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

An odor sensing system with chemosensitive resistors was used to identify the gases generated from overheated cables to prevent fire. Three different electric cables for a distribution cabi-net were used. The cables had an insulation layer made of polyvinyl chloride (PVC) or cross-linked polyethylene (XLPE). The heat resistance of the cables was tested by differential thermal and ther-mogravimetric analyses. The thermal decomposition products of the cables were investigated by gas chromatography-mass spectrometry (GC-MS). For the odor sensing system, two types of 16-channel array were used to detect the generated gases. One contains high-polarity GC stationary phase materials and the other contains GC stationary phase materials of high to low polarity. The system could distinguish among three cable samples at 270 °C with an accuracy of about 75% through both arrays trained with machine learning. Furthermore, the system could achieve a recall rate of 90% and a precision rate of 70% when the abnormal temperature was set above the cables’ allowable conductor temperature at 130 °C. The odor sensing system could effectively detect the abnormal heating of the cables before the occurrence of fire. Therefore, it is helpful for fire prediction and detection systems in factories and substations.

DOI： 10.3390/chemosensors9090261

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

This publisher's note contains corrections toOpt. Lett. 46, 262 (2021).

DOI： 10.1364/OL.433647

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

Materials with biomolecule-compatible functional groups are desirable for the fabrication of microdisk lasers used in bio-sensing applications. In this study, a microdisk laser was fabricated using a low-viscosity hyper branched polymer FC-V-50 using ink-jet printing, and was surface-modified at room temperature within a relatively short time compared to conventional methods. The carboxyl functional group of the FC-V-50 polymer was used for surface modification and biotinylation. The adsorption characteristics of the microdisk laser were evaluated using bovine serum albumin, avidin, and streptavidin. This study reports the first demonstration of label-free biosensing using the FC-V-50 polymer-based microdisk laser.

DOI： 10.1364/OME.415000

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

In this study, we developed an odor sensor system using chemosensitive resistors, which outputted multichannel data. Mixtures of gas chromatography stationary materials (GC materials) and carbon black were used as the chemosensitive resistors. The interaction between the chemosensitive resistors and gas species shifted the electrical resistance of the resistors. Sixteen different chemosensitive resistors were fabricated on an odor sensor chip. In addition, a compact measurement instrument was fabricated. Sixteen channel data were obtained from the measurements of gas species using the instrument. The data were analyzed using machine learning algorithms available on Weka software. As a result, the sensor system successfully identified alcoholic beverages. Finally, we demonstrated the classification of restroom odor in a field test. The classification was successful with an accuracy of 97.9%.

DOI： 10.1109/JSEN.2020.3016678

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

A blended FC-V-50 and TZ-001 polymer-based microdisk laser was fabricated by the ink-jet printing method and used for biosensing applications. The FC-V-50 polymer has a negative charge due to the presence of carboxyl functional groups, and the TZ-001 polymer has a positive charge due to the tertiary amine group at a pH of seven. In biosensing applications, non-specific adsorption due to opposite charges of biomolecules and microdisk surfaces can adversely affect the performance of the biosensor. By mixing FC-V-50 and TZ-001 polymers in different ratios, the microdisk surface charge was controlled, and the non-specific adsorption of bovine serum albumin and lysozyme was studied. In addition, the label-free biosensing of streptavidin was demonstrated using a blended polymer-based microdisk laser. This work reports, to the best of our knowledge, the first demonstration of a blended polymer microdisk laser for controlling the non-specific adsorption of biomolecules.

DOI： 10.1364/OL.412993

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

Hyper branched polymer FC-V-50 based microdisk lasers with different edge angles were fabricated by ink-jet printing method. Then, effect of edge angle on mode shift was investigated by monitoring the physical adsorption of BSA protein.

