http://www.mm.kyushu-u.ac.jp/lab_03/en/index.html
Our research interests are material sciences focusing on the development of functional materials, analysis of functional properties, and design and application of functional devices. Our research activities are classified into two the following categories.

(1) Development and basic understanding of chemical sensors. Major effort is directed to gas sensors using semiconducting or ion-conducting oxides.

*Semiconductor type gas sensor Wet preparation of SnO2 and WO3 for microstructure control of gas sensors. Control of micro porous structure for thin film semiconductor gas sensors. Analysis of diffusion-reaction for semiconductor gas sensors Elucidation of basic characteristics of semiconductor gas sensors. Microprobe (STM) analysis of surface properties of oxide semiconductors Development of high sensitive gas sensors for medical use.

*Solid electrolyte type gas sensor Investigation of solid electrolyte CO2 sensor. Elaboration of compact type sensor operative at low temperature. New capacitive type gas sensor combining MIS structure and solid electrolyte. Evolution of gas sensors combining FET and solid electrolyte for NO2 detectioｎ. Design of compact NO2 sensing system using FET-combined type gas sensor. Exploration of new solid electrolytes for gas sensors.

(2) Development and application of novel functional inorganic materials (mostly mixed oxides or their composites) are under investigation for oxygen electrode catalysis, new type oxygen-separating membranes, ceramic coatings, by wet-process, and thin film using dielectric materials.

Design of gas diffusion-type oxygen reduction electrode. Exploration of reverse micelle method for preparation of efficient oxygen cathode. Development of oxygen electrode for metal-air battery. Development of oxygen permeable membrane with thin layer-on-porous support structure. Exploration of new materials for oxygen permeable membranes. Exploration of wet-coating of ceramics on metals. Characterization of ceramic films wet-coated on metals. Wet preparation of dielectric thin films for memory device. Exploration of high temperature PTC thermister. .

