Vol. 22, Supplement B(2006)

ハイブリッド型ゾル－ゲル膜修飾電極によるグルコースの高選択的バイ
オセンシング

HIGHLY SELECTIVE BIOSENSING OF GLUCOSE USING
HYBRID SOL-GEL FILM-MODIFIED ELECTRODE

Department of Applied Chemistry, Faculty of Engineering,
Saitama Institute of Technology Fukaya-shi Saitama 369-0293

Novel organic-inorganic hybrid silica-derived sol-gel film was modified on the Pt electrode to fabricate highly selective and rapid interference-free amperometric glucose biosensor. A bovine serum albumin (BSA) and chitosan (CHT) were physically incorporated into the sol-gel film composed of three kinds of silicates (i.e., 3-aminopropyltriethoxysilane (APTES), tetraethoxysilane (TEOS) and triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (FAS)). Finally, glucose oxidase (GOx) was cross-linked with amino residue of the hybrid sol-gel film using glutaraldehyde (GA). The BSA and CHT were effective not only to increase the permselectivity of H₂O₂ but also to provide suitable microenvironment for the immobilized GOx. Moreover, FAS was much effective to reduce interference currents　of AA, UA and ACT to nA level (less than 1/100 of the response current of H₂O₂). The resulting organic-inorganic hybrid sol-gel film-modified Pt electrode allowed highly sensitive (sensitivity: 1.61nA/μM, detection limit: 5μM) and rapid (100% response in <3 s) determination of glucose even in the presence of possible interferents.

アルコール酸化酵素を用いたホルムアルデヒド測定バイオセンサの開発

Development of biosensor immobilized alcohol oxidase to measure formaldehyde

Bio-Nano Electronics Research Center, Toyo University, Kujirai 2100,
Kawagoe, Saitama 350-8585

We developed the formaldehyde sensor immobilized alcohol oxidase (AOX) on a platinum black electrode by using a polyallylamine membrane.
AOX catalyses the oxidation of formaldehyde to generate the formic acid and hydrogen peroxide. A platinum black electrode can detect hydrogen peroxide as Amperometric sensor. A platinum black electrode is effective to the immobilization of the enzyme by its porousness.
In addition, the alcohol to be catalyzed by the AOX was interrupted by the polyallylamine membrane.
The electrode incorporating alcohol oxidase was found to exhibit a high selectivity to formaldehyde. The response current of the sensor increased with increasing formaldehyde concentration. The linear range of the sensor signals corresponds to 0.1-10 mM formaldehyde.

超弾性合金を芯材に用いた体内埋め込み測定用バイオセンサの作製

○高岡宏樹,　森山健史,　山本美穂,　安澤幹人,　今井信治^*,　Raeann Gifford^*,　George S. Wilson^**

PREPARATION OF IN VIVO MEASUREMENT TYPE BIOSENSOR USING SUPER-FLEXIBLE
ALLOY WIRE AS THE CORE MATERIAL

Hiroki TAKAOKA, Kenji MORIYAMA, Miho YAMAMOTO, Mikito YASUZAWA, Shinji
IMAI^*, Raeann GIFFORD^*, George S. WILSON^**

Department of Chemical Science and Technology, The University of
Tokushima,
Tokusima 770-8506, Japan
^*Toyo Precision Parts MFG. Co., Ltd., Kashihara, Nara 634-0836
^** Department of Chemistry, University of Kansas,
Lawrence, Kansas 66045, USA

In the development of in vivotype glucose sensor, miniaturization of the sensor size and flexibility is quite importance to reduce damage to the tissue from sensor implantation.Super flexible Ni-Ti alloy wire with a diameter of 100mm was applied as a core material in order to obtain fine and flexible sensor. Gold plating and platinum plating were performed on Ni-Ti wire to obtain sensing region with platinum surface and was applied for glucose sensor. Pt sensing region prepared on Au plated Ni-Ti presented good response to hydrogen peroxide and the applied glucose sensor also showed good response to glucose. Back ground current and current noise were significantly lower than that prepared from Pt sputtering on Ni-Ti wire.

微細針状マルチチャンネルセンサ作製を目的とした微小領域への選択的酵素固定技術の開発

DEVELOPMENT OF PRECISE ENZYME-LOCALIZING TECHNIQUE FOR MULTI-CHANNEL
SENSOR FABRICATION

Department of Chemical Science and Technology,
The University of Tokushima, Tokusima 770-8506, Japan
^* Department of Chemistry, University of Kansas,
Lawrence, Kansas 66045, USA

In addition to precise localization of enzyme on a minute sensing region, prevention of the enzyme adsorption onto inappropriate electrode surface is essential on the fabrication of multichannel enzyme sensor. Masking of a platinum electrode surface was performed by dipping the electrode in allyl derivatives solution and was removed by applying a potential of 1.50 V (vs. Ag/AgCl). The effect of the introduction of allyl derivatives to prevent enzyme adsorption was evaluated by using electrochemical procedure and optical procedure. Negatively charged allyl sulfonic acid could prevent the adsorption of glucose oxidase significantly, since the pI of GOx is 4.2 and negatively charged at neutral media. Optical procedure provided reliable results than that obtained from electrochemical procedure.

ペルヒドロポリシラザンを用いたタンパク質吸着抑制表面形成技術の開発

Department of Chemical Science and Technology, The University of
Tokushima, Tokusima 770-8506, Japan

Hydrophilic surface modification was performed on glass and stainless plate using perhydropolysilazane (PZ) and polyethylene glycol (PEG). The water contact angle was lower on the surface prepared using higher molecular weight PEG. Although, the introduction of monoalkoxy PEG to the surface of silica was performed without any matter, dialkoxy PEG did not react with PZ and silica film without PEG was obtained on the surface. Molar ratio of protein adsorption of fibrinogen to albumin (F/A molar ratio), which was adopted as the indicator of biocompatibility, was measured. The F/A molar ratio was lowered by the surface modification of PEG. PEG surface modification contributed to improve the biocompatibility.

AuゲートChemical CCDの酸化還元物質応答とメディエーター型酵素センサへの応用

RESPONSE OF THE GOLD-GATE CHEMICAL CCD FOR REDOX SPECIES
AND ITS APPLICATION OF MEDIATOR TYPE ENZYME SENSOR

^a Graduate School of Science and Engineering, University of Toyama,3190 Gofuku, Toyama 930-8555, Japan
^b Graduate School of Natural Science and Technology, Okayama University,3-1-1 Tsushima-naka, Okayama 700-8530, Japan

We found originally that the gold-gate chemical CCD (C-CCD) is sensitive for redox species such as ascorbic acid in a measuring solution. The basic research demonstrated that the gold-gate C-CCD could detect electron transfer equilibrium between the gold thin layer and various redox species. Therefore, we examined to apply the gold gate C-CCD for redox enzyme sensor with redox mediator. For example, the enzyme reaction of glucose dehydrogenase (GDH) was certainly detected with the gold-gate C-CCD by using ferricyanide as an electron mediator. This result suggested that the gold-gate C-CCD was a very promising transducer to fabricate a new type of bioelectronics sensors for clinical, food and environmental analysis.

Chemical CCDを用いた酸化還元酵素と金ゲート部との直接電子移動反応の検出

DETECTION OF DIRECT ELECTRON TRANSFER BETWEEN REDOX ENZYME
AND GOLD GATE BY USING CHEMICAL CCD

^a Graduate School of Natural Science and Technology, Okayama University,
3-1-1 Tsushima-naka, Okayama 700-8530, Japan
^b Graduate School of Science and Engineering for Research, University of Toyama,
3190 Gofuku, Toyama 930-8555, Japan

Very recently, our group found originally that the electron transfer between redox compounds in measuring solution and the gold thin film covered on the insulator gate was detectable very sensitively with the Chemical CCD. Therefore, in this study the PQQ-dependent fructose dehydrogenase(PQQ-FDH), which was able to transfer electron to metal electrode, was immobilized onto the gold-gate of the Chemical CCD to measure the catalytic electron transfer in the presence of the substrate. Decrease of Chemical CCD output was observed by fructose addition and the output change showed substrate specificity. The result certainly demonstrated that the enzyme oxidation of the substrate and the electron transfer from the enzyme to the gold-gate could be detected with the gold-gate Chemical CCD. The output change of the FDH-immobilized gold-gate Chemical CCD depended on the concentration of fructose and the Michaelis-Menten curve was obtained. From these results, we would like to conclude the Chemical CCD with the gold gate was very effective for measurement of direct electron transfer between adsorbed redox enzyme and gold thin film on the insulator gate surface. This study might develop new field of bioelectronics sensors and bioelectronics devices.

