Publishing type：Research paper (scientific journal)   Publisher：IEEE Sensors Letters  

Localized surface plasmon resonance (LSPR) technology facilitates rapid gas detection but faces challenges regarding selectivity and fabrication complexity. This study presents a pioneering method for fabricating LSPR gas sensor arrays with pixel patterns using inkjet printing. By adjusting the compositions of Au nanoparticle (AuNP)/Ag nanoparticle (AgNP) ink patterns and incorporating various fluorescent dyes, spectrum information can be gathered to enable precise gas discrimination. Specifically, we have integrated 32 units within a compact 5 times 10 mathrm{m}{ { mathrm{m } }2} area to form the subpixel sensor array, thereby minimizing sensor scale and enhancing gas selectivity. In addition, principal component analysis is employed to enhance selectivity among the six common gases. Notably, this letter marks the first fabrication of LSPR gas sensor subpixel pattern arrays through inkjet printing, which combines Au/Ag nanoparticles and fluorescent pigments. Despite its limited scale, this device offers high information density. This letter on subpixel patterned LSPR gas sensor arrays introduces a novel method for sensor fabrication and demonstrates significant potential for enabling rapid, sensitive, and selective gas detection in future research endeavors.

DOI： 10.1109/LSENS.2024.3419812

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Language：English   Publisher：PLoS ONE  

Our previous studies indicate the abundant and diverse presence of yet-to-be-cultured microorganisms in the micropore-filtered fractions of various environmental samples. Here, we isolated a novel bacterium (designated as strain TMPK1T) from a 0.45-μm-filtered soil suspension by using a gel-filled microwell array device comprising 900 microwells and characterized its phylogenetic and physiological features. This strain showed low 16S rRNA gene sequence identities (<91%) and low average nucleotide identity values (<70%) to the closest validly described species, and belonged to a novel-family-level lineage within the order Rhodospirillales of Alphaproteobacteria. Strain TMPK1T exhibited small cell sizes (0.08–0.23 μm3) and had a high cyclopropane fatty acid content (>13%), and these characteristics were differentiated from other Rhodospirillales bacteria. A comprehensive habitability search using amplicon datasets suggested that TMPK1T and its close relatives are mainly distributed in soil and plant-associated environments. Based on these results, we propose that strain TMPK1T represents a novel genus and species named Roseiterribacter gracilis gen. nov., sp. nov. (JCM 34627T = KCTC 82790T). We also propose Roseiterribacteraceae fam. nov. to accommodate the genus Roseiterribacter.

DOI： 10.1371/journal.pone.0304366

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Publishing type：Research paper (scientific journal)   Publisher：IEEE Sensors Journal  

Surface-enhanced Raman scattering (SERS) gas sensing is important in various fields, including environmental monitoring, health diagnosis, and food safety. We used a one-step sputtering method to fabricate a SERS gas sensor to detect and recognize volatile organic aromatic compound (VOAC) vapors using close-set and open-set models. Four pure VOAC vapors (acetophenone, anisole, anethole, and benzaldehyde), and mixtures of the compounds were analyzed using the SERS sensor. Normalized Raman spectra of the target compounds were preprocessed using the principal component analysis (PCA) and discrete wavelet transform (DWT) dimension-reduction methods before analysis. For closed-set recognition, three classical classifiers, (naive Bayesian classifier (NBC), support vector machines (SVM) classifier, and random forest classifier (RFC)) were used to identify three vapor datasets (normalized, PCA- and DWT-based datasets). The best accuracy (99.4%) was achieved using the PCA-based dataset by SVM classifier. For open-set recognition, the dataset was first imported into a convolutional neural network (CNN) to extract features, and then three open-set recognition models, (Softmax, Openmax, and class anchor clustering (CAC)) were applied. The open-set classifier performances for different open problems were assessed using dataset openness values of 0.0871, 0.1835, and 0.3333. CAC gave an area under receiver operating characteristic (AUROC) of 0.846 for discriminating between known and unknown samples and an accuracy of 94.5% for classifying the known vapor samples at an openness of 0.0871. The SERS sensor effectively detected vapor-phase compounds and could distinguish between the target compounds in both close-set and open-set recognition scenarios.

DOI： 10.1109/JSEN.2024.3383053

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Publishing type：Research paper (scientific journal)   Publisher：IEEJ Transactions on Electrical and Electronic Engineering  

Surface-Enhanced Raman Scattering (SERS) technique is used to fabricate the gas sensor, which is developed for the visualization of the spatial distribution of gas evaporating from odor source. The 3 × 3 SERS sensor array is put on the odor source and then scanned by the home-made detection system to obtain the Raman spectra of the odor. The intensities of the characteristic peaks from the collected spectra are used to draw a heatmap graph. After the heatmap graph is processed by the noise reduction, the localization of the odor source can be clearly identified through the resulting graph. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

DOI： 10.1002/tee.23988

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Sensors  

The spatial distribution of gas emitted from an odor source provides valuable information regarding the composition, size, and localization of the odor source. Surface-enhanced Raman scattering (SERS) gas sensors exhibit ultra-high sensitivity, molecular specificity, rapid response, and large-area detection. In this paper, a SERS gas sensor array was developed for visualizing the spatial distribution of gas evaporated from benzaldehyde and 4-ethylbenzaldehyde odor sources. The SERS spectra of the gas were collected by scanning the sensor array using an automatic detection system. The non-negative matrix factorization algorithm was employed to extract feature and concentration information at each spot on the sensor array. A heatmap image was generated for visualizing the gas spatial distribution using concentration information. Gaussian fitting was applied to process the image for localizing the odor source. The size of the odor source was estimated using the processed image. Moreover, the spectra of benzaldehyde, 4-ethylbenzaldehyde, and their gas mixture were simultaneously detected using one SERS sensor array. The feature information was recognized using a convolutional neural network with an accuracy of 98.21%. As a result, the benzaldehyde and 4-ethylbenzaldehyde odor sources were identified and visualized. Our research findings have various potential applications, including odor source localization, environmental monitoring, and healthcare.

DOI： 10.3390/s24030790

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Publisher：Proceedings of IEEE Sensors  

Microbial volatile organic compounds (MVOCs) can serve as a diagnostic tool for assessing the respiratory status of microorganisms. Localized surface plasmon resonance (LSPR) sensors are noted for their rapid response and straightforward operation; however, they often struggle to provide specific information about the detected substances and to differentiate between gas types. In contrast, gas sensors utilizing surface-enhanced Raman spectroscopy (SERS) technology offer excellent selectivity and can generate unique 'fingerprint' signals, enabling easy identification and distinction of various gas molecules. Integrating these two technologies promises to enhance the visualization of volatile organic compound distributions both more effectively and expeditiously.

DOI： 10.1109/SENSORS60989.2024.10785178

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Sensors  

Odor information fills every corner of our lives yet obtaining its spatiotemporal distribution is a difficult challenge. Localized surface plasmon resonance has shown good sensitivity and a high response/recovery speed in odor sensing and converts chemical information such as odor information into optical information, which can be captured by charge-coupled device cameras. This suggests that the utilization of localized surface plasmon resonance has great potential in two-dimensional odor trace visualization. In this study, we developed a two-dimensional imaging system based on backside scattering from a localized surface plasmon resonance substrate to visualize odor traces, providing an intuitive representation of the spatiotemporal distribution of odor, and evaluated the performance of the system. In comparative experiments, we observed distinct differences between odor traces and disturbances caused by environmental factors in differential images. In addition, we noted changes in intensity at positions corresponding to the odor traces. Furthermore, for indoor experiments, we developed a method of finding the optimal capture time by comparing changes in differential images relative to the shape of the original odor trace. This method is expected to assist in the collection of spatial information of unknown odor traces in future research.

DOI： 10.3390/s23239525

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：IEEE Sensors Letters  

Visualization of gaseous chemical substances, such as odors, is very challenging, and few studies are being conducted to address this issue. These odor visualization technologies are expected to be more beneficial for various applications, such as detecting hazardous or human relating gas source localization. Currently, semiconductor gas sensors are commonly used for gas measurements; however, these sensors have disadvantages, such as slow response time and inability to detect multiple types of gases. Furthermore, it is difficult to understand how gases are distributed in space. Thus, we have developed a gas sensor utilizing localized surface plasmon resonance (LSPR). LSPR gas sensors enable real-time, high-speed response and recovery, and by analyzing wavelength information using a hyperspectral camera, gas imaging and identification become possible. In this letter, we conducted experiments on visualizing the spatiotemporal distribution of multiple gases and identifying gas space through the analysis of spectral information using a 2-D LSPR gas sensor and a hyperspectral camera. As a result, we successfully visualized and identified the distribution of each gas in a situation where multiple gases were present by performing principal component analysis analysis on the spectral data obtained from hyperspectral images.

