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Kenshi Hayashi Last modified date:2024.04.26

Graduate School
Undergraduate School
Other Organization
Administration Post
Dean of the Graduate School of Systems Life Sciences

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 Reseacher Profiling Tool Kyushu University Pure
Organic Electronic Device Lab. .
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
Field of Specialization
electronic materials, organic electronics, sensor technology, electronic device
Total Priod of education and research career in the foreign country
Outline Activities
Developments of odor and taste sensor have been carried out using functional electronic and organic materials based on nanotechnology and surface science. High sensitive measurement for odor substances or biometrics is the main problem on technical purposes. Qualitative analyses are also important thema of odor and taste sensing. On educational area, functional devices and measurement technology for undergraduate and master course are treated from basic to very advanced matter. Inteligent sensor technology, Inc. USE inc, and IBC inc are co-worker on various sensor system developments. Chemical sensor system society of The institute of electrical engineers of Japan is the main society for investigatiion on sensors.
Research Interests
  • Information service using odor cluster matching
    keyword : odor code, odor cluster, matching, odor map, information service, odor data base, metainformation
  • Visualization of odor space
    keyword : visualization, odor, fluorescent probe, molecular recognition
  • Measurement and coding of odor quality and quantity
    keyword : odor sensor, substructure of odor molecule, odor code, odor display
  • Novel devices using molecular wire and organic electronic material.
    keyword : molecular wire, nano wire, tunnel current, odor
  • Biometrics by odor sensing
    keyword : biometrics, odor sensor, odor type
  • Malodor sensing
    keyword : Super sensitive odor sensing
  • Study on taste sensor
    keyword : taste sensor
Academic Activities
1. Development and application of odor image sensor for body odor.
1. Chen Lin、Chen Bin、Matsuo Takuya、Sassa Fumihiro、Hayashi Kenshi, Recognition of Mixture Vapors using SERS Gas Sensor Fabricated by the Sputtering Method, IEEE Sensors Journal, 10.1109/JSEN.2024.3383053, 2024.04.
2. Chen Lin, Guo Hao, Matsuo Takuya, Sassa Fumihiro, *Hayashi Kenshi, Visualization of the Gas Spatial Distribution of the Odor Source by SERS Gas Sensor, IEEJ Transactions on Electrical and Electronic Engineering, 10.1002/tee.23988, 876-881, 2024.01.
3. Yang Zhongyuan, Sassa Fumihiro,Hayashi Kenshi, An Odor Trace Visualization System Using a Two-Dimensional Backside Scattering Localized Surface Plasmon Resonance Gas Sensor, Sensors, 10.3390/s23239525, 23, 9525-9525, 2023.11.
4. Chen Lin,Guo Hao,Wang Cong,Chen Bin,Sassa Fumihiro,Hayashi Kenshi, Two-Dimensional SERS Sensor Array for Identifying and Visualizing the Gas Spatial Distributions of Two Distinct Odor Sources, Sensors, 10.3390/s24030790, 790-790, 2024.04.
5. Xiao Ye, Lingpu Ge, Tianshu Jiang, Hao Guo, Bin Chen, Chuanjun Liu, Kenshi Hayashi, Fully Inkjet-Printed Chemiresistive Sensor Array Based on Molecularly Imprinted Sol-Gel Active Materials., ACS sensors, 10.1021/acssensors.2c00093, 2022.06, The fabrication of chemiresistive sensors by inkjet printing is recognized as a breakthrough in gas-sensing applications. One challenge of this technology, however, is how to enhance the cross-selectivity of the sensor array. Herein, we present a ketjen black (KB) ink and molecularly imprinted sol-gel (MISG) inks to support the fabrication of a fully inkjet-printed chemiresistive sensor array, enabling the highly accurate recognition of volatile organic acids (VOAs) on the molecular level. The MISG/KB sensor array was prepared on a glossy photographic paper with a three-layer structure: a circuit layer by a commercial silver ink, a conductive layer by a KB ink, and an active selective layer by MISG inks imprinted by different templates. Hexanoic acid (HA), heptanoic acid, and octanoic acid were used as templates to prepare the MISGs and as targets to evaluate the detection and discrimination performance of the sensor array. Three resultant MISG/KB sensors exhibited high sensitivity and selectivity to VOA vapors. The limit of detection and imprinting factor were 0.018 ppm and 7.82, respectively, for HA-MISG/KB sensors to the corresponding target. With linear discriminant analysis of the gas responses, the MISG/KB sensor array can realize high discrimination to VOAs in single and binary mixtures. Furthermore, the proposed sensor array showed strong sensor robustness with excellent consistency, durability, bending, and humidity resistance. This work developed a fully inkjet-printed chemiresistive sensor array, enabling the realization of high cross-selectivity detection, achieving low-cost, scalable, and highly reproducible sensor fabrication, moving it closer to reliable, commercial, and wearable multi-analyte human body odor analysis potential..