酵素固定化ポリマレイミドスチレン膜を用いるアンペロメトリックバイオセンサー

埼玉工大院工

○王秀云、内山俊一

AMPEROMETRIC BIOSENSORS USING THE ENZYME IMMOBILIZED POLYSTYRENE MEMBRANES

Xiuyun WANG^{a, b}, Shunichi UCHIYAMA^a

^aDepartment of Materials & Science, Graduate of School of Engineering,
Saitama Institute of Technology, 1690 Fusaiji Okabe, Saitama 369-0293
^bAnshan University of Science and Technology,
185 Qianshan Zhong Road, Anshan, Liaoning, China

Novel amperometric vitamin C (L-ascorbic acid) sensor and amplified uric acid sensor have been developed by coating the gold electrode surface with polystyrene (PS) membrane containing polymaleimidostyrene (PMS) modified enzyme. The spherical micelle-like island structures of membranes were observed by scanning electron microscope (SEM). The amperometric uric acid biosensor combined with the uricase immobilized polystyrene membrane can be chemically amplified by the substrate recycling using dithiothreitol (DTT). The amplification factor for 5.0×10-7 M uric acid was increased to 28.6 when 5.0×10-2 M DTT was added to the substrate solution. The good linear relationship between vitamin C and amperometric current response at constant potential was obtained in a concentration range from 0.01 mM to 0.8 mM when the gold electrode was equipped with PS membrane containing PMS immobilized ascorbate oxidase (ASOD).

DEVELOPEMNT OF NOVEL SUPPORTING MATERIALS FOR IMMOBILIZING ENYMES AND THE
APPLICATION OF THE PREPARATION TO MICRO BIOSENSING

Department of Applied Chemistry, Faculty of Engineering,
Kanagawa Institute of Technology
1030 Shimo-Ogino, Atsugi-shi, Kanagawa-ken, 243-0292

A novel synthetic method of silica monolith having amino groups in the structure of the silica was developed as supporting materials for enzymes and the immobilized monolithic silica column was applied to a biosensor based on flow injection analysis (FIA). A (Boc)2O (di-tert-butyl dicarbonate) was used as a protectant of amino group of APTES (aminopropyl triethoxysilane), and synthesized Boc-APTES was mixed with TMOS (tetramethoxysilane) to fabricate a monolithic silica column. L-Histidine decarboxylase was immobilized onto the silica monolith with use of glutaraldehyde for crosslinking the enzyme and the silica monolith was applied to an FIA system for L-histidine. A flow-type of the biosensing system used in this study was assembled with a sample injection valve, a gas-diffusion device armed with an immobilized L-histidine decarboxylase, and a UV/VIS detector. The gas diffusion device had a double tubing structure. The inner tubing was a gas permeable tubing and bromothymol blue as a coloring agent was pumped through in this tubing. The outer tubing was silica capillary tubing for flowing carrier solution and a monolithic silica column was fabricated in the caplillary and L-histidine decarboxylase was immobilized onto the silica monolith. Standard
urea solutions were measured through monitoring variations in absorbance resulting from pH shift attributable to CO₂ molecules enzymatically generated in acidic condition. A good linear relationship was obtained between the concentration of L-histidine (100 uM - 2.5 mM) and the change in absorbance.

蒸発的濃縮による微小領域への酵素の高密度固定化とその効果

HIGHLY CONCENTRATIVE IMMOBILIZATION OF AN ENZYME ON A SMALL AREA BY
EVAPORATIVE CONCENTRATION AND ITS EFFECT

Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1
Tennodai, Tsukuba, Ibaraki 305-8573

A highly concentrated enzyme-immobilized layer was formed only on a small working electrode and the behavior of the electrode as an amperometric sensor was examined. To this end, a super-hydrophobic layer was formed in an area other than the sensitive area by using polytetrafluoroethylene (PTFE) beads. A small droplet of an enzyme solution containing glucose oxidase (GOD) and bovine serum albumin (BSA) was concentrated to the sensitive area by evaporation and crosslinked. A significant improvement in current density and extension of the linear range of the calibration plot was achieved in batch-style measurements. The dependence of the output current on the amount of enzyme and the size of the working electrode was examined. The output current increased as the enzyme loading increased, and the current density increased with smaller working electrodes. The sensor fabricated by this novel method was incorporated in a micro flow channel. The dependence of the output current on flow rate and channel height were very weak and the conversion efficiency increased at higher concentrations, which was a significant contrast to the enzyme electrodes fabricated by the conventional method.

人工酵素膜を分子インターフェイスとして利用したATPsバイオセンサの構築

九工大院生命体 ^a、科学技術振興機構 CREST ^b

○池野慎也 ^a,b、吉田徹哉 ^a、春山哲也 ^a,b

NANO-DESIGNED ARTIFICIAL ENZYME MEMBRANE BASED ATPS SENSOR FOR BIO-SURVEY

Shinya IKENO ^a,b, Tetsuy^a YOSHIDA ^a and Tetsuy^a HARUYAMA ^a,b

^a Department of Biological Function and Engineering, Kyushu Institute of
Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196
^b CREST, Japan Science and Technology Agency, Kawaguchi-shi, Saitama,
332-0012

It goes without saying that an importance of ATP and its derivative in biological systems.
These ATP and derivatives has been given genetic name to ATPs, because ATPs can be employed bio-survey marker. In the present study, artificial enzyme has been designed and synthesized as membrane form in order to fabricate ATPs sensor for bio-surveillance. The artificial enzyme membrane, which is synthesized through metal coordinative self assembly, involves a swarm of metal-complex the nano cavities. It shows a remarkable catalytic activity on dephosphorylation of phosphate ester. By using the artificial enzyme membrane coated electrode, ATP concentration can be measured through an electrochemical reduction of the dephosphorylation product (PO43-) at -250 mV vs. Ag/AgCl. It is a strong point that the artificial enzyme sensor can monitor all of ATPs all together. Such the mass monitoring cannot perform in any other way except for artificial enzyme because it can be designed as loose molecular selectivity.

マイクロ化学センサによる非侵襲生体計測への応用と実用化

COMMERCIALIZATION OF A MICRO-CHEMICAL SENSOR AND ITS APPLICATION TO A
NON-INVASIVE BLOOD CONSTITUENT MONITORING SYSTEM

R&D Department, TANITA Corporation
1-14-2, Maeno-cho, Itabashi-ku, Tokyo, 174-8630, Japan

The initial goal of this project had built a novel non-invasive blood constituent monitoring system. To pursue it, we　developed ion sensitive field effect transistors and micro-planer amperometric chemical sensors to detect bio-chemical concentration in very small body fluid samples. Additionally, we studied sensor structures, fabrication processes, and non-invasive blood glucose monitoring systems to commercialize micro-chemical sensors for medical applications. The　results have been integrated to introduce a quantitative urine glucose meter on the market.
I summarized a review of our studies in a row.

Department of Bioenginnering, Faculty of Engineering, Soka University 1-236
Tangi, Hachioji, Tokyo 192-8577

Simazine (CAT) is one of the triazine herbicides, and reported to be an endocrine disrupting chemical. Recently, we have reported the molecularly imprinted polymer selective to CAT (CAT-MIP). CAT-MIP was composed of the methacrylic acid (MAA) as the functional monomer and the ethylene glycol dimethacrylate (EDMA) as the cross-linker, and bound more CAT selectively than the structural analogues.
The reductive current of CAT was detected by amalgamated gold electrode which was alloyed with mercury. CAT sensing based on CAT-MIP was performed by extracting CAT through the CAT-MIP particles packed column, and then the reductive current of the eluted solution was measured electrochemically. The reductive current of CAT depended on the concentration of CAT loaded. CAT sensor showed higher response to CAT than the structural analogues. The environmental standard limit for water quality, CAT 3 ppb, was detected more than the structural analogues. Thus, CAT sensor was shown to be selective to CAT.