DOI： 10.1109/LSENS.2023.3301847

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：IEEE Sensors Letters  

Localized surface plasmon resonance (LSPR) offers rapid gas detection but faces selectivity and fabrication complexity challenges. This letter reports a method of fabricating LSPR gas sensor arrays with pixel patterns by inkjet printing. We developed Au/Ag nanoparticles ink with different compositions to collect spectrum information for accurate gas discrimination. In addition, principal component analysis (PCA) is used to realize the selectivity among four common gases that we often encounter in our daily lives. For the first time, this work demonstrates the fabrication of LSPR gas sensors through inkjet printing. Based on the LSPR phenomenon for gas detection, it shows great potential for rapid, sensitive, and selective gas detection for future research.

DOI： 10.1109/LSENS.2023.3300820

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Japanese Journal of Applied Physics  

This study aims to develop a microfluidic-based taste sensor for detecting time-dependent human taste sensations. Lipid polymer membranes were welded to perforated polycarbonate films with organic solvents to monitor the adsorption and desorption of taste substances to lipid polymer membranes and to physically immobilize lipid polymer membranes to withstand the pressure of a pumped liquid. A polydimethylsiloxane flow channel was bonded chemically to the polycarbonate film with the lipid polymer membrane using 3-aminopropylethoxysilane. A fabricated microfluidic-based taste sensor could measure the membrane potential change with time due to the adsorption and desorption of tannic acid, an astringency substance, onto a lipid polymer membrane. The proposed sensor could be useful as a tool for assessing the time-course changes in human taste.

DOI： 10.35848/1347-4065/acb4fa

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Publisher：2023 22nd International Conference on Solid-State Sensors, Actuators and Microsystems, Transducers 2023  

Surface-Enhanced Raman Scattering (SERS) technique is used to fabricate the gas sensor, which is developed for the visualization of the odor source localization. The 3 × 3 SERS sensor array is put on the odor source and then scanned by the home-made detection system to obtain the Raman spectra of the odor. The intensities of the characteristic peaks from the collected spectra are used to draw a heatmap graph. After the heatmap graph is processed by the noise reduction, the localization of the odor source can be clearly identified through the resulting graph.

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Publisher：2023 22nd International Conference on Solid-State Sensors, Actuators and Microsystems, Transducers 2023  

Visualization of gaseous chemical substances such as odors is important technology, and this technology has the potential to be applied to various applications, such as searching for people at disaster sites and identifying hazardous materials. As an alternative technology to olfaction, semiconductor gas sensors are currently used to measure gases, but these sensors have problems such as slow response and slow sensor recovery, and it is also difficult to measure spatial distribution. We utilized, gas sensors using localized surface plasmon resonance (LSPR) gas sensor which have a real-time, fast response and fast recovery, making it possible to perform gas imaging and identification. Here, experiments were conducted to visualize and identify the spatiotemporal distribution of multiple gases using an 2D LSPR gas sensor and a hyperspectral camera.

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Publishing type：Research paper (international conference proceedings)   Publisher：Proceedings of IEEE Sensors  

Microbial volatile organic compounds (MVOCs) could be detected and used to understand the metabolic state of microorganisms. The gas sensor developed using the Surface Enhanced Raman Scattering (SERS) technique possesses ultra-high sensitivity and excellent selectivity, which is suitable for detecting low-concentration and complex MVOCs. Here, an odor source is simulated as a microbial community, and a 2D SERS sensor array is utilized to visualize the odor spatial distribution and localize the odor source. The Raman spectra of the odor adsorbed onto the sensor surface are collected after scanning the sensor array. A heatmap image is obtained by using the intensities of the characteristic peaks from the acquired Raman spectra. Thus, the odor spatial distribution is presented, and the localization of the odor source is determined by the image.

DOI： 10.1109/SENSORS56945.2023.10325081

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers in Microbiology  

In order to exploit the microbes present in the environment for their beneficial resources, effective selection and isolation of microbes from environmental samples is essential. In this study, we fabricated a gel-filled microwell array device using resin for microbial culture. The device has an integrated sealing mechanism that enables high-density isolation based on the culture of microorganisms; the device is easily manageable, facilitating observation using bright-field microscopy. This low-cost device made from polymethyl methacrylate (PMMA)/polyethylene terephthalate (PET) has 900 microwells (600 μm × 600 μm × 700 μm) filled with a microbial culture gel medium in glass slide-sized plates. It also has grooves for maintaining the moisture content in the micro-gel. The partition wall between the wells has a highly hydrophobic coating to inhibit microbial migration to neighboring wells and to prevent exchange of liquid substances. After being hermetically sealed, the device can maintain moisture in the agarose gels for 7 days. In the bacterial culture experiment using this device, environmental bacteria were isolated and cultured in individual wells after 3 days. Moreover, the isolated bacteria were then picked up from wells and re-cultured. This device is effective for the first screening of microorganisms from marine environmental samples.

DOI： 10.3389/fmicb.2022.1031439

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：npj Flexible Electronics  

A method was used to fabricate a fully inkjet-printed gas sensor matrix on photographic paper. An electrode matrix comprising 36 interdigital electrodes in a high-density layout that is easy to integrate has been fabricated using a combination of insulating ink and commercial silver ink. Molecular-imprinted polymer (MIP) inks were then made using a simple solution mixing method, and these inks were printed together with carbon black ink on the electrode matrix to complete production of the sensor. Finally, experimental dynamic sensing of volatile organic compounds verifies that for detection of gases corresponding to the MIP template molecules, the MIP layer offers improvements in both sensitivity and selectivity when compared with non-imprinted polymer layers. The matrix can produce a response of more than 20% to 3 ppm propenoic acid gas through adjustment of the printing times for the carbon black layer and the MIP layer.

DOI： 10.1038/s41528-022-00168-6

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Language：Japanese   Publisher：Japan Sciety for Environmental Biotechnology  

DOI： 10.50963/jenvbio.22.1_69

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The Surface-Enhanced Raman Scattering (SERS) technique is utilized to fabricate sensors for gas detection due to its rapid detection speed and high sensitivity. However, gases with similar molecular structures are difficult to directly discriminate using SERS gas sensors because there are characteristic peak overlaps in the Raman spectra. Here, we proposed a multiple SERS gas sensor matrix via a spin-coating functional polymer to enhance the gas recognition capability. Poly (acrylic acid) (PAA), Poly (methyl methacrylate) (PMMA) and Polydimethylsiloxane (PDMS) were employed to fabricate the polymer film. The high design flexibility of the two-layer film was realized by the layer-by-layer method with 2 one-layer films. The SERS gas sensor coated by different polymer films showed a distinct affinity to target gases. The principle component analysis (PCA) algorithm was used for the further clustering of gas molecules. Three target gases, phenethyl alcohol, acetophenone and anethole, were perfectly discriminated, as the characteristic variables in the response matrix constructed by the combination of gas responses obtained 3 one-layer and 3 two-layer film-coated sensors. This research provides a new SERS sensing approach for recognizing gases with similar molecular structures.

DOI： 10.3390/s21165546

Language：English   Publishing type：Research paper (scientific journal)  

We report the draft genome sequence of novel Rhodospirillales bacterium strain TMPK1, isolated from a micropore-filtered soil suspension. This strain has a genome of 4,249,070 bp, comprising 4,151 protein-coding sequences. The genome sequence data further suggest that strain TMPK1 is an alphaproteobacterium capable of carotenoid production.

DOI： 10.1128/MRA.00393-21

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Chemiresistor sensor matrix prepared by full-printing processes
Herein, we report a novel full printing process for fabricating chemiresistor gas sensor matrixes on photographic paper with an inkjet printer. Sensor matrices, which can increase a number of sensors significantly compared to a serial sensor array, were printed on one piece of A4 photographic paper. Each sensor matrix contains 36 interdigital electrodes in an area of less than 11 mm2, which greatly improves the density of the sensor. The basic architecture of the sensor matrix is electrodes that row and column intersecting. In order to insulate the row and column electrodes from meeting each other, an insulating layer needs to be fabricated at the point of intersection between the row and column electrodes. The insulation layer was produced by adjusting the number of printing passes and shape of the printing pattern of color pigment ink. Carbon black (CB) was used to form a chemosensitive composite by changing its resistivity with a specific polymer for the preparation of sensing material. In order to make the sensing material can be printed, it is necessary to disperse CB first. CB was dispersed in aqueous solution with sodium dodecyl sulfate added as a surfactant to lower the surface tension, which enabled printing of CB using an inkjet printer. Some polymers have certain adsorption characteristics for gases. According to the different gas properties, the adsorption characteristics are also different. By adding polyethylene glycol polymer to the CB layer, the response to four gases with different properties is improved. Compared with the drop coating, the full-printing sensors not only reduces the production time significantly, but also improves the gas response magnitude to ethanol by about three times. The results demonstrate that the developed sensor can be used as a low cost, disposable, and easily printable chemical sensor.

