance of low-dimensional materials

  • Non-diffusive molecular transport in graphene liquid cells

    Sota Hirokawa, Hideaki Teshima, Pablo Solís Fernández, Hiroki Ago, Yoko Tomo, Qin Yi Li, Koji Takahashi

    第59回 フラーレン・ナノチューブ・グラフェン総合シンポジウム  2020年9月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    Non-diffusive molecular transport in graphene liquid cells

  • 透過型電子顕微鏡を用いた三相界線ピニングのナノスケール観察

    廣川颯汰, 手嶋秀彰, Pablo Solís Fernández, 吾郷弘樹, 李秦宜, 高橋厚史

    熱工学コンファレンス2020  2020年10月 

     詳細を見る

    記述言語:その他  

    国名:その他  

  • 先行液膜を介した凝縮マイクロ液滴の自発移動

    手嶋秀彰, Misra Sirshendu, 高橋厚史, Mitra Sushanta

    日本機械学会熱工学コンファレンス2020  2020年10月 

     詳細を見る

    記述言語:その他  

    国名:その他  

  • ナノバルブ合体挙動の液中TEM観察

    ナグ サルタック, 正覚雄善, 生田竜也, 李秦宜, 高橋厚史, 河野正道

    日本機械学会 熱工学コンファレンス2020  2020年10月 

     詳細を見る

    記述言語:その他  

    国名:その他  

    Nanobubble dynamics during merging revealed using in-situ liquid cell electron microscopy

  • TEMを用いたナノバブルの温度応答に関する実験的研究

    正覚 雄善, Sarthak Nag, 塘 陽子, 李 秦宜, 生田 竜也, 河野 正道, 髙橋 厚史

    化学とマイクロ・ナノシステム学会  2020年10月 

     詳細を見る

    記述言語:その他  

    国名:その他  

▼全件表示

MISC

  • 水のナノスケール直接観察手法について (特集 熱流体の可視化計測)

    塘 陽子, 髙橋 厚史

    伝熱 = Journal of the Heat Transfer Society of Japan   2019年10月

     詳細を見る

    記述言語:日本語  

    In Situ Nanoscale Observation of Water Using TEM

  • 水のナノスケール直接観察手法について

    塘 陽子、高橋厚史

    伝熱   2019年10月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

    In Situ Nanoscale Observation of Water Using TEM

  • 固液界面ナノバブルの実験について

    高橋厚史、手嶋秀彰

    伝熱   2018年4月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

    固液界面ナノバブルとは固体と液体の界面に存在する厚さが5-100 nm程度,直径が約1 m以下の気相のことで,潤滑や洗浄をはじめとして固液界面が存在する多くの研究分野でその存在の有無や影響が議論されてきた.これまでに,目に見えるマクロな気泡とは異なる性質を持っているらしいことはわかってきたが全ての実験結果を説明できる統一的な理論は未だに存在していない.沸騰現象との関連も非常に興味深いのだが,液中を漂うマイクロバブル・ナノバブルに比べると国内における認知度は低く研究例はいまだ少ない.そこで本稿では,伝熱の研究者・技術者に少しでも興味を持ってもらうために,これまでに報告された固液界面ナノバブルの特性・生成方法・計測方法・理論について紹介する.

  • C222 ナノ粒子の相変化を利用した透過型電子顕微鏡内でのナノスケール温度分布計測

    野本 一真, 生田 竜也, 西山 貴史, 高橋 厚史

    熱工学コンファレンス講演論文集   2014年11月

     詳細を見る

    記述言語:日本語  

    Micro/nanoscale temperature measurement is a key technique to understand the thermal transport of nanomaterials. In this work, we treat nanoscale temperature distribution of individual MWCNT using a transmission electron microscope (TEM) and phase transition of metal nanoparticles. Nanoparticles are deposited on an individual CNT which bridges between Pt electrodes and are heated by Joule heating. Metal nanoparticles reach them melting point, and contrast change occurs in TEM images because of liquid-solid transition. Temperature distribution can be obtained as below or above the melting point. Spatial resolution depends on the size of nanoparticle and it's about 100nm.

  • C221 周波数変調原子間力顕微鏡を用いた固液界面ナノバブル計測

    西山 貴史, 高橋 厚史, 高田 保之

    熱工学コンファレンス講演論文集   2014年11月

     詳細を見る

    記述言語:日本語  

    Highly-stable nanoscale gas domains that called nanobubbles and micropancakes at the solid-liquid interfaces have been widely studied for over a decade. On the other hand, boiling is applied to many industrial machines due to its high heat transfer coefficient. However, a very complex mechanism of boiling, especially bubble nucleation, is still not sufficiently understood. In the present study we adopted the high sensitivity atomic force microscopy measurement mode, frequency modulation atomic force microscope (FM-AFM), to investigate the influence of the solid-liquid interface nanobubbles on the bubble nucleation of boiling. It revealed the presence of very thin 0.1-0.6 nm thickness gas-phase that is different from the conventional nanobubbles.