ALPカラムを用いた亜鉛(Ⅱ)イオンのフローインジェクション微量計測

Department of Applied Chemistry, Faculty of Engineering,
Kanagawa Institute of Technology
1030 Shimo-Ogino, Atsugi-shi, Kanagawa-ken, 243-0292

An alkaline phosphatase (ALP) column as a recognition element for zinc(II) ions was applied to a photometric flow system. The enzymes covalently fixed onto porous glass beads (pore size: 24.2 nm) were packed into a small polymer column (0.1 mL). A water-jacketed holder (303 K) in which the enzyme-packed column being placed was incorporated into the system equipped with a flow-through cell mounted in a UV/VIS detector. The catalytic activity was assessed by monitoring variations in absorbance at 405 nm attributable to p-nitrophenol formed in the hydrolysis of p-nitrophenyl phosphate as the substrate. Exposing the column to 20 mM EDTA (pH 4.0) caused remarkable decrease in the catalytic activity. Then, subsequent introduction of 1.0 mM zinc(II) ions to the column sufficiently reactivated the activity. The activity partially recovered was a function of zinc(II) ions injected. The once chelator-exposed column was also reactivated by adding cobalt(II) ions solution. However, injection of cobalt(II) ions into the metal-free column did not reveal the catalytic activity in the presence of N-dimethylcarboxylsarcosine (DTCS) as masking agents. Thus, zinc(II) ions in a range of 1.0 to 100 uM could be photometrically determined.

白金および酸化イリジウム上における過酸化水素とアジ化物イオンの電気化学的挙動

ELECTROCHEMICAL BEHAVIORS OF HYDROGEN PEROXIDE
AND AZIDE IONS ON PLATINUM OR IRIDIUM DIOXIDE ELECTRODES

^a Department of Environmental Systems Science, Doshisha University
Kyo-tanabe, Kyoto 610-0394
^b Dept. of Applied Science for Integrated System Eng., Kyushu Institute of Technology
Tobata, Kitakyushu 804-8550

The electrochemical behaviors of hydrogen peroxide and azide ions in the buffer solution (pH=6.7) were investigated with platinum or IrO₂ electrodes by voltammetric techniques. The electrodes were prepared by thermal decomposition method using alumina or titanium plates as a substrate. The H₂O₂ oxidation on the Pt electrode occurred at more positive potentials than the N3-oxidation, in which the latter results in the strong adsorption of N₃ on the electrode surface. The IrO₂ electrode also showed the voltammetric response to the H₂O₂ oxidation with a possibility of IrO₂ as an electrochemical sensing material for H₂O₂, while no current was observed for the oxidation of N₃- to N₃, suggesting that the IrO₂ electrode is highly sensitive to H₂O₂ oxidation in the coexistence of N₃-. Under a possible situation that the adsorption and accumulation of N₃ on the Pt electrode would hinder the active surface for H₂O₂ oxidation in H₂O₂ or glucose sensors using NaN₃ as a preservative of a carrier solution, the IrO₂ electrode could be one of the promising candidates to suppress the degradation in sensitivity and selectivity for H₂O₂ detection in a long-term or intermittent operations.

Soichiro SUZUKI, Satoko TAKASE, and Youichi SHIMIZU

Department of Applied Chemistry, Faculty of Engineering,
Kyushu Institute of Technology,
1-1 Sensui-cho, Tobata, City of Kitakyushu 804-8550

A new all-solid-state impedance metric hydrogen-phosphate ion (HPO42－) sensor device have been fabricated using BaTiO₃ as a transducer and spinel-type oxide thin-film (Co₂MO₄, M = Rh, Fe, Al) as a receptor,　respectively. AC impedance measurement was carried out using flow-cell system with boric-acid buffer solution with hydrogen-phosphate ion at pH=9.3. The Co₂RhO₄/BaTiO₃　sensor device was found to show impedance responses to hydrogen-phosphate ion at the concentration range between 5×10－4M and 1.0×10－2M with the 90% response time of ca. 150s. The Co₂RhO₄ / BaTiO₃ device showed the best response characteristics among the tested devices in terms of sensitivity and restoration rate, although it still have some problems about ion selectivity and response mechanism.

Department of Applied Chemistry, Faculty of Engineering,
Kyushu Institute of Technology,
1-1 Sensui-cho, Tobata, City of Kitakyushu 804-8550

The metal thin-film electrode based sensors were prepared by electrodepositing onto Au-Al₂O₃ substrate from aqueous solution of metal-salts. The metal-thin-film electrodes were characterized by means of XRD, FE-SEM and XPS, etc. The Co/Fe thin-film electrode showed the best EMF response characteristic among the metal thin-films tested. The electrode exhibited a linear potentiometric response to hydrogen-phosphate ion at the concentration range between 1 × 10^-4 and 1 × 10^-2 M with a Nernst's slope of -42.3 mV/decade in pH 5. The sensor had high potentials of fast response rate, high selectivity, and sensitivity. The electrode also could be used for more than 7 weeks. The sensor seems to be successfully used as an indicator electrode in potentiometric titration of hydrogen-phosphate ion.

Department of Pure and Applied Chemistry, Faculty of Science and Technology,
Tokyo University of Science, 2641, Yamazaki, Noda-shi, Chiba, 278-8510

A disposable chloride ion sensor was fabricated by the screen-printing method.．The sensor chip consists of the Ag/AgCl working and reference electrodes.．The response of the sensor was proportion to the logarithm of
chloride ion concentration and obeyed the Nernst equation. It is shown that the sensor was insensitive to three ionic species, Na^＋, K^＋, Ca^2＋. These electrodes were prepared by low-cost materials (Ag, AgCl, KCl ink) and the
simple fabrication processes. The present system is potentially applicable to water quality analysis.

1価‐1価電解質溶液における水晶振動子共振周波数変化特性

CHARACTERISTICS OF THE RESONANT-FREQUENCY SHIFT
OF THE QUARTZ CRYATAL MICROBALANCE IN MONOVALENT ELECTROLYTE SOLUTIONS

Minoru YOSHIMOTO, Shin TOKIMURA, Shigeru KUROSAWA

Department of Bioengineering, Faculty of Engineering, Kagoshima University,
1-21-40 Korimoto, Kagoshima 890-0065, Japan
National Institute of Advanced Industrial Science and Technology (AIST),
1-1 Higashi, Tsukuba 305-8565, Japan

We report the novel characteristics of the series resonant-frequency shift, delta F, of the one-face sealed quartz crystal microbalance (QCM) in the electrolyte solutions. In the present study, we used NaCl, KCl, LiCl, NaNO₃ and CH₃COONa of monovalent electrolytes. These experiments reveal that, in all the solutions, the delta F values vary linearly with an increase in the square root of the density-viscosity product of the solutions, and the immersion angle dependence of delta F appears. In addition, the slop values of delta F in the monovalent electrolyte solutions are equal to those of a Newtonian liquid. We have also found that the intercept values of delta F dependent only on the cation species emerge.

ルテニウム錯体内封リポソームを用いるタンパク質の高感度定量

HIGHLY SENSITIVE DETECTION OF PROTEINS
BASED ON RUTHENIUM COMPLEX ENCLOSED IN A LIPOSOME

Highly sensitive detection of trace component was developed by the method which combined immunological reaction, electrochemiluminescence (ECL) and liposome to amplify the signal. The merit of the analytical method is that the measurement ends in a short time, and that it can also improve the problem of the pretreatment. Firstly, a BSA antibody-modified liposom was prepared and the fluorescent species tris(2,2'-bipyridine)- ruthenium(II) complex ([Ru(bpy)3]2+) is enclosed in the liposome. In the analytical procedure, the liposome was put on BSA-modified gold working electrode on which the antigen-antibody reaction occurred. The liposome was then destroyed by addition of ethanol in high efficiency. Finally, the complex leaked from the liposome gave ECL on application of a potential. We achieved sensitive determination of BSA antibody; the detection limit is 10-14~10-12mol. The use of Ru complex with two animo groups allowed to enhance the sensitivity.