6. Lin Chen, Hao Guo, Fumihiro Sassa, Bin Chen, Kenshi Hayashi, Sers gas sensors based on multiple polymer films with high design flexibility for gas recognition, Sensors, 10.3390/s21165546, 21, 16, 2021.08, 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..
7. Bin Chen, Chuanjun Liu, Liang Shang, Ying Huang, Shaohua Yang, Xiaoyan Sun, Changhao Feng, Kenshi Hayashi, Electron transfer during binding processes between thiolate molecules and Au nano-islands, Applied Surface Science, 10.1016/j.apsusc.2018.12.138, 473, 49-54, 2019.04, We investigated electron transfer during the time-dependent binding processes between thiolate molecules and Au nano-islands by observing tunneling current with an interdigitated microelectrode supporting the sputtered Au nano-islands (IME@AuNI). The time-dependent optical and electrical signal variation during the binding process was examined for five kinds of thiolates. As the immersion time was prolonged, the optical absorbance increased, whereas the current passing through the IME@AuNI decreased. Importantly, the spectral and current characteristics depended on the thiolate structure, because of the formation of capping layer in accordance with thiolate structure. These results are mainly attributed to synergistic effects of electron transfer from Au nano-islands to thiolate molecules and bridging effects of thiolate molecules among Au nano-islands..
8. Liang Shang, Chuanjun Liu, Bin Chen, Kenshi Hayashi, Plant Biomarker Recognition by Molecular Imprinting Based Localized Surface Plasmon Resonance Sensor Array Performance Improvement by Enhanced Hotspot of Au Nanostructure, ACS Sensors, 10.1021/acssensors.8b00329, 3, 8, 1531-1538, 2018.08, Detection of plant volatile organic compounds (VOCs) enables monitoring of pests and diseases in agriculture. We previously revealed that a localized surface plasmon resonance (LSPR) sensor coated with a molecularly imprinted sol-gel (MISG) can be used for cis-jasmone vapor detection. Although the selectivity of the LSPR sensor was enhanced by the MISG coating, its sensitivity was decreased. Here, gold nanoparticles (AuNPs) were doped in the MISG to enhance the sensitivity of the LSPR sensor through hot spot generation. The size and amount of AuNPs added to the MISG were investigated and optimized. The sensor coated with the MISG containing 20 μL of 30 nm AuNPs exhibited higher sensitivity than that of the sensors coated with other films. Furthermore, an optical multichannel sensor platform containing different channels that were bare and coated with four types of MISGs was developed to detect plant VOCs in single and binary mixtures. Linear discriminant analysis, k-nearest neighbor (KNN), and naïve Bayes classifier approaches were used to establish plant VOC identification models. The results indicated that the KNN model had good potential to identify plant VOCs quickly and efficiently (96.03%). This study demonstrated that an LSPR sensor array coated with a AuNP-embedded MISG combined with a pattern recognition approach can be used for plant VOC detection and identification. This research is expected to provide useful technologies for agricultural applications..
9. Zhongyuan Yang, Fumihiro Sassa, Kenshi Hayashi, A Robot Equipped with a High-Speed LSPR Gas Sensor Module for Collecting Spatial Odor Information from On-Ground Invisible Odor Sources, ACS SENSORS, 10.1021/acssensors.8b00214, 3, 6, 1174-1181, 2018.06, 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..