  • 20pm3-PM020 集束イオンビームを用いたフォノン熱伝導の実験的研究

    楢崎 将弘, 高橋 厚史, 生田 竜也, 西山 貴史, 林 浩之, 高田 保之

    マイクロ・ナノ工学シンポジウム   2014年10月

     詳細を見る

    記述言語:日本語  

    We conducted an experiment to investigate phonon thermal conduction in multi-walled carbon nanotube. Length dependence of thermal conductivity of a multi-walled carbon nanotube up to 10 μm is reported by applying quasi-ballistic thermal conduction model for experimentally obtained thermal conductance. We suggest that phonon thermal conduction in this length is still in ballistic or quasi-ballistic region. Experimental equipment used for this experiment are T-type sensor for thermal conductance measurement, focused ion beam (FIB) irradiation to control the sample length and phonon free path, and transmission electron microscopy (TEM) to evaluate the size and uniformity of the defects induced by FIB irradiation.

  • G114 固液界面ナノバブルの形成および成長過程に関する研究(OS-7:マイクロ・ナノ熱工学(1))

    西山 貴史, 高橋 厚史, 高田 保之

    熱工学コンファレンス講演論文集   2013年10月

     詳細を見る

    記述言語:日本語  

    Boiling is applied to many industrial machines due to its high heat transfer coefficient. However, a very complex mechanism of boiling, especially bubble nucleation, is still not sufficiently understood. On the other hand, numerous experiments have revealed the existence of soft domains that called nanobubbles at the solid-liquid interface. In this study, to investigate the influence of the solid-liquid interface nanobubbles on the bubble nucleation of boiling, an atomic force microscope is used to characterize the morphology of nanobubbles. The temperature dependence of the nanobubbles and temporal changes are also observed.

  • C215 ESEMを用いたグラファイト面上の液滴凝縮過程に関する研究(OS-9:沸騰・凝縮伝熱および混相流の最近の展開(3))

    山田 寛, 草場 彰, 生田 竜也, 西山 貴史, 高橋 厚史, 高田 保之

    熱工学コンファレンス講演論文集   2013年10月

     詳細を見る

    記述言語:日本語  

    Heat transfer performance of dropwise condensation is higher than filmwise one due to droplet removal from the condensed surface. In order to further enhancement of its performance, removal of microscale droplet is a key issue. However, condensation mechanism at microscale on hydrophobic-hydrophilic hybrid surface is not understood, although all surfaces are consisted with those combinations. In this study, we conducted condensation experiments on a graphite surface at 0℃ and 550 to 600 Pa by using environmental scanning electron microscope (ESEM). Nanoscale step-terrace structures on graphite surface are obtained by using an atomic force microscope (AFM) before ESEM experiments. It was found that condensed droplets with diameter of 150 to 300 nm are lined up along step edges at over 150 nm intervals. In addition, we found that most droplets are on the steps of height of 1 nm and shorter droplet intervals are induced by higher steps and shorter terrace width. Our results were analyzed by an extended nucleation theory and we found that water molecules attracted on steps play an important role for droplet condensation.

  • B121 カーボンナノチューブ-周囲気体間の熱伝達に関する実験的研究(OS-6:マイクロ・ナノ熱工学(2))

    廣谷 潤, 山田 寛, 生田 竜也, 西山 貴史, 高橋 厚史

    熱工学コンファレンス講演論文集   2012年11月

     詳細を見る

    記述言語:日本語  

    Carbon nanotubes (CNTs) have high intrinsic thermal conductivity and high surface-to-volume ratio, thus CNT-based fins is considered to be promising for hign performance device cooling. In addition, exploring the heat transfer between a CNT and gases is important not only for CNT-based gas sensors but also for scientific interest oi mterfacial heat transport. In this work, we have developed novel technique for measuring heat transfer coefficients between an individual carbon nanotube and surrounding gases (Air, N_2, Ar, He) using platinum hot film sensor. Measured heat transfer coefficients quantitatively show good agreement with estimated values by kinetic gas theory at atmospheric pressure but do not match with theoretical prediction at low pressure regime.

  • ナノ材料における熱伝導

    高橋厚史、藤井丕夫

    化学と教育   2011年10月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • G33 100nmオーダーのチューブ内におけるイオン液体界面の観察(G3マイクロ・ナノ熱工学I)

    中山 教憲, 高橋 厚史, 生田 竜也, 西山 貴史

    日本機械学会九州支部講演論文集   2011年3月

     詳細を見る

    記述言語:日本語  

    G33 Observation of ionic liquid interface in a nanotube

  • ナノ材料の熱物性計測

    高橋厚史、藤井丕夫

    伝熱 日本伝熱学会   2009年1月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • CANEUS2004会議報告とナノテクの牽引役について

    上森規光、高橋厚史

    日本航空宇宙学会誌   2005年6月

     詳細を見る

    記述言語:日本語   掲載種別:機関テクニカルレポート,技術報告書,プレプリント等  

    Report on CANEUS2004

  • 欧米におけるマイクロ・ナノ技術の航空宇宙分野への応用最前線

    高橋厚史

    航空と宇宙 日本航空宇宙工業会会報   2005年3月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • 懸架白金薄膜面方向の熱伝導率および電気伝導度の測定