高倍率２次元ＳＰＲイメージングセンサにおける同一画像中での画質均質化

IMPROVEMENT OF FOCUS BALANCE OF SPR IMAGES IN THE HIGH POWERED
TWO-DIMENSIONAL SPR IMAGING SENSOR

Faculty of Engineering, University of Toyama, Toyama-shi, Toyama 930-8555,
Japan, and NTT Advanced Technology Corp., Atsugi-shi, Kanagawa 243-0124,
Japan

We are developing the single cell based lymphocyte micro array chip system for the screening of antigen-specific B lymphocytes, which are necessary for the development of antibody medicines. Final target is to detect antibody production from a single lymphocyte. A two-dimensional surface plasmon resonance imaging sensor (2D-SPR) might be a promising tool for this purpose. But, in a 2D-SPR sensor based on the Kretschmann configuration, focusing the whole SPR image is difficult especially when the high powered
lens was used, and this makes the high powered 2D-SPR measurement difficult.
In this study, optical diaphragms were equipped to the microscopic lens of the 2D-SPR sensor and the focus balance of SPR images was improved.

Atsushi SEKI, Kiyoshi KOYANAGI, Masayuki SHIRAKAWA, Mitsuhiro IGA, Kazuhiro
WATANABE

A SPR sensor based on a hetero-core structured fiber optic was fabricated by covering its surface with a thin　silver film. Self-assemble monolayer (SAM) of alkanethiol was prepared on it and the propagating loss spectra were measured. The formation of the SAM film leaded to a peak shift in the SPR spectra to long wavelength side. In addition, according to increasing of alkyl chain length, the shift was increased. Furthermore, BSA as a model of antigen was immobilized on it, and antigen-antibody binding reaction was detected as a change of refractive index on the sensor surface.

機能性チオール自己組織化膜を用いたSPRセンサによるTNTの超高感度検出

ULTRA-HIGHLY SENSITIVE TNT DETECTION BY SPR SENSOR
USING FUNCTIONALIED THIOLATE SELF-ASSEMBLED MONOLAYER

○Toshikazu KAWAGUCHI, Dhesingh RAVI SHANKARAN, Sook-jin KIM, Kiyoshi TOKO,
Kiyoshi MATSUMOTO, Norio MIURA

Art, Science and Technology Center for Cooperative Research, Kyushu University,
Kasuga-shi, Fukuoka, 816-8580, Japan

The SPR immunosensors for highly sensitive detection of explosive compounds are reported here. The novel immunosensor surface prepared by self-assembly method could be reused over 100 times by regeneration using pepsin-HCl solution. The detectable range for TNT was between 7 ppt and 10 ppb, and it was almost comparable with that of immunosensor prepared by physical adsorption method so far utilized by our group. The present immunosensor could measure the amount of TNT in sample solution within 2 min, and showed excellent selectivities to TNT and TNPh against various TNT analogs.

SPR免疫センサによる低分子匂い物質(ベンズアルデヒド)の高感度分析

○K. V. Gobi^a 、松本清^a 、都甲潔^a 、池崎秀和^b 、三浦則雄^a

ENHANCED SENSITIVITY OF SURFACE-PLASMON-RESONANCE BASED IMMUNOSENSOR IN TRACE DETECTION OF A LOW-MOLECULAR-WEIGHT FRAGRANT, BENZALDEHYDE

K. Vengatajalabathy GOBI,^a Kiyoshi MATSUMOTO,^b Kiyoshi TOKO,^c Hidekazu IKEZAKI,^d Norio MIURA^a

^a Art, Science and Technology Center for Cooperative Research (KASTEC),
Kyushu University, Kasuga-shi, Fukuoka 816-8580
^bGraduate School of Agriculture, Kyushu University, Fukuoka-shi 812-8581
^cGraduate School of Information Science and Electrical Engineering,
Kyushu University, Fukuoka-shi 812-8581
^d Intelligent Sensor Technology (Insent) Incorporation, Atsugi-shi, Kanagawa 243-0032

We report here our preliminary investigations on the development of a surface plasmon resonance (SPR) immunosensor for detection of trace amounts of benzaldehyde (BZ) based on the indirect competitive immunoreaction between benzaldehyde-ovalbumin conjugate (BZ-OVA) and anti-BZ antibody. The immunosensor exhibited excellent sensitivity for the detection of BZ over a wide concentration range of 50 ppt - 300 ppb, and the response time was no more than 5 min. After an immunoaffinity binding cycle, regeneration of the active functional sensor surface can be effected by using a pepsin solution. The immunosensor exhibited high reproducibility and stable response on repeated use of a same sensor chip, enabling multiple-use at continuous flow-through production lines.

機能性チップを用いたSPR免疫センサによる牛乳アレルゲンα-カゼインの検出

オムロン株式会社

豊田　良、山崎　琢也、○岩坂　博之

DETECTION OF α-CASEIN INDUCING COW’S MILK ALLERGY
BY SPR IMMUNOSENSOR USING FUNCTIONAL CHIP

Ryo TOYOTA, Takuya YAMAZAKI, and Hiroyuki IWASAKA

Omron Corporation Electronic Components Company R&D Div. Engineering
Center Nishikusatsu 2-1-2, Kusatsu-shi, Siga, 525-0035, Japan

Detection of α-casein inducing cow’s milk allergy was studied by SPR immunosensor using a functional chip with self assembled two-component monolayer on gold surface. This immunosensor was capable of highly sensitive detection with simplicity and for a short detection time and its detectable range was between 0.001 μg/ml and 10 μg/ml.
Characteristics the experimental sensor indicate expectation of developing a new food-allergen sensor of highly sensitive quantification of allergen contains in specific raw food materials such as egg, wheat, buckwheat and peanut.

Graduate School of Environment and Information Sciences, Yokohama National
University Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan

Genetic diagnosis requires rapid and sensitive systems which can be operated at room temperature. In this report, to meet this requirement, we propose a new DNA sensing system which combines DNA detection based on aggregation of gold nanoparticles and an optical waveguide (OWG). Furthermore, we try to utilize an electroluminescence material Alq3 as a built-in light source attached onto the OWG; this type of OWG systems has the merit that we can cover a broad wavelength region in sensing the optical changes taking place on the OWG. We have demonstrated that the new DNA sensing system using model DNA (target and probe).

NUMERICAL SIMULATION OF ELEMETAL ANALYSIS USING　PLASMA IN MICRO FLUIDIC
CHANNEL

Isao KUMAGAI,Hirokazu MATSUMOTO,Tamotsu YAMAMOTO,
Eiichi TAMIYA and Yuzuru TAKAMURA

School of Materials Science, Japan Advanced Institute of Science and Technology,1-1
Asahidai, Nomi-shi, Ishikawa 923-1292
Tenor, Inc.18-20 Sumiyoshimachi, Nonoichimachi, Ishikawa-gun, Ishikawa 921-8813
Japan Science and Technology Agency(JST),Kawaguchi Center Building4-1-8,
Honcho, Kawaguchi-shi, Saitama 332-0012

A handy atomic emission spectrometer was developed for heavy metal measurements using liquid electrode plasma. When voltage was applied in a special micro fluidic channel that was filled with sample electrolytic solution, H₂O gas bubble was formed by Joule heating, and subsequently generated plasma emits light in the bubble. It is very important to control the bubble position for stable and measurements. In this report, the temperature in the micro fluidic channel and the nucleation frequency of the bubble was calculated by numerical simulation and the results were compared to those of experimental. Furthermore, the optimization of micro fluidic channel shape was described.