10. Xiaoguang Ying, Hiro-Taka Yoshioka, Chuanjun Liu, Fumihiro Sassa, Kenshi Hayashi, Molecular imprinting technique in putrescine visualized detection, SENSORS AND ACTUATORS B-CHEMICAL, 10.1016/j.snb.2017.11.128, 258, 870-880, 2018.04, 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. (C) 2017 Elsevier B.V. All rights reserved..
11. Chuanjun Liu, Liang Shang, Hiro Taka Yoshioka, Bin Chen, Kenshi Hayashi, Preparation of molecularly imprinted polymer nanobeads for selective sensing of carboxylic acid vapors, Analytica Chimica Acta, 10.1016/j.aca.2018.01.004, 1010, 1-10, 2018.01, The detection and discrimination of volatile carboxylic acid components, which are the main contributors to human body odor, have a wide range of potential applications. Here, a quartz crystal microbalance (QCM) sensor array based on molecularly imprinted polymer (MIP) nanobeads is developed for highly sensitive and selective sensing of typical carboxylic acid vapors, namely: propionic acid (PA), hexanoic acid (HA) and octanoic acid (OA). The MIP nanobeads were prepared by precipitation polymerization with methacrylic acid (MAA) as a functional monomer, trimethylolproane trimethacrylate (TRIM) as a crosslinker, and carboxylic acids (PA, HA and OA) as the template molecules. The precipitation polymerization resulted in nano-sized (150-200 nm) polymer beads with a regular shape. The polymerization conditions were optimized to give a functional monomer, crosslinker, and template ratio of 1:1:2. We investigated the imprinting effect using both QCM and GC/MS measurements comparing vapor absorption characteristics between the imprinted and non-imprinted (NIP) nanobeads. A four-channel QCM sensory array based on the NIP and the three types of MIP nanobeads was fabricated for sensing the three types of carboxylic acid vapor at concentrations on the ppm level. The output of the sensor array was analyzed by both a non-supervised method (principle component analysis: PCA) and supervised method (linear discrimination analysis: LDA). LDA showed a better discrimination ability than PCA. A 96%-classification rate was achieved by applying leave-one-out cross-validation to the LDA model. The high sensitivity and selectivity of the sensor array was attributed to the imprinting effect of the nano-sized polymer beads. The developed MIP nanobeads, together with other types of MIPs, show promise as materials for artificial receptors in vapor and odorant sensing..
12. Liang Shang, Chuanjun Liu, Yoichi Tomiura, Kenshi Hayashi, Machine-Learning-Based Olfactometer Prediction of Odor Perception from Physicochemical Features of Odorant Molecules, Analytical Chemistry, 10.1021/acs.analchem.7b02389, 89, 22, 11999-12005, 2017.11, Gas chromatography/olfactometry (GC/O) has been used in various fields as a valuable method to identify odor-active components from a complex mixture. Since human assessors are employed as detectors to obtain the olfactory perception of separated odorants, the GC/O technique is limited by its subjectivity, variability, and high cost of the trained panelists. Here, we present a proof-of-concept model by which odor information can be obtained by machine-learning-based prediction from molecular parameters (MPs) of odorant molecules. The odor prediction models were established using a database of flavors and fragrances including 1026 odorants and corresponding verbal odor descriptors (ODs). Physicochemical parameters of the odorant molecules were acquired by use of molecular calculation software (DRAGON). Ten representative ODs were selected to build the prediction models based on their high frequency of occurrence in the database. The features of the MPs were extracted via either unsupervised (principal component analysis) or supervised (Boruta, BR) approaches and then used as input to calibrate machine-learning models. Predictions were performed by various machine-learning approaches such as support vector machine (SVM), random forest, and extreme learning machine. All models were optimized via parameter tuning and their prediction accuracies were compared. A SVM model combined with feature extraction by BR-C (confirmed only) was found to afford the best results with an accuracy of 97.08%. Validation of the models was verified by using the GC/O data of an apple sample for comparison between the predicted and measured results. The prediction models can be used as an auxiliary tool in the existing GC/O by suggesting possible OD candidates to the panelists and thus helping to give more objective and correct judgment. In addition, a machine-based GC/O in which the panelist is no longer needed might be expected after further development of the proposed odor prediction technique..