DOI： 10.1088/2058-8585/abec19

Language：Others   Publishing type：Research paper (other academic)  

The Localized Surface Plasmon Resonance (LSPR) gas sensor is a promising for mounting on the robot due to an advantage of high-speed response speed and low power consumption. In addition, it is possible to change the characteristic by coating fluorescent dye on the LSPR surface. In this research, we have developed a robot equipped with multi LSPR gas sensor module for the purpose of the identification of gas species.

DOI： 10.1109/SENSORS47125.2020.9278605

Language：Others   Publishing type：Research paper (other academic)  

2D LSPR gas sensor with Au/Ag core-shell structure coated by fluorescent dyes
LSPR (Localized Surface Plasmon Resonance) based 2D (Two-dimensional) gas sensor system which can measure and identify multi-gases with high spatial resolution have been developed. The gas sensor detects optical changes promoted by the gas on the LSPR substrate with hyperspectral camera. Basically, LSPR gas sensor does not have a molecular selectivity, then the identification of gas species is difficult. To overcome the disadvantage, LSPR substrates based on Au/Ag core-shell structure with spectral gas-discriminating ability through optical interaction were fabricated by spin coating fluorescent dyes. Using the LSPR coupled with fluorescent dyes, this sensor provides rich spectral information about the detecting molecules and can discriminates gas species.

DOI： 10.1109/SENSORS47125.2020.9278828

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Geosmin (GSM) with an earthy odor resembling is often accompanied by 2-methylisoborneol (MIB), which caused the earthy and musty taste of drinking water. To detect trace GSM solution, we designed gas sensor by Surface-enhanced Raman Scattering (SERS) technology which has the capacity of single molecule detection. With our ultra-high sensitivity detection system, response range from 10 ppt to 10 ppb geosmin in ultrapure water was confirmed. Additionally, 100 ppt geosmin in tap water was detectable.

DOI： 10.1109/SENSORS47125.2020.9278909

Language：English  

Microfabricated electrochemical sensing devices
Electrochemistry provides possibilities to realize smart microdevices of the next generation with high functionalities. Electrodes, which constitute major components of electrochemical devices, can be formed by various microfabrication techniques, and integration of the same (or different) components for that purpose is not difficult. Merging this technique with microfluidics can further expand the areas of application of the resultant devices. To augment the development of next generation devices, it will be beneficial to review recent technological trends in this field and clarify the directions required for moving forward. Even when limiting the discussion to electrochemical microdevices, a variety of useful techniques should be considered. Therefore, in this review, we attempted to provide an overview of all relevant techniques in this context in the hope that it can provide useful comprehensive information.

DOI： 10.1039/c9lc01112a

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2D LSPR multi gas sensor array with 4-segmented subpixel using Au/Ag core shell structure
LSPR (Localized Surface Plasmon Resonance) based 2D (2 Dimensional) gas imaging sensor system which can capture spatial distribution of each constituent of mixed gas have been developed. The gas image sensor detects the gas promoted optical changes occurred on the LSPR substrate by CCD camera. Basically, LSPR gas sensor does not have a molecular selectivity, then the identification of gas species is difficult. To overcome the disadvantage, pixelated LSPR substrate based on Au/Ag core-shell structure which has different gas response properties is fabricated by photo-induced metal growth by mask-less exposure system using a commercial video projector.

DOI： 10.1109/SENSORS43011.2019.8956635

Language：Others   Publishing type：Research paper (other academic)  

Mixture of gas molecules must be accurately detected for gas sensor. However, there are certain difficulties in identifying the type of gas and detecting its concentration by chemical sensors. SERS (Surface Enhanced Raman Scattering) is a promising method for high sensitive gas detection because of its ability of molecule discrimination. However, it is difficult for SERS sensor to identify gases with the similar structure. In this research, we have developed a more selective SERS sensor with molecular filter layers. Molecular filter property is studied by coating a filter polymer film on the SERS substrate. The characteristics of the sensor with two membrane structures were also studied and different filtering properties were obtained.

DOI： 10.1109/SENSORS43011.2019.8956884

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Invisible Odor Trace Tracking with LSPR based High Speed Gas Sensor Robot System
Various odor robots have been developed for finding gas sources. However, the response speed of sensors is now a major limit for the promotion of odor robot using chemical substances information. In this research, we have developed a robot equipped with two LSPR (Localized Surface Plasmon Resonance) gas sensor module that can quickly respond to gas molecules at a high speed of above 25 Hz and set a specific algorithm for tracking the invisible odor line on the ground.

DOI： 10.1109/SENSORS43011.2019.8956599

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This paper introduces a new method to fabricate a large - scale sensor array. By printing electrodes on photographic paper and making insulating layers, 6×6 arrays of sensors were obtained. Different gas selective can be printed in different units to detect different gases. Thus, production of multiple sensors in a small area with low cost was realized. On a piece of A4 photo paper, 30 sensor matrices can be printed at the same time. Each sensor array has 36 sensing units, thus theoretically identifying up to 36 gases. The sensor is suitable to be used in wearable devices to identify human skin gases due to its flexible substrate, low production cost and simple manufacturing process. In this experiment, molecular imprinted polymer (MIP) solution [1], carbon black (C.B.) conductive solution and insulating solution are prepared as ink, which can be used for ink-jet printer printing. This makes the method of developing the sensor more flexible. Compared with the sensor developed by micropipette to drop the MIP solution and C.B. conductive solution, the sensor developed by a printer has better uniformity.

DOI： 10.1109/SENSORS43011.2019.8956795

Language：Others   Publishing type：Research paper (other academic)  

This paper proposes a flexible gas sensor array system fabricated by full printing process, which can simultaneously monitor a variety of gases. The production of sensors using a low-cost, large-scale, high-speed printing technology throughout the process. Realizing the production of multiple sensors in a small area with low cost. Detection of a variety of gases using a sensor array. The results show that it is possible to make a full-printing gas sensor by acetylene carbon black (Φ20 nm) ink and molecularly imprinted polymer (MIP) ink; 36 sensors are formed on a 3cm-3cm paper; and the gases such as acetic acid and hexanoic acid are well recognized.

DOI： 10.1109/TRANSDUCERS.2019.8808512

Language：Others   Publishing type：Research paper (other academic)  

Odor Trace Visualization by Mobile Robot Equipped with Two-Dimensional LSPR Gas Sensor
This paper presents a Localized Surface Plasmon Resonance (LSPR) based high speed gas sensor module for gas sensing applications, including visualization of invisible odor trail. Innovative claims include: (1) the use of a double layer film with Au/Ag nanoparticles for gas detection; (2) high speed response characteristic; and (3) visualization of odor trail pattern with high spatial resolution. The results show a significant change in reflection light with ethanol vapor; response speed of 1 second; and a clear image of visualized odor trail of letter "Q" of a 3 mm line width.

DOI： 10.1109/TRANSDUCERS.2019.8808400

Language：Others   Publishing type：Research paper (other academic)  

Gas Visualization with Photo-Induced 2D Pixel Patterned Au/Ag Core-Shell LSPR Imaging Device by Mask-Less Exposure System
Visualization of the distribution of various gases makes us possible to recognize environmental circumstances, e.g., localization of dangerous chemical sources or human body odorants in the case of disaster scene. Localized surface plasmon resonance (LSPR) can detect various gases with changes of surrounding dielectric constant, and can be used gas sensor with high response / recovery speed and high spatial resolution, i.e., 2 dimensional LSPR gas sensor gas work as a gas image sensor device. The gas image sensor detects the gas distribution occurred on the LSPR substrate by an ordinal image sensor. The general LSPR gas sensor, however, does not have a molecular selectivity, then the identification of gas species is difficult. To overcome such disadvantages, pixelated LSPR substrate based on Au/Ag core-shell structure is fabricated by photo-induced growth by mask-less exposure system using a commercial video projector.