一体型プラスチックチップを用いた小型SPRセンサ

オムロン株式会社

○岩坂博之、中川武彦、早瀬哲生、酒井一訓

DEVELOPMENT OF A COMPACT SURFACE PLASMON RESONANCE (SPR) SENSOR
BY ALL-IN-ONE PLASTIC CHIP

Hiroyuki IWASAKA, Takehiko NAKAGAWA, Tetsuo HAYASE, Ichinori SAKAI

Omron Corporation Electronic Components Company R&D Div. Engineering
Center Nishikusatsu 2-1-2, Kusatsu-shi, Siga, 525-0035, Japan

A SPR sensing system has high sensibility but it was large-scale. We developed the SPR sensor that is small, easy operation by plastic SPR sensor chip. As a result, the miniaturization was achieved by the SPR sensor with eight channels (350×250×270mm). Moreover, the sensor chip was able to achieve 10% or less by the difference of the SPR sensibility.

Ｔ型マイクロチャネルを用いた高感度表面プラズモン共鳴免疫センサの開発

DEVELOPMENT OF A HIGHLY SENSITIVE SURFACE PLASMON RESONANCE BASED
IMMUNOSENSOR USING A T-SHAPED MICROCHANNEL

National Institute of Advanced Industrial Science and Technology (AIST),
1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, University of Hyogo, 3-2-1 Kouto,
Kamigori-cho, Ako-gun, Hyogo 678-1297

We have developed an on-chip immunosensor designed to determine B-type natriuretic peptide (BNP, which is one of the most important cardiac markers) based on a poly-dimethylsiloxane based a T-shaped micro flow channel combined with a surface plasmon resonance (SPR) sensor system. The immunosensor makes it simplifies multi-step immunoassays by the simultaneous use of a labeled-enzymatic reaction and the real-time monitoring of enzymatic product accumulation in a microfluidic device. We can measure trace levels of BNP safely and quickly by monitoring the shift in SPR angle caused by the accumulation and formation of a thiol monolayer using a portable SPR system.

電気化学発光とエレクトロウェッティングを利用したマイクロセンシングシステム

Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1
Tennodai, Tsukuba, Ibaraki 305-8573

An integrated micro sensing system was fabricated with functions including microfluidic transport, mixing of solutions, generation of electrochemiluminescence (ECL), and detection. The system consisted of a polydimethylsilixane (PDMS) substrate with a flow channel structure and three-electrode systems formed on a glass substrate used for microfluidic transport and the generation of ECL. Sample solution and a reagent solution containing tris(2,2’-bipiridyl)ruthenium (II) (Ru(bpy)32+) were transportedin hydrophilic flow channels by controlling valves which function based on electrowetting. The two solutions were mixed in the reaction chamber. The ECL was generated by applying a potential to a platinum working electrode and detected by a photodiode. The generation of ECL from various amino acids was examined. Clear ECL was observed and the ECL intensity depended on the concentration of the amino acids.

○蒲田歩美^a、岸上康弘^b、菊池麻里子^b、芳賀信^b、鈴木博章^a

Ayumi KABATA ^a, Yasuhiro KISHIGAMI ^b, Mariko KIKUCHI ^b, Makoto HAGA ^b and
Hiroaki SUZUKI ^a

^a Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1
Tennodai, Tsukuba, Ibaraki 305-8573
^b Faculty of Pharmaceutical Sciences, Tokyo University of Science, Nod^a,
Chiba, 278-8510

To minimize the burden for diabetes care, a micro insulin administration system was developed based on an electrochemical principle. Major components of the device were a thin-film two-electrode system incorporated in a closed compartment, a silicone rubber diaphragm to separate an electrolyte solution from an insulin solution, and a reservoir for insulin. A microneedle was attached to the outlet. Hydrogen bubbles were grown on a platinum working electrode. Accompanying this change, a pressure was exerted to the insulin solution in the reservoir. When the insulin solution was injected into an anesthetized rat, the decrease in the plasma glucose level (PGL) was observed depending on the dose of insulin. A glucose sensor was also developed to monitor the glucose level. Glucose concentration of a sample solution collected from a rat by reverse iontophoresis (RIP) could be measured.

唾液中のNOアッセイ用ラボチップの開発

(産総研)

○脇田慎一、宮道隆、田中喜秀、永井秀典、鳴石奈穂子、吉野公三、
松岡克典、吉田康一、二木鋭雄

DEVELOPMENT OF LAB-ON-A-CHIP FOR RAPID SALIVARY NO ASSAY

Shin-ichi WAKIDA^a, Takashi MIYADO^a, Yoshihide TANAKA^a, Hidenori NAGAI^a,
Nahoko NARUISHI^a, Kohzoh YOSHINO^b, Katsunori MATSUOKA^b, Yasukazu YOSHIDA^a, Etsuo NIKI^a

^a 　Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka 1-8-31, Ikeda, Osaka 563-8577

^b　 Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka 1-8-31, Ikeda, Osaka 563-8577

Nitric oxide (NO) has been identified as a mediator in many physiological functions. Moreover, NO is one of the typical oxidative stress markers and reactive nitrogen oxygen species. We have investigated a human salivary NO assay using a microfluidic CZE (Capillary Zone Electrophoresis) chip made of quartz glass with UV (214 nm) detection. The assay can quantitatively analyze NO metabolites, nitrite (NO₂-) and nitrate (NO₃-). Using microfluidic controls under effective electrophoretic conditions, complete separation of NO₂- and NO₃- in artificial human saliva was achieved within 14 seconds (s). The limits of detection (LOD) with a signal-to-noise ratio of 3 (S/N=3) obtained for NO₂- and NO₃- were 47 and 22 uM, respectively. All relative standard deviation (RSD) for peak heights and areas were less than 10 % using an internal standard method. This preliminary NO assay in human saliva was applied. The proposed microfluidic NO assay is a candidate tool for smart, fast, painless! and convenient point of care testing (POCT) for salivary diagnostics.

マイクロチップ液体クロマトグラフィーのためのオンチップ電気化学フローセルの開発

DEVELOPMENT OF AN ON-CHIP ELECTROCHEMICAL FLOW CELL
FOR MICROCHIP LIQUID CHROMATOGRAPHY

Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Nishi 8, Kita 13, Sapporo 060-8628, Japan

We have developed an electrochemical flow cell on a chip for microchip reversed-phase liquid chromatography (LC) by using poly(dimethylsiloxane) (PDMS) and polystyrene. Working, reference, and counter electrodes for the flow cell were fabricated by Au deposition on polystyrene chip, photolithography, and wet etching. To form a flow cell, PDMS channel was attached to the polystyrene chip with the electrodes. The separation column was fabricated in polystyrene by packing octadecyl silica particles. In this flow cell, the effect of working electrode width on chromatographic resolution was studied using catechins. The resolutions at electrode width of 50 and 5000 μm were both 1.9. The effect of electrode width on sensitivity (S/N ratio) was also evaluated in electrode sizes of 50-5000 μm. The narrower electrode provided higher S/N ratio: The S/N ratio for 50 μm was four-fold higher than that for 5000 μm. This effect was discussed, based on the current density of each electrode width and numerical simulation. The detection limits for catechin, epicatechin, and epigallocatechin gallate were 350, 450, and 160 nM, respectively.

^aDepartment of Material Science and Biotechnology, Graduate school of
Science and Engineering, Ehime University, Matsuyama 790-8577
^bShinyei Kaisha, Nishi-ku, Kobe 651-2241

Resistive-type humidity sensors using polyaniline composite films were fabricated and long-term stability of those sensors by application of ac voltage was investigated. The use of the film composed of the electron conductive polyaniline (PANI) and the polystyrene (PSt) was effective to depress the sensor drift caused by electrolysis. However, another drift seems to be caused by morphology change of the composite film was observed. To prevent the morphology change, cross-linked polystyrene (c-PSt) with divinylbenzene (DVB) was used as a matrix polymer.
The sensor using composite films of PANI/c-PSt showed the excellent initial sensing characteristics and long-term stability.