13. Liang Shang, Chuanjun Liu, Bin Chen, Kenshi Hayashi, Development of molecular imprinted sol-gel based LSPR sensor for detection of volatile cis-jasmone in plant, Sensors and Actuators, B: Chemical, 10.1016/j.snb.2017.12.123, 260, 617-626, 2017.11, Detection of cis-jasmone (CJ) enables monitoring of growth pressure in plants, which is especially useful for sensing attacks by herbivores. Here, a sensitive and selective nanocomposite-imprinted, localized surface plasmon resonance (LSPR) sensor for CJ vapor was fabricated. Gold (Au) nano-islands were prepared by vacuum sputtering of Au nanoparticles on a glass substrate, followed by thermal annealing. Titanium molecularly imprinted sol-gels (MISGs) were spin-coated on the Au nano-islands as an adsorption layer for enhancing the selectivity of the optical sensor. Gas molecules were detected by using a small spectrometer to monitor variations in absorption spectra. In addition, the functional monomer and the ratio of matrix materials to functional monomers in the MISGs were investigated and optimized. MISGs that contained the functional monomer trimethoxyphenylsilane at a 3:1(v:v) ratio exhibited a higher sensitivity and selectivity than other films. The optical sensor would have advantages of low cost, selectivity, sensitivity, and repeatability. The limit of CJ detection in air was 3.5 ppm (signal/noise = 3). Thus, the sensor is expected to be a potential tool for CJ monitoring in agriculture applications..
14. Liang Shang, Chuanjun Liu, Yoichi Tomiura, Kenshi Hayashi, Odorant clustering based on molecular parameter-feature extraction and imaging analysis of olfactory bulb odor maps, Sensors and Actuators, B: Chemical, 10.1016/j.snb.2017.08.024, 255, 508-518, 2017.08, Progress in the molecular biology of olfaction has revealed a close relationship between the structural features of odorants and the response patterns they elicit in the olfactory bulb. Molecular feature-related response patterns, termed odor maps (OMs), may represent information related to basic odor quality. Thus, studying the relationship between OMs and the molecular features of odorants is helpful for better understanding the relationships between odorant structure and odor. Here, we explored the correlation between OMs and the molecular parameters (MPs) of odorants by taking OMs from rat olfactory bulbs and extracting feature profiles of the corresponding odorant molecules. 178 images of glomerular activities in olfactory bulb that are corresponding to odorants were taken from the OdorMapDB, a publicly accessible database. The gray value of each pixel was extracted from the images (178 × 357 pixels) to fabricate an image matrix for each odorant. Forty-six molecular feature parameters were calculated using BioChem3D software, which was used to construct a second matrix for each odorant. Correlation analysis between the two matrixes was first carried out by establishing coefficient maps. Results from hierarchical clustering showed that all parameters could be segregated into seven clusters, and each cluster showed a relatively similar response pattern in the olfactory bulb. Using the information from the OMs and MPs, we mapped odorants in 2D space by incorporating dimension-reducing techniques based on principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE). Artificial neural network models based on the OM and MP feature values were proposed as a means to identify odorant functional groups. An OM-PCA-based model calibrated via extreme learning machine (ELM) was 94.81% and 93.02% accuracy for the calibration and validation sets, respectively. Similarly, an MP-t-SNE-based model calibrated by ELM was 86.67% and 93.35% accuracy for the calibration set and the validation set, respectively. Thus, this research supports a structure-odor relationship from a data-analysis perspective..
15. Masashi Watanabe, Chuanjun Liu, Kenshi Hayashi, Growth orientation control of metal nanostructures using linearly polarized light irradiation, THIN SOLID FILMS, 10.1016/j.tsf.2016.11.039, 621, 137-144, 2017.01, Controlled orientation of metal nanostructures on a solid substrate was realized by irradiating a pre-deposited nanoseed layer with linearly polarized light in a growth solution containing metal cations. The resulted nanostructures showed the different transmittance spectra for two orthogonal polarized lights, which indicated an anisotropic growth induced by polarized light. The investigation on the growth conditions demonstrated that the wavelength of the irradiated light and the existence of cetyl cetyltrimethylammonium bromide used as surfactant could affect the anisotropic degree of the oriented nanostructures. It was suggested that the polarized lights enhanced the anisotropic local electric field of Au seed nanoparticles, which resulted in the oriented growth of metal nanostructures during the reduction process in the solution. The approach reported in this work can be used in the device fabrication based on oriented metal nanostructures, such as photocatalysts or optical sensors..