DOI： 10.1364/CLEOPR.2020.C2D_2

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

The bitterness sensor with negatively charged lipid polymer membrane has been reported to perform high sensitivity and selectivity to bitterness of medicines. However, the conventional cleaning solution cannot completely remove residual substances after measuring high concentration bitter samples. Surfactant is an important cleaning agent used for membrane materials. This paper reported the effects of four kinds of surfactants in cleaning the lipid polymer membrane of the bitterness sensor. Among these surfactants, anionic surfactant linear alkylbenzene sulfonate (LAS) showed no detectable impact on membrane integrity and a good cleaning effect for the bitterness sensor.

DOI： 10.1109/ISOEN.2019.8823187

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

In this study, we have fabricated multichannel odor sensor using chemosensitive resistors. The chemosensitive resistors were made from complex of carbon black and gas chromatography stationary materials (GC materials). The electrical resistance of the chemosensitive resistor changed by sensing gas species. We have fabricated an odor sensor chip, which had 16 types of chemosensitive resistors. In addition, we developed a measurement instrument with compact size. The odor sensor chip was embedded in the instrument to construct an odor sensor system. The sensor system outputted the data of 16 channels if sensing gas species. The data have been analyzed using machine learning algorithms that were available on software Weka. As a result, it was successful to identify alcohol beverages by sensing their odor using the sensor system.

DOI： 10.1109/ISOEN.2019.8823511

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

We propose an artificial intelligence-based chemical-sensing system integrating a porous gate field-effect transistor (PGFET) array modified by gas chromatography stationary phase materials and machine-learning techniques. The chemically sensitive PGFET array generates cross-reactive signals for computational analysis and shows potential for applications to compact intelligent sensing devices, including mobile electronic noses.

DOI： 10.1039/c8me00097b

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

In this study, we developed a surface plasmon resonance (SPR) sensor chip based on 2,4,6-trinitrotoluene (TNT) recognition peptide-modified single-walled carbon nanotubes (SWCNTs). The carboxylic acid-functionalized SWCNTs were immobilized on a 3-aminopropyltriethoxysilane (APTES)-modified SPR Au chip surface. Through π-stacking between the aromatic amino acids and SWCNTs, the TNT recognition peptide TNTHCDR3 was immobilized onto the surface of the SWCNTs. The peptide–SWCNTs-modified sensor surface was confirmed and evaluated by atomic force microscope (AFM) observation. The peptide–SWCNTs hybrid SPR sensor chip exhibited enhanced sensitivity with a limit of detection (LOD) of 772 ppb and highly selective detection compared with commercialized carboxymethylated dextran matrix sensor chips.

DOI： 10.3390/s18124461

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

In this study, 2,4,6-trinitrotoluene (TNT) binding peptide was synthesized and screened for TNT specific detection using surface plasmon resonance (SPR) sensor. The TNT binding peptide was rational design and synthesized through amino acid sequence from complementarity determining region (CDR) in the anti-TNT monoclonal antibody, which was produced from hybridoma cell using TNP-KLH conjugate as antigen. Three TNT binding peptide sequences were obtained from the heavy chain of CDR1 named TNTHCDR1, TNTHCDR2 from CDR2 and TNTHCDR3 from CDR3 of anti-TNT antibody. Screening process of three candidate peptides were carried out by using the SPR sensor with direct determination, which the peptide was directly immobilized on the sensor chip CM7 surface through amine coupling reaction. The results demonstrated that peptide TNTHCDR3 was determined as TNT binding peptide and no non-specific binding was observed. The selectivity of TNT binding peptide TNTHCDR3 was also testified by six kinds of TNT analogues. The results indicated the specific binding between TNT and peptide TNTHCDR3.

DOI： 10.1016/j.snb.2018.02.075

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

This paper describes a preliminary test for sum-frequency generation (SFG) spectroscopy analysis of lipid polymer membranes. The SFG technique is used to analyze surface and structural information of molecules at gas-solid, gas-liquid, liquid-solid interfaces. A specially designed SFG system, which allows to analyze orientational polarization of polymer molecules at interfaces between a lipid polymer membrane and liquid/gas/solid, is being developed in our laboratory. A laser-induced damage threshold test of lipid polymer membranes was conducted in an early stage of this work.