ジアミノ化合物を導入した共重合ポリマーを塗布したQCMのトルエン蒸気検知特性

Department of Material Science and Biotechnology, Graduate school of Science
and Engineering, Ehime University, Matsuyama 790-8577

The QCM-type toluene vapor sensors were fabricated using copolymers reacted with N,N-dimethyl-1,3-propanediamine (DMPDA) as a sensor coating. Two-types of copolymers, poly(styrene-co-chlorometyl styrene) (P(St-co-CMSt)) and poly(methylmethacrylate-co-chloromethyl styrene) (P(MMA-co-CMSt)) were comparatively used to investigate the effect of chemical structure, composition, and film thickness of copolymers on the sensing characteristics. Introduction of DMPDA into these copolymers was effective to improve the sensitivity and the response characteristics. The P(MMA-co-CMSt) reacted with DMPDA showed large composition and film thickness dependence of the sensitivity, resulting in the five times larger sensitivity compared with the result obtained for P(St-co-CMSt).

○仲野純章^a、梶田進^a、才原康弘^a、山浦真一^b、木村久道b、井上明久^b

Sumiaki NAKANO ^a, Susumu KAJITA ^a, Yasuhiro SAIHARA ^a,
Shin-ichi YAMAURA ^b, Hisamichi KIMURA ^b and Akihisa INOUE ^b

^a Matsushita Electric Works, Ltd., 1048, Kadoma, Osaka 571-8686
^b Institute for Materials Research, Tohoku University, 2-1-1, Katahira,
Sendai, Miyagi 980-8577

We have proposed and examined a new-type of hydrogen sensor which can be used in water. In this work, some Pd-based glassy alloys have been prepared by the single-roller melt-spinning technique, and been investigated whether or not they have the sensing property for hydrogen dissolved in water. The electrical resistance of each alloy increases when immersed in hydrogen-dissolved water, and recovers to the initial level when immersed in water without dissolved-hydrogen. It is expected that the Pd-based glassy alloys can be used in future as a hydrogen sensor in water.

Graduate School of Environment and Information Sciences, Yokohama National
University

Most death in fire are due to CO gas poisoning and suffocation. To be used as the fire detector, a CO sensor has to have the sensitivity threshold of about 1ppm. Optical waveguide sensors are known for their high sensitivity, and at the same time do not use components that might spark a fire. There fore we are herein presenting a CO detecting method combining optical waveguide technology and the color reaction of CO with （NH₄）2MoO₄. Our sensor with SiO₂-（NH₄）2MoO₄ film plated on TiO₂ /K⁺ compound optical waveguide can detect the CO concentration less than 1ppm.

DEVELOPMENT OF AMPEROMETRIC NO GAS SENSOR
USING GRAPHITE FOR MONITORING OF COMBUSTION GAS

Komyo Rikagaku Kogyo K.K.

1-8-28 Shimonoge, Takatsu-ku, Kawasaki-City 213-0006,Japan

We have developed an amperometric nitric oxide(NO) gas sensor for monitoring of combustion gas. The working electrode of the sensor consists of porous menbrane　and graphite powder. The sensor showed no signal by high concentration CO in combustion gas. In addition, the NO signal of the sensor did not incsrease after H2S exposure .

陽極酸化TiO₂膜を用いたダイオード型水素センサのPd極の合金化

（¹長大院生産科学，²（株）クラレ，³長大工）
○坂本恵子¹，松浦幹也²，兵頭健生³，清水康博³，江頭　誠³

EFFECTS OF Pd-BASED ELECTRODE COMPOSITIONS ON THE H₂ SENSING PROPERTIES
OF DIODE-TYPE SENSORS CONSISTING OF ANODICALLY OXIDIZED TiO₂ FILMS

Keiko SAKAMOTO¹, Mikiya MATSUURA², Takeo HYODO³, Yasuhiro SHIMIZU³ and Makoto EGASHIRA³

¹Department of Materials Engineering and Molecular Science, Nagasaki
University, 1-14 Bunkyo-machi, Nagasaki 852-8521
²Optical Device R&D Center, Kuraray Co., Ltd., Tsukuba-shi, Ibaraki 305- 0841
³Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521

Effects of Pd-based electrode compositions (Pd, Pd-Ag or Pd-Pt) on the H₂ sensing properties of diode-type TiO₂ film gas sensors have been investigated. All the sensors obtained showed much larger sensor currents in H₂ balanced with N₂, compared with those in H₂ balanced with air. The currents of the sensors equipped with alloy-electrodes (Pd-Ag or Pd-Pt) in H₂ balanced with N₂ were much larger than those of the sensor equipped with Pd, while the Pd-Ag electrode only gave relatively better H₂ responses in air flowing among the three kinds of electrodes tested. The pretreatment atmosphere at 600℃ also seemed to be important for controlling their H₂ sensing properties. These results may suggest that the chemisorbed oxygen on the electrode surfaces (or noble metal oxide layer), diffusivity of H atoms in the metals and hydrogen storage capacity are absolutely essential for improving the H₂ response behavior.

新規材料設計と電極構造のナノ設計による半導体ガスセンサの高感度化

HIGH SENSITIVITY SEMICONDUCTOR GAS SENSORS USING NOVEL SENSING MATERIALS
AND NANO-DESIGN OF ELECTRODE STRUCTURE

Department of Applied Chemistry, Faculty of Science and Engineering,
Ritsumeikan University, Kusatsu-shi, Shiga 525-8577, Japan

High sensitivity semiconductor gas sensors are strongly needed in the fields of environmental monitoring, VOC monitoring, bad-smelling gas detection, medical applications, and so on. The author’s group has developed them by using novel sensing materials (mixed oxides) and nano design of electrode structure. It was found that the mixed oxides having trirutile (ZnSb₂O₆), spinel (CdGa₂O₄), and perovskite (BaSnO₃) structure showed significantly high sensor responses to dilute volatile sulfides such as H₂S and CH₃SH. On the other hand, the WO₃ thick film sensor exhibited extremely high sensor response to dilute NO₂ and had potential for environmental NO₂ monitoring when the Au interdigitated microelectrode was employed. Concerning the electrode structure, the micro-gap effect was found in the NO₂ sensing using WO₃ sensor, i.e., the sensor response was increased with decreasing gap size less than 0.8 μm. The micro-gap effect was contributed to the larger response at oxide-electrode interface than at grain boundary and the increasing contribution of interface with decreasing gap size, suggesting the importance of nano design of electrode structure for high sensitivity semiconductor gas sensor. The similar micro-gap effects were also observed for the Cl₂ sensing using In₂O₃ sensor as well as the H₂S sensing using SnO₂ sensor.

固体電解質型センサ用検知極材料の物理的特性が
CO₂検知特性に及ぼす影響

（¹長大工，TDK基礎材料開発センター）
○兵頭健生¹，古野　忠¹，熊澤志津子²，清水康博¹，江頭　誠¹

EFFECTS OF WORKING ELECTRODE MATERIALS ON THE CO₂ SENSING PROPERTIES OF
SOLID-ELECTROLYTE GAS SENSORS

Takeo HYODO¹, Tadashi FURUNO¹, Shizuko KUMAZAWA², Yasuhiro SHIMIZU¹ and Makoto EGASHIRA¹

¹Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521
²Materials R&D Center, TDK Corporation, Ichikawa-shi, Chiba 272-8558

Effect of oxide powder addition to a working electrode material on the CO₂ sensing properties of solid-electrolyte gas sensors has been investigated. CO₂ was adsorbed on the surface of most oxides after treatment at 400℃ in dry air, while the coexistence of H₂O reduced the amount of adsorbed CO₂ species. But, little chemisorbed CO₂ species could be formed on the surface at temperatures higher than 100℃. It was revealed that the amounts of CO₂ and H₂O species adsorbed on the oxides had no effect on the CO₂ response and humidity cross-response. On the other hand, the CO₂ response decreased and the humidity cross- response increased with an increase in the resistance of the oxides tested. This result may suggest that the strict conductivity control of working electrodes is an important factor for achieving high performance of potentiometric CO₂ sensors.