    張 興, 謝 華清, 藤井 丕夫, 高橋 厚史, 吾郷 浩樹, 清水 哲夫, 阿部 秀和

    熱物性 : Japan journal of thermophysical properties   2005年1月

     詳細を見る

    記述言語:英語  

    Measurements of In-Plane Thermal Conductivity and Electrical Conductivity of Suspended Platinum Thin Film

  • MEMSのトレンドと微小気泡のダイナミクス

    高橋厚史

    混相流   2002年1月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

    Trends in MEMS and Dynamics of Microbubble, KONSORYU, Vol. 16, No. 3, PP198-206

  • 小さなスケールの熱・流れ現象:気泡を用いたマイクロモーター

    高橋厚史

    ながれ(日本流体力学会誌), 第20巻, 第2号, pp.92-98, 2001年4月   2001年4月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • ガスタービンの超小型化に向けて:チップ成形とスラスタへの応用

    高橋厚史

    日本ガスタービン学会誌   2001年4月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

    Microfabrication and Application to Thruster

  • マイクロスケールの非一様温度場中の単一気泡の挙動

    高橋厚史

    日本機械学会熱工学部門ニュースレター, 30号, pp.11-12, 2000   2000年9月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • マランゴニ効果を用いたマイクロアクチュエーター

    高橋厚史, 永山邦仁, 浅野種正

    応用物理, 第69巻, 第6号, pp.676-679, 2000   2000年6月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

  • レーザーアブレーション法によるカーボン薄膜の作成とその評価

    吉武 剛, 西山 貴史, 青木 肇, 水津 光司, 高橋 厚史, 永山 邦仁

    電気学会論文誌. A, 基礎・材料・共通部門誌 = The transactions of the Institute of Electrical Engineers of Japan. A, A publication of Fundamentals and Materials Society   1999年8月

     詳細を見る

    記述言語:日本語  

    Carbon Thin Films Prepared by Pulsed Laser Deposition

▼全件表示

産業財産権

特許権   出願件数: 4件   登録件数: 1件
実用新案権   出願件数: 0件   登録件数: 0件
意匠権   出願件数: 0件   登録件数: 0件
商標権   出願件数: 0件   登録件数: 0件

所属学協会

  • 日本顕微鏡学会

  • 日本航空宇宙学会

  • 日本熱物性学会

  • 日本機械学会

  • 応用物理学会

  • 日本伝熱学会

▼全件表示

委員歴

  • 日本機械学会   評議員   国内

    2023年4月 - 2024年3月   

  • 日本機械学会   熱工学部門長   国内

    2023年4月 - 2024年3月   

  • 日本伝熱学会   理事   国内

    2022年5月 - 2023年5月   

  • 日本機械学会   運営委員   国内

    2015年4月 - 2016年3月   

  • 日本機械学会   熱工学部門表彰委員会委員長   国内

    2015年4月 - 2016年3月   

  • 日本伝熱学会   理事   国内

    2013年5月 - 2015年5月   

▼全件表示

学術貢献活動

  • 実行委員長

    第60回日本伝熱シンポジウム  ( 福岡市 ) 2023年5月

     詳細を見る

    種別:大会・シンポジウム等 

  • 議長 国際学術貢献

    The 6th International Symposium on Micro and Nano Technology  ( Fukuoka Japan ) 2017年3月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:160

  • 実行委員 国際学術貢献

    The 11th Asian Thermophysical Properties Conference (ATPC 2016)  ( Yokohama Japan ) 2016年10月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:300

  • 国際委員 国際学術貢献

    The First Pacific Rim Thermal Engineering Conference  ( Hawaii UnitedStatesofAmerica ) 2016年3月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:500

  • 実行委員会副委員長

    第52回日本伝熱シンポジウム  ( 福岡 ) 2015年6月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:700

  • 組織委員 国際学術貢献

    The 5h International Symposium on Micro and Nano Technology  ( Calgary Canada ) 2015年5月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

  • 技術委員 国際学術貢献

    The 5th International Conference on Heat Transfer and Fluid Flow in Microscale  ( Marseille France ) 2014年4月 - 現在

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

  • 技術委員 国際学術貢献

    PowerMEMS2011  ( Seoul Korea ) 2011年11月 - 現在

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:200

  • 事務局長 国際学術貢献

    The 4th International Conference on Heat Transfer and Fluid Flow in Microscale  ( Fukuoka Japan ) 2011年9月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

  • 組織委員 国際学術貢献

    ASME⁄JSME 2011 8th Thermal Engineering Joint Conference  ( Hawaii UnitedStatesofAmerica ) 2011年3月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:400

  • 組織委員

    第31回日本熱物性シンポジウム  ( 福岡市 ) 2010年11月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:150

  • 技術委員 国際学術貢献

    PowerMEMS2010  ( Leuven Belgium ) 2010年11月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:200

  • 技術委員 国際学術貢献

    PowerMEMS2009  ( Washington DC UnitedStatesofAmerica ) 2009年11月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:150

  • 論文委員 国際学術貢献

    27th ISTS  ( つくば ) 2009年7月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:500

  • 技術委員 国際学術貢献

    PowerMEMS2008  ( Sendai Japan ) 2008年11月 - 現在

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:150

  • 論文委員 国際学術貢献

    26th ISTS  ( 浜松 ) 2008年6月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:500