DOI： 10.1109/TRANSDUCERS.2019.8808591

Language：Others   Publishing type：Research paper (other academic)  

Localized Surface Plasmon Resonance (LSPR) based gas sensor is a promising way to break the bottleneck of the sensing speed of traditional semiconductor gas senor for mobile robot use. In this study, we developed a two-dimensional gas visualization system based on LSPR phenomenon with Au/Ag nanoparticles for high speed and high spatial resolution sensing. The 9-hour silver growth on the surface of Au nanoparticles layer has been shown to reduce the influence of transmitted light (noise) on visualization while ensuring sensitivity. An invisible odor trace similar to letter 'U' with a line width of 3 mm was visualized by CCD camera through the LSPR sensor film. The intensity changes of the image every 1 second showed of the developed system's high response speed and spatial resolution.

DOI： 10.1109/ISOEN.2019.8823230

Language：Others   Publishing type：Research paper (other academic)  

If we can quickly recognize the distribution of dangerous gases, it will be useful in places such as disaster scene. Localized surface plasmon resonance (LSPR) gas sensor is known as a gas sensor with high response / recovery speed and high spatial resolution. However, the general LSPR gas sensor does not have a molecular selectivity and it is difficult to identify the gas species. We made gas selected pixelated LSPR substrate based on Au/Ag core-shell structure by photo-induced growth by exposure system using the photomask.

DOI： 10.1109/ISOEN.2019.8823375

Language：Others   Publishing type：Research paper (other academic)  

Probe gas sensing system based on reflected light detection from localized surface plasmon resonance
The present study explored a probe type gas detection system which can be used to detect the gas conveniently. The gas sensing mechanism is utilizing Localized Surface Plasmon Resonance (LSPR) sensor which based on the reflected light change caused by the refractive index changes of gas where exposing to the metal nanoparticles layer. The LSPR layer was prepared by vacuum sputtering of AuNPs on a glass substrate, growing in silver growth solution and consequently thermal annealing. An optical system which composed of fiber probe, light source and spectrometer was developed to detect the change of reflected light. It was found that compared with incident light irradiating from metal nanoparticles side, glass side could obtain clearer spectra peak. In addition, a LSPR sensor which had 5 hours silver growth time has the best response to acetic acid gas. This work demonstrated that the reflection detection system has a great potential in gas detecting area.

DOI： 10.1109/ISOEN.2019.8823157

Language：Others   Publishing type：Research paper (other academic)  

Detection of volatile organic components (VOCs) is meaningful to agricultural field, bio recognition and so on. In this study, we developed an array type gas sensor to detect VOCs. This sensor is based on localized surface plasmon resonance (LSPR). Molecularly Imprinted Sol-Gels (MISG) were patterned on the surface of Au nano-islands to add molecular selectivity. The substrate is separated into 9 regions on AuNPs by using polyimide tape partitions and spin coating MISG solutions for each region. Multi channels sensor was fabricated with this substrate after this process. The sensor's sensitives were compared for each channel. The result indicated that the sensitivity of target gas channel was higher than into others.

DOI： 10.1109/ISOEN.2019.8823275

Language：Others  

Our living environment is surrounded by a variety of odors. The visualized detection of odorant molecules may explore many new applications that cannot be realized by conventional sensors. This chapter introduces some novel sensing technologies that can be used to visualize both the odor space and odor quality. Fluorescence imaging sensors are developed to record the shape of odor sources and the spatiotemporal distribution of odor flows. Multispectral imaging-based odor visualization shows power in the structure-related discrimination of different odorant molecules. Localized surface plasmon resonance (LSPR) sensors based on metal nanoparticles show advantages in high-speed response and recovery in gas or vapor sensing. A sensor robot based on the LSPR sensors is developed to visualize the odor information from on-ground odor sources. In addition, data analysis based on physicochemical parameters of odorant molecules is carried out to demonstrate the difference of odor quality by using network-graph techniques.

DOI： 10.1016/B978-0-12-815409-0.00018-8

Language：Others   Publishing type：Research paper (other academic)  

The microbeads shape sensor film was developed in this work combines fluorescent dye agents whose fluorescent intensity can be influenced in touch of a specific odor, and Molecular Imprinting Polymer. Like photographic films, the fluorescent dye microbeads film can visualize the odor gas diffusion with the CCD camera. To enhance the fluorescence intensity of Quinine Sulfate increases in the water environment, hydrogel was applied in the film. For developing multi-odor sensors, we made four kinds of fluorescent microbeads to test whether the interaction among fluorescent dyes happened. It turned out microbeads structure successfully remained characters of every fluorescent dye.

DOI： 10.1109/ICSENS.2018.8589830

Language：Others   Publishing type：Research paper (other academic)  

Various odor robots have been developed for gas source localization in plume with specific algorithm. However, sensor response speed is now a major limit for the promotion of odor robot using chemical substances information. In this research, we have fabricated a Localized surface plasmon resonance based gas sensor which can show a quick response to gas molecular at a high speed of above 25Hz. The sensor was mounted on a mobile robot for gas sources detection successfully. Furthermore, a two-dimensional gas sensor based on the same technique was developed for visualization of spatial distribution of gas flow.

DOI： 10.1109/ICSENS.2018.8589909

Language：Others   Publishing type：Research paper (other academic)  

Patternable actuator film for monolithic soft micro robot process was developed. The film is consisted from thermal bimorph actuation layer and extra functional layer including driving heater layer and elastic mechanical buffer layer. A cantilever arm actuator fabricated by patterning the film was operated with 2 V applied voltage. Multi actuator device or micro robot can be fabricated without assembling process by appropriate patterning process with this film.

DOI： 10.1109/ICSENS.2018.8589717

Language：English   Publishing type：Research paper (scientific journal)  

A robot equipped with a high-speed LSPR gas sensor module for collecting spatial odor information from on-ground invisible odor sources
Improving the efficiency of detecting the spatial distribution of gas information with a mobile robot is a great challenge that requires rapid sample collection, which is basically determined by the speed of operation of gas sensors. The present work developed a robot equipped with a highspeed gas sensor module based on localized surface plasmon resonance. The sensor module is designed to sample gases from an on-ground odor source, such as a footprint material or artificial odor marker, via a fine sampling tubing. The tip of the sampling tubing was placed close to the ground to reduce the sampling time and the effect of natural gas diffusion. On-ground ethanol odor sources were detected by the robot at high resolution (i.e., 2.5 cm when the robot moved at 10 cm/s), and the reading of gas information was demonstrated experimentally. This work may help in the development of environmental sensing robots, such as the development of odor source mapping and multirobot systems with pheromone tracing.

DOI： 10.1021/acssensors.8b00214

Language：Others   Publishing type：Research paper (scientific journal)  

This work is an exploration into visualizing measurement of putrescine specific adsorption by photographing colorized molecule imprinting chromogenic hydrogel. Membranes are prepared with imitate templates 1,4-butylene glycol, adipic acid or succinic acid, respectively and ninhydrin is used as chromogenic agent for target molecule putrescine. The adsorbing concentration on MIP is reflected in the form of visible violet-colored stain differed in shape and shade, which are recorded by hyper spectral camera and proceeded into intuitive 3D isohypse surfaces plot. By quantifying the height of surface peaks, imprinting efficiency is estimated in accordance with polyvinyl alcohol concentration and crosslinking degree. The imprinting efficiency of three imitate molecule templates is also discussed.

DOI： 10.1016/j.snb.2017.11.128

Language：Others   Publishing type：Research paper (other academic)  

Odorants measurement using hyperspectral imaging and PVC film including multi fluorescent probes
Odor imaging sensor was developed with odorants sensing mechanism based on the complicated fluorescence interactions between the multi-fluorescent-probes and odorants. In this research, poly vinyl chloride (PVC) films including various fluorescent probe were developed, and fluorescence properties of the film were investigated. Using the multi fluorescent probe film, fluorescence intensity change spectrum to various odorants was measured, and odorants could be clustered by their chemical structure by multi-variate analyses of hyper spectra images.

DOI： 10.1109/ICSENS.2017.8234328

Language：Others   Publishing type：Research paper (other academic)  

We developed a dynamic photo-tunable gas adsorbent based on smart (photo sensitive) material and molecularly imprinted polymer (MIP) technology [1]. Gas adsorption property of the material, mixture of photochromic materials and polymethyl methacrylate (PMMA), can be controlled reversible and continuously by irradiation of with light different wavelength. As a result, gas sensor which is composed of a quartz crystal microbalance (QCM) coated with the developed adsorbent was fabricated. This sensor system can detect a certain gas molecule corresponding to the adsorbent property from gas mixture with only one sensor node.