16. Liang Shang, Chuanjun Liu, Masashi Watanabe, Bin Chen, Kenshi Hayashi, LSPR sensor array based on molecularly imprinted sol-gels for pattern recognition of volatile organic acids, Sensors and Actuators, B: Chemical, 10.1016/j.snb.2017.04.048, 249, 14-21, 2017.01, Volatile organic acids are important compounds contained in human body odor. The detection and recognition of volatile organic acids in human body odor are significant in many areas. The present study explored a possibility to use localized surface plasmon resonance (LSPR) of Au nanoparticles (AuNPs) and molecularly imprinted sol-gels (MISGs) as the sensitive layer to recognize typical organic acid odorants, propanoic acid (PA), hexanoic acid (HA), heptanoic acid (HPA) and octanoic acid (OA), from human body. The LSPR layer was prepared by vacuum sputtering of AuNPs on a glass substrate and consequently thermal annealing. The sensitive layer was fabricated by spin-coating molecularly imprinted titanate sol-gel on the AuNPs layer. A homemade optical device was developed to detect the change of transmittance, which was caused by the index changes of organic acid vapors where selecting absorbed by the MISG layers. It was found that compared with MISG coated samples, samples coated with non-imprinted sol gel (NISG) shown no responses to any acid vapors. For the MISG coated sensors, the LSPR sensitivity was affected by the spin coating speed. In addition, a sensor array based on MISGs with different templates (HA, HPA and OA) was constructed to detect the organic acids in single and their binary mixtures. The sensor response was analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). A 100% classification rate was achieved by leave-one-out cross-validation technique for LDA model. This work demonstrated that the MISGs coated LSPR sensor array has a great potential in organic acid odor recognition of human body odor..
17. Bin Chen, Chuanjun Liu, Lingpu Ge, Kenshi Hayashi, Localized surface plasmon resonance gas sensor of Au nano-islands coated with molecularly imprinted polymer: Influence of polymer thickness on sensitivity and selectivity, SENSORS AND ACTUATORS B-CHEMICAL, 10.1016/j.snb.2016.03.117, 231, 787-792, 2016.08, α-Pinene is a kind of biomarker vapors emitted by plant during metabolism process. In this work, A localized surface plasmon resonance (LSPR) sensors based on the large and closely-packed Au nano-islands were propose to be coupled with the molecularly imprinted polymer (MIP) film for α-pinene vapor detection. Au nano-island film was prepared through repeated Au sputtering and annealing with cycles as many as 18. MIPα-pinene was prepared using methacylic acid as monomer, ethylene glycol dimethylacrylate as cross-linker, and α-pinene as the template molecule. Pre-polymerized MIPα-pinene solution was spin-coated on Au nano-island films at a series of speeds. The influence of spin coating speed on polymer thickness and target vapor binding capability was investigated. The result demonstrated that thick polymer layer could bind more template molecules than the thin one, which verified our speculation that there were more specific template binding sites in thick polymer layer. In addition, the in-situ response of MIPα-pinene coated Au nano-island film to α-pinene vapor was verified to be rapid (in less than 10 s) and reversible. The selective α-pinene vapor adsorption and absorption characteristics of MIPα-pinene coated Au nano-islands film to α-pinene vapor was observed comparing with the responses to γ-terpinene and limonene vapors..