  • 技術委員 国際学術貢献

    PowerMEMS2006  ( Berkeley, CA UnitedStatesofAmerica ) 2006年11月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

  • 技術委員 国際学術貢献

    CANEUS 2006  ( Toulouse France ) 2006年8月 - 2006年6月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:300

  • 論文委員 国際学術貢献

    25th ISTS  ( 金沢 ) 2006年6月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:500

  • 組織委員 国際学術貢献

    Second International Conference on Transport Phenomena in Micro and Nanodevices  ( Barga Italy ) 2006年5月 - 2006年6月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

  • 技術委員 国際学術貢献

    PowerMEMS2005  ( 東京 ) 2005年11月

     詳細を見る

    種別:大会・シンポジウム等 

    参加者数:100

▼全件表示

共同研究・競争的資金等の研究課題

  • 固気液三相接触線の未踏学理

    2024年4月 - 2028年3月

      詳細を見る

    担当区分:研究代表者 

  • 固気液三相界線の分子的描像へと迫る新たな走査プローブ顕微鏡法

    研究課題/領域番号:22K18772  2022年 - 2024年

    日本学術振興会  科学研究費助成事業  挑戦的研究(萌芽)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 固液界面上の厚さ数ナノメートルの特異な流体相に関する実験的研究

    2020年4月 - 2024年3月

      詳細を見る

    担当区分:研究代表者 

  • 固液界面上の厚さ数ナノメートルの特異な流体相に関する実験的研究

    研究課題/領域番号:20H02089  2020年 - 2023年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 二次元材料とナノ計測の融合による相変化伝熱の革新

    2018年10月 - 2024年3月

      詳細を見る

    担当区分:研究代表者 

    CREST「ナノスケール・サーマルマネージメント基盤技術の創出」

  • 二次元材料とナノ計測の融合による相変化伝熱の革新

    2018年 - 2023年

    戦略的創造研究推進事業 (文部科学省)

      詳細を見る

    担当区分:研究代表者  資金種別:受託研究

  • エクセルギー損失削減のための熱交換・熱制御技術

    2018年 - 2019年

    NEDO エネルギー・環境新技術先導プログラム

      詳細を見る

    担当区分:研究分担者  資金種別:受託研究

  • 次世代エレクトロニクス熱物性の計測技術基盤

    2017年4月 - 2020年3月

      詳細を見る

    担当区分:研究代表者 

  • 次世代エレクトロニクス熱物性の計測技術基盤

    研究課題/領域番号:17H03186  2017年 - 2019年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 透過型電子顕微鏡による気液相変化のナノスケール直接観察

    研究課題/領域番号:16K14174  2016年 - 2017年

    科学研究費助成事業  挑戦的萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 「優れた若手研究者の採用拡大支援」事業

    2016年 - 2017年

    国立大学改革強化推進補助金・特定支援型「優れた若手研究者の採用拡大支援」事業

      詳細を見る

    資金種別:学内資金・基金等

  • ナノ空間熱探査によるカーボン材料の多次元熱伝導評価

    2014年4月 - 2017年3月

      詳細を見る

    担当区分:研究代表者 

  • ナノ空間熱探査によるカーボン材料の多次元熱伝導評価

    研究課題/領域番号:26289047  2014年 - 2016年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 液中走査型熱顕微鏡の開発

    研究課題/領域番号:26630067  2014年 - 2015年

    科学研究費助成事業  挑戦的萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 固気液相界面メタフルイディクス

    2011年 - 2016年

    戦略的創造研究推進事業 (文部科学省)

      詳細を見る

    担当区分:研究分担者  資金種別:受託研究

  • 界面熱抵抗に関する原子スケールでの実験的研究

    研究課題/領域番号:23360101  2011年 - 2013年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • グラフェン鎖の1次元化によるナノチューブを超える弾道的熱伝導の発現

    研究課題/領域番号:23656153  2011年 - 2012年

    科学研究費助成事業  挑戦的萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 熱の超伝導をもたらす1次元鎖の実材料化

    研究課題/領域番号:22651054  2010年

    科学研究費助成事業  挑戦的萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • ナノワイヤ材料の熱物性と原子レベル構造に関する実験的研究

    研究課題/領域番号:20360099  2008年 - 2010年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • カーボンナノチューブの流体感知性能のナノセンサ計測

    研究課題/領域番号:20656140  2008年 - 2009年

    科学研究費助成事業  萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • カーボンナノチューブ1本の熱伝導率計測

    研究課題/領域番号:20048006  2008年 - 2009年

    科学研究費助成事業  特定領域研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • ナノ材料の生成機構を科学する温度制御デバイスの開発

    研究課題/領域番号:16656073  2004年 - 2005年

    科学研究費助成事業  萌芽研究

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • マイクロ・ナノ加工オープン化教育データベース構築

    2003年 - 2004年

    九州大学教育研究プログラム・研究拠点形成プロジェクト

      詳細を見る

    担当区分:研究代表者  資金種別:学内資金・基金等

  • マイクロ熱流体システムにおける多孔質構造と超微細加熱

    研究課題/領域番号:14702029  2002年 - 2004年

    科学研究費助成事業  若手研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 超小型衛星・航空機用マイクロ液体スラスターの試作研究