WO₃/ZrO₂を用いた抵抗変化式厚膜型センサ
におけるプロトン導電機構

(名大院工^a、日本特殊陶業^b)　

○柏木幸一^a, 遠藤忠嗣^a, 清水研一^a, 西山寛幸^b, 柿元志郎^b, 菅谷聡^b, 横井等^b, 薩摩篤^a

Proton Sensing Mechanism on Thick film Ammonia Sensor
using tungstated-sirconia as Sensing Material

Kouichi KASHIWAGI^a, Tadashi ENDOU^a, Kenichi SHIMIZU^a, Hiroyuki NISHIYAMA^b,
Toshirou KAKIMOTO^b, Satoshi SUGAYA^b, Hitoshi YOKOI^b, Atushi SATSUMA^a

^a Department of Applied Chemistry, Nagoya University,
Nagoya-shi, Aichi 464-0814
^b R&D Center, NGK Spark Plug Co.Ltd,
Komaki, Aichi 485-8510

The sensing mechanism WO₃/ZrO₂ thick film ammonia sensor was investigated by using in-situ FT/IR and Electrochemical Impedance Spectroscopy. The contribution of surface adsorbed as NH₄⁺ species on electrical conductivity was indicated. The mobility, which determined as electrical conductivity per surface concentration of NH₄⁺, was dependent on the surface W-OH species. The sensing mechanism involving adsorption of NH₄⁺ on surface W-OH was proposed.

^a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,
Kasuga-shi, Fukuoka 816-8580
^b National Institute for Environmental Studies, Tsukuba-shi, Ibaraki 305-8506
^c Art, Science and Technology Center for Cooperative Research, Kyushu University,
Kasuga-shi, Fukuoka 816-8580

Recently, we have proposed and examined new-type impedancemetric sensors using yttria-stabilized zirconia (YSZ) and oxide sensing-electrode (SE) for detection of total NOx, water vapor, hydrogen-containing gases and hydrocarbons (HCs). In the case of hydrocarbon sensor, the use of ZnO (+8.5 wt.% Pt)-SE was found to give sensitive and selective detection of C₃H₆ in the concentration range of 10 - 800 ppm under wet condition. Here, we examined the characteristics of this type impedancemetric sensor to lower concentration of C₃H₆, with the aim of environmental monitoring of HCs. As a result, the present sensor was found to detect C₃H₆ sensitively down to 0.2 ppm at 600℃ in the presence of 1 vol.% H₂O when the potential of +200 mV (vs. Pt-CE/RE) was applied to SE. In this case, the sensitivity varied almost linealy with the concentration of C₃H₆ in the range of 0.2-1.6 ppm, and the interference with other gases such as CO₂, NO₂ was small. Thus, it seems that the present sensor has a potential to use for monitoring of environmental HCs.

安定化ジルコニアとNiO薄膜検知極を用いたプレナー型センサのNO₂検知特性

(九大産学連携センター)

◯Vladimir V. Plashnitsa, 上田太郎，三浦　則雄

NO₂ SENSING PERFORMANCES OF PLANAR SENSOR
USING STABILIZED ZIRCONIA AND THIN-NIO SENSING ELECTRODE

○Vladimir V. PLASHNITSA, Taro UEDA and Norio MIURA

Art, Science and Technology Center for Cooperative Research,
Kyushu University, Kasuga-shi, Fukuoka 816-8580

The nano-sized NiO thin-films were prepared by means of r.f. sputtering of pure nickel on an YSZ substrate, followed by oxidation to NiO and sintering at 1000-1200℃ (1 h). The obtained 60-180 nm-thick NiO films were examined as SE for the YSZ-based planar NO₂ sensor at 600-800℃ under dry and wet conditions. As a result, it was found that 120 nm-thick NiO-SE sintered at 1100℃ showed the highest NO₂ sensitivity as well as rapid response/recovery even at operating temperatures below 800℃. The effect of water vapor on the NO₂ sensing performances of the sensor using thin NiO-SEs was examined based on the results of polarization-curves measurements.

ジルコニアドープセリアを用いた抵抗型酸素センサの高速応答評価

EVALUATION OF FAST RESPONSE PROPERTIES
OF RESISTIVE OXYGEN SENSOR USING ZIRCONIA-DOPED CERIA

National Institute of Advanced Industrial Science and Technology (AIST)
2266-98 Anagahora, Shimo-Shidami, Moriyama-ku, Nagoya, Aichi 463-8569

Response properties of resistive oxygen sensor using zirconia-doped ceria (Ce0.9Zr0.1O₂) thick film were investigated by pressure modulation method (PMM) which was the method to measure the amplitude of the output of the oxygen sensor under the condition that the oxygen partial pressure is changed periodically. The PMM results revealed that the resistive oxygen sensor using Ce0.9Zr0.1O₂ thick film prepared in this study has the ability to respond precisely when the oxygen partial pressure periodically changes at a period of 50 ms or more. The rate-limiting step of the response of Ce0.9Zr0.1O₂ thick film was almost diffusion of oxygen vacancies. We also estimated the diffusion coefficient of the oxygen vacancy.films from a perspective of sensitivity (oxygen partial pressure dependence of the resistance).

Au櫛型電極を用いたWO₃薄膜センサの水素検知メカニズム

（横浜国立大学大学院工学研究院、パナソニック四国エレクトロニクス株式会社）

○鈴木勇摩、岡崎慎司、横山　隆、畑山　健^*、山田　修^*、平中弘一^*

SENSING CHARACTERISTICS OF A CHEMORESISTOR-TYPE HYDROGEN GAS SENSOR USING　PLATINUM-SUPPORTED WO₃ THIN FILM WITH Au COMB ELECTRODES

Yuma SUZUKI, Shinji OKAZAKI, Takashi YOKOYAMA, Ken HATAKEYAMA*,
Osamu YAMADA^*, Kouichi HIRANAKA^*

Graduate School of Engineering, Yokohama National University Tokiwadai 79-5,
Hodogayaku, Yokohama 240-8501, Japan
^*Panasonic Shikoku Electronics Co., Ltd. 247 Fukutake Saijo,
Ehime, 793-8501 Japan　

A chemoresistor-type hydrogen gas sensor using platinum-supported tungsten trioxide (Pt/WO₃) thin film was characterized. The film was deposited on quartz substrate by sol-gel method. This sensor utilizes change of impedance of Pt/WO₃ thin film. The electrical impedance at 1 kHz was measured with Au comb electrodes patterned on the substrate. Under the dry condition, impedance of the film sharply decreased. This resulted from the formation of tungsten bronze whose electrical resistivity is lower than that of WO₃. When the atmosphere containing hydrogen gas was replaced with air, the impedance rapidly increased and reached to its initial level. However, the sensor response under humid condition considerably differed from the response under dry condition. This characteristic could be attributed to the existence of H₂O in the film.

金くし型マイクロ電極を有するWO₃薄膜センサの低濃度芳香族VOCに対する検知特性

SENSING PROPERTIES TO DILUTE AROMATIC VOCs OF WO₃ THIN FILM SENSORS EQUIPPED
WITH Au INTERDIGITATED MICROELECTRODE

Department of Applied Chemistry, Faculty of Science and Engineering,
Ritsumeikan University, Kusatsu-shi, Shiga 525-8577
^*Advanced Technologies Fusion Laboratory, Matsushita Electric Works,
Ltd., Kadoma, Osaka 571-8686

WO₃ thin film sensors equipped with Au interdigitated microelectrode have been investigated for the detection of dilute aromatic VOCs (toluene, xylene, ethylbenzene, and styrene). The microdrop of H₂WO₄ suspension was dropped on microelectrode, dried, and calcined in air at 500 ℃ for 3h to be WO₃ thin film microsensor. The effects of film thickness and the line spacing in microelectrode were examined. The WO₃ thin film sensor (thickness : ca. 200 nm) showed higher sensor response (S=Ra/Rg) than the thick film sensor, while the smaller line spacing brought about the higher response. The WO₃ thin film sensor equipped with 2 μm line spacing exhibited the highest sensor response to dilute aromatic VOCs with quick response-recovery characteristics at 500 ℃. The sensor response to 1 ppm VOCs was the highest to styrene (S=110), while it to 0.01 ppm VOCs was the highest to xylene (S=6). The sensor response to toluene was the lowest in the concentration range of 0.01 to 1 ppm. Consequently, the high sensitivity sensors to dilute aromatic VOCs were obtained by combining WO₃ thin film and Au interdigitated microelectrode.

貴金属添加酸化スズゾルの水熱合成と薄膜ガスセンサのガス検知特性

HYDROTHERMAL SYNTHESIS OF NOBLE METAL LOADED TIN OXIDE SOL
AND SENSING PROPERTIES OF THIN FILM GAS SENSORS

Department of Applied Chemistry, Faculty of Science and Engineering, Ritsumeikan University,
Kusatsu-shi, Shiga 525-8577

Noble metal loaded SnO₂ sol solutions (Pt-SnO₂, Pd-SnO₂, Au-SnO₂) have been synthesized under hydrothermal condition. All of sol solutions obtained were transparent. From TEM and SEM images of noble metal loaded SnO₂ thin films prepared from sol solutions, a lot of SnO₂ particles and a few and large Au particles were observed, but Pt and Pd particles (or small Au particles) couldn’t be observed. The resistances in air (Ra) and the sensor responses of noble metal loaded SnO₂ thin film sensors were higher than those of pure SnO₂ sensor. Further, in XPS, Pt4f peaks were observed for Pt-SnO₂ thin film and the binding energy shifts to lower energy side in O1s and Sn₃d levels were also observed for all of noble metal loaded SnO₂ films. These results suggest that the small noble metal particles are certainly added into SnO₂ thin film. The noble metal loaded SnO₂ sol solution enable us to fabricate the modified SnO₂ thin film sensor in one step.

^a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
Kasuga, Fukuoka 816-8580, Japan

For loading PdO precisely on SnO₂ nanoparticle, two kinds of procedure by a reverse micelle method were investigated. In the case of process (A), aqueous solutions of Sn(OH)₆］2- (1) and Pd²⁺ (2) were brought into reverse micelle solutions by NP-6 surfactant and cyclohexane solvent, respectively. Solution (1) was mixed with solution (2), and the resulting mixed-solution was subjected to collect a precursor of SnO₂-supported PdO by centrifugal separation. In the case of process (B), solution of Sn(OH)₄ was used instead of solution (1). TEM images showed that the process (B) gave smaller PdO on SnO₂ nanoparticles. In addition, the thick film prepared through the process (B) showed higher electric resistance in air than that through the process (A). From the above results, it seems that the process (B) is suitable for loading nanosized PdO as compared with the process (A).

Response transient analysis of semiconductor gas sensor
by switching gas at high speed

^* Interdisciplinary Graduate School of Engineering Sciences, Kyushu
University, Kasuga, Fukuoka 816-8580, Japan
^** Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan

In order to investigate response transient of semiconductor gas sensor, a new apparatus practicable to switch gas at high speed was assembled. SnO₂ thick film (1 mm) gas sensor was tested at 250-350 ℃ in the apparatus. The electric resistance of sensor operated at 350℃, for which the reaction rate is fairly fast, reached to a constant value within 0.3 s after switching from air to 1000 ppm H₂. On the other hand, that of sensor operated at 250 ℃, for which the reaction rate is slow, gradually changed and reached to a constant value around 1 s after switching. This means that gas diffusion in the sensing film is very fast and the measurement of usual response transient evaluated time to replace dead volume over the sensing film with target gas. It was found that the electric resistance of recovery at 350 ℃, when the switching interval decreased from 10 s to 0.5 s, didn’t reach to same value, although that of response reached to same value. However when the operating temperature was set at 250 ℃, both of response and recovery changed with decreasing the switching interval. These results show that this new apparatus can evaluate reaction rate on the sensing materials.

Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
Kasuga-shi, Fukuoka 816-8580, Japan

A new catalytic combustion type gas sensor using positive temperature coefficient (PTC) thermistor as a transducer was investigated for detection of inflammable gases, because PTC thermistor shows low electric resistance at curie temperature (Tc) and remarkable change in the electric resistance over Tc. Ba0.998La0.002TiO₃-δ based on donor doped barium titanate (La-doped BaTiO₃) was prepared through solid state reaction method, the resulting PTC showed fairly large change in electric resistance around Tc of 125 ℃. The sensor element of Ba0.998La0.002TiO₃-δ attached Pt electrodes was found to exhibit fairly good response to H₂ in the range of 600-1000 ppm diluted with air at elevated temperature (125 ℃).

○東野　翼¹，沢田史子¹，大薮多可志¹，竹井義法²，南戸秀仁²，都甲　潔³　

Tsubasa Higashino¹, Ayako Sawada¹, Takashi Oyabu¹,Yoshinori Takei², Hidehito Nanto² and Kiyoshi Toko³

¹Kanazawa Seiryo University, 10-1 Ushi, gosho, kanazawa-shi, isikawa 920-8620
²Kanazawa Institute of Technology, 7-1 Ougigaoka, Nonoichi, Ishikawa 921 - 8501
³Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581

Detecting technique of smoldering fire was examined using tin oxide gas sensors. Eight sensors were set in a room. They were same type. Four kinds of materials were adopted as a fire source. The materials were cotton cloth, wallpaper, curtain cloth and woodchip, which were main smoldering fire-sources. The sensor outputs to the smoldering fire for the materials were examined. The differential characteristic of the output was derived to analyze. As for the results, it becomes obvious that the sensor located at higher position had a higher sensitivity and it could sense the fire instantaneously. It is thought that the generated gases rise up directly toward the ceiling and reflect downward. A small type of electric cooking stove was used as a fire source. The surface temperature of the stove plate arrived at 340 ℃. A bar was adopted to set the sensors freely. In this experiment, three bars were adopted and the heights of the sensor position were 50, 100, 150 and 200 cm ! from the floo r. It is effective to locate the sensor at ceiling.
The sensor characteristics were analyzed using principal component analysis (PCA). The system could discriminate wallpaper, woodchip and curtain as the result of PCA. It could not discriminate curtain and cotton cloth. Each fire can identify in four minutes.

○山崎登志成、沈岩柏、劉志甫、金成姫、喜久田寿郎、中谷訓幸

Toshinari YAMAZAKI, Yanbai SHEN, Zifu LIU, Chengji JIN, Toshio KIKUTA, Noriyuki NAKATANI

Undoped and Pd-doped SnO₂ films were deposited on oxidized Si substrates by DC magnetron sputtering under various discharge gas pressures (0.4-24 Pa) and substrate temperatures (RT-400 ℃). The films were generally composed of columnar grains. The film density decreased from 6.7×103kg/m3 to 3.1×103kg/m3 with increasing discharge gas pressure and decreasing substrate temperature. The effective surface area evaluated by BET method showed that most of the columnar grains were surrounded by gaps in porous films. The sensitivity to H₂ at 1000 ppm was measured at various operation temperatures between room temperature and 300 ℃. It was found that Pd-doped films showed higher sensitivities than undoped films and that both the sensitivity of undoped films and that of Pd-doped films increased with decreasing density. It was also found that in Pd-doped films the operation temperature at which the sensitivity showed a maximum decreased with decreasing density. Thus, a Pd-doped film with a density as low as of 3.1 showed the highest sensitivity ((Ra-Rg)/Rg) of 4470 at an operation temperature of 100 ℃.

Pt担持タングステン酸ジルコニアを感応層とする水素センサ

Department of Applied Chemistry, Graduate School of Engineering,
Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan

The sensor element with Pt-modified solid acids thick films show sensing properties to H₂. Pt-WO₃/ZrO₂ shows highest sensitivity properties; the sensitivity changes linearly with H₂ concentration in a range 0.02-1.2%, the ensitivity does not markedly change with concentration of coexisting H₂O and O₂, and high response is achieved at low temperature (150℃). A sensing mechanism including dissociative adsorption of on Pt and subsequent formation of H⁺ on the solid acid supports is proposed.

Vol. 22, Supplement B (2006)

Abstracts