DOI： 10.1109/TRANSDUCERS.2017.7994313

Language：Others   Publishing type：Research paper (scientific journal)  

Review of Microfluidic Devices for On-Chip Chemical Sensing
Microfluidic techniques can be a basis to realize user-friendly microanalytical devices of high performance. Required operations include injection of solutions to reaction chambers, volume measurement, and mixing of solutions. For this purpose, the use of surface tension is attractive. In hydrophobic flow channels, solutions can be moved stably in the form of plugs. Otherwise, solutions can be transported by capillary action in a hydrophilic flow channel and stopped at a hydrophobic valve. The valve can be opened autonomously by switching the mixed potential by wetting a zinc electrode formed in a controlling flow channel. In this review paper, we introduce some of our microfluidic devices particularly focusing on devices that work based on surface tension.

DOI： 10.1002/ecj.11944

Language：Others   Publishing type：Research paper (other academic)  

Highly sensitive optical sensing of molecules can be achieved by using localized surface plasmon generated at metal nanostructures, such as SERS-based sensing. We fabricated SERS-active silver nanostructures by using polarized light irradiation, and evaluated their response properties to rhodamine 6G. In this paper, it is shown that strong Raman signals of rhodamine 6G and large variation in optical transmission have been obtained. Especially, the transmission spectra of the silver nanostructures grown under the irradiation of polarized light showed unique polarizing properties derived from different modes of localized surface plasmons, which would be useful in smart optical sensing.

DOI： 10.1109/ICSENS.2016.7808850

Language：Others   Publishing type：Research paper (other academic)  

Various devices are developed to obtain information of odor for crisis evasion in dangerous situation. However, the improvement of sensing methodology is lagging. Therefore, some novel odor sensors with high sensitivity, selectivity and short response time are required. Gas detection based on surface enhanced Raman scattering (SERS) is a promising technology to realize such sensor. We developed a sandwich structured SERS substrate with an organic layer, which was placed between an Au thin layer and a gold nano particles (AuNPs) layer. Furthermore, the organic layer was reconfigured to molecularly imprinted polymer (MIP) for selective gas detection. Raman spectrum obtained with a MIP-SERS substrate shows the appearance of peak based on 2-phenylethanol that is targeted gas molecule. Compared with non-imprinted polymer (NIP), MIP substrate showed stronger SERS signals.

DOI： 10.1109/ICSENS.2016.7808604

Language：Others   Publishing type：Research paper (other academic)  

Gas sensor with high molecular selectivity is highly demanded in many fields of industry or disaster relief. Molecularly imprinted polymer (MIP) can recognize target gas by specific adsorption for template molecule. In this study, a novel chemiresistor, gas sensor which combined with MIP and conductive nanoparticles has been developed. The gases were distinguished based on molecularly structure by MIP. If gas molecule is absorbed into this polymer, structures and properties of conductive composites are changed. It causes electric resistance changed. It is conceivable that the degree of resistance change is dependent upon the amount of absorption. Moreover, MIP absorbs larger quantity of template molecule than similar gas molecule. So this MIP chemiresistor can be used for measurement of specific target gas based on magnitude of response. Measurement results of gas sensing showed that larger response was produced by MIP chemiresistor for the template molecule than other gas and NIP (non-imprinted polymer) composite. It means that a sensor which could both recognizing molecules and transduce electrical signal simultaneously was successfully developed.

DOI： 10.1109/ICSENS.2016.7808660

Language：English   Publishing type：Research paper (scientific journal)  

Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor clusters with specific molecular properties and uses this combinatorial information in odor discrimination. This suggests that measurement and clustering of odor molecular properties (e.g., polarity, size) using an artificial sensor is a promising approach to odor sensing. Here, adsorbents composed of composite materials with molecular recognition properties were developed for odor sensing. The selectivity of the sensor depends on the adsorbent materials, so specific polymeric materials with particular solubility parameters were chosen to adsorb odorants with various properties. The adsorption properties of the adsorbents could be modified by mixing adsorbent materials. Moreover, a novel molecularly imprinted filtering adsorbent (MIFA), composed of an adsorbent substrate covered with a molecularly imprinted polymer (MIP) layer, was developed to improve the odor molecular recognition ability. The combination of the adsorbent and MIP layer provided a higher specificity toward target molecules. The MIFA thus provides a useful technique for the design and control of adsorbents with adsorption properties specific to particular odor molecules.

DOI： 10.3390/s16111974

Language：English   Publishing type：Research paper (scientific journal)  

Microfluidic Separation of Redox Reactions for Coulometry Based on Metallization at the Mixed Potential
Coulometric detection of an analyte in a solution at nanoliter scale was conducted by having redox reactions proceed simultaneously on a platinum electrode. The analyte was oxidized on a part of the electrode in one flow channel and silver was deposited on an array of circular microelectrodes formed in another flow channel at a mixed potential. Coulometric determination of the deposited silver showed a steep change in the generated charge as a result of the complete oxidation of silver. The short measurement time after the start of the coulometry suppressed the increase in background charge, resulting in significant lowering of the detection limit. The lower detection limit for H O was 30 nM (3σ). To improve selectivity and minimize the influence of coexisting interferents, the shifting of the mixed potential, application of a permselective membrane, and electrochemical elimination of the interferents were effective modifications. 2 2

DOI： 10.1021/acs.analchem.6b01234

Language：Others   Publishing type：Research paper (scientific journal)  

Electrochemical Bubble-Based Bidirectional Microfluidic Transport
With the aim of application to biochemical analyses, efficient bidirectional microfluidic transport was achieved through the reversible electrochemical production and shrinkage of hydrogen bubbles. A three-electrode system with a platinum black working electrode, a Ag/AgCl reference electrode, and a platinum auxiliary electrode was incorporated into a poly(dimethylsiloxane) structure containing the necessary flow channels and compartments. The influence of the electrode and flow channel structures on the operation of the system was investigated. The production and shrinkage of bubbles was achieved by applying appropriate potentials to the working electrode, which minimized the influence of spontaneous shrinkage resulting from the oxidizing effect of dissolved oxygen. Device performance depended on the structure of the working electrode, meaning that further optimization will be necessary. The device was shown to withdraw solution through a minimally invasive needle and to process liquid plugs in a microfluidic system.

DOI： 10.1021/acssensors.5b00059

Language：Others   Publishing type：Research paper (scientific journal)  

This paper describes the fabrication of a microelectromechanical-system (MEMS) mirror array for a wavelength-selective switch (WSS). The MEMS mirror array, in which a lot of closely spaced adjacent mirrors are electrostatically operated, consists of a MEMS mirrors and a mirror-drive electrodes. In order to reduce electrical interference, comb-shaped ground walls with a high aspect ratio of about 20 are monolithically integrated with the MEMS mirror chip. Further, U-shaped gold electroplating walls are formed in the mirror-drive electrode chip. With these walls, each MEMS mirror successfully operates with low electrical interference. © 2013 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.precisioneng.2013.05.008

Language：Others   Publishing type：Research paper (scientific journal)  

Droplet-based microfluidic sensing system for rapid fish freshness determination
A microfluidic device was constructed for on-site determination of fish freshness by using adenosine-5′-triphosphate (ATP) concentration as an indicator of freshness. In the device, extracts from fish and reagent solutions were processed in the form of droplets separated by air. The volumes of the droplets of the extract solution, a solution containing enzyme substrates, and a washing buffer solution were measured in branched flow channels. To simplify the structure and procedure for mixing solutions, a wider portion was formed in one flow channel to merge the droplets. A row of droplets was ejected from each of three branched flow channels, merged in the wider portion, and transported to a sensing region located downstream. ATP was detected using two enzymatic reactions involving glycerol kinase (GK) and glycerol-3-phosphate oxidase (G3PO). A linear relationship between the generated current and ATP concentration was confirmed, and ATP detection from jack mackerel extracts was carried out. A distinct change in the current was observed with the fresh extracts as in the case of standard solutions. The obtained data correlated well with those obtained by high-performance liquid chromatography (HPLC). © 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2012.05.043

Language：Others   Publishing type：Research paper (scientific journal)  

Miniaturized shape memory alloy pumps for stepping microfluidic transport
A shape memory alloy (SMA) actuator and a polydimethylsiloxane (PDMS) elastic tube were used to realize a simple pump. A liquid plug in a flow channel could be moved forward and backward reversibly by exploiting the shape memory properties of the actuator. Two SMA sheets were used to create a peristaltic pump capable of moving a solution forward and backward over a long distance. The stepping transport caused by applying pulses of electric power facilitated the adjustment of the plug's position. Manipulations such as volume measurement and the merging of two plugs were demonstrated using a microfluidic device with a T-junction. © 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2011.12.085