18. Bin Chen, Chuanjun Liu, Yiyuan Xie, Pengfei Jia, Kenshi Hayashi, Localized Surface Plasmon Resonance Gas Sensor based on Molecularly Imprinted Polymer Coated Au Nano-island Films: Influence of Nanostructure on Sensing Characteristics, IEEE Sensors Journal, 10.1109/JSEN.2016.2536629, 16, 10, 3532-3540, 2016.05, A localized surface plasmon resonance gas sensor based on Au nano-island films coated with molecularly imprinted polymer (MIP) layer was developed to selectively detect terpene vapor emitted from plants. Au nano-islands were deposited on a glass substrate through repeated Au sputtering and annealing. The MIP layer was coated on Au nano-island films by spin-coating a pre-polymerized solution containing methacrylic acid as monomer, ethylene glycol dimethylacrylate as crosslinker, and α-pinene as the template molecule. The influence of nanostructure on the refractive index (RI) sensing characteristics was mainly investigated in this paper. The result demonstrated that the structure of Au nano-island films could be controlled by Au sputtering-annealing cycle. Increase in the sputteringannealing cycle induced the size increase and the inter-particle distance decrease of Au nano-island films. In addition, spectral red shift, decrease in transmittance, and increase in absorbance were observed under this procedure as well. The typical RI sensing evaluation parameters Δλmax, ΔTmin, and ΔAmax achieved the maximum values: 9.75 nm, and 9%, 0.42 under 3 and 18 Au sputtering-annealing cycles. Au nano-island films under 3 and 18 Au sputtering-annealing cycles were coated with the MIP, and the response of MIP-coated Au nano-island sensor to α-pinene vapor was verified to be fast, reversible, and reproducible..
19. Bin Chen, Masami Mokume, Chuanjun Liu, Kenshi Hayashi, Irradiation Wavelength Dependent Photocurrent Sensing Characteristics of AuNPs/P3HT Composites on Volatile Vapor, IEEE Sensors Journal, 10.1109/JSEN.2015.2487278, 16, 3, 596-602, 2016.02, Gas sensing characteristics of Au nanoparticles (AuNPs)/3-hexylthiophene-2, 5-diyl (P3HT) composite based on photocurrent detection under different irradiation wavelengths were investigated. AuNPs with different structures were prepared either by the vacuum sputtering/annealing method or by the wet chemical synthesis based on seed growth. AuNPs/P3HT composites were prepared by the dip coating method. The optical features of P3HT and Au nanostructure/P3HT composite were investigated. The optical absorption increase of AuNPs film was observed after P3HT coating, which was attributed to the interaction between the P3HT and the Au nano-islands. New shoulder peaks and the phenomenon of one spectral peak splitting into two were observed in the absorption spectra of the composite film, which confirmed the interaction between the AuNPs and the P3HT further. The photoconductivity characteristics of the P3HT and AuNPs with spectral peak position at 580-nm (AuNPs580)/P3HT composite films were investigated utilizing LED light source with different dominate wavelengths. The wavelength-dependent photocurrent change ratio I/I0 of both the P3HT and the AuNPs580/P3HT composite films was observed. The maximum I/I0 of the P3HT and AuNPs580 composite films emerged under LED irradiation with a dominate wavelength 590 nm, which was mainly ascribed to the antenna effect from the Au nano-islands, the carrier injection from nanostucture to P3HT, localized surface plasmon resonance coupling among Au nanostructures, and plasmon coupling between the Au nano-islands and the P3HT molecules. The response of Au nano-island/P3HT composite to ethanol vapor showed that the response and recovery time was shorter than 2 s. Furthermore, gas sensing characteristics were verified to be irradiation wavelength dependent. Irradiation light source with a dominate wavelength 590 nm produced the largest I/I0 1.07..
20. Hiro-Taka Yoshioka, Chuanjun Liu, Kenshi Hayashi, Multispectral fluorescence imaging for odorant discrimination and visualization, SENSORS AND ACTUATORS B-CHEMICAL, 10.1016/j.snb.2015.07.073, 220, 1297-1304, 2015.12, A concept based on multispectral fluorescence imaging was proposed in this paper for the discrimination and visualization of odorants. Fluorescent dyes with different excitation/emission spectra were mixed into agarose gel to prepare a multiple probe sensing film. Odorants remained in environment were recorded on the sensing film via a process called odorant exposure. The odorant-induced fluorescence change of the film under various excitation lights was captured by a CCD camera to obtain multispectral images. It was demonstrated that the use of multiple fluorescence probes provided discrete emission bands, which increased the dimensions of vector space of the multispectral images. Complicated interactions between probes and probes, probes and odorants resulted in the diversiform fluorescence change patterns of the images. Combined with principal component analysis (PCA), different odorants could be discriminated and clustered in the principal component spaces in association with their molecular structures. A hand-shape odorant mark with region-segmented components was visualized with high spatial resolution. Additionally, the technique also succeeded in the visualized demonstration of an airflow containing mixed odorants. Compared with the existing gas and odor sensing technologies, the multispectral fluorescence imaging can be used not only to discriminate different odorants, but also to visualize their time-averaged spatial distribution in environment. Due to its novelty and high information acquisition ability, it can be expected as a new and powerful tool in odor sensing. (C) 2015 Elsevier By. All rights reserved..