Research Interests

• Design of high performance gas sensors
  keyword : gassensors, design, high sensitivity, high selectivity
  1995.08In order to realize high performances of gas sensors, i.e. high sensitivity, high selectivity, long stability and so on, new designs for material are researched..
• Development of high performance oxygen reduction electrode for Lithium-air battery
  keyword : oxygen reduction electrode, brin electrolysis, metal-air battery, perovskite-type oxide, nano particles
  2009.04Gas diffusion-type oxygen or air electrodes have high potentiality in energy-related new technologies, such as brine electrolysis, fuel cells, and metal-air batteries. Perovskite-type oxide is one of the catalysts for gas diffusion-type oxygen electrode. We are trying to prepare nano-sized particles of perovskite-type oxide by using wet process and to design new electrode using nano-particles..
• Preparation of nano-sized SnO2 particles by using hydrothermal treatment for highly sensitive gas sensors
  keyword : gas sensors, hydrothermal treatment, high sensitivity, SnO2, nano-particles
  1995.08Stable colloidal suspensions of tin oxide were synthesized by subjecting conventionally prepared tin oxide gels to hydrothermal treatment in an autoclave. This sensor film using the tin dioxide exhibited an outstanding by high sensitivity to 800 ppm H2, compared with conventional tin oxide elements of a sintered block type..
• Design of ultrasensitive semiconductor gas sensors by high order structure control
  keyword : high order structure control, ultrasensitive sensor, semiconductor, gas sensors, receptor
  1999.04It is of interest to consider how to design higher order structure favorable for high sensitivity. For thin film devices, we can conceive two ways for it. Increasing grain size would give rise to higher sensitivity through increasing utility factor. Even when grain size is kept the same, higher sensitivity would be obtained if the grains are brought into clusters of a certain size in the film. The importance of higher order structure control mentioned above indicates the importance of the methods of preparation and processing of the sensing materials as well. The wet preparation methods including colloidal processing are worthy of being exploited thoroughly for this purpose. It is challenging to load each colloidal particle of SnO2 with foreign metal like Pd for surface modification. Doping each particle with other oxides for valence control is also worth challenging..
• Development of key technologies for micro gas sensors
  keyword : micro fabrication, gas sensors, ubiqhitous sensor, IT
  2004.04Recent progress of information technology (IT) has shown the necessity of constructing ubiquitous sensor networks associated with wireless communication facilities. Wearable sensors are also in the waiting list. Gas sensor people are requested to challenge these formidable tasks. In order to overcome these difficulties, we are developing micro gas sensor based on material sciences. For ubiquitous gas sensor, especially, sensor materials suitable for micro device are required while keeping sensitivity as well as selectivity..
• Design of solid electrolyte gas sensors for detection of enviroment related gases
  keyword : oxidic gas, enviromental protection, gas sensors, solid electrolyte, auxiliary phase
  1995.08Sensory detection of oxygenic gases such as CO,, NO, (NO and NO,), and SO, (SO, and SO,) has become increasingly important for protecting global as well as living environments. A new group of solid electrolyte-based electrochemical devices attached with a layer of auxiliary phase are emerging as attractive sensors for the detection of oxygenic gases such as CO2, NOX and SOX. In order to realize excellent sensing performances in oxygenic gases, optimization of the auxiliary phases and the reference electrode is important..
• Analysis of Electronic structure on surface of SnO2 (110) by STM
  keyword : STM, SnO2, electronic structure, oxygen adsorption, gas sensors