Language：English   Publishing type：Research paper (scientific journal)  

Coulometric detection of components in liquid plugs by microfabricated flow channel and electrode structures
Coulometry has been demonstrated to be effective for determining the analyte in a liquid plug on the nanoliter-scale confined in a flow channel. A plug prepared in a rhombus structure of an auxiliary flow channel was placed on a thin-film three-electrode system, and hydrogen peroxide was detected as a model analyte. Under a fixed potential, the current decayed rapidly, particularly in shallow flow channels, thus making reproducible amperometric detection difficult. On the other hand, the increasing charge during coulometry facilitated the measurements. A constricted flow channel structure with an array of platinum strips for the working electrode was effective at efficiently consuming the analyte to improve the sensitivity and lower the detection limit. Compared to the case of a single short working electrode with the same area, a 4-fold increase in sensitivity was observed for the best combination of flow channel height and interstrip distance. With an increase in the generated current while maintaining the background at a low level, the detection limit was lowered from 1.3 μM to 410 nM using working electrodes with the same area. Furthermore, the processing of solutions containing l-glutamate or l-glutamate oxidase and the detection of l-glutamate were demonstrated. © 2010 American Chemical Society.

DOI： 10.1021/ac102289a

Language：English   Publishing type：Research paper (scientific journal)  

Engineering of capillary-like structures in tissue constructs by electrochemical detachment of cells
A major challenge in the development of functional thick tissues is the formation of vascular networks for oxygen and nutrient supply throughout the engineered tissue constructs. This study describes an electrochemical approach for fabrication of capillary-like structures, precisely aligned within micrometer distances, whose internal surfaces are covered with vascular endothelial cells. In this approach, an oligopeptide containing a cell adhesion domain (RGD) in the center and cysteine residues at both ends was designed. Cysteine has a thiol group that adsorbs onto a gold surface via a gold-thiolate bond. The cells attached to the gold surface via the oligopeptide were readily and noninvasively detached by applying a negative electrical potential and cleaving the gold-thiolate bond. This approach was applicable not only for a flat surface but also for various configurations, including cylindrical structures. By applying this approach to thin gold rods aligned in a spatially controlled manner in a perfusion culture device, human umbilical vein endothelial cells (HUVECs) were transferred onto the internal surface of capillary structures in collagen gel. In the subsequent perfusion culture, the HUVECs grew into the collagen gel and formed luminal structures, thereby forming vascular networks in vitro. © 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2009.11.104

Language：English   Publishing type：Research paper (scientific journal)  

Micropatterned cocultures were fabricated with 3 extracellular matrices, hyaluronic acid (HA), fibronectin, and collagen. The feature of the fabrication processes is to avoid the use of potentially cytotoxic materials and utilize capillary force of the solution and interactions between the extracellular matrix components. The coculture system can be used to investigate the effects of heterocellular interactions on cellular fate. Direct heterocellular connections between hepatocytes and fibroblasts were visualized by the transcellular diffusion of fluorescein in this coculture system. The interactions between hepatocytes and fibroblasts were crucial for the maintenance of albumin synthesis by hepatocytes. The coculture system was also beneficial for investigating the effects of cell-cell interactions on the induction of embryonic stem (ES) cell differentiation. In cocultures grown in a sea-island pattern, ES cells formed isolated colonies surrounded by PA6 cells and differentiated into neurons with branched neurites that extended from the colonies. This versatile and biocompatible coculture system could potentially be a powerful tool for investigating cell-cell interaction and for tissue engineering applications. © 2009 The Society for Biotechnology, Japan.

DOI： 10.1016/j.jbiosc.2009.06.013

Language：Others   Publishing type：Research paper (scientific journal)  

Biochip with integrated pumps for plug-based sequential exchange of solutions
A novel method for exchanging solutions used in biochemical analyses and a device to carry out the exchange are proposed. An array of plugs formed using six injectors was transported in a microflow channel using a main pump located at one end of the main flow channel. The injectors and main pump were operated on the basis of the change in volume caused by the electrolysis of water. Bubbles were produced from working electrodes; these bubbles caused a diaphragm placed below the injectors to inflate and occlude the inlet of the solution reservoir. Increase in the number of bubbles caused the reservoir to inject the solution into the main flow channel in the form of a plug. Each plug was individually transported downstream to the sensing area by the main pump, which was operated in a similar manner to the injector. The device was used for the detection of a tumor marker, α-fetoprotein (AFP). Plugs of necessary solutions were individually transported to the sensing area with immobilized primary antibodies to allow antigen-antibody binding, cleaning, and detection. The fluorescence intensity from the antibodies showed clear dependence on the concentration of AFP. The immobilization of antibodies could also be carried out on-chip. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2009.04.048

Language：English   Publishing type：Research paper (scientific journal)  

A microfluidic device and operation to handle liquid plugs for biochemical analyses were developed for efficient handling of plugs of many solutions. A major part of the device was a T-junction consisting of a main flow channel and a handling flow channel. Unit operations including attachment of plugs, division of a plug, sorting of plugs, and formation of plugs of various lengths enabled controlled sequential reactions in a microflow channel. Rapid mixing could easily be achieved by moving a plug formed by merging two plugs back and forth. The device could be used for efficient characterization of performance in bio/chemical sensing. In experiments using L-glutamate oxidase, plugs containing an enzyme or a substrate were formed, mixed sequentially, and the intensity of fluorescence from plugs of different concentrations of L-glutamate or pHs could be measured simultaneously. Cross-contamination of plugs by neighboring plugs poses a problem in using the same flow channel repeatedly. However, the influence could be minimized by using a cleansing plug placed between them in a sufficiently hydrophobic flow channel and by processing the plugs at a low velocity. The device can be a critical component for microprocessing in various bio/chemical analyses. © 2008 American Chemical Society.

DOI： 10.1021/ac800492v

Language：English  

Eletrochemical principles provide key techniques to promote the construction of bio/chemical microsystems of the next generation. There is a wealth of technology for the microfabrication of bio/chemical sensors. In addition, microfluidic transport in a network of flow channels, pH regulation, and automatic switching can be realized by electro-chemical principles. Since the basic components of the devices are electrode patterns, the integration of different components is easily achieved. With these techniques, bio/chemical assays that require the exchange of solutions can be conducted on a chip. Furthermore, autonomous microanalysis systems that can carry out necessary procedures are beginning to be realized. In this article, techniques developed in our group will be comprehensively introduced. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/elps.200700581

Event date： 2020.10

Language：English  

Country：Other  

Event date： 2019.10

Language：English  

Venue：Montreal   Country：Canada  

LSPR (Localized Surface Plasmon Resonance) based 2D (2 Dimensional) gas imaging sensor system which can capture spatial distribution of each constituent of mixed gas have been developed. The gas image sensor detects the gas promoted optical changes occurred on the LSPR substrate by CCD camera. Basically, LSPR gas sensor does not have a molecular selectivity, then the identification of gas species is difficult. To overcome the disadvantage, pixelated LSPR substrate based on Au/Ag core-shell structure which has different gas response properties is fabricated by photo-induced metal growth by mask-less exposure system using a commercial video projector.

Event date： 2019.10

Language：English  

Venue：Montreal   Country：Canada  

Mixture of gas molecules must be accurately detected for gas sensor. However, there are certain difficulties in identifying the type of gas and detecting its concentration by chemical sensors. SERS (Surface Enhanced Raman Scattering) is a promising method for high sensitive gas detection because of its ability of molecule discrimination. However, it is difficult for SERS sensor to identify gases with the similar structure. In this research, we have developed a more selective SERS sensor with molecular filter layers. Molecular filter property is studied by coating a filter polymer film on the SERS substrate. The characteristics of the sensor with two membrane structures were also studied and different filtering properties were obtained.

Event date： 2019.10

Language：English  

Venue：Montreal   Country：Canada  

Various odor robots have been developed for finding gas sources. However, the response speed of sensors is now a major limit for the promotion of odor robot using chemical substances information. In this research, we have developed a robot equipped with two LSPR (Localized Surface Plasmon Resonance) gas sensor module that can quickly respond to gas molecules at a high speed of above 25 Hz and set a specific algorithm for tracking the invisible odor line on the ground.