21. Masahiro Imahashi, Masashi Watanabe, S. K. Jha, Kenshi Hayashi, Olfaction-inspired Sensing using a Sensor System with Molecular Recognition and Optimal Classification Ability for Comprehensive Detection of Gases, Sensors, 14, 5221-5238, 2014.03.
22. Bin Chen, Chuanjun Liu, Masashi Watanabe, Kenshi Hayashi, Layer-by-Layer Structured AuNP Sensors for Terpene Vapor Detection, IEEE SENSORS JOURNAL, 10.1109/JSEN.2013.2264803, 13, 11, 4212-4219, 2013.11.
23. Masahiro Imahashi, Kenshi Hayashi, Concentrating materials covered by molecular imprinted nanofiltration layer with reconfigurability prepared by a surface sol-gel process for gas-selective detection, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 10.1016/j.jcis.2013.05.051, 406, 186-195, 2013.09.
24. Chuanjun Liu, Yudai Furusawa, Kenshi Hayashi, Development of a fluorescent imaging sensor for the detection of human body sweat odor, SENSORS AND ACTUATORS B-CHEMICAL, 10.1016/j.snb.2013.03.111, 183, 117-123, 2013.07.
25. Chen Bin, Ota Manami, Mokume Masami, LIU Chuanjun, HAYASHI Kenshi, High-speed Gas Sensing using Localized Surface Plasmon Resonance of Sputtered Noble Metal Nanoparticles, 電気学会論文誌. E, センサ・マイクロマシン準部門誌 = The transactions of the Institute of Electrical Engineers of Japan. A publication of Sensors and Micromachines Society, 10.1541/ieejsmas.133.90, 133, 3, 90-95, 2013.03, High speed gas sensing devices can be applied in a number of areas where a better understanding of gas distribution is needed, such as in environmental monitoring and safety- and security-related fields. In this paper, we present a localized surface plasmon resonance (LSPR) sensor that was realized using sputtered Au and Ag nanoparticles (NPs), which can be used in robots for high-speed gas detection. The NPs' LSPR response, a red-shift of the minimum transmittance in wavelength (Δλmin), and a decrease in the minimum transmittance (ΔTmin) for ethanol gas, were investigated and compared using Au and Ag NPs under the same sputtering conditions but using a different thermal annealing process for the reshaping of the NPs. The results obtained show that NPs with a larger aspect ratio can generate a large LSPR response. The response characteristics confirmed that this LSPR sensor can be used for high-speed gas detection..
26. Bin Chen, Chuanjun Liu, Manami Ota, Kenshi Hayashi, Terpene detection based on localized surface plasma resonance of thiolate-modified Au nanoparticles, IEEE Sensors Journal, 10.1109/JSEN.2012.2231672, 13, 4, 1307-1314, 2013.02, The detection of terpene vapors, a group of biomarker vapors emitted by plants during their growth process, is an efficient way to monitor plant growth status and control plant pests and disease. In this study, a gas sensor based on the localized surface plasma resonance (LSPR) of Au nanoparticles (Au NPs) is proposed for the terpene vapors detection. Au ion sputtering method is used to deposit Au NPs on transparent glass substrates. The dependence of transmission spectra on the morphology of Au NPs prepared by different sputtering conditions is investigated. In order to enhance the sensitivity and selectivity of the sensor, thiolate modification is applied to form the selective soluble monolayer on the surface of Au NPs. The results indicate that different thiolates could form different steric capping layers, and the responding ability of the LSPR sensor is verified by a red-shift of the minimum transmittance in wavelength (Δλmin) and a decrease in the minimum transmittance (ΔTmin) upon exposure to terpene vapors..