  2001.04～2007.03Surface structure of SnO2 (110) treated thermally under oxidative condition was investigated by STM. After thermal treatment under oxidative condition, the [001]-oriented wide rows and dark spots beside the [001]-oriented fine rows were observed. Compared with the surface reduced by hydrogen, it is attributed the observed wide rows and dark spots to O2− (molecularity adsorption) and O− (adsorption with negative charge), respectively..
• New type gas sensor combined semiconductor transducer and solid electrolyte
  keyword : transistor, diode, gas sensors, solid electrolyte, transducers
  1998.04New gas sensor using Field effect transistor or MOS diode as a transducer are investigated for detection of NO2 and CO2. This kind of sensor has two apparent advantages over the usual solid electrolyte device, i.e. high input impedance and elimination of a counter electrode. This nature may be particularly important for a potentiometric gas sensor using an auxiliary phase. Especially gas sensor combined FET and solid electrolyte has long stability as well as sensing properties..
• Study of gas sensors using new solid electrolyte
  keyword : solid electrolyte, gas sensors, Bismuth oxide, perovskite-type oxide
  2001.04The complex metal oxides, BiCuVOx, as a new solid electrolyte are investigated for electrochemical characterization based on oxygen concentration battery. The use of a perovskite-type oxide instead of Pt as a electrode was found to enable the cell to work at 400 ◦C and above. In addition, this sensor can detect organic gases, alcohol and aldehyde, rather than other inflammable gases..
• Development of gas sensors for medical use
  keyword : medical use, ethylene oxide, N2O, gas sensors, system
  1998.04Recently new gas sensors for medical use required. To detect gases (ethylene oxide, N2O and so on) used in hospital, we are exploring the possibility of developing gas sensors..
• Development of high performance oxygen reduction electrode for brine electrolysis and metal-air battery
  keyword : oxygen reduction electrode, brin electrolysis, metal-air battery, perovskite-type oxide, nano particles
  1995.08Gas diffusion-type oxygen or air electrodes have high potentiality in energy-related new technologies, such as brine electrolysis, fuel cells, and metal-air batteries. Perovskite-type oxide is one of the catalysts for gas diffusion-type oxygen electrode. We are trying to prepare nano-sized particles of perovskite-type oxide by using wet process and to design new electrode using nano-particles..
• Design of high performance oxygen permeable menbrane
  keyword : oxygen separation, oxygen enrichment, perovskite-type oxide, mix conductor, oxygen defect
  1999.10Oxygen-enriched air is receiving attention in terms of energy savings and exhaust gas reduction. Therefore, new oxygen-enrichment technologies are needed. According to our research, perovskite-type oxides, which exhibit a mixed conductivity, can be used as oxygen separation membranes to readily separate oxygen using only the concentration gradient, making electrodes and external circuits unnecessary. We are studying novel materials and designing optimal separation membranes..
• Ceramic coating on metals by using wet process
  keyword : wet process, ceramics, coating, corrosion protection, high temperature
  2001.04～2006.03Ceramic coating on metals have been developed for various industrial applications to protect the metals from corrosion, erosion or abrasion, or to endow the metal works with a decorative color. The object of thermal barrier coating is to provide thermal insulation to metal components. We tried to develop ceramic coating technologies based on wet processes..
• Study of PZT dielectric thin film for high density memory
  keyword : PZT, wet process, memory, low temperature, thin film, high density
  1996.04～2005.03For realizing a PZT memory device in practice, several technical problems such as crystallized temperature, flatness and uniformity of PZT grains, film thickness and so on, must be solved. We tried to investigate low-temperature wet preparation of dielectric thin films with flatness and uniformity for PZT high-density memories..