    研究課題/領域番号:13555267  2001年 - 2003年

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • マイクロヒーター群によって駆動されるマイクロ気泡周囲の熱流体機構

    研究課題/領域番号:12570168  2000年 - 2001年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • ミクロ空間での不均質過熱状態における気泡生成機構の解明

    研究課題/領域番号:10750153  1998年 - 1999年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 高周波パルスレーザー加熱を用いた超音速空力騒音の基本機構の解明

    研究課題/領域番号:09751007  1997年 - 1998年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 空力騒音の低減を目指したパルスレ-ザ-照射によるミクロな圧力波源の生成

    研究課題/領域番号:08750209  1996年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 音源としての非球形気泡の微小振動機構に関する研究

    研究課題/領域番号:07750198  1995年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 細管出口近傍での吐出気泡の分裂振動音に関する研究

    研究課題/領域番号:06750176  1994年

    科学研究費助成事業  奨励研究(A)

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

  • 気流にさらされた平板エッジ騒音に関する研究

    研究課題/領域番号:1244  1991年 - 1992年

    日本学術振興会  科学研究費助成事業  特別研究員奨励費

      詳細を見る

    担当区分:研究代表者  資金種別:科研費

▼全件表示

教育活動概要

  • 熱物理学およびミクロ流動物理学を大学院対象に講義
    航空宇宙基礎物理学および宇宙利用工学を学部3年生対象に開講
    航空宇宙工学実験を学部3年生対象に開講
    基幹物理学1A演習を学部1年生対象に開講
    研究室所属学生を対象にゼミを開催

担当授業科目

  • 航空宇宙工学実験

    2024年4月 - 2024年9月   前期

  • 航空宇宙基礎物理学

    2023年10月 - 2024年3月   後期

  • ミクロ流動物理学

    2023年10月 - 2024年3月   後期

  • 日本語コミュニケーション

    2023年4月 - 2024年3月   通年

  • 機械航空工学卒業研究(航空)

    2023年4月 - 2024年3月   通年

  • 熱物理学

    2023年4月 - 2023年9月   前期

  • ミクロ流動物理学

    2022年10月 - 2023年3月   後期

  • 航空宇宙工学実験

    2022年10月 - 2023年3月   後期

  • 航空宇宙基礎物理学

    2022年10月 - 2023年3月   後期

  • 日本語コミュニケーション

    2022年4月 - 2023年3月   通年

  • 機械航空工学卒業研究(航空)

    2022年4月 - 2023年3月   通年

  • 日本語コミュニケーション(航空)

    2022年4月 - 2023年3月   通年

  • Advanced Thermophysical Engineering

    2022年4月 - 2023年3月   通年

  • Applied Thermophysical Engineering

    2022年4月 - 2022年9月   前期

  • 産業活動実習Ⅰ(航空)

    2022年4月 - 2022年9月   前期

  • 熱物理学

    2022年4月 - 2022年9月   前期

  • 宇宙利用学B

    2021年12月 - 2022年2月   冬学期

  • 航空宇宙基礎物理学B

    2021年12月 - 2022年2月   冬学期

  • 航空宇宙伝熱学B

    2021年12月 - 2022年2月   冬学期

  • 航空宇宙基礎物理学

    2021年10月 - 2022年3月   後期

  • 航空宇宙工学実験

    2021年10月 - 2022年3月   後期

  • ミクロ流動物理学

    2021年10月 - 2022年3月   後期

  • 宇宙利用学A

    2021年10月 - 2021年12月   秋学期

  • 航空宇宙基礎物理学A

    2021年10月 - 2021年12月   秋学期

  • 航空宇宙伝熱学A

    2021年10月 - 2021年12月   秋学期

  • エネルギー変換基礎論IB

    2021年6月 - 2021年8月   夏学期

  • 航空宇宙工学演習Ⅱ

    2021年4月 - 2022年3月   通年

  • 機械航空工学卒業研究

    2021年4月 - 2022年3月   通年

  • 日本語コミュニケーション

    2021年4月 - 2022年3月   通年

  • 航空宇宙工学インターンシップⅠ

    2021年4月 - 2022年3月   通年

  • 航空宇宙工学インターンシップⅡ

    2021年4月 - 2022年3月   通年

  • 航空宇宙工学演習Ⅰ

    2021年4月 - 2022年3月   通年

  • 熱物理学

    2021年4月 - 2021年9月   前期

  • エネルギー変換基礎論Ⅰ

    2021年4月 - 2021年9月   前期

  • 熱物理学

    2021年4月 - 2021年9月   前期

  • 熱物理学

    2021年4月 - 2021年9月   前期

  • エネルギー変換基礎論IA

    2021年4月 - 2021年6月   春学期

  • 航空宇宙基礎物理学

    2020年10月 - 2021年3月   後期

  • 航空宇宙工学実験

    2020年4月 - 2021年3月   通年

  • 熱物理学講究

    2020年4月 - 2021年3月   通年

  • 熱物理学実験

    2020年4月 - 2021年3月   通年

  • 基幹物理学1A演習

    2020年4月 - 2020年9月   前期

  • 熱物理学

    2020年4月 - 2020年9月   前期

  • 基幹物理学1A

    2020年4月 - 2020年9月   前期

  • 航空宇宙基礎物理学

    2019年10月 - 2020年3月   後期

  • 宇宙利用学

    2019年10月 - 2020年3月   後期

  • ミクロ流動物理学

    2019年10月 - 2020年3月   後期

  • 航空宇宙工学実験

    2019年4月 - 2020年3月   通年

  • 熱物理学講究

    2019年4月 - 2020年3月   通年

  • 熱物理学実験

    2019年4月 - 2020年3月   通年

  • 基幹物理学1A演習

    2019年4月 - 2019年9月   前期

  • 熱物理学

    2019年4月 - 2019年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2018年10月 - 2019年3月   後期