Event date： 2019.10

Language：English  

Venue：Montreal   Country：Canada  

This paper introduces a new method to fabricate a large - scale sensor array. By printing electrodes on photographic paper and making insulating layers, 6×6 arrays of sensors were obtained. Different gas selective can be printed in different units to detect different gases. Thus, production of multiple sensors in a small area with low cost was realized. On a piece of A4 photo paper, 30 sensor matrices can be printed at the same time. Each sensor array has 36 sensing units, thus theoretically identifying up to 36 gases. The sensor is suitable to be used in wearable devices to identify human skin gases due to its flexible substrate, low production cost and simple manufacturing process. In this experiment, molecular imprinted polymer (MIP) solution [1], carbon black (C.B.) conductive solution and insulating solution are prepared as ink, which can be used for ink-jet printer printing. This makes the method of developing the sensor more flexible. Compared with the sensor developed by micropipette to drop the MIP solution and C.B. conductive solution, the sensor developed by a printer has better uniformity.

Event date： 2019.6

Language：English  

Venue：Berlin   Country：Germany  

This paper proposes a flexible gas sensor array system fabricated by full printing process, which can simultaneously monitor a variety of gases. The production of sensors using a low-cost, large-scale, high-speed printing technology throughout the process. Realizing the production of multiple sensors in a small area with low cost. Detection of a variety of gases using a sensor array. The results show that it is possible to make a full-printing gas sensor by acetylene carbon black (Φ20 nm) ink and molecularly imprinted polymer (MIP) ink; 36 sensors are formed on a 3cm-3cm paper; and the gases such as acetic acid and hexanoic acid are well recognized.

Event date： 2019.6

Language：English  

Venue：Berlin   Country：Germany  

This paper presents a Localized Surface Plasmon Resonance (LSPR) based high speed gas sensor module for gas sensing applications, including visualization of invisible odor trail. Innovative claims include: (1) the use of a double layer film with Au/Ag nanoparticles for gas detection; (2) high speed response characteristic; and (3) visualization of odor trail pattern with high spatial resolution. The results show a significant change in reflection light with ethanol vapor; response speed of 1 second; and a clear image of visualized odor trail of letter "Q" of a 3 mm line width.

Event date： 2019.6

Language：English  

Venue：Berlin   Country：Germany  

Visualization of the distribution of various gases makes us possible to recognize environmental circumstances, e.g., localization of dangerous chemical sources or human body odorants in the case of disaster scene. Localized surface plasmon resonance (LSPR) can detect various gases with changes of surrounding dielectric constant, and can be used gas sensor with high response / recovery speed and high spatial resolution, i.e., 2 dimensional LSPR gas sensor gas work as a gas image sensor device. The gas image sensor detects the gas distribution occurred on the LSPR substrate by an ordinal image sensor. The general LSPR gas sensor, however, does not have a molecular selectivity, then the identification of gas species is difficult. To overcome such disadvantages, pixelated LSPR substrate based on Au/Ag core-shell structure is fabricated by photo-induced growth by mask-less exposure system using a commercial video projector.

Event date： 2019.5

Language：English  

Venue：Fukuoka   Country：Japan  

Localized Surface Plasmon Resonance (LSPR) based gas sensor is a promising way to break the bottleneck of the sensing speed of traditional semiconductor gas senor for mobile robot use. In this study, we developed a two-dimensional gas visualization system based on LSPR phenomenon with Au/Ag nanoparticles for high speed and high spatial resolution sensing. The 9-hour silver growth on the surface of Au nanoparticles layer has been shown to reduce the influence of transmitted light (noise) on visualization while ensuring sensitivity. An invisible odor trace similar to letter 'U' with a line width of 3 mm was visualized by CCD camera through the LSPR sensor film. The intensity changes of the image every 1 second showed of the developed system's high response speed and spatial resolution.

Event date： 2019.5

Language：English  

Venue：Fukuoka   Country：Japan  

If we can quickly recognize the distribution of dangerous gases, it will be useful in places such as disaster scene. Localized surface plasmon resonance (LSPR) gas sensor is known as a gas sensor with high response / recovery speed and high spatial resolution. However, the general LSPR gas sensor does not have a molecular selectivity and it is difficult to identify the gas species. We made gas selected pixelated LSPR substrate based on Au/Ag core-shell structure by photo-induced growth by exposure system using the photomask.

Event date： 2019.5

Language：English  

Venue：Fukuoka   Country：Japan  

The present study explored a probe type gas detection system which can be used to detect the gas conveniently. The gas sensing mechanism is utilizing Localized Surface Plasmon Resonance (LSPR) sensor which based on the reflected light change caused by the refractive index changes of gas where exposing to the metal nanoparticles layer. The LSPR layer was prepared by vacuum sputtering of AuNPs on a glass substrate, growing in silver growth solution and consequently thermal annealing. An optical system which composed of fiber probe, light source and spectrometer was developed to detect the change of reflected light. It was found that compared with incident light irradiating from metal nanoparticles side, glass side could obtain clearer spectra peak. In addition, a LSPR sensor which had 5 hours silver growth time has the best response to acetic acid gas. This work demonstrated that the reflection detection system has a great potential in gas detecting area.

Event date： 2019.5

Language：English  

Venue：Fukuoka   Country：Japan  

Detection of volatile organic components (VOCs) is meaningful to agricultural field, bio recognition and so on. In this study, we developed an array type gas sensor to detect VOCs. This sensor is based on localized surface plasmon resonance (LSPR). Molecularly Imprinted Sol-Gels (MISG) were patterned on the surface of Au nano-islands to add molecular selectivity. The substrate is separated into 9 regions on AuNPs by using polyimide tape partitions and spin coating MISG solutions for each region. Multi channels sensor was fabricated with this substrate after this process. The sensor's sensitives were compared for each channel. The result indicated that the sensitivity of target gas channel was higher than into others.

Event date： 2018.10

Language：English  

Venue：New Delhi   Country：India  

The microbeads shape sensor film was developed in this work combines fluorescent dye agents whose fluorescent intensity can be influenced in touch of a specific odor, and Molecular Imprinting Polymer. Like photographic films, the fluorescent dye microbeads film can visualize the odor gas diffusion with the CCD camera. To enhance the fluorescence intensity of Quinine Sulfate increases in the water environment, hydrogel was applied in the film. For developing multi-odor sensors, we made four kinds of fluorescent microbeads to test whether the interaction among fluorescent dyes happened. It turned out microbeads structure successfully remained characters of every fluorescent dye.

Event date： 2018.10

Language：English  

Venue：New Delhi   Country：India  

Various odor robots have been developed for gas source localization in plume with specific algorithm. However, sensor response speed is now a major limit for the promotion of odor robot using chemical substances information. In this research, we have fabricated a Localized surface plasmon resonance based gas sensor which can show a quick response to gas molecular at a high speed of above 25Hz. The sensor was mounted on a mobile robot for gas sources detection successfully. Furthermore, a two-dimensional gas sensor based on the same technique was developed for visualization of spatial distribution of gas flow.

Event date： 2018.10

Language：English  

Venue：New Delhi   Country：India  

Patternable actuator film for monolithic soft micro robot process was developed. The film is consisted from thermal bimorph actuation layer and extra functional layer including driving heater layer and elastic mechanical buffer layer. A cantilever arm actuator fabricated by patterning the film was operated with 2 V applied voltage. Multi actuator device or micro robot can be fabricated without assembling process by appropriate patterning process with this film.

Event date： 2017.10 - 2017.11

Language：English  

Venue：Glasgow   Country：United Kingdom  

Odor imaging sensor was developed with odorants sensing mechanism based on the complicated fluorescence interactions between the multi-fluorescent-probes and odorants. In this research, poly vinyl chloride (PVC) films including various fluorescent probe were developed, and fluorescence properties of the film were investigated. Using the multi fluorescent probe film, fluorescence intensity change spectrum to various odorants was measured, and odorants could be clustered by their chemical structure by multi-variate analyses of hyper spectra images.