Current and Past Project

• The Japanese and Korean teams have tackled the problem in the fabrication of a next-generation micro-sensor device. The teams tried to develop a base technology for fabricating a micro-sized sensing layer from stable suspensions of metal/oxide hetero-structured nanoparticles such as Pd/SnO2 and Au/TiO2 prepared by wet chemical routes. Then, the teams fabricated gas sensing layers on substrates equipped with a micro-heater and micro-electrodes fabricated by a MEMS process, and examined the basic properties of micro-gas sensors in terms of sensitivity, selectivity, and stability.

Academic Activities

Books

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Papers

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1.	Ken WATANABE, Shingo IDE, Takashi KUMAGAI, Takaaki FUJINO, Koichi SUEMATSU, Kengo SHIMANO, Oxygen pumping based on c-axis-oriented lanthanum silicate ceramics : challenge toward low operating temperature, Journal of the Ceramic Society of Japan, 127, 1-4, 2019.01.
2.	＠Koichi Suematsu, ＃Wataru Harano, ＃Tokiharu Oyama, ＃Yuka Shin, ＠Ken Watanabe, ＠Kengo Shimanoe, Pulse-driven semiconductor gas sensors toward ppt level toluene detection, Analytical chemistry, 90, 11219-11223, 2018.09.
3.	Masayoshi Yuasa, Tsubasa Matsuyoshi, Tetsuya Kida, Kengo Shimanoe, Discharge/charge characteristic of Li-air cells using carbon-supported LaMn0.6Fe0.4O3 as an electrocatalyst, Journal of Power Sources , 242 , pp. 216-221, 2013.11.
4.	Masayoshi Yuasa, Naoki Tachibana, Kengo Shimanoe, Oxygen reduction activity of carbon-supported La1-xCa xMn1-yFeyO3 nanoparticles, Chemistry of Materials , 25 (15) , pp. 3072-3079 (2013.7), 2013.07.
5.	Kengo Shimanoe, Masayoshi Yuasa, Tetsuya Kida, Noboru Yamazoe, Material design based on wet process for highly sensitive semiconductor gas sensors, Gas sensors based on semiconducting metal oxides –new directions, pp.16-17, 2009.12.
6.	Kengo Shimanoe, Kohei Yoshida, Masayoshi Yuasa, Noboru Yamazoe, Microstructure Control of SnO2-based Gas Sensor Using Cluster Sols, International Conference on Sol-Gel Processes for Advanced Ceramics, pp.185-186, 2009.10.
7.	Kengo Shimanoe, Aya Nishiyama, Masayoshi Yuasa, Tetsuya Kida, Noboru Yamazoe, Microstructure control of WO3 film by adding nano-particles of SnO2 for NO2 detection in ppb level, EurosensorXXIII(Procedia Chemistry), Vol. 1 (1), pp. 212-215, 2009.09.
8.	K. Shimanoe, K. Ikari, Y. Shimizu, N. Yamazoe, STM observation of SnO2 (110) thermal-treated under oxidative condition, Sensors and Actuators B, Vol. 118, pp. 90-93, 2006, 2006.10.
9.	M. Kugishima, K. Shimanoe, N. Yamazoe, C2H4O sensing properties for thick film sensor using La2O3-modified SnO2, Sensors and Actuators B, Vol. 118, pp. 171-176, 2006, 2006.10.
10.	J. P. Lukaszewicz, S. Imaizumi, M. Yuasa, K. Shimanoe, N. Yamazoe, New approach towards preparation of efficient gas diffusion-type oxygen reduction electrode, Journal of Materials Science, Vol. 41, pp. 6215-6220, 2006, 2006.10.
11.	Y. Muroya, K. Shimanoe, Y. Haruta, Y. Teraoka, N. Yamazoe, Addition of alkali silicate to grain size-controlled ceramic coatings for dense film, Journal of the Ceramic Society of Japan, 114(4), 308-312, 2006, 2006.04.

