Vol. 15, Supplement B (1999)

Vol. 15, Supplement B (1999)

Proceedings of the 29th Chemical Sensor Symposium
September 13-14, 1999

Abstracts

1.
電析白金/ポリイオンコンプレックス複合電極を用いたバイオセンサ

目黒正大，桑原貴之，逢坂哲彌

早大理工，早大材研

BIOSENSOR BASED ON THE COMPOSITE FILM ELECTRODE OF ELECTRODEPOSITED PLATINUM WITH POLYION COMPLEX

Masahiro Meguro, Takayuki Kuwahara, Tetsuya Osaka

Department of Applied Chemistry, School of Science and Engineering; Kagami Memorial Laboratory for Materials Science and Technology, Waseda University
Shinjuku-ku, Tokyo 169-8555, Japan

A glucose sensor based on a combination of electrodeposited platinum with polyion complex (PIC) containing glucose oxidase (GOD) formed onto platinum electrode was fabricated. This glucose sensor electrochemically detects H₂O₂ generated by an enzymatic reaction between glucose and oxygen, which is catalyzed by GOD, on the platinum electrode. The morphology of electrodeposited platinum in the PIC film observed by scanning electron microscopy (SEM) and the result of energy dispersive X-ray microanalysis (EDX) suggest that the electrodeposited platinum grew to lift the PIC layer. However, at some locations of the film, a composite structure of platinum and PIC was formed, in which platinum particles were widely dispersed in the vicinity of the enzyme molecules. This morphology enables the oxidation of H₂O₂ to be more effective, resulting in the improved performance of the glucose sensor.

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2.
D-アミノ酸オキシダーゼ固定化ポリイオンコンプレックス膜の作製

矢吹聡一，水谷文雄，平田芳樹

工技院生命研

PREPARATION OF POLYION COMPLEX MEMBRANE CONTAINING D-AMINO ACID OXIDASE

Soichi YABUKI, Fumio MIZUTANI and Yoshiki HIRATA

National Institute of Bioscience and Human-Technology
Higashi 1-1, Tsukuba, Ibaraki 305-8566, Japan

Polyion complex membrane containing D-amino acid oxidase was prepared from a mixture of poly-L-lysine, polystyrene sulfonate and enzyme solutions: the solutions were mixed on the glassy carbon electrode and the electrode was dried for 4 hrs. The enzyme electrode was used for the detection of D-amino acid by the measuring of oxidation current for hydrogen peroxide at the base electrode. When response to D-alanine (ALA) was measured, current response was proportional to the ALA concentration up to 0.5 mM, response time was ~30 s. Lower detection limit was 5 μM of ALA. The electrode could be used as a biosensor for D-amino acid. Long-term stability of the enzyme electrode was examined: 40 days after the preparation, the response current became 1.2 times of the initial value. The phenomenon would be caused by the swelling the polymer with water.

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3.
複合耐熱性酵素を用いたISFET型バイオセンサによるグルコシド化合物センシング

青木　一仁、石丸　雄大、飯田　武揚

埼玉大工

GLUCOSIDES SENSING BY ISFET BIOSENSOR USING MULTI-THERMOSTABLE ENZYMES

Kazuhito AOKI, Yoshihiro ISHIMARU, and Takeaki IIDA

Department of Functional Materials Science , Faculty of Engineering, Saitama University
255 Shimo-okubo, Urawa-shi, Saitama-ken 338-8570, Japan

An ion sensitive field-effect transistor (ISFET) was applied to the determination of glycosides. The pH-sensing gate of ISFET was covered with the immobilized thermostable enzymes using thermostableβ-D-glucosidase and thermophilic glucokinase. The β-glucoside sensor responded to β-glucosides such as salicin and esculin. The sensor exhibited higher thermostability than that of non-thermostable enzyme. The sensor also responded to lactose at pH 9.0 and 60 ℃. However, at the pH of 7.0, it was found that the sensor was also able to respond to lactose at 50 ℃. The ATP solution gradually decomposed to change the pH of the solution at the rate of about pH 0.1 for 3 days. Few differences were found within 9 days between ATP solution stored at 4 ℃ and another one freshly prepared at same pH.

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4.
Con Aと未修飾酵素累積膜を用いたバイオセンサー

小林由佳、安斉順一

東北大院薬

BIOSENSORS BASED ON MULTILAYER FILMS COMPOSED OF Con A AND UNMODIFIED ENZYMES

Yuka KOBAYASHI and Jun-ichi ANZAI

Graduate School of Pharmaceutical Sciences, Tohoku University
Aramaki, Aoba-ku, Sendai 980-8578, Japan

Enzyme multilayer films were prepared using Con A and glycoenzymes (GOx and HRP) without any chemical modification. The formation behavior of the multilayer film was studied by UV spectrophotometry and electrochemistry. The silylated quartz slide was immersed in a fluorescein-modified Con A solution and a GOx solution alternately. The absorbance, originating from the fluorescein moiety, increased in proportion to the number of deposition. The Con A/GOx multilayer film was prepared on the surface of Pt electrode. The response current to β-D-glucose depended on the number of GO x layers deposited. These results show that constant amount of Con A and GOx were immobilized upon each deposition and enzyme films thus prepared are catalytically active. H₂O₂ sensors based on Con A/HRP multilayer films were also evaluated.

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5.
電解重合法による酵素固定電極の作製

安澤幹人・藤井慎二・山田哲也・椚　章・今井信治^*

徳島大工・東洋精密工業^*

PREPARATION OF ENZYME-IMMOBILIZED ELECTRODES USING THE ELECTROPOLYMERIZATION METHOD

Mikito YASUZAWA, Shinji FUJII, Tetsuya YAMADA, Akira KUNUGI and Shinji IMAI^*

Department of Chemical Science and Technology, Faculty of Engineering The University of Tokushima
2-1 Minamijosanjima, Tokushima 770-8506, Japan

New enzyme-immobilized electrode was prepared by electropolymerization of pyrrole derivatives having saccharide units, 1-(6-D-gluconamidohexyl)pyrrole (GHP), in the presence of glucose oxidase. The long-term stability of the obtained electrode was examined over 90 days and showed relatively constant response current from the first day of measurement. Moreover, the response currents of this electrode were approximately twenty times higher than that of the electrode obtained from 1-(3-D-gluconamidopropyl)pyrrole, which the distance between pyrrole groups and saccharide units are three methylene (-CH2-) groups less than that of GHP. The response current of the electrodes prepared from GHP was approximately not influenced by the addition of urea, D-(-)-fructose, asorbic acid,or acetaminophen. However, the influence of uric acid was not negligible.

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6.
電流計測アセチルコリンエステラーゼバイオセンサ構築のためのポリピロール膜の電気化学的形成

オルガ　フェドセヴァ、石丸雄大、飯田武揚

埼玉大工

ELECTROCHEMICAL FORMATION OF POLYPYRROLE FILM FOR CONSTRUCTION OF THE AMPEROMETRIC ACETYLCHOLINESTERASE-BASED BIOSENSOR

Olga V. FEDOSSEEVA, Yoshihiro ISHIMARU, and Takeaki IIDA

Department of Functional Materials Science, Faculty of Engineering, Saitama University
255 Shimo-okubo, Urawa-shi, Saitama-ken, 338-8570, Japan

Acetylcholinesterase (AChE) has attracted much attention because of its usefulness as a sensitive indicator of a normal nerve-muscle interaction. Acetylcholinesterase is a specific cholinesterase, hydrolyzing predominantly choline esters. This report deals with electrochemical formation of polypyrrole film for construction of the amperometric acetylcholinesterase-based biosensor. The cell with a stationary mercury film-covered electrode (SMFC) and the Pt auxiliary electrode as the polypyrrole modified electrode was used. The activity of immobilized acetylcholinesterase was determined amperometrically by SMFE using thioester as a substrate. The analytical characteristics of the polypyrrole-modified platinum electrode, including electrodeposition of the enzyme with and without the polypyrrole were studied. The diffusion of the enzyme through the polypyrrole film was analyzed electrochemically by comparison of the current responses obtained from the Pt/polypyrrole/AChE and Pt/AChE/polypyrrole electrodes, respectively. The optimal conditions for the fabrication of the Pt black layer on the platinum electrode, and the characteristics of the resulting electrode were also investigated.

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7.
シロキサンポリマーを利用したアンペロメトリックグルコースセンサ

水谷文雄、矢吹聡一、飯島誠一郎

生命工研

AMPEROMETRIC GLUCOSE SENSOR USING A SILOXANE POLYMER LAYER

Fumio MIZUTANI, Soichi YABUKI, and Seiichiro IIJIMA

National Institute of Bioscience and Human-Technology
1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan

An amperometric glucose-sensing electrode based on the cathodic detection of oxygen consumption during the glucose oxidase (GOx) reaction was prepared as follows. A platinum electrode was modified with polydimethylsiloxane (PDMS), and a GOx-layer was placed on the PDMS layer. The oxygen permeability and hydrohobic property of the PMDS layer made it possible to monitor the oxygen consumption rate without interference from the hydrogen peroxide. The concentration of glucose (0.01-1.2 mM) could be determined from the decrease in the cathodic current at -0.1 V vs. Ag/AgCl, without any interference from uric acid and acetaminophen.

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8.
ピラノースオキシダーゼ充填カラムを用いたフローアンペロメトリックバイオセンシング

佐藤　生男、小池　真条、橋本　昌一郎

神奈川工科大学

FLOW-AMPEROMETRIC BIOSENSING WITH USE OF A PYRANOSE OXIDASE COLUMN

Ikuo SATOH, Shinjou KOIKE, and Masaichiro HASHIMOTO

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

Pyranose oxidase from Coriolus versicolor covalently immobilized on porous glass beads was tested as a recognition element for determination of D-glucose. The amperometric FIA system was assembled with a column containing the immobilized enzymes mounted in a water-jacketed holder and a polarographic oxygen electrode in a flow-through cell. Variations in oxygen levels at the outlet of the column was successively monitored and used as the measure of the catalytic activity. The responses attributable to consumption of dissolved oxygen were observed by injecting the substrate solutions. A calibration graph was obtained between up to 2.0 mM of the substrate solutions and decreases in dissolved oxygen. Although the column was used at room temperature for about 5300 assays during two years and three months, it showed significantly well operational-stability.

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特別講演
電気化学マイクロセンサ-分析デバイスの脳神経科学への応用

丹羽　修、鳥光　慶一

NTT生活環境研究所、ＮＴＴ物性基礎研究所

APPLICATION OF ELECROCHEMICAL MICROSENSORS AND ANALYTICAL DEVICES FOR NEUROSCIENCE

Osamu NIWA and Keiichi TORIMITSU

NTT Lifestyle and Environmental Technology Laboratories, NTT Basic Research Laboratories
3-1, Morinosato, Wakamiya, Atsugi, Kanagawa 243-0198, Japan

The direct observation of neurotransmitters is extremely important as regards studying the signal transmission mechanism between individual nerve cell. Various microsensors including microelectrodes, enzyme modified electrodes, on-line sensors have been developed for real time-measurement of neurotransmitters. In this article, the electrochemial microsensors and analytical devices used for in vivo and in vitro analysis of neurotransmitters are reviewed. 　

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受賞講演.
生体機能分子修飾電極の作製とバイオセンサへの応用研究

水谷文雄

生命工研

PREPARATION AND USE OF ELECTRODES MODIFIED WITH BIOFUNCTIONAL MOLECULES

Fumio MIZUTANI

National Institute of Bioscience and Human-Technology
1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan

Biosensors combining the specificity of biological reactions with electrochemical signal transduction have attracted increasing interest in the last two decades. Particular efforts in this field have recently been directed to the establishment of simple, rapid and reproducible procedures for constructing biosensors. Techniques for preparing chemically-modified electrodes (CMEs) are useful for this purpose. This paper focuses upon our research results for the preparation of biosensors of CME-type; the use of biochemically- or chemically-modified proteins, and that of polyion complex membranes as enzyme matrices or anti-interference layers are described.

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9.
抗体累積膜の抗原結合特性の解析

斉木　秀和　、星　友典　、安斉　順一

東北大院薬

ANTIGEN-BINDING PROPERTY OF ANTIBODY MULTILAYER

Hidekazu Saiki, Tomonori Hoshi, and Jun-ichi Anzai

Graduate School of Pharmaceutical Sciences, Tohoku University
Aramaki, Aoba-ku, Sendai 980-8578, Japan

Spatially ordered multilayer films of antibody were prepared by a layer-by-layer deposition of avidin and biotin-labeled antibody on the surface of quartz slide. The deposition behavior of the multilayer films was monitored spectrophotometrically using dye-labeled avidin or directly from the absorbance of the proteins. The spectrophotometric date showed that the antibody and avidin can be built into spatially ordered multilayer structure by the layer-by-layer deposition. The antibody retained the binding activity in part to the antigen: only the outermost 3 or 4 layers of antibody exhibited the binding activity. A further improvement will be needed to develop the multilayer films in which the antibody fully exhibits binding activity.

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10.
マイクロ酸素電極による全血pO₂の測定

鈴木博章、渡辺郁友、菊池佑二^*

筑波大物質工、農水省食総研^*

MEASUREMENT OF pO₂ USING A MICROMACHINED OXYGEN ELECTRODE

Hiroaki SUZUKI, Ikutomo WATANABE, and Yuji KIKUCHI^*

Institute of Materials Science, University of Tsukuba
1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
^*National Food Research Institute
2-1-2 Kannondai, Tsukuba, Ibaraki 305-8642, Japan

A micromachined Clark-type oxygen electrode was used to measure pO₂ in whole blood. A cathode and an anode were formed on a glass substrate by photolithography. A micro container for the electrolyte solution was formed on a silicon substrate using anisotropic etching. A slicone rubber gas-permeable membrane was formed on the sensitive area. Four types of oxygen electrodes with cathodes whose dimensions ranged from 200 μm□ to 500 μm□ were fabricated. Good linear calibration curves were obtained. In using samples of small volumes, however, the consumption of oxygen by the oxygen electrode itself posed a problem. An influence is the dependence of the output current on stirring. By using a smaller cathode, the influence could be reduced. The oxygen electrode was used to measure pO₂ in whole blood. The obtained pO₂ values were fairly close to those obtained by a commercial blood gas analyser.

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11.
薄膜酸素電極を用いたフレキシブルバイオセンサーの開発

谷本智志^*、室富大介^*、平塚淳典^**、宮地寛登^**、佐々木聰^**、矢野和義^*、池袋一典^**、三林浩二^*、軽部征夫^**

東海大工^*・東大先端研^**

DEVELOPMENT　OF　A　FLEXIBLE　BIOSENSOR USING　A　FILM－TYPE　OXYGEN　ELECTRODE

Satoshi TANIMOTO^*, Daisuke MUROTOMI^*, Atsunori HIRATSUKA^**, Hirotaka MIYACHI^**, Satoshi SASAKI^**, Kazuyoshi YANO^**, Kazunori IKEBUKURO^**, Kohji MITSUBAYASHI^*, and Isao KARUBE^**

^*Department of Electrical Engineering, School of Engineering, TOKAI University
1117 Kitakaname Hiratsuka-shi, Kanagawa 259-1292, Japan
^**Research Center for Advanced Science and Technology, The University of Tokyo
4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan

A flexible biosensor was constructed by immobilized glucose oxidase using photocrosslinkable poly(vinyl alcohol) onto a sensitive area of a film-type oxygen electrode, which was fabricated by sealing electrolyte solution (0.1mol/l KCl) by both gas- and non-permeable weldable membranes with Pt- and Ag/AgCl-coated electrodes. The amperometric biosensor was evaluated by measuring the reduction current of dissolved oxygen consumed by the enzymatic reaction of glucose oxidase using a computer controlled potentiostat with A/D converter. The device was linearly related to the glucose concentration over range of 0-1.381 mmol/l, with a correlation coefficient of 0.998. The flexible biosensor (thickness: 0.153 mm) is well suited for non-invasive detection of glucose or other analytes in biological fluids, such as tears, sweat, airway mucus, and saliva.

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12.
Fe²⁺・ポリイオンコンプレックス被覆電極によるNOセンシング

春山哲也、相澤益男

東工大・院　生命情報

NO SENSING USING Fe²⁺ / POLYIONCOMPLEX COVERED ELECTRODE

Tetsuya HARUYAMA, Masuo AIZAWA

Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology
Nagatsuta, Midori-ku, Yokohama 226-8501, Japan

Electrochemical NO sensing system has been developed using 1,4,8,11-tetraaza cyclotetradecane (cyclam)-F3(II)complex. NO⁺ was found to be electrochemically oxidized through cyclam-Fe(II)-NO⁺ on an electrode. For assembling an electrochemical sensor for NO, cyclam-Fe(II) was immobilized on an Pt electrode by poly-histidine / poly stylene complex. NO was determined in the concentration range from 0.1 uM to 30 uM, when the electrode potential was controlled at -100 mV vs. AgAgCl.

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13.
室内空気汚染物に対する植物の選択的浄化作用

小野寺武，木村春彦，大薮多可志^*

金沢大工，金沢経済大経済^*

SELECTIVE PURIFICATION ABILITY OF PLANT FOR INDOOR AIR-POLLUTANTS

Takeshi ONODERA, Haruhiko KIMURA and Takashi OYABU^*

Kanazawa University
Kodatsuno, Kanazawa 920-8667, Japan
^*Kanazawa University of Economics
Gosho-machi, Kanazawa 920-0813, Japan

Purification characteristics of Epipremnum aureum (Golden pothos) for formaldehyde, toluene and xylene are examined, and the characteristics for mixture gas of formaldehyde and toluene or xylene are also examined using two kinds of gas sensors. Thy are a combustible gas and ammonia sensors. As results, {\it Epipremnum aureum} has high purification ability to formaldehyde, and has low ability to toluene and xylene. In the mixture gas, same characteristics are derived >from some experiments. Thus, Epipremnum aureum has an ability of selective purification for formaldehyde.

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14.
アルデヒドガス用バイオセンサの開発

中山義浩、橋本祐樹、三林浩二

東海大工

DEVELOPMENT OF A GAS-PHASE BIOSENSOR FOR ALDEHYDE CHEMICALS

Yoshihiro NAKAYAMA, Yuki HASHIMOTO and Kohji MITSUBAYASHI

Deptment of Electrical Engineering, School of Engineering, TOKAI University
1117 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan

A gas-phase biosensor for aldehyde chemicals was constructed using an immobilized aldehyde dehydrogenase (ALDH) enzyme electrode and a flow reaction cell with both gas- and liquid-phase compartments separated by a porous diaphragm membrane. The output signal of the ALDH biosensor with a flow injection system was found to　be used measure acetaldehyde in the liquid phase over the range 0 to 3.0 mmol/l, with correlation coefficient of 0.996. The has-phase biosensor can be detected gaseous acetaldehyde and the sensor output was found to be related to the acetaldehyde concentration in the gas phase. Potential applications of the aldehyde gas-sensor include the analysis of the aldehyde compounds and an environmental assessment.

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15.
トリメチルアミン用バイオセンサの開発

橋本祐樹、中山義浩、三林浩二

東海大工

DEVELOPMENT OF A BIOSENSOR FOR TRIMETHYLAMINE

Yuki HASHIMOTO ,Yoshihiro NAKAYAMA and Kohji MITSUBAYASHI

Deptment of Electrical Engineering, School of Engineering, TOKAI University
1117 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan

"Fish-odor syndrome" is a human disorder characterized by an impaired ability to convert the malodorous TMA to its odorless N-oxide. In human, TMA is metabolized exclusively to TMAO excreted in the urine. Fiavin-containing monooxygenase 3 (FMO3) has been reported to catalyze the majority of TMAO formation in vivo. The trimethylamine biosensor was constructed using a commercially available dissolved oxygen sensor with both FMO3 and Glucose-6-phosphate dehydrogenase (G6PDH) immobilized membranes. FMO3 was shown to catalyze an NADPH-dependent oxygenation of trimethylamine, and G6PDH was then used for the NADPH-generating system. The current decrease of the FMO3 immobilized biosensor was found to be linearly related to the trimethylamine concentration over the range 0 to 150 mmol/l, with a correlation coefficient of 0.992. Potential applications of the trimethylamine sensor include the diagnosis of "Fish-odor syndrome" and the evaluation of fish freshness.

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16.
温度補正機構を用いた小型ＳＰＲセンサの開発

大出明、外山滋、山内繁、碇山義人

国立リハ研

DEVELOPMENT OF SMALL-SIZED SPR SENSOR HAVING THERMAL COMPENSATING MECHANISM

Akira OHIDE, Shigeru TOYAMA, Shigeru YAMAUCHI, and Yoshihito IKARIYAMA

Research Institute, National Rehabilitation Center for the Disabled
4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan

Stabilization method of SPR signal fluctuation due to thermal change has been examined. Here, an experimental SPR setup, where a thermistor was embedded in the stainless holder of the flow through cell attached to the sensor, was newly fabricated. The temperature was artificially changed during continuous measurements. The correlation between the cell temperature and the resonance angle was better than that of the chamber temperature. The fluctuation of the resonance signal was explained in terms of the change in the refractive index of the solution.

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18.
アポ酵素活性化法による亜鉛(Ⅱ)イオンの微量計測

佐藤　生男、有賀　貴子、佐藤　祐美子

神奈川工科大学

MICRODETERMINATION OF ZINC(II) IONS BASED ON THE APOENZYME REACTIVATION METHOD

Ikuo SATOH, Takako ARIGA, and Yumiko SATOH

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

Alkaline phosphatase immobilized onto porous glass beads was packed into a small polymer column and then used as a recognition element for zinc(II) ions in flow streams. The sensing system was assembled with the column housed in a water-jacketed holder and a quartz flow-through cell attached to a UV/VIS monitor. The catalytic activity was assessed by injecting 0.1 ml of 2 mM p-nitrophenyl phosphate(pH 8.0). The column could be regenerated by introducing 100 mM 2,6-pyridine dicarboxylate solution to remove zinc(II) ions complexed in the active site of the enzyme molecules. Submicromolar levels in zinc(II) ions were photometrically determined through its reactivation of the apoenzyme, i.e. ,metal-free enzyme. Performance of the system was examined.

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19.
ヒスタミン電極の開発と肥満細胞からのヒスタミン遊離測定への応用

勝　孝、廣戸敬毅

岡山大薬

DEVELOPMENT OF A HISTAMINE-SENSITIVE MEMBRANE ELECTRODE AND ITS APPLICATION TO THE DETERMINATION OF HISTAMINE RELEASE FROM MAST CELLS

Takashi KATSU and Hiroki HIRODO

Faculty of Pharmaceutical Sciences, Okayama University
Tsushima, Okayama 700-8530, Japan

We developed a histamine-sensitive membrane electrode using prothiofos (O-(2,4-dichlorophenyl) O-ethyl S-propyl phosphorodithioate), an agricultural chemical, as a membrane solvent and sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate as an ion-exchanger in a poly(vinyl chloride) membrane matrix. This electrode exhibited a near-Nernstian response to histamine in the concentration range 5 * 10^-5 - 1 * 10^-2 M with a slope of 56 mV per concentration decade in a physiologically balanced salt solution containing 154 mM NaCl, 2.7 mM KCl, 0.9 mM CaCl₂, 5.6 mM glucose and 10 mM 4-(2-hydroxyethyl)-2-piperazineethanesulfonic acid (HEPES)-NaOH (pH 7.4). The limit of detection was 2 * 10^-5 M. We used this electrode to determine histamine release from mast cells. The histamine concentrations determined with the histamine electrode agreed well with those determined by an established fluorimetric assay.

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20.
炭化水素を検知対象とする安定化ジルコニアと酸化物電極を組み合わせた混成電位型センサ

白石泰一、島ノ江憲剛、三浦則雄^*、山添　曻

九大院総理工、九大先端セ^*

MIXED-POTENTIAL TYPE SENSOR BASED ON STABILIZED ZIRCONIA AND OXIDE ELECTRODE FOR THE DETECTION OF HYDROCARBONS

Taiichi SHIRAISHI, Kengo SHIMANOE, Norio MIURA^* and Noboru YAMAZOE

Graduate School of Engineering Sciences, Kyushu University
^*Advaced Science and Technology Center for Cooperative Research, Kyushu University
Kasuga-shi, Fukuoka 816-8580, Japan

By using an oxide sensing electrode, a stabilized-zirconia based sensor was developed for the selective detection of hydrocarbons at high temperature. Among the fourteen kinds of oxides tested, CdO was found to be best suited for the sensing electrode of a tubular zirconia device, giving selective and quick response to C₃H₆ in air at 600°C. The EMF value of the device was almost linear to the logarithm of C₃H₆ concentration in the range 50-800 ppm. The cross sensitivities to the other gases, such as CH₄, C₂H₄, C₂H₄, C₃H₈, H₂, CO, NO and NO₆, were small or insignificant. Furthermore, a compact planar device (probe-type), which required no reference gas, was also fabricated. The C₃H₆ sensitivity of the planar device was found to be little influenced by a change in oxygen concentration in the sample gas. A sensing mechanism involving mixed potential was confirmed based on the measurments of polarization curves.

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21.
固体電解質厚膜型ガスセンサの湿式プロセッシングと応答特性

清水陽一、相田　健

九工大工

SOLID-ELECTROLYTE THICK-FILM GAS SENSOR PREPARED BY SOL-GEL METHOD

Youichi SHIMIZU* and Takeshi SODA

Department of Applied Chemistry, Faculty of Engineering, Kyushu Institute of Technology
Tobata, Kitakyushu 804-8550, Japan

A planar-type solid-state electrochemical gas sensor using an Na-ion conductor (NASICON) thick-film and a perovskite-type thin-film electrode could be prepared by novel sol-gel methods using aqueous complex and/or polymer - based precursors. NASICON thin-film could be fabricated onto alumina substates by spin-coating a tartaric acid - based gel, drying at 150 C, and sintering at 1000 C for 3h. Preparation of perovskite-type oxide thin-films at 500 C was also developed by the use of PVA - acetylacetone polymer precursor. The sensor device combined with LaNiO₃ and NASICON thin-film showed high sensitivity to CO₂ at 300-400 C. The 90% response time to 1000 ppm CO₂ was as short as 10-30s at 300-400 C.

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22.
Au-Li₂CO₃-La₂O₃を検知極に用いたCO₂センサ

池谷拓速、松井光彦

（株）トクヤマ　

CO₂ sensor using Au-Li₂CO₃-La₂O₃ as detecting electrode

Hirotoshi IKEYA, Mitsuhiko MATSUI

Tokuyama Corp.
2023-1 Endo,Fujisawa-city Kanagawa 252-0816, Japan

Until now, it has been hard to obtain sufficient properties in the solid state CO₂ gas sensor. This is because of its low humidity resistance of alkali metal carbonates used as the detecting electrode. In order to improve the humidity resistance, rare-earth metal oxide such as La₂O₃ is added into lithium carbonate with mixing ratio of the two substances being 1:10. This sensor exhibits fairly good sensing properties when it is laid under high humidity atmosphere.

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23.
混合傾斜層挿入型酸素センサの高濃度酸素雰囲気中特性

奥野辰行、飯尾元昭、稲葉忠司^*、佐治啓市^*、高橋英昭^*

矢崎計器株式会社・株式会社豊田中央研究所^*

CHARACTERISTICS OF AN OXYGEN SENSOR WITH THE GRADED LAYER ELECTRODE IN HIGH-CONCENTRATION OF OXYGEN GAS.

Tatsuyuki OKUNO, Motoaki IIO, Tadashi INABA, Keiichi SAJI and Hideaki TAKAHASHI

Yazaki Meter Co., Ltd. Gas Equipment Development Department
Tenryu, Shizuoka 431-3393, Japan
Toyota Central R&D Labs., Inc. Electric Device Division
Nagakute, Aichi 480-1192, Japan

We developed a limiting current type oxygen sensor using sputtered ZrO₂ and Pt thin film, and turned the sensor to practical use. In addition, the sensor was improved for stability by inserting a Pt/ZrO₂ graded layer between the Pt electrode and the ZrO₂ electrolyte. In this study, the graded layer of the sensor was fabricated by HELICON sputtering equipment, and the stability of the sensor performance was investigated in high oxygen atmospheres. Dureing an intermittent ON(1hr)-OFF(1hr) operation of 250cycles, the sensor showed stable I-V characteristics even in 90%O₂/N₂ mixture. From the durability test and SEM observations,it has been found that the sensor with graded layer electrode has high durability for operations in high oxygen atmospheres, and a large deterioration of the electrode-electrolyte interface of this sensor does not occur.

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25.
アミノ基を側鎖に有する高分子膜を用いたQCM型SO₂ガスセンサの開発

玉井浩二、松口正信、酒井義郎

愛媛大工

QCM-TYPE SO₂ GAS SENSOR USING A POLYMER WITH AMINO GROUP

Koji TAMAI, Masanobu MATSUGUCHI, and Yoshiro SAKAI

Department of Applied Chemistry, Faculty of Engineering, Ehime University

QCM-type SO₂ gas sensor was prepared using poly(styrene-co-chloromethyl styrene) derivatives. Three kinds of diamino compounds, such as DMEDA, DMPDA, and DPEDA, were intorduced in the copolymer as the SO₂ sorption site. The response time of the sensors were affected by the kind of amino group as well as the measuring temperature. Among them, the sensor containing DPEDA had the shortest response time and the good reproducibility, while the sensitivity was the lowest.

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26.
各種金属フタロシアニン薄膜のNO₂ガス応答特性

長澤　忠、大場康之、村上健司、渡邊健蔵

静大電子研

NO₂ GAS RESPONSE CHARACTERISTICS OF VARIOUS METAL PHTHALOCYANINE THIN FILMS

Tadashi NAGASAWA, Yasuyuki OHBA，Kenji MURAKAMI and Kenzo WATANABE

Research Institute of Electronics, Shizuoka University
3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011, Japan

In order to realize a high sensitive NO₂ gas sensor, thin films of several metal phthalocyanines (MPc’s) have been deposited on a glass substrate by the vacuum sublimation method. Effects of the central metals in the MPc molecules have been investigated on the gas-sensing characteristics for those thin films. It was found that the conductivity and sensitivity of MPc films are closely related to an oxidation potential of the MPc materials themselves. Response characteristics to the NO₂ gas ambience also vary with the films. AFM studies reveal that the response characteristics are influenced greatly by the shape and microstructure of the films.

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27.
アルミフタロシアニンの重合化とNO₂ガス応答特性

平山久美子、村上健司、渡邊健蔵

静大電子研

POLYMERRIZATION AND NO₂ GAS RESPONSE CHARACTERISTICS OF Al-PHTHALOCYANINE THIN FILMS

Kumiko HIRAYAMA，Kenji MURAKAMI and Kenzo WATANABE

Research Institute of Electronics, Shizuoka University
3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011, Japan

Sensing properties of Cu-phthalocyanine thin film-based NO₂ gas sensor are strongly related to the film microstructures. We have tried to control the microstructures through a polymerization of source materials. Relations between the film microstructures and the NO₂ gas sensing properties have been investigated precisely for the polymerized Al-phthalocyanine thin films.

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28.
I層により安定化を図ったM-I-SiCダイオードの水素検知特性

中込真二、吾妻照宣

石巻専修大理工

HYDROGEN SENSING PROPERTY OF M-I-SiC DIODE STABILIZED BY INSULATOR LAYER

Shinji NAKAGOMI and Terunobu AZUMA

School of Science and Engineering, Ishinomaki Senshu University
Ishinomaki 986-8580, Japan

Electrical characteristics of MS and MIS diodes based on catalytic metal and silicon carbide structure in hydrogen and oxygen ambient were compared before and after high temperature operation process. MS type diode suffered a large change in current-voltage property. MIS structure seems to be better for the stability. The sensitivity of the MIS device to low concentration hydrogen was studied in region to 300℃. The voltage response to hydrogen was measured under a constant current. It has a good responsibility and reproducibility even to a few ppm hydrogen. The hydrogen sensitivity at lower concentration was increased with an decrease in operating temperature. Hydrogen sensitivity was decreased with increasing coexistent oxygen gas.

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29.
複合酸化物を用いる温度ーNO_x同時検知が可能な新しい容量型センサ

石原達己、鎌倉和美、西口宏泰、滝田祐作

大分大工

CAPACITIVE TYPE GAS SENSOR FOR SIMULTANEOUS DETECTION OF TEMPERATURE AND NO_x GAS CONCENTRATION

Tatsumi Ishihara, Kazumi Kamakura, Hiroyasu Nishiguhci, and Yusaku Takita

Department of Applied Chemistry, Faculty of Engineering, Oita University
Dannoharu 700, Oita 870-1192, Japan

Simultaneous detection of gas and temperature by the same sensor element was investigated. Since the capacitance and resistance of the oxide are independent theoretically, gas concentration and temperature were detected by capacitance and resistance. Large part of the investigated oxide exhibited a change not only in capacitance but also in resistance. Among the investigated mixed oxides, capacitance and resistance of 20SrSnO₃-80Fe₂O₃ were only affected by NO_x concentration and temperature respectively. Therefore, simultaneous detection of NO_x and temperature became possible by using capacitance and resistance of this mixed oxide.

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30.
WO₃上でのSO₂の吸着挙動とSO₂ガス検知特性

松永直樹、兵頭健生、清水康博、江頭　誠

長崎大工

SO₂-ADSORPTION BEHAVIOR AND SO₂-SENSING PROPERTIES OF WO₃

Naoki MATSUNAGA, Takeo HYODO, Yasuhiro SHIMIZU and Makoto EGASHIRA

Department of Materials Science and Engineering, Faculty of Engineering, Nagasaki University
1-14 Bunkyo-machi, Nagasaki 852-8521, Japan

The sensitivity of various metal oxides to 800 ppm SO₂ balanced with air has been investigated.　SnO₂ and In₂O₃-5 mol% MgO exhibited a resistance decrease upon exposure to SO₂ at 100 ℃, whereas a resistance increase at 200～300 ℃.　However, the sensitivities calculated from both resistance changes were relatively small.　WO₃ also exhibited a resistance increase upon exposure to SO₂ at 400 ℃, whereas a resistance decrease at 600 ℃.　The resistance changes were largest among the metal oxides tested.　A.c. impedance measurement revealed that the resistance measured under a d.c. voltage was dominated by the grain boundary resistance.　From the TPD spectra of SO₂ and O₂ from WO₃ subjected to SO₂-preadsorption at different temperatures and the resistance changes during the TPD measurement, it was anticipated that SO₂^- was formed at different adsorption sites from those for oxygen at 400 ℃.　At 600 ℃, however, it was suggested that O^2- species on the surface was substituted for by SO₄^- or SO₃^-, in addition to the consumption of them by the reaction with SO₂.

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31.
SnO₂半導体のガス感度の湿度依存

久世　恭、高橋祥夫

新コスモス電機株式会社

DEPENDENCE OF GAS SENSITIVITY ON HUMIDITY IN SEMICONDUCTOR SENSOR

Takashi KUSE , Sachio TAKAHASHI

New Cosmos Electric Co.,Ltd.
2-5-4 Mitsuya-Naka,Yodogawa-ku,Osaka 532-0036, Japan

The effects of humidity on gas sensitivity of SnO₂, In₂O₂3 and ZnO thick film sensors with different thicknesses of 30,100 and 200μm, were investigated. The long span effect of humidity on gas sensitivity was investigated in detail. Further, the relationship between the humidity effect and the sensor temperature was investigated. It is expected that these findings are useful for design of sensor structure reducing the effects of humidity on gas sensitivity.

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特別講演
空気質からみたガスセンサの新しい展開

中原　毅

フィガロ技研

DEVELOPMENT OF GAS SENSORS FOR AIR QUALITY

Takeshi NAKAHARA

FIGARO ENGINEERING INC.,
1-5-11, Senbanishi, Minoo-Shi, Osaka 562-8505, Japan

Novel gas sensors for air quality were developed and put in the practical use in various applications. (1) Semiconductor gas sensor for auto-damper control system: SnO₂ and WO₃ were adopted as sensing materials to detect exhaust gases from gasoline and diesel vehicles. The sensing unit incorporated with a signal processing software showed good performance in damper control. (2) Semiconductor gas sensor for VOC detection: WO₃ as a sensing material showed high sensitivity to volatile organic compounds such as toluene and xylene.
(3)Solid electrolyte CO₂ sensor:CO₂ sensor composed of NASICON （Na₃Zr₂Si₂PO₁₂）as a solid electrolyte and Li₂CO₃ as an auxiliary electrode was developed. Combining the sensor and a signal processing software made possible to monitor the CO₂ concentration in an office precisely.

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清山賞受賞講演
電流応答型電気化学ガスセンサに関する研究

石地　徹

理研計器株式会社

A STUDEY ON THE AMPEROMETRIC GAS SENSOR USING ELECTROLYTIC SOLUTION

Toru ISHIJI

Riken Keiki, Co.,Ltd. Research Department
2-7-6 Azusawa, Itabashi-ku, Tokyo 174-8744, Japan

Amperometric gas sensors based on electrode reactions of gases are attractive for detection of various kinds of gases. I have investigated to realize a reliable gas detection by means of gas permeable electrode/electrolytic solution cell system. An amperometric sensor using a gold thin-film electrode showed good selectivity for arsine against coexisting solvent vapors. Sensitivity and reliability of HF sensor have been improved by a study of the electrolytic solution composition. New carbon dioxide and ammonia gas sensors have been developed by means of pH dependent metal oxide electrode reaction. A hand made oxygen gas sensor has been developed to arouse scientific interest for young students as an educational equipment.

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32.
酸化物半導体を用いたＶＯＣ測定センサの開発

角崎雅博, 山崎茂一, 藤城敏史, 寺澤孝志, 龍山智榮^*, 星野昌則^**, 南政克^***, 山田浩美^****

富山県工業技術センタ－・富山大工^*・コ－セル^**・北陸電気工業^***・東洋化工^****

DEVELOPMENT OF METAL-OXIDE SEMICONDUCTOR SENSORS FOR DETECTION OF VOC.

Masahiro Kadosaki, Shigekazu Yamazaki, Takasi Terasawa, Satoshi Fujiki Chiei Tatsuyama^*, Masanori Hoshino^**, Masayoshi Minami^*** and Hiromi Yamada^****

Toyama Industorial Technology Centor, 383 Takada,Toyama 930-0866, Japan
^*Faculty of Engineering, Toyama Univesity, 3190 Gofuku,Toyama 930-8555, Japan　
^**Cosel Co.,Ltd., 1-6-43 Kamiakae,Toyama 930-0816, Japan
^***Hokuriku Electric Ind.Co.,Ltd., 3158 Shimo-okubo,osawano,Toyama 939-2292, Japan
^****Toyo Kako Co.,Ltd., 1350 Shimo-umezawa, Namerikawa, Toyama 936-0857, Japan

Recently, the number of people taken ill in new house by indoor-air pollution, is steadily increasing. The phenomenon is what is called "sick house syndrome". Mostly it is caused by formaldehyde and VOC (Volatile Organic Compound) included in adhesive or paint. To develop a semiconductore type VOC sensor, a work was carried out for exploring high sensitive oxide semiconductor materials to formaldehyde, xylene, toluene. Among 23 metal oxides examined, SnO₂, WO₃, In₂O₃, ZnO, Co₃O₄ and Cr₂O₃ showed relatively high sensitivity. Also, the sensing property of SnO₂ element to formaldehyde was extremely improved by addtion of Ag, but the sensors had short lifetime. In this work, in order to improve the sensitivity to VOC in air using another additive, the VOC sensing properties of SnO₂ loaded with metal oxides are investigated. Among the 14 metal oxides loaded, MnO₂ was found to be the most effective promoter for the SnO₂-based sensors. The addition of 3 wt%MnO₂ enhances the sensitivity to 100 ppm formaldehyde in air by about two order of magnitude at 200℃

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33.
半導体式ニオイセンサの空気清浄機器への応用

河口智博、水野江利子、横尾栄寿、瀬戸口泰弘、中原　毅、安永　進

フィガロ技研

APPLICATIONS OF SEMICONDUCTOR ODOR SENSOR TO AIR CLEANERS

Tomohiro KAWAGUCHI, Eriko MIZUNO, Eijyu YOKOO, Yasuhiro SETOGUCHI, Takeshi NAKAHARA and Susumu YASUNAGA

Figaro Engineering Inc,
1-5-11 Senbanishi, Minoo-shi, Osaka 562-8505, Japan

In order to operate air cleaners automatically, the demand for gas sensors that can detect various odors at high sensitivity has increased. In this study we investigated two types of new gas sensors. "Sensor A(TGS2602)" exhibited high sensitivity to several volatile organic compound gases, and was effective to detect building material odors, such as varnish, wood adhesive and wood preservatives. On the other hand, "Sensor B(under development)" exhibited high sensitivity to sulfur and nitrogen compound gases, and was effective to detect offensive odors, such as kitchen garbage, toilet smells and so on. Furthermore, as these sensors exhibit low sensitivity to odorless gases, such as H₂, they can monitor the effect of deodorization as compared to usual sensors(TGS2600) when an air cleaner is operated.

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34.
ジエトキシジメチルシシランで表面化学改質したPd及びPt/SnO₂のガス検出特性

和田憲治，江頭　誠^*

佐世保高専，長崎大工^*

GAS-SENSING PROPERTIES OF Pd- AND Pt-LOADED SnO₂ SUBJECTED TO SURFACE CHEMICAL MODIFICATION WITH DIETHOXYDIMETHYLSILANE

Kenji WADA and Makoto EGASHIRA^*

Department of Chemistry and Biotechnology, Sasebo National College of Technology
1-1 Okishin-cho, Sasebo-shi, Nagasaki 857-1193, Japan
^*Department of Materials Science and Engineering, Faculty of Engineering, Nagasaki University
1-14 Bunkyo-machi, Nagasaki-shi 852-8521, Japan

Effects of Pd- or Pt-loading on the gas-sensing properties of SnO₂ subjected to repeated surface chemical modification with diethoxydimethylsilane (DEMS) have been investigated in relation to the variations in temperature programmed desorption (TPD) of oxygen and in catalytic oxidation activity. Pt-loaded SnO₂ was superior to Pd/SnO₂ in H₂-sensing, and the H₂ sensitivity increased markedly, accompanied by an increase in H₂ oxidation activity, with repeated surface modification. On the other hand, Pd/SnO₂ was superior to Pt/SnO₂ in CH₄-sensing, and the modification for three times resulted in the maximum sensitivity of S=38 at 400°C. Response and recovery characteristics of the CH₄-sensing were satisfactory at 400°C. However, the sensitivity decreased with further modification, although the catalytic activity was not so much influenced by the modification in accordance with the almost unchanged amount of PdO species measured by TPD. Anyway, the Pd/SnO₂ sensor subjected to modification with DEMS was found to be a promising CH₄ sensor.

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35.
温熱指標とガスセンサ出力との関係

中本義徳，大藪多可志，南保英孝^*，木村春彦^*

金沢経済大経，金沢大工^*

RELATIONSHIP BETWEEN THERMAL INDEX AND GAS SENSOR OUTPUT

Yoshinori NAKAMOTO, Takashi OYABU, Hidetaka NAMBO^* and Haruhiko KIMURA^*

Faculty of Economics, Kanazawa University of Economics
Ushi 10, Gosho-machi, Kanazawa, Ishikawa 920-8620, Japan
^*Faculty of Engineering, Kanazawa University
2-40-20, Kodatsuno, Kanazawa, Ishikawa 920-8667, Japan

As human grow older, sensitivities become dull. Especially, the sensitivity for thermal index goes down. So, it is important to compensate or act for the sensitivity. By the way, the output of tin oxide gas sensor is influenced by temperature, humidity and atmospheric pressure. The comfortable index in a residential environment is related with these elements. Therefore, it is researched to derive the comfortable index based on the sensor output. In this report, it is clarified that high level of the comfortable index is equivalent to usual level of the temperature index and humidity index chiefly, and, low level of the comfortable index is equivalent to high level of humidity index. The sensor output of comfortable index is about 2.0V, and uncomfortable index is about 1.7V.

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36.
酸化物半導体修飾メソポーラスシリカの調製とセンサ材料への応用

寺岡靖剛、山崎　敦、森口　勇、鹿川修一、朝長成之^*、安武昭典^*、泉　順^*

長崎大工・三菱重工長崎研究所^*

PREPARATION OF MESOPOROUS SILICA MODIFIED WITH　SEMICONDUCTOR OXIDES AND ITS APPLICATION TO GAS SENSOR MATERIALS

Yasutake TERAOKA, Atsushi YAMAZAKI, Isamu MORIGUCHI, Shuichi KAGAWA, Nariyuki TOMONAGA^*, Akinoro YASUTAKE^* and Jun IZUMI^*

Department of Applied Chemistry, Faculty of Engineering, Nagasaki University
Nagasaki 852-8521, Japan
^*Nagasaki Research & Development Center, Mitsubishi Heavy Industries, Ltd.
Nagasaki, 851-0392, Japan

The coating of the inner wall of mesoporous silica with SnO₂ and TiO₂ has been investigated by a layer-by-layer coating technique to prepare "(semi)conductive mesoporous materials. Mosoporous silicas (MPS) with pore diameters between 23 and 36 Å and specific surface areas between 1200 and 1450 m² g^-1 were suspended and stirred in water for 1 h and dried at 110 ℃ overnight. The precursor materials, SnCl₄ and Ti(OC₄H₉)₄, were fixed on the wall through the reaction with hydroxyl groups by refluxing solutions of precursors suspended with MPS powder, followed by drying and calcination at 550 ℃ for 6 h. Characterization of products with respect to mesopore structure and UV-Vis absorption clearly indicates that the inner wall of MPS is coated with SnO₂ and TiO₂ progressively with increasing the number of the hydroxylation-fixation-calcination cycle (up to 3 times in this study). 　

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37.
一般家庭トイレにおけるニオイセンサ特性

大薮多可志^*、笠原浩^*2、南戸秀仁^*3、小野寺武^*4、筒口善央^*5、中原毅^*6

金沢経済大学^*、新コスモス電機^*2、金沢工業大学^*3、金沢大学^*4、石川県工業試験場^*5、フィガロ技研^*6

Odor Sensing Characteristics in a Lavatory of General Home

Takashi OYABU^*, Hiroshi KASAHARA^*2 , Hidehito NANTO^*3 , Takeshi ONODERA^*4, Yoshiteru Doguchi^*5 and Takeshi NAKAHARA^*6

^*Kanazawa University of Economics, Kanazawa 920-8620, Japan
^*2New Cosmos Electric Co. LTD., Osaka 532-0036, Japan
^*3Kanazawa Institute of Technology, Kanazawa 924-0838, Japan
^*4Faculty of Engineering, Kanazawa University, Kanazawa 920-8667, Japan
^*5Industrial Research Institute of Ishikawa Prefecture, Kanazawa, 920-0223, Japan
^*6Figaro Engineering Inc., Osaka, 562-8505, Japan

Six odor sensors, which are of the metal-oxide semiconductor type, are installed in the lavatory of a general residence. Features of sensor-output patterns are derived by monitoring the odors. Frequency of lavatory-use and its intervals are detected and kinds of excretion are also identified. As for the results, two or three sensors react to urine and four or five sensors react to feces. The patterns, for example degree of fluctuation and inclination of output characteristic, differ with the subjects. This system can be applied to homes for the aged house to survey the residents' behaviors. The odor sensor system is also effective for monitoring the indoor environment without an infringement of privacy.

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38.
白金薄膜による乾電池駆動型ＣＯセンサ用ヒータ

山本信幸、藤森裕樹

トクヤマ、フィガロ技研

HEATERS FOR BATTERY－OPERATED CO SENSOR FROM PLATINUM THIN FILMS

Nobuyuki YAMAMOTO and Yuki FUJIMORI

Tokuyama Corp.
2023-1，Endo，Fujisawa-shi，Kanagawa252-0816, Japan
Figaro Engineering Inc.
1-5-11，Senbanishi，Mino-shi，Osaka562-8505, Japan

We have developed heaters for battery-operated CO sensor from Platinum thin films． We used Platinum thin films to sensing electrode，too．The gas sensing layer was printed on Platinum thin films．From various examination，heater size was reduced and voltage was increased and ON period was short．In the case of a duty ratio of 4msec every 30 sec，the effective power consumption was about 0.06mW． This CO sensor can be operated by three ＡＡ type batteries for two years．

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39.
In₂O₃系高感度・高選択性水素センサ

勝木章、福井清

新コスモス電機株式会社

HIGHLY SENSITIVE AND SELECTIVE H₂ GAS SENSOR BASED ON SINTERED In₂O₃

Akira KATSUKI and Kiyoshi FUKUI

New Cosmos Electric Co., Ltd.
3-6-25, Mitsuya-Naka, Yodogawa-Ku, Osaka 532-0036, Japan

A highly sensitive and selective H₂ sensor based on In₂O₃ was developed by use of a hot wire type semiconductor sensor commercially available. The powder of In₂O₃ was sintered in a bead(0.50 mmφ) covering over a platinum wire(0.02 mmφ) coil. Then, a SiO₂ accumulated dense layer was formed near the surface of the porous bead by chemical vapor deposition(CVD) of hexamethyldisiloxane(HMDS). The sensitivity to H₂ was about forty times as large as a current sensor based on SnO₂. The sensor had also a very high selectivity to H₂ (eg., the sensitivity to 5 ppm H₂ was equal to that to 1000 ppm C₂H₅OH). Moreover, the sensor had a minor humidity dependence and a long term stability(about 900 days). Thus, indium oxide was a suitable material for the highly sensitive and selective H₂ sensor.

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40.
Au・La₂O₃/SnO₂系アンモニアセンサ

西田幸子福井清

新コスモス電機株式会社

NH₃ GAS SENSOR BASED ON Au La₂O₃/SnO₂ WITH PROTECTION COAT OF TiO₂

Sachiko NISHIDA and Kiyoshi FUKUI

New Cosmos Electric Co.,Ltd.,
2-5-4, Mitsuya-Naka, Yodogawa-Ku, Osaka 532-0036, Japan

A NH₃ gas sensor based on a hot wire type semiconductor sensor has been put into practical use. The NH₃ gas sensor consisted of double sintered layers: an inner sensing layer of 0.02 at%Au, 4 mol%La₂O₃ supported on SnO₂ (a sphere with the diameter of 0.45 mmφ)and an outer protection layer of TiO₂(anatase, thickness of 0.1mm). The sensor temperature was ca. 300℃. The sensitivity to 25 ppm NH₃ was ca. 40 mV. From a practical point of view, some important performances of the NH₃ gas sensor were discussed in the present report: selectivity, response, influence of humidity, and long term stability.

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41.
Ｌａ³⁺及びＹ³⁺を複合添加した酸化錫半導体ＣＯ₂センサの開発と実用化

花田真理子、翁長一夫、西口昌志^*、小野内　徹^*

エフアイエス・松下精工^*

DEVELOPMENT OF CO₂ GAS SENSOR USING La³⁺ AND Y³⁺ DOPED SnO₂ SEMICONDUCTOR

Mariko HANADA, Kazuo ONAGA, Masashi NISHIGUCHI^* and Toru ONOUCHI^*

FiS Inc.
3-36-3 Kitazono, Itami-shi, Hyogo 664-0891, Japan
^*Matsushita Seiko Co., Ltd.
4017 Takagi-cho, Kasugai, Aichi 486-8522, Japan

To develop an inexpensive and compact CO₂ gas sensing system for indoor air quality control, we have developed a CO₂ gas sensor using SnO₂ doped with La³⁺ and Y³⁺. The specific properties of the sensor are, 1) Yttrium addition prevented La from aggregation on the SnO₂ surface under high humidity, 2) Filter made of silica gel and Pt effectively reduced the sensitivity to ethyl alcohol and humidity, 3) A pinhole disk placed between the filter and the sensor element removed the moisture effect due to the use of the silica gel filter. This CO₂ sensor was proved to have sufficient performance in practical use.

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42.
酸化錫半導体CO₂センサの高感度化及び高精度化の検討

香田弘史、西口昌志^*、小野内　徹^*

エフアイエス・松下精工^*

IMPROVEMENT OF SENSITIVITY AND ACCURACY OF SnO₂ SENSOR FOR CO₂ DETECTION

Hiroshi KODA, Masashi NISHIGUCHI^* and Toru ONOUCHI^*

FiS Inc.
3-36-3 Kitazono, Itami-shi, Hyogo 664-0891, Japan
^*Matsushita Seiko Co., Ltd.
4017 Takagi-cho, Kasugai, Aichi 486-8522, Japan

We have newly developed two types of CO₂ gas sensors to improve the characteristics of the CO₂ gas sensor which has been marketed domestically since 1997. One is a small bead type gas sensor doped with La,Y and Pd and can detect CO₂ and H₂ with a single element. The other is a plate type SnO₂ sensor composed of a compensation element and a detection element, and decreases the noise gas influence on the remaining CO₂ sensitivity. The performance of these two types of CO₂ sensors was satisfactory in a practical use.

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