DOI： 10.1109/ICSensT.2017.8304474

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

This paper reports the improvement of a bitterness sensor based on a lipid polymer membrane consisting of phosphoric acid di-n-decyl ester (PADE) as a lipid and bis(1-butylpentyl) adipate (BBPA) and tributyl o-acetylcitrate (TBAC) as plasticizers. Although the commercialized bitterness sensor (BT0) has high sensitivity and selectivity to the bitterness of medicines, the sensor response gradually decreases to almost zero after two years at room temperature and humidity in a laboratory. To reveal the reason for the deterioration of the response, we investigated sensor membranes by measuring the membrane potential, contact angle, and adsorption amount, as well as by performing gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS).We found that the change in the surface charge density caused by the hydrolysis of TBAC led to the deterioration of the response. The acidic environment generated by PADE promoted TBAC hydrolysis. Finally, we succeeded in fabricating a new membrane for sensing the bitterness of medicines with higher durability and sensitivity by adjusting the proportions of the lipid and plasticizers.

DOI： 10.3390/s17112541

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

In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT) binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR) of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR) sensor. By antigen-docking simulation and screening, the TNT binding candidate peptides were obtained as TNTHCDR1 derived from the heavy chain of CDR1, TNTHCDR2 derived from CDR2, and TNTHCDR3 from CDR3 of an anti-TNT antibody. The binding events between candidate peptides and TNT were evaluated using the SPR sensor by direct determination based on the 3-aminopropyltriethoxysilane (APTES) surface. The TNT binding peptide was directly immobilized on the maleimide-functionalized sensor chip surface from N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS). The results demonstrated that peptide TNTHCDR3 was identified and selected as a TNT binding peptide among the other two candidate peptides. Five kinds of TNT analogues were also investigated to testify the selectivity of TNT binding peptide TNTHCDR3. Furthermore, the results indicated that the APTES-GMBS-based SPR sensor chip procedure featured a great potential application for the direct detection of TNT.

DOI： 10.3390/s17102249

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

Mimicking the biological olfaction, large odor-sensor arrays can be used to acquire a broad range of chemical information, with a potentially high degree of redundancy, to allow for enhanced control over the sensitivity and selectivity of artificial olfaction systems. The arrays should consist of the largest possible number of individual sensing elements while being miniaturized. Chemosensitive resistors are one of the sensing platforms that have a potential to satisfy these two conditions. In this work we test viability of fabricating a 16-element chemosensitive resistor array for detection and recognition of volatile organic compounds (VOCs). The sensors were fabricated using blends of carbon black and gas chromatography (GC) stationary-phase materials preselected based on their sorption properties. Blends of the selected GC materials with carbon black particles were subsequently coated over chemosensitive resistor devices and the resulting sensors/arrays evaluated in exposure experiments against vapors of pyrrole, benzenal, nonanal, and 2-phenethylamine at 150, 300, 450, and 900 ppb. Responses of the fabricated 16-element array were stable and differed for each individual odorant sample, proving the blends of GC materials with carbon black particles can be effectively used for fabrication of large odor-sensing arrays based on chemosensitive resistors. The obtained results suggest that the proposed sensing devices could be effective in discriminating odor/vapor samples at the sub-ppm level.

DOI： 10.3390/s17071606

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

High-potency sweeteners are applied to low-calorie diets and bitterness-masking ingredients in pharmaceutical products. We have studied taste sensors with lipid polymer membranes based on potentiometric measurement system for high-potency sweeteners. However, the sensor also responds to astringency substances because of hydrophobic characteristics of the lipid polymer membrane. In this study, we developed a new taste sensor using a lipid polymer membrane for saccharin sodium and acesulfame potassium as negatively charged high-potency sweeteners. We optimized the quantities and types of lipids and plasticizers for the fabrication of the sensor with high selectivity and sensitivity. We succeeded in the fabrication of the new sensor, the output of which could be suppressed under-5 mV for astringency substances. Moreover, the sensor has a good sensitivity and selectivity for saccharin sodium and acesulfame potassium.