  • 航空宇宙工学実験

    2018年4月 - 2019年3月   通年

  • 熱物理学講究

    2018年4月 - 2019年3月   通年

  • 熱物理学実験

    2018年4月 - 2019年3月   通年

  • 熱物理学

    2018年4月 - 2018年9月   前期

  • 基幹物理学1A演習

    2018年4月 - 2018年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2017年10月 - 2018年3月   後期

  • 航空宇宙工学実験

    2017年4月 - 2018年3月   通年

  • 熱物理学講究

    2017年4月 - 2018年3月   通年

  • 熱物理学実験

    2017年4月 - 2018年3月   通年

  • 基幹物理学1A演習

    2017年4月 - 2017年9月   前期

  • 熱物理学

    2017年4月 - 2017年9月   前期

  • 航空宇宙基礎物理学Ⅰ

    2017年4月 - 2017年9月   前期

  • ミクロ流動物理学

    2016年10月 - 2017年3月   後期

  • 航空宇宙基礎物理学Ⅱ

    2016年10月 - 2017年3月   後期

  • 熱物理学講究

    2016年4月 - 2017年3月   通年

  • 熱物理学実験

    2016年4月 - 2017年3月   通年

  • 航空宇宙工学実験

    2016年4月 - 2017年3月   通年

  • 熱物理学

    2016年4月 - 2016年9月   前期

  • 航空宇宙基礎物理学Ⅰ

    2016年4月 - 2016年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2015年10月 - 2016年3月   後期

  • 航空宇宙工学実験

    2015年4月 - 2016年3月   通年

  • 熱物理学実験

    2015年4月 - 2016年3月   通年

  • 熱物理学

    2015年4月 - 2015年9月   前期

  • 航空宇宙基礎物理学Ⅰ

    2015年4月 - 2015年9月   前期

  • ミクロ流動物理学

    2014年10月 - 2015年3月   後期

  • 航空宇宙基礎物理学Ⅱ

    2014年10月 - 2015年3月   後期

  • 航空宇宙工学実験

    2014年4月 - 2015年3月   通年

  • 熱物理学特論

    2014年4月 - 2015年3月   通年

  • 熱物理学実験

    2014年4月 - 2015年3月   通年

  • 熱物理学

    2014年4月 - 2014年9月   前期

  • 航空宇宙基礎物理学Ⅰ

    2014年4月 - 2014年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2013年10月 - 2014年3月   後期

  • Aerospace Engineering 1

    2013年10月 - 2014年3月   後期

  • 航空宇宙工学実験

    2013年4月 - 2014年3月   通年

  • 熱物理学特論

    2013年4月 - 2014年3月   通年

  • 熱物理学実験

    2013年4月 - 2014年3月   通年

  • 航空宇宙基礎物理学Ⅰ

    2013年4月 - 2013年9月   前期

  • 熱物理学

    2013年4月 - 2013年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2012年10月 - 2013年3月   後期

  • Aerospace Engineering 1

    2012年10月 - 2013年3月   後期

  • ミクロ流動物理学

    2012年10月 - 2013年3月   後期

  • 航空宇宙工学実験

    2012年4月 - 2013年3月   通年

  • 熱物理学特論

    2012年4月 - 2013年3月   通年

  • 熱物理学実験

    2012年4月 - 2013年3月   通年

  • 航空宇宙基礎物理学Ⅰ

    2012年4月 - 2012年9月   前期

  • コアセミナー

    2012年4月 - 2012年9月   前期

  • 熱物理学

    2012年4月 - 2012年9月   前期

  • 航空宇宙基礎物理学Ⅱ

    2011年10月 - 2012年3月   後期

  • Advanced Engineering

    2011年10月 - 2012年3月   後期

  • 航空宇宙工学実験

    2011年4月 - 2012年3月   通年

  • 熱物理学実験

    2011年4月 - 2012年3月   通年

  • 熱物理学特論

    2011年4月 - 2012年3月   通年

  • 航空宇宙基礎物理学Ⅰ

    2011年4月 - 2011年9月   前期

  • 熱物理学

    2011年4月 - 2011年9月   前期

  • コアセミナー

    2011年4月 - 2011年9月   前期

  • ミクロ流動物理学

    2010年10月 - 2011年3月   後期

  • 航空宇宙基礎物理学Ⅱ

    2010年10月 - 2011年3月   後期

  • 航空宇宙基礎物理学Ⅰ

    2010年10月 - 2011年3月   後期

  • 熱物理学特論

    2010年4月 - 2011年3月   通年

  • 熱物理学実験

    2010年4月 - 2011年3月   通年

  • 熱物理学演習Ⅱ

    2010年4月 - 2011年3月   通年

  • 熱物理学演習Ⅰ

    2010年4月 - 2011年3月   通年

  • 熱物理学

    2010年4月 - 2010年9月   前期

  • 工業数学演習

    2010年4月 - 2010年9月   前期

  • ミクロ熱物理学

    2009年10月 - 2010年3月   後期

  • 航空宇宙基礎物理学Ⅰ

    2009年10月 - 2010年3月   後期

  • 熱物理学演習Ⅰ

    2009年4月 - 2010年3月   通年

  • 熱物理学特論

    2009年4月 - 2010年3月   通年

  • 熱物理学実験

    2009年4月 - 2010年3月   通年

  • 熱物理学演習Ⅱ

    2009年4月 - 2010年3月   通年

  • 工業数学演習

    2009年4月 - 2009年9月   前期

  • ミクロ熱物理学

    2008年10月 - 2009年3月   後期

  • ミクロ流動物理学

    2008年10月 - 2009年3月   後期

  • 熱物理学特論

    2008年4月 - 2009年3月   通年

  • 熱物理学演習Ⅰ

    2008年4月 - 2009年3月   通年

  • 熱物理学演習Ⅱ

    2008年4月 - 2009年3月   通年

  • 熱物理学実験

    2008年4月 - 2009年3月   通年

  • 工業数学演習

    2008年4月 - 2008年9月   前期

  • ミクロ熱物理学

    2007年10月 - 2008年3月   後期

  • 熱物理学演習Ⅰ

    2007年4月 - 2008年3月   通年

  • 熱物理学特論

    2007年4月 - 2008年3月   通年

  • 熱物理学実験

    2007年4月 - 2008年3月   通年

  • 熱物理学演習Ⅱ

    2007年4月 - 2008年3月   通年

  • 工業数学演習

    2007年4月 - 2007年9月   前期

  • ミクロ熱物理学演習

    2007年4月 - 2007年9月   前期

  • 工業数学演習

    2007年4月 - 2007年9月   前期

  • ミクロ流動物理学

    2006年10月 - 2007年3月   後期

  • ミクロ熱物理学

    2006年10月 - 2007年3月   後期

  • ミクロ熱物理学演習

    2006年4月 - 2006年9月   前期

▼全件表示

FD参加状況

  • 2023年3月   役割:参加   名称:独・蘭・台湾での産学連携を垣間見る -Industy 4.0・量子コンピュー ティング・先端半導体-

    主催組織:部局

  • 2020年10月   役割:参加   名称:総合選抜について

    主催組織:部局

  • 2020年5月   役割:参加   名称:オンサイト授業 vs. オンライン授業:分かったこと,変わったこと

    主催組織:全学

  • 2020年3月   役割:参加   名称:M2B学習支援システム講習会

    主催組織:全学

  • 2018年11月   役割:参加   名称:ハラスメント防止

    主催組織:全学

  • 2018年6月   役割:参加   名称:入試改革

    主催組織:部局

  • 2017年12月   役割:参加   名称:メンタルヘルス研修会

    主催組織:全学

  • 2016年6月   役割:参加   名称:ハラスメント防止のための研修会

    主催組織:全学

  • 2014年3月   役割:参加   名称:平成25年度第3回工学部(府)FD

    主催組織:学科

  • 2013年9月   役割:講演   名称:科学研究費補助金獲得セミナー

    主催組織:学科

  • 2007年3月   役割:参加   名称:全学FD

    主催組織:全学

  • 2002年1月   名称:A&A

▼全件表示

他大学・他機関等の客員・兼任・非常勤講師等

  • 2013年  清華大学  国内外の区分:国外 

    学期、曜日時限または期間:博士課程学生受入

  • 2008年  清華大学  国内外の区分:国外 

    学期、曜日時限または期間:博士課程学生派遣

その他教育活動及び特記事項

  • 2016年  クラス担任  学部

  • 2015年  クラス担任  学部

  • 2014年  クラス担任  学部

  • 2011年  クラス担任  学部

  • 2009年  クラス担任  学部

  • 2008年  クラス担任  学部

  • 2000年  クラス担任  学部

▼全件表示

社会貢献・国際連携活動概要

  • ナノ材料の熱物性研究を中国清華大学と共同して推進中

社会貢献活動

  • ジェットエンジンと航空宇宙工学と九州大学

    愛媛県立松山東高校  2018年10月

     詳細を見る

    対象:幼稚園以下, 小学生, 中学生, 高校生

    種別:セミナー・ワークショップ

  • セミナー「第73回大阪大学機械工学系技術交流会」にて講演

    大阪大学大学院工学研究科機械工学専攻  大阪  2014年11月

     詳細を見る

    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

  • セミナー「高熱伝導材料開発のためのカーボンナノチューブ/グラファイトの熱伝導性と複合化技術」にて講演

    (株)技術情報協会  東京  2014年3月

     詳細を見る

    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

  • 九州大学における航空宇宙工学の教育と研究

    愛媛県立松山東高校  2013年9月

     詳細を見る

    対象:幼稚園以下, 小学生, 中学生, 高校生

    種別:セミナー・ワークショップ

  • 九州大学における航空宇宙工学の研究最前線

    鹿児島県立鶴丸高校  2006年10月

     詳細を見る

    対象:幼稚園以下, 小学生, 中学生, 高校生

    種別:セミナー・ワークショップ

  • 欧米の航空宇宙分野へのマイクロナノ技術の動向について

    日本航空宇宙工業会  東京  2005年2月

     詳細を見る

    対象:社会人・一般, 学術団体, 企業, 市民団体, 行政機関

    種別:セミナー・ワークショップ

▼全件表示

政策形成、学術振興等への寄与活動

  • 2022年4月 - 2024年3月   日本機械学会

    登録者4000人以上の日本機械学会熱工学部門の部門長および副部門長として学術振興へ寄与した。

外国人研究者等の受け入れ状況

  • University of Alberta, Canada

    受入れ期間: 2023年12月 - 2024年1月   (期間):2週間以上1ヶ月未満

    国籍:中華人民共和国

    専業主体:日本学術振興会

  • The University of Arizona

    受入れ期間: 2022年6月 - 2022年8月   (期間):1ヶ月以上

    国籍:中華人民共和国

    専業主体:日本学術振興会

  • Academia Sinica, Taiwan

    受入れ期間: 2022年6月 - 2022年7月   (期間):2週間以上1ヶ月未満

    国籍:台湾

    専業主体:日本学術振興会

  • 受入れ期間: 2020年4月 - 2021年3月   (期間):1ヶ月以上

    国籍:中華人民共和国

    専業主体:科学技術振興機構

  • Purdue University

    受入れ期間: 2019年7月 - 2019年8月   (期間):2週間以上1ヶ月未満

    国籍:アメリカ合衆国

    専業主体:科学技術振興機構

  • University of Texas

    受入れ期間: 2017年3月   (期間):2週間以上1ヶ月未満

    国籍:アメリカ合衆国

    専業主体:日本学術振興会

▼全件表示

海外渡航歴

  • 1997年2月 - 1998年9月

    滞在国名1:アメリカ合衆国   滞在機関名1:University of California, Berkeley

学内運営に関わる各種委員・役職等

  • 2021年4月 - 2023年3月   学科 航空宇宙工学科長

  • 2021年4月 - 2023年3月   学科 航空宇宙工学コース長

  • 2021年4月 - 2022年3月   部門 航空宇宙工学部門長

  • 2020年11月 - 2021年3月   学府 工学府学務委員会委員長

  • 2020年11月 - 2021年3月   学部 工学部学務委員会委員長

  • 2020年4月 - 2021年3月   部門 航空宇宙工学部門長代理

  • 2020年4月 - 2021年3月   専攻 航空宇宙工学専攻長代理

  • 2020年4月 - 2021年3月   学科 航空宇宙工学コース長代理

  • 2019年4月 - 2021年3月   研究院 改組WG委員

  • 2019年4月 - 2021年3月   学部 工学部学務委員会副委員長

  • 2019年4月 - 2021年3月   学府 工学府学務委員会副委員長

  • 2018年4月 - 2021年3月   研究院 運営審議会委員

  • 2018年4月 - 2021年3月   学部 技術部運営委員会委員

  • 2018年4月 - 2019年3月   部門 航空宇宙工学副部門長

  • 2018年4月 - 2019年3月   専攻 航空宇宙工学副専攻長

  • 2018年4月 - 2019年3月   学科 航空宇宙工学コース長代理

  • 2017年4月 - 2019年3月   学部 同窓会評議員

  • 2016年4月 - 2020年3月   学府 教育企画委員会

  • 2016年4月 - 2020年3月   研究院 工学国際連携委員会

  • 2016年4月 - 2018年3月   研究院 工学部・工学府教育企画委員会

  • 2016年4月 - 2018年3月   研究院 附属循環型社会システム工学研究センター運営委員会

  • 2014年4月 - 2016年3月   研究院 工学紀要編集委員会

  • 2013年4月 - 2014年3月   学科 航空宇宙工学コース長

  • 2013年4月 - 2014年3月   専攻 航空宇宙工学専攻長

  • 2013年4月 - 2014年3月   部門 航空宇宙工学部門長

  • 2013年2月 - 2013年9月   全学 カーボンニュートラルエネルギー国際研究所第二棟WG委員

  • 2012年9月 - 2013年3月   研究院 工学研究院コラボ棟WG委員

  • 2011年4月 - 2013年3月   学府 入試委員会委員

  • 2011年4月 - 2013年3月   学部 入試委員会委員

  • 2010年4月 - 2015年3月   全学 加速器・ビーム応用科学センター運営委員会

  • 2009年4月 - 2018年3月   全学 中央分析センター伊都分室委員

  • 2004年4月 - 2006年3月   研究院 Annual Report 編集委員

  • 2002年4月 - 現在   研究院 法人化業務運営検討委員・衛生専門部会委員

  • 2002年4月 - 2009年3月   全学 中央分析センター工学分室委員

▼全件表示