27. Chuanjun Liu, Zhiyun Noda, Kazunori Sasaki, Kenshi Hayashi, Development of a polyanilinenanofibe-based carbon monoxide sensor for hydrogen fuel cell application,, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2012.06.096, 37, 13529-13535, 2012.07.
28. Masahiro Imahashi, Kenshi Hayashi, Odor clustering and discrimination using an odor separating system, Sensors and Actuators B:Chemical, 10.1016/j.snb.2012.03.041, 166, 685-694, 2012.03, In this study, odor evaluation and discrimination are examined. First, an odor separating system that imitates the odor receptive mechanism of biological olfaction is developed. This system enables a rough detection of odor by measuring the molecular size and polarity of odorants. Using representative odor materials that belong to different biological glomeruli clusters, odor information extracted on time course patterns can be obtained by the system. The extracted features can be used for creating an odor map similar to the one created in the receptive mechanism, which can classify qualities by their odor-cluster attributes. Mixed odors can be discriminated and decomposed into their elemental clusters. The map obtained from this study can be used for odor matching analysis. © 2012 Elsevier B.V. All rights reserved..
29. C. Liu, K. Hayashi, K. Toko, Template-Free Deposition of Polyaniline Nanostructures on Solid Substrates with Horizontal Orientation, Macromolecules, 10.1021/ma1023878, 44, 7, 2212-2219, 2011.03, By investigating the electrochemical nucleation and growth of polyaniline (PANI) on the insulating gap area of an interdigitated electrode, a template-free, in-situ approach is developed to obtain PANI nanowires and nanofibers with horizontal orientation on solid substrates. Experimental results show that the deposition process of PANI on the gap area is significantly influenced by polymerization conditions (such as polymerization current and time) and surface characteristics of the substrates (such as hydrophilicity/hydrophobicity and roughness). The concentration of solution-formed oligomers and the nucleation amount of the oligomers on the solid surface determine the morphology and orientation of the nanostructures. Controlling the deposition with high oligomer concentrations and limited nucleation amounts on the substrate is the key to the horizontal orientation. Gas sensing experiments confirm that the horizontal orientation of the nanostructures helps to improve the sensitivity and response time of sensor devices. Because of its simplicity, the approach proposed in this paper can be used in the fabrication of nanostructured conducting polymer chemiresistive gas sensor with high sensitivity but low cost. © 2011 American Chemical Society..
30. Hirotaka Matsuo, Kenshi Hayashi, Detection of odor map image using optical method, Proceeding of International Conference on Advanced Mechatronics, 165-170, 2010.10.
31. MATSUO H., Detection of odor map image using optical method, Proceedings of The 5^ International Conference on Advanced Mechatronics, 2010, 10.1299/jsmeicam.2010.5.165, 2010, 0, 165-170, 2010.06.
32. C. Liu, K. Hayashi, K. Toko, Electrochemical Deposition of Nanostructured Polyaniline on an Insulating Substrate, Electrochemistry Communications, 10.1016/j.elecom.2009.10.030, 12, 1, 36-39, 2010.01, In order to obtain practicable nano-conducting polymer resistive sensors, we investigated the electrochemical deposition of polyaniline (PANI) on the insulating gap area of an interdigitated electrode with a gap width as great as 100 μm. We revealed that the nucleation and growth of PANI on the insulating substrate were influenced by the surface character of the substrate such as hydrophilicity and roughness. By controlling the polymerization conditions, homogeneous PANI films with various nanostructures could be obtained across the insulating gap to form resistive junctions. Among them, a loose 2D nanowire network structure showed the best sensing performance upon exposure to ammonia gas with a low concentration. © 2009 Elsevier B.V. All rights reserved..
Educational Activities
I charge in Electrical circuit II, where lecture on basis of electrical circuit analysis and exercise are performed. Electromagnetics are also lectured in Undergraduate Programs and Courses.
In graduate school, advanced functional device, electronic measurement technology and measurement technology on biometrics are lectured. Organic electronics and sensor devices are also aim of the lectures.
Other Educational Activities
  • 2011.11.
  • 2010.11.
  • 2009.08.
  • 2009.08.
  • 2009.10.
  • 2007.08.
  • 2006.03.