Presentations

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1.	K. Shimanoe, K. Suematsu, K. Watanabe, High performance MEMS-type gas sensors , The 22nd International Conference on Solid State Ionics, 2019.06.
2.	＠K. Shimanoe,W. Harano,T. Ohyama,＠K. Suematsu,＠K. Watanabe,＠M. Nishibori, MEMS Gas Sensors Based on Metal Oxide Nano Particles, CIMTEC2018 (14th International Ceramics Congress), 2018.06, For materials design of the semiconductor gas sensors, my group reported three important key factors, receptor function, transducer function and utility factor [1]. Such material designs are useful for devices in operating constant-heating. On the other hand, however, MEMS-type gas sensors in operating pulse-heating, which is one of the candidates for IoT sensors, need additional designs. So, we report new idea of materials and operation for MEMS-type gas sensors. SnO2 is typical sensor material, but the sensor in operating pulse-heating gives interesting sensing properties different from that of constant-heating. By pulse-heating in inflammable gas, the gas response was high at first 100ms and gradually reached to value obtained by constant-heating. The magnitude of first response was dependent on the concentration of inflammable gas (toluene). Furthermore, special additives to the sensing film gave enhancement in gas response [2]. References [1] N. Yamazoe, K. Shimanoe (2007), Overview of gas sensor technology, In D. K. Aswal and S. K. Gupta (Eds.) Science and Technology of Chemiresistor Gas Sensors, Nova Science Publishers, Inc., pp. 1-31. [2] K. Shimanoe, N. Ma, T. Oyama, M. Nishibori, K. Watanabe, ECS Trans., 75 (16), 31-37 (2016)..
3.	Kengo Shimanoe, Update of Materials Design for Semiconductor Gas Sensors , Special Seminar on Functional Devices in Jilin University, 2017.12.
4.	Kengo Shimanoe,Ken Watanabe,Suematsu Koichi, Gas sensing properties of MEMS-type metal oxide gas sensor: Design of receptor function for pulse-heating mode, 12th Asian Conference on Chemical Sensors, 2017.11.
5.	Kengo Shimanoe, Yongjiao Sun, Koichi Suematsu, Ken Watanabe, Noriko Saito, Isao Sakaguchi, Reactive oxygen species on oxide semiconductors, GOSPEL WORKSHOP 2017, 2017.11, Semiconductor gas sensors for detecting inflammable gases generate signals in electric resistance by reaction of inflammable gases and oxygen adsorbed on metal oxides. In the case of SnO2, two kinds of oxygen adsorption species, O2- and O-, were reported. However, in 2013, we reported how two oxygen adsorption species were formed, and also it became clear that the influence of water vapor on sensor response was due to the change in oxygen adsorption species. To understand oxygen adsorption species on metal oxides is very important to obtain high sensor performance. In this presentation, we report oxygen adsorption species on various metal oxides under dry and humid conditions. Table 1 shows oxygen adsorption species on various metal oxides and their modified oxides under dry and humid conditions. For neat-SnO2, the water vapor influences oxygen adsorption species. In short, dry air gives O2- at 350oC and wet air changes O2- to O-. Consequently, the thickness of space charge layer is reduced, and it brings a decrease in the electric resistance. In addition, the number of O- adsorption species is also decreased fairly. Therefore, the number of oxygen and electron to participate in a reaction with the inflammable gases decreases extraordinarily, and the sensor response lowers. However, such degradation in sensor response can be improved by surface modification and Pd-loading. The oxygen adsorption species remains O2- even in wet atmosphere although the number of adsorbed oxygen decreases. From these results, it is understood that such surface control is important for improvement of sensor response. For other oxides such as In2O3 and ZnO, the oxygen adsorption species are also shown in Table 1. Interestingly, In2O3 gives O2- in both dry and wet atmospheres although the electric resistance in wet atmosphere decreases as compared with that in dry atmosphere. However, WO3 is in contrast to such oxides because oxygen adsorption species with negative charge, O2- and O-, were not observed. From the measurements of electric resistance under different oxygen partial pressure and the TPD (temperature program desorption), molecular-type oxygen (O2-) seems to adsorb on the surface of WO3 although such species doesn’t have strong oxidation power. However, WO3 shows ability for oxidation to inflammable gases. Therefore, it is thought that surface lattice oxygen participates in reaction with inflammable gases. For practical use, we need materials design based on the understanding of oxygen adsorption species..
6.	Kengo Shimanoe, Materials Design for Metal Oxide Semiconductor Gas Sensors, Seminar on Functional Materials in KAIST, 2017.07.
7.	Kengo Shimanoe, Ken Watanabe, Koichi Suematsu, Maiko Nishibori, High performance of MEMS-type semiconductor gas sensor in operating pulse-heating, The 15th International Nanotech Symposium & Nano-Convergence Expo (NANO KOREA), 2017.07.
8.	Kengo Shimanoe, High Performance of Semiconductor Gas Sensors: Which of transducer function and utility factor is effective for sensitivity ?, 8th International Conference on Electroceramics (ICE2017), 2017.05.
9.	Kengo Shimanoe, N. Ma, T. Oyama, H. Uchino, Maiko Nishibori, Ken Watanabe, Material Design of Semiconductor Gas Sensors for Practical Use, 2016 MRS Fall Meeting & Exhibit, 2016.11.
10.	Kengo Shimanoe, Materials design for MEMS-type metal oxide semiconductor gas sensors, The 3rd International conference & Exhibition for Nanopia(NANOPIA 2016), 2016.11.
11.	K. Shimanoe, K. Suematsu, K. Watanabe, M. Nishibori, Materials design for MEMS-type metal oxide semiconductor gas sensors, The 6th NIMS‐UR1‐CNRS‐SG WORKSHOP, 2016.10.
12.	Kengo Shimanoe, Materials Design for Gas Sensors, Materials Colloquium in Seoul National University, 2016.09, Semiconductor gas sensors are widely used for detection of inflammable and toxic gases. To detect such low concentration gases, we have reported materials design including important three functions i.e. receptor function, transducer function and utility factor. Receptor function concerns the ability of the oxide surface to interact with the target gas. In addition, when the surface is loaded with a foreign receptor like PdO, it acts as a receptor stronger than the adsorbed oxygen. In addition, we found that small size of PdO (less than 3nm) shows high sensor response to inflammable gases even under humid condition. Transducer function concerns that the electron transport through the contact can thus be achieved by migration or tunneling of the surface electrons, indifferent to the bulk electrons inside. The device resistance is then inversely proportional to the surface density of electrons. Therefore the sensor response enhances with increasing oxygen partial pressure. For the utility factor, the target gas molecules diffuse the inside of a sensing body while reacting with the oxide surface. The above design and combination of three factors give gas detection in ppb level. However, for practical use, we must pay attention to water vapor poisoning. Under humid condition, it is well known that water molecules adsorbed on the surface give a large effects on the sensitivity and selectivity. For SnO2, the sensor response deeply concerns oxygen adsorption species which is O2- and O- in dry and wet atmosphere, respectively. To enhance the sensor response, we proposed importance of surface modification and nano-size Pd loading on SnO2. For surface modification, we found that Fe3+ and Sb5+ modifications gave O2- adsorption species under humid condition. In addition, Pd nano-size loading showed constant sensor response even by changing humidity. Those material designs are important for practical use, and should be introduced to MEMS gas sensors. In the presentation, the above will be shown..
13.	K. Shimanoe, N. Ma, T. Oyama, K. Suematsu, K. Watanabe, M. Mishibori, High Performance of Metal Oxide Semiconductor Gas Sensors Under Humid Condition: Approach from Materials Design, The 16th International Meeting on Chemical Sensors (IMCS 2016), 2016.07.
14.	K. SHIMANOE, T. Oyama, N. Ma, M. Nishibori, K. Watanabe, MEMS-type Gas Sensors using Metal Oxides Semiconductor, The International Conference on "nanoFIS 2016 - Functional Integrated nano Systems", 2016.06.
15.	Kengo Shimanoe, Nan Ma, Ryohei Kato, Maiko Nishibori, New Semiconductor Gas Sensor Based on Enhancing Oxygen Partial Pressure, The 5th International Conference “Smart and Multifunctional Materials, Structures and Systems” (CIMTEC 2016), 2016.06, Semiconductor gas sensors are widely used for detection of inflammable and toxic gases. To detect such low concentration gases, we have reported materials design including important three functions i.e. receptor function, transducer function and utility factor. Receptor function concerns the ability of the oxide surface to interact with the target gas. In addition, when the surface is loaded with a foreign receptor like PdO, it acts as a receptor stronger than the adsorbed oxygen. In addition, we found that small size of PdO (less than 3nm) shows high sensor response to inflammable gases even under humid condition. Transducer function concerns that the electron transport through the contact can thus be achieved by migration or tunneling of the surface electrons, indifferent to the bulk electrons inside. The device resistance is then inversely proportional to the surface density of electrons. Therefore the sensor response enhances with increasing oxygen partial pressure. For the utility factor, the target gas molecules diffuse the inside of a sensing body while reacting with the oxide surface. In this presentation, we explain the above design and combination of three factors. In addition, the receptor function enhanced by increasing oxygen partial pressure in the sensing film will be presented for usual type and MEMS-type gas sensors..
16.	Kengo Shimanoe, Material Design of Oxide Semiconductor Gas Sensors for High Performance under Humid Condition: Determination of Oxygen Adsorption Species, The11th　Pacific Rim conference　of Ceramic SOcienties (PACRIM11), 2015.08.
17.	Kengo Shimanoe, Determination of oxygen adsorption species on oxide semiconductor for highly sensitive gas sensor under humid condition, GOSPEL Workshop 2015, 2015.06.
18.	Kengo Shimanoe, Nan Ma, Miyuki Sasaki, Koichi Suematsu, Masayoshi Yuasa, Development of Oxide Semiconductor Gas Sensors for High Sensitivity under Humid Conditions, The 31th Internathional Korea-Japan Seminar on Ceramics, 2014.11.
19.	K. Shimanoe, K. Suematsu, M. Yuasa, T. Kida , Material Design For Mems-Type Semiconductor, The 7th Asia-Pacific Conference on Transducers and Micro/Nano Technologies (APCOT2014), 2014.06.
20.	Kengo Shimanoe, Effect of water vapor on SnO2-based gas sensors:Toword high response under humid condition, 韓国センサ学会, 2013.11.
21.	Kengo Shimanoe, New material designs for MEMS-type gas sensor, 15th ISOEN（ International Symposium on Olfaction and Electronic Nose）, 2013.07.
22.	Kengo Shimanoe, Awaiting　Solution　toward　New　Generation　of　semiconductor　Gas　Sensor, Collaborative Conference on Materials Research (CCMR) 2013, 2013.06.
23.	K. Shimanoe, Material design of semiconductor gas sensors, 2012 summer Seminar in Chiang Mai University, 2012.08.