Event date： 2017.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：筑波大学   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学 五福キャンパス   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学 五福キャンパス   Country：Japan  

Event date： 2017.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学 病院キャンパス   Country：Japan  

Event date： 2016.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：対馬市交流センター   Country：Japan  

Event date： 2016.12

Language：English   Presentation type：Oral presentation (general)  

Venue：対馬市交流センター   Country：Japan  

Event date： 2016.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：対馬市交流センター   Country：Japan  

Event date： 2016.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：対馬市交流センター   Country：Japan  

Event date： 2016.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京電機大学 東京千住キャンパス   Country：Japan  

Event date： 2016.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：静岡大学浜松キャンパス   Country：Japan  

Event date： 2016.10 - 2016.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Caribe Royale All-Suite Hotel and Convention Center   Country：United States  

Event date： 2016.10 - 2016.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Caribe Royale All-Suite Hotel and Convention Center   Country：United States  

Event date： 2016.10 - 2016.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Caribe Royale All-Suite Hotel and Convention Center   Country：United States  

Event date： 2016.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：平戸文化センター／平戸市未来創造館   Country：Japan  

Event date： 2016.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：平戸文化センター／平戸市未来創造館   Country：Japan  

Event date： 2016.10

Language：Japanese  

Venue：平戸文化センター／平戸市未来創造館   Country：Japan  

Event date： 2016.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：平戸文化センター／平戸市未来創造館   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宮崎大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宮崎大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宮崎大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宮崎大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：東京ビッグサイト　東5ホール　センサエキスポジャパン2016展示会場内　セミナーE   Country：Japan  

Event date： 2016.6

Language：Japanese  

Venue：金沢市文化ホール   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢市文化ホール   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢市文化ホール   Country：Japan  

Event date： 2016.6

Language：English   Presentation type：Oral presentation (general)  

Venue：KANAZAWA BUNKA HALL   Country：Japan  

Event date： 2013.5

Language：English  

Venue：Toronto, ON   Country：Canada  

This paper describes the correlation between microelectromechanical-system (MEMS) membrane curvature and implanted argon in a microelectromechanical-system membrane. When a free-standing silicon membrane, fabricated through ashing of an organic film, is cleaned by exposure to argon plasma to remove the oxidized surface, the membrane is curved uniformly. The curvature is released by annealing. Total-reflection X-ray fluorescence analysis before/after annealing reveals that argon, which is implanted into the crystal lattice of silicon by argon plasma exposure, is desorbed by annealing. This analysis also indicates that there is a linear correlation between the curvature change and implanted argon.

Event date： 2011.6

Language：English  

Venue：Beijing   Country：China  

Coulometric analysis is effective in the analysis of an analyte in a liquid plug of a very small volume. However, in the conventional coulometric detection, it took time to collect analyte molecules dissolved in the solution. To solve this problem, we used a novel method to achieve significant enhancement of sensitivity by using a one-electrode system. As a model analyte, hydrogen peroxide was oxidized in a flow channel and silver was deposited simultaneously on another electrode in another flow channel. Coulometric detection of the deposited silver showed a step change of generated charge. As a result, measurement time was reduced significantly (less than 2 s), although conventional methods took more than 60 s to achieve the same sensitivity. This shorter measurement time also suppressed the influence of background noise, resulting in significant lowering of the detection limit.

Event date： 2011.6

Language：English  

Venue：Beijing   Country：China  

An integrated microfluidic chip to handle liquid plugs of the nL order was fabricated. The chip consisted of a T-junction, shape memory alloy (SMA) micro plumps, and an electrochemical sensor. The weight of the chip including all the components was only 1.5 g. The device was operated by a computer control system connected to the chip. Driving voltage was less than 5 V. In the detection of an analyte using this chip, the volume of a sample solution was precisely measured at the T-junction, which was then separated into a liquid plug. The plug was subsequently transported to the electrochemical sensor. As a demonstration, the concentration of hydrogen peroxide was measured by coulometry. The measured charge was clearly dependent on the concentration of hydrogen peroxide.

Event date： 2011.6

Language：English  

Venue：Beijing   Country：China  

A plug-based on-chip titration device, constructed with a glass substrate and a poly (dimethylsiloxane) (PDMS) substrate, was used for acid-base titration. The device features a volume-regulation unit to produce plugs of a uniform volume used for titration. Although the volume of plugs formed by only injecting a solution and air simultaneously from a T-junction distributed in a wide range, the plug volume became markedly uniform using the volume-regulation unit. Acid-base titration could be conducted using this device. Furthermore, freshness of rice was evaluated by titrating fatty acid in a rice grain with a KOH solution using phenolphthalein as a pH-indicator. Rice samples harvested in different years and from different areas as well as of different species were analyzed using this device. Difference was observed clearly in the titration curves. New rice showed a color change at an early stage, whereas the color change delayed with aged rice.

Event date： 2009.6

Language：English  

Venue：Denver, CO   Country：United States  

Applicability of coulometric detection was tested for the analysis of an analyte in a liquid plug confined in a PDMS microflow channel. A plug prepared in the flow channel was placed on a three-electrode system and hydrogen peroxide was detected. With plugs of a small volume, the depletion of the analyte was rapid, making reproducible amperometric detection difficult particularly when the flow channel was shallow. On the other hand, coulometric detection showed a clear relationship between the generated charge and the concentration. However, when the volume of the plug was large, only a part of the analyte was used for detection, suggesting the possibility to improve the detection sensitivity further. The device was also tested in the detection of L-glutamate.

Event date： 2007.10

Language：English  

Venue：Atlanta, GA   Country：United States  

A microfluidic device that forms a row of liquid plugs in a micro flow channel was fabricated, and its applicability to an on-chip enzyme-linked immunosorbent assay (ELISA) was demonstrated. The nanoliter liquid plugs were formed by six independent pumps and were mobilized in the micro-flow channel using a main pump. The operation of the pumps was based on the volume change caused as a result of the electrochemical production of hydrogen bubbles. When the bubbles were produced in the pumps, a polydimethylsiloxane (PDMS) diaphragm at the bottom of the compartment inflated and closed an inlet hole at the top of the reservoir. The solution in the reservoir was forced to be injected into the flow channel forming a liquid plug. After six plugs were formed, they were mobilized to a reaction chamber one by one to allow an antigen-antibody binding, cleansing, and detection. This simple and reliable liquid handling system could be applied to the detection of a tumor maker, α-fetoprotein (AFP).

Language：Japanese  

Country：Japan  

Coulometric detection of an analyte in a liquid plug formed in a microflow channel
Applicability of coulometric detection was tested for the analysis of an analyte in a liquid plug confined in a PDMS microflow channel. A plug prepared in the flow channel was placed on a three-electrode system and hydrogen peroxide was detected. With plugs of a small volume, the depletion of the analyte was rapid, making reproducible amperometric detection difficult particularly when the flow channel was shallow. On the other hand, coulometric detection showed a clear relationship between the generated charge and the concentration. However, when the volume of the plug was large, only a part of the analyte was used for detection, suggesting the possibility to improve the detection sensitivity further. The device was also tested in the detection of L-glutamate. ©2009 IEEE.

Language：Japanese  

Country：Japan  

Language：English  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

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Country：Japan  

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Country：Japan  

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Country：Japan  

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Country：Japan  

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Country：Japan  

ケミカルセンサ バイオ ・ マイクロ システム ゴウドウ ケンキュウカイ ケミカルセンサ ノ カオリ,ミズ センシングデバイス エ ノ オウヨウ 、 バイオ ・ マイクロ システム エ ノ オウヨウ オヨビ イッパン

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Photopatterning Odor imaging device with pixelated multi-gas sensor with Au/Ag core-shell structure

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Basic study of energy harvesting type gas sensor using VOC gas in the environment

Language：Japanese  

Country：Japan  

Measurement of environmental VOCs around humans by portable MIP chemiresistor arrays

Language：Japanese  

Country：Japan  

Creation of model to estimate molecular parameter using sensor data

Language：Japanese  

Country：Japan  

Measurement of the Spatially Distributed Gas Information with Vertical LSPR based High Speed Gas Sensor Robot System

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Language：Japanese  

Country：Japan  

Detection and identification of VOCs by differential surface-enhanced Raman scattering

Language：Japanese  

Country：Japan  

Human behavior detection by odor sensor system

Language：Japanese  

Country：Japan  

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CiNii Research

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Language：Japanese   Publisher：電気学会  

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

CiNii Research

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

CiNii Research

J-GLOBAL

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Language：Japanese   Publisher：Institute of Electrical Engineers of Japan  

CiNii Research

J-GLOBAL

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Language：Japanese   Publisher：電気学会  

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Language：Japanese   Publisher：電気学会  

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Microfluidic techniques can be a basis to realize user-friendly microanalytical devices of high performance. Required operations include injection of solutions to reaction chambers, volume measurement, and mixing of solutions. For this purpose, the use of surface tension is attractive. In hydrophobic flow channels, solutions can be moved stably in the form of plugs. Otherwise, solutions can be transported by capillary action in a hydrophilic flow channel and stopped at a hydrophobic valve. The valve can be opened autonomously by switching the mixed potential by wetting a zinc electrode formed in a controlling flow channel. In this review paper, we introduce some of our microfluidic devices particularly focusing on devices that work based on surface tension.

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)