DOI： 10.1109/ISOEN.2017.7968932

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

The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor arrays based on molecularly imprinted sol-gel (MISG) materials were developed in this work for highly sensitive detection and highly selective recognition of typical aldehyde vapors including hexanal (HAL); nonanal (NAL) and bezaldehyde (BAL). The MISGs were prepared by a sol-gel procedure using two matrix precursors: tetraethyl orthosilicate (TEOS) and tetrabutoxytitanium (TBOT). Aminopropyltriethoxysilane (APT); diethylaminopropyltrimethoxysilane (EAP) and trimethoxy-phenylsilane (TMP) were added as functional monomers to adjust the imprinting effect of the matrix. Hexanoic acid (HA); nonanoic acid (NA) and benzoic acid (BA) were used as psuedotemplates in view of their analogous structure to the target molecules as well as the strong hydrogen-bonding interaction with the matrix. Totally 13 types of MISGs with different components were prepared and coated on QCM electrodes by spin coating. Their sensing characters towards the three aldehyde vapors with different concentrations were investigated qualitatively. The results demonstrated that the response of individual sensors to each target strongly depended on the matrix precursors; functional monomers and template molecules. An optimization of the 13 MISG materials was carried out based on statistical analysis such as principle component analysis (PCA); multivariate analysis of covariance (MANCOVA) and hierarchical cluster analysis (HCA). The optimized sensor array consisting of five channels showed a high discrimination ability on the aldehyde vapors; which was confirmed by quantitative comparison with a randomly selected array. It was suggested that both the molecularly imprinting (MIP) effect and the matrix effect contributed to the sensitivity and selectivity of the optimized sensor array. The developed MISGs were expected to be promising materials for the detection and recognition of volatile aldehydes contained in exhaled breath or human body odor.

DOI： 10.3390/s17020382

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

A taste sensor using a lipid/polymer membrane, i.e., an electronic tongue with global selectivity, has been developed for objective evaluation of the taste of foods and beverages. Moreover, the taste sensor has been also contributing to safety of foods, e.g., the sensor membrane with strong hydrophobicity was used to detect sodium dodecyl sulfate (SDS), a negatively charged surfactant, which was generally added into the pesticide because of its strongly melting effect. An immersion process in monosodium glutamate (MSG) solution, called 'MSG preconditioning' was needed to obtain the change in membrane electric potential caused by adsorption (CPA) for sensor membrane before measurement. However, what happened to sensor membrane during MSG preconditioning is unclear. In this paper, we examined the relationship between the CPA value and the period of MSG preconditioning. The amount of adsorbed SDS and MSG was measured to figure out whether the CPA value is related to the amount of adsorption. As a result, with the precondition process progressed, the CPA values showed concentration dependence on SDS concentration, and increased to a peak by preconditioning for one day then decreased to a stable state after that. The amount of adsorbed SDS depended on the SDS concentration but did not change with the increasing of preconditioning time. In conclusion, we revealed that the most suitable time of MSG preconditioning for the membrane for SDS was one day. The CPA value was affected by both the surface charge density and the amount of absorption.

DOI： 10.1109/ICSensT.2016.7796341

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

A taste sensor based on lipid/polymer membranes has been reported being possible to detect the masking of bitter substances or masking on bitterness receptors (physical masking or biochemical masking). However, it was difficult to express the bitterness suppression by sweeteners, which is decided by the balance of substances produced in human's brain (functional masking). High-potency sweeteners are one of the sweeteners used for bitterness-masking in food and pharmaceutical industry. The objective of this study is to evaluate the bitterness-masking effect of high-potency sweeteners using the taste sensor. A bitterness sensor was used to evaluate the bitterness of quinine hydrochloride, and sweetness sensors for high-potency sweeteners were used to evaluate the sweetness of aspartame and saccharine sodium. The sensory evaluation was also carried out to examine the bitterness suppression effect of high-potency sweeteners. The bitterness-prediction formulas were proposed with the aid of a model regression analysis using two outputs from the bitterness sensor and the sweetness sensor for high-potency sweeteners. As a result, the predicted bitterness showed a good correlation with the human taste when aspartame or saccharine sodium was added to quinine hydrochloride. Thus, this study provided an effective method to evaluate the bitterness suppressed by high-potency sweeteners.

DOI： 10.1016/j.snb.2016.05.009

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

A taste sensor that uses lipid/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning”. However, what happens to the lipid/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning.

DOI： 10.3390/s16020230

Language：English  

DOI： doi:10.3390

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

It is possible to evaluate the taste of foods or medicines using a taste sensor. The taste sensor converts information on taste into an electrical signal using several lipid/polymer membranes. A lipid/polymer membrane for bitterness sensing can evaluate aftertaste after immersion in monosodium glutamate (MSG), which is called “preconditioning”. However, we have not yet analyzed the change in the surface structure of the membrane as a result of preconditioning. Thus, we analyzed the change in the surface by performing contact angle and surface zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS) and gas cluster ion beam time-of-flight secondary ion mass spectrometry (GCIB-TOF-SIMS). After preconditioning, the concentrations of MSG and tetradodecylammonium bromide (TDAB), contained in the lipid membrane were found to be higher in the surface region than in the bulk region. The effect of preconditioning was revealed by the above analysis methods.

DOI： 10.3390/s150922439

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

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

We developed a compact measurement system for surface plasmon fluorescence spectroscopy (SPFS) and a sensor surface for the detection of 2,4,6-trinitrotoluene (TNT). We employed a laser diode as a light source in the optical system for exciting fluorescence. Then, a fan-shaped beam was irradiated from the laser diode to a Au thin film using a beam expander. Fluorescence emission was captured using a photomultiplier detector. The sensor surface was modified with TNT analogues via a self-assembled monolayer. A limit of detection in the ppt range for TNT was obtained using a fluorescence-labeled anti- TNT monoclonal antibody in the SPFS system by indirect competitive assay.

DOI： 10.1109/ICSENS.2014.6984999

Language：English  

DOI： 10.3390/bios3040374

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

In this study, we modified a surface plasmon resonance immunosensor chip with a polymer using surface-initiated atom transfer polymerization (SI-ATRP) for the highly sensitive detection of 2,4,6-trinitrotoluene (TNT). To immobilize a TNT analogue on the polymer, mono-2-(methacryloyloxy)ethylsuccinate (MES), which has a carboxyl group, was used in this study. However, the anti-TNT antibody may adsorb non-specifically on the polymer surface by an electrostatic interaction because MES is negatively charged. Therefore, a mixed monomer with MES and diethylaminoethylmethacrylate (DEAEM), which has a tertiary amino group and is positively charged, was prepared to obtain electroneutrality for suppressing the nonspecific adsorption. The detection of TNT was performed by inhibition assay using the polymer surface. To ensure high sensitivity to TNT, the affinity between the surface and the antibody was optimized by controlling the density of the initiator for ATRP by mixing two types of self-assembled monolayer reagents. As a result, a limit of detection of 5.7 pg/mL (ppt) for TNT was achieved using the optimized surface. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

DOI： 10.3390/s130709294

Language：English  

DOI： 10.1109/JSEN.2013.2269697

Language：English  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：早稲田大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都大学   Country：Japan  

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：九州大学   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：愛媛大学   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：愛媛大学   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：愛媛大学   Country：Japan  

Event date： 2014.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Event date： 2013.11 - 2013.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学   Country：Japan  

Event date： 2013.11 - 2013.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学   Country：Japan  

Event date： 2005.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡工業大学   Country：Japan  

Event date： 2003.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎ハウステンボス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：早稲田大学   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Country：China  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Country：Thailand  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan