カーボンナノチューブを用いるNADセンサ動作の定電位化

Shizuoka University, Hamamatsu-shi, Shizuoka 432-8561

Using a surface acoustic wave, liquid droplet can be manipulated. In this paper, we present a digital microfluidic system on a SAW substrate. A droplet is controlled with a surface acoustic wave (SAW) streaming and measured with an interdigitated electrode (IDE) sensor. As sensor and actuator are integrated on the same surface, We named it “Micro-Laboratory”. First, the micro-laboratory is fabricated on a piezoelectric substrate and demonstrated. The results indicate that the proposed micro-laboratory is used as a digital micro fluidic system. However, disposable system is required for measuring biomolecules. Therefore, we propose novel integrated system of sensor and actuator for droplets. The system consists of glass plate/matching layer/piezoelectric substrate. Using three-layer structure, droplets are manipulated and mixed by SAW and measured by a sensor on the glass plate. The novel system was demonstrated and confirmed its validity through experiments.

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生体成分計測用バイオFETの研究開発（IV）FET硝酸イオンチェッカのセンサ特性

産総研^a、阪工大工^b

○脇田 慎一^a、吉田 尚弘^b、小林 智樹^b、澁谷 康彦^b

R & D OF BIOFET FOR BIOLOGICAL MONITORING（IV）SENSOR CHARACTERISTICS
OF FET NITRATE CHECKERS

Shin-ichi WAKIDA ^a, Naohiro YOSHIDA ^b, Tomoki KOBAYASHI ^b and Yasuhiko SHIBUTANI <sup>b

a</sup> National Institute of Advanced Industrial Science and Technology (AIST),
Midorigaoka 1-8-31, Ikeda, Osaka 563-8577
^b Faculty of Engineering, Osaka Institute of Technology,
Omiya 5-16-1, Asahi, Osaka 535-8585, Japan

To develop high performance nitrate ion-selective field-effect transistors (ISFETs) to detect a human salivary nitrate, we have investigated sensing materials, such as phenanthroline derivatives, and also polymer membrane materials, such as poly(vinyl chloride) (PVC), poly(vinyl chloride) calboxylated (PVC-COOH) and so on. We prepared highly sensitive and selective prototype of FET NO₃- checkers based on NO₃--ISFETs using the suitable copper(I) complex ([Cu(bcp)₂]NO₃) as a nitrate- sensing material, 2-nitrophenyl dodecylether (NPDDE) as a liquid membrane material (plasticizer) and above mentioned polymer membrane materials using the commercialized FET pH checker. We studied the sensor characteristics of prototype of FET nitrate checkers, such as linear response range and selectivity. FET NO₃- checkers showed excellent linear characteristics from 10-5.5 M to 10-0.5 M with a response time of less than a few seconds. FET NO₃- checkers also showed the same selectivity. The sensor characteristics of FET NO₃- checkers are almost identical with the corresponding ion-selective electrodes (ISEs) as expected. We applied human saliva after pretreatment using a cartridge column packed with cation-exchange resin of the silver form using direct potentiometry. In any case, we obtained relatively good correlation with conventional ion chromatography.

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参照電極が不要な新型マイクロイオンセンサの開発

岡山大学

○井上豊崇、小田和代、山田博信、紀和利彦、塚田啓二

DEVELOPMENT OF A NEW TYPE MICRO ION SENSOR WITHOUT A REFERENCE ELECTRODE

Toyotaka INOUE, Kazuyo ODA, Hironobu YAMADA, Toshihiko KIWA and Keiji TSUKADA

Okayama University,
1-1-1 Tsushima-naka, Kita-ku, Okayama-shi, Okayama 700-8530

An ion-selective electrode (ISE) is known as the chemical device to analyze a variety of ions in field of chemical analysis. For ISE measurement system, a reference electrode is absolutely necessary to measure the ion concentration. To measure small amount of sample, sensor has to be miniaturized. However, the miniaturization of the reference electrode is very difficult due to its structure. In this study, we developed a new-type ion sensor can measure without a reference electrode. The developed sensor measured an inside membrane potential change directly. To evaluate performance of the new-type sensor, we compared a conventional type ion-selective electrode and a coated wire electrode. As a result, the developed sensor showed a good sensitivity and selectivity.

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金属合金電極を用いた起電力型環境イオンセンサの設計

九工大院工

○中村英靖，高瀬聡子，清水陽一

A POTENTIOMETRIC ENVIRONMENTAL ION-SENSOR BASED ON METAL-ALLOY FILM ELECTRODE

Hideyasu NAKAMURA, Satoko TAKASE, and Youichi SHIMIZU^*

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

Metal-film electrode based environmental ion-sensors were tried to prepare by an electrodepositing method. The Co₈₀-Ni₂₀ film electrode showed the best EMF response characteristic for H₂PO₄^- among the metal-film sensors tested. The sensor exhibited a linear potentiometric response characteristics to H₂PO₄^- at the concentration range between 1.0 × 10^-5 and 1.0 × 10^-2 M with a slope of -59 mV/dec. at pH 5. The sensor showed relatively fast response, high selectivity, and sensitivity, in spite of its poor the endurance of the metal-alloy film. In addition, the Al-Mg/Fe electrode was found to show a good function as the NO₃^- sensor. The Al-Mg/Fe electrode exhibited a linear potentiometric response to nitrate ion at the concentration range between 1.0×10^-3 and 1.0×10^-2 M with 90% response time of 1 min at pH 9. The Al-Mg/Fe electrodes also have good stability.

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種々の圧力で堆積したTiO₂スパッタ膜の構造とH₂ガスセンサ特性

富山大

○長田　康彦、山崎　登志成、喜久田　寿郎

STRUCTURE AND H₂ SENSING PROPERTY OF TiO₂ SPUTTERED FILMS
DEPOSITEDE UNDER VARIOUS PRESSURES

Yasuhiko NAGATA, Toshinari YAMAZAKI and Toshio KIKUTA

Graduate School of Engineering, University of Toyama
Gofuku 3190, Toyama 930-8555

TiO₂ films were deposited by DC magnetron sputtering under various discharge gas pressures. The structure of the films was investigated with focus on porosity, which was evaluated by density and effective surface area. Furthermore, the H₂ sensing property of the films annealed at 500℃ was investigated at various operating temperature in ambient air. Films deposited under a low pressure were rather smooth while the films deposited under a high pressure were composed of columnar grains. As-deposited films were amorphous. They crystallized to be of anatase structure by annealing at 500℃. As the pressure during deposition increased, pores developed between columnar grains. In the most porous film deposited at 12 Pa, the sidewalls of the columnar grains were mostly exposed. A dense film deposited under a low pressure showed sensitivity only at an operating temperature above 200℃. As the porosity increased, the sensing temperature decreased. The most porous film showed a rather high sensitivity even at a low temperature of 100℃.

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半導体ガスセンサにおける粒子サイズと感応膜利用効率の関係

九大院総理工

○藤山 修平、 湯浅 雅賀、 木田 徹也、 山添　曻、 島ノ江 憲剛

INVESTIGATION OF THE RELATIONSHIP BETWEEN GRAIN SIZE AND UTILITY OF
SENSING FILM FOR DESIGN OF SNO₂ GAS SENSORS

Shuhei FUJIYAMA ^a , Masayoshi YUASA ^b , Tetsuya KIDA ^b , Noboru YAMAZOE ^b , Kengo SHIMANOE ^b

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

To investigate of the relationship between grain size and utility of sensing film, thin film sensor devices different in crystallite size were fabricated. SnO₂ sols were prepared by a seed-assisted hydrothermal method, in which 4 nm SnO₂ was used as a seed crystal. It was found that the developed method can control the particle size of SnO₂ between 4 and 17nm by hydrothermal treatment at 200～250℃ at 10MPa. The smaller in initial crystallite size, the larger the crystallite size after calcination grew. The sensor responses to different molecular size gases (H₂ and H₂S) were investigated. For small size of gas molecular, the grain size factor was more effective than the utility factor. However, for large size of gas molecular, the situation was reversed.

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ナノおよびミクロンサイズ酸化スズを組み合わせたCH₄センサの開発

宮崎大工

○酒井　剛、吉川 由樹、木島　剛

DEVELOPMENT OF CH₄ SENSOR BY COMBINATION OF NANO- AND MICRO-SIZE SnO₂ PARTICLES

Go SAKAI, Yuki KIKKAWA and Tsuyoshi KIJIMA

Department of Applied Chemistry, Faculty of Engineering, University of Miyazaki,
Miyazaki-shi, Miyazaki 889-2192

In this study, nano-size SnO₂ prepared from hydrothermal treatment of stannic acid gel and micro-size SnO₂ prepared by hydrolysis of Na₂SnO₃ with benzenesulfonic acid at liquid-liquid interface, respectively, were combined together to form micro-pore induced sensing body consisting of nano-size SnO₂ particles. It was found that the covering treatment of nano-size SnO₂ on micro-size SnO₂ gave slightly change in specific surface area as well as volume and typical value of meso-pores. It was also found that the enhancement of sensitivity to CH₄ and lower temperature operation could be realized by combination of nano- and micro-size SnO₂ as well as introduction of sensitizer, Pd.

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ジルコニアドープセリア検出材とイットリアドープセリア温度補償材を有する抵抗型酸素センサ

産総研

○伊豆典哉、西﨑涼香、申ウソク、伊藤敏雄、西堀麻衣子、松原一郎

RESISTIVE OXYGEN SENSOR USING A SENSING MATERIAL OF ZIRCONIA-DOPED CERIA
AND A TEMPERATURE COMPENSATING MATERIAL OF YTTRIA-DOPED CERIA

Noriya IZU, Sayaka NISHIZAKI, Woosuck SHIN, Toshio ITOH, Maiko NISHIBORI, and Ichiro MATSUBARA

National Institute of Advanced Industrial Science and Technology (AIST),
Nagoya-shi, Aichi 463-8560

In this study, we investigated into temperature compensating materials for a resistive oxygen sensor using Ce_0.9Zr_0.1O₂ as a sensing material for lea-burn engines. Since a temperature dependence of a temperature compensating material should be the same as that of the sensing material, Y concentration of CeO₂-Y₂O₃ material was optimized as the temperature compensating material. As a result, it was revealed that the optimized Y concentration was 50 mol% (Ce_0.5Y_0.5O_2-δ). The resistance of Ce_0.5Y_0.5O_2-δ was independent of air-to-fuel ratio (oxygen partial pressure) so that it was confirmed to function as a temperature compensating material. Sensing elements which comprised Ce_0.9Zr_0.1O₂ and Ce_0.5Y_0.5O_2-δ as sensing and temperature compensating materials, respectively, on an alumina substrate were fabricated and temperature dependence of outputs of the sensing element was investigated. As a result, the output was approximately independent of temperature in the wide range of 500 to 800°C and it became clear that the sensor is able to distinguish a difference of 0.04 in excess air factor.

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Synthesis Characterization and Gas Sensing Properties of TiO₂ Nanostructures

Ahsanulhaq Qurashi, Toshinari Yamazaki, Toshio Kikuta

Department of Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555, Japan

We demonstrate the growth of TiO₂ nanostructures by novel hydrothermal synthesis technique at low temperature. Field emission scanning electron microscopy revealed that nanoparticles and nanorod-like morphology of TiO₂. Detailed structural analysis revealed that TiO₂ nanoflower-like structures are single crystalline with good crystal quality. However TiO₂ nanoparticles are polycrystalline in nature with high crystallintiy. These TiO₂ nanostructures also have potential applications in ultrasensitive gas sensors, chemical and biosensor devices, where well defined easily accessible crystal surface is required. Hydrogen sensors made from TiO₂ nanostructures showed excellent performance at low temperature.

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超音波噴霧熱分解法により調製したマクロポーラス酸化物粉末のNO₂検知特性

長崎大院生産科学^a，長崎大工^b

○兵頭健生^a，元村仁美^b，松尾勝秀^b，清水康博^b，江頭　誠^b

NO₂ SENSING PROPERTIES OF MACROPOROUS OXIDES POWDERS
PREPARED BY ULTRASONIC SPRAY PYROLYSIS

Takeo HYODO^a, Hitomi MOTOMURA^b, Katsuhide MATSUO^b, Yasuhiro SHIMIZU^band Makoto EGASHIRA^b

^a Graduate School of Science and Technology, Nagasaki University,
^b Faculty of Engineering, Nagasaki University,
1-14 Bunkyo-machi, Nagasaki 852-8521

Submicron-sized In₂O_3- and WO_3-based spherical powders with well-developed spherical macropores (the size of macropores: 80~110 nm) were prepared by pyrolysis of atomized precursor aqueous solutions containing polymethylmethacrylate (PMMA) microspheres as a template. Among all In₂O_3-based spherical powders, macroporous (mp_-) In₂O₃ without any additives showed the largest response to 10 ppm NO₂ in air, especially at 150°C, with relatively fast response and recovery speeds. On the other hand, the response of mp-WO₃ to 10 ppm NO₂ in air increased with an increase in the post-annealing temperature, and the mp_-WO₃ which was annealed at 650°C showed the largest response at 150°C among all WO_3-based spherical powders. In addition, a dense WO₃ spherical powder prepared without PMMA microspheres in the precursor solution also showed relatively high and stable response to 10 ppm NO₂.

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酸化ニッケルスパッタ膜の多孔性評価とNO₂検出特性

富山大学院理工学教育部

○米澤　正隆、山崎　登志成、喜久田　寿郎

POROSITY CHARACTERIZATION AND NO₂ SENSING PROPERTY OF NIO SPUTTERED FILMS

Masataka Yonezawa, Toshinari Yamazaki, Toshio Kikuta

Graduate School of Science and Engineering, University of Toyama,
Gofuku 3190, Toyama 930-8555

NiO films were deposited by DC magnetron sputtering under various pressures. The structure of the films was investigated using X-ray diffraction, scanning electron microscopy, measurement of density, and measurement of effective surface area. The films were generally composed of columnar grains. As the pressure increased, the porosity of the film increased. In other words, voids developed between columnar grains, and the density decreased. The sensitivity to NO₂ at a concentration of 1 ppm in dry air was also investigated for the films annealed at 400℃ at an operating temperature from room temperature to 300℃. The resistance decreased upon exposure to NO₂. As the porosity increased, the sensitivity increased. The highest sensitivity obtained in this study was 3.2 at 200℃ measured for the most porous film deposited at 12 Pa. After exhaust of NO₂, the resistance of the film recovered to the initial value at 150℃ and above. It did not recover to the initial value below 100 ℃.

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層状有機無機ハイブリッドによるアルデヒドセンサのXPS分析

産総研

○伊藤　敏雄、松原　一郎、申　ウソク、伊豆　典哉、西堀　麻衣子

XPS STUDY OF LAYERED ORGANIC-INORGANIC HYBRIDS AS ALDEHYDE SENSORS

Toshio ITOH, Ichiro MATSUBARA, Woosuck SHIN, Noriya IZU, and Maiko NISHIBORI

National Institute of Advanced Industrial Science and Technology (AIST),
Shimo-shidami, Moriyama-ku, Nagoya 463-8560

VOC gas sensing properties have been investigated for the layered organic-inorganic hybrids of semiconductive molybdenum trioxide (MoO₃) thin films with polyaniline (PANI) or polyaniline derivatives, e.g. poly (5, 6, 7, 8-tetrahydro-1-naphthylamine) (PTHNA). The hybrids can detect aldehyde gases of several tens ppb level. However, the resistance drift problem should be solved for long-term stability. XPS studies reveal that the resistance drift of the hybrids is caused by adsorbing oxygen molecules from the atmosphere. The adsorption of sufficient oxygen molecules by annealing in air at a temperature higher than operating temperature can reduce the resistance drift phenomena. Moreover, it seems that the resistive responses to aldehyde gases tend to be affected by intercalation temperatures during the thin film process.

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電極触媒活性の精密制御に基づいた
ガスセンシング技術の開発と各種デバイスへの応用展開

名大院環境

○日比野高士

GAS SENSING TECHNIQUES BASED ON ACTIVATION OF ELECTROCATALYSTS
AND THEIR APPLICATIONS TO VARIOUS DEVICES

Takashi HIBINO

Graduate School of Environmental Studies, Chikusa-ku, Nagoya University,
Nagoya 464-8601

In this study, we propose two new concepts for developing gasoline hydrocarbon and diesel particulate sensors. A sensor device was constructed from two PdIYSZIAu, which were attached to each other with their Pd electrodes in the interior side of the assembly. When the sample gases consisting of CH, O₂ and H₂O were fed to the sensor at 750℃, electromotive force values were generated from the one cell and then compensated by pumping O₂ electrochemically from the other cell. Currents applied to the latter cell linearly increased with CH₄ concentration, but were not influenced by changing O₂ concentration. In another sensor device, PtIYSZIPt, electrochemical oxidation of carbon was made by water vapor present in the atmosphere. An active oxygen species was formed via water-vapor electrolysis over the Pt electrode, oxidizing carbon to carbon dioxide, with a current efficiency of approximately 100%. This reaction causes a large jump in the measured electrode potential, providing information on the carbon amount.

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Pd-Au共担持触媒を利用した吸着燃焼式マイクロVOCセンサの高性能化

長崎大院生産^a、矢崎総業^b、長崎大工^c

○杠 泰成^a、兵頭 健生^a、笹原 隆彦^b、清水 康博^c、江頭 誠^c

DEVELOPMENT OF HIGH SENSITIVE ADSORPTION/COMBUSTION-TYPE GAS SENSORS
WITH AN ALUMINA CATALYST CO-LOADED WITH Pd AND Au

Yasunari YUZURIHA^a, Takeo HYODO^a, Takahiko SASAHARA^b,
Yasuhiro SHIMIZU^c, and Makoto EGASHIRA^c

^a Graduate School of Science and Technology, Nagasaki University,
1-14 Bunkyo-machi, Nagasaki 852-8521
^b Research and Technology Center, Yazaki Corporation,
1500 Mishuku, Susono, Shizuoka 410-1194
^c Faculty of Engineering, Nagasaki University,
1-14 Bunkyo-machi, Nagasaki 852-8521

Gas sensing properties of adsorption/combustion-type gas sensors have been modified by controlling the composition of Pd/Au ratio (total loading amount of Pd and Au: 10 wt%) loaded on γ-Al₂O₃ catalyst or the additive amounts of α-Al₂O₃ powder to the catalyst loaded with Pd and Au. The sensor using the γ-Al₂O₃ catalyst loaded with 80 wt% Pd and 20 wt% Au showed the largest response to ethanol in air, probably due to the improvement of the catalytic activity for ethanol oxidation. In addition, the addition of 10 wt% α-Al₂O₃ to the γ-Al₂O₃ catalyst loaded with 80 wt% Pd and 20 wt% Au was also very effective in improving the sensor response, probably because of the enhancement of the thermal conductivity.

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吸着燃焼式ガスセンサによるエタノール選択検知

矢崎総業株式会社

○高橋　信之、笹原　隆彦

SELECTIVE DETECTION OF ETHANOL USING AN ADSORPTION/CONBUTION-TYPE
MICRO GAS SENSOR

Nobuyuki TAKAHASHI, Takahiko SASAHARA

Research and Technology Center, Yazaki Corp., Susono-shi, Shizuoka 410-1194

Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan

We investigated selective detection of adsorptive organic compounds using an adsorption/combustion-type gas sensor. We recognized the advantages adding various oxides to Pt/γ-Al₂O₃ so that catalytic properties of Pt/γ-Al2O3 changed variously. Through investigation of adding various oxides, we confirmed the sensor employed Pt/Al₂O₃-La₂O₃ as the sensing layer　and Pt/Al₂O₃-Cr₂O₃ as the compensating layer showed a large response peak to ethanol without responding to　toluene, acetone, and formaldehyde. Moreover the sensor showed response to only ethanol in mixed gases atmosphere of ethanol, toluene, acetone, and formaldehyde.

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感温部にバルクサーミスタを用いた低温動作可能な接触燃焼式ガスセンサの開発

株式会社 村田製作所

○中村 大佐、天野 優、山田 一、牛見 義光、伊藤 吉博

DEVELOPMENT OF CATALYTIC COMBUSTION TYPE GAS SENSOR WITH BULK
THERMISTOR FUNCTIONING AT LOW TEMPERATURE

Daisuke NAKAMURA , Masaru AMANO , Hajime YAMADA , Yoshimitsu USHIMI , and Yoshihiro ITO

Murata Mfg. Co.,Ltd. 10-1, Higashikotari 1-chome, Nagaokakyo-shi, Kyoto 617-8555

We have developed a new type of catalytic combustion gas sensor that can operate at lower temperature than existing sensors. Instead of using Pt coils, we use thermistor as temperature-sensing material that has high temperature coefficient of resistance. Bulk thermistor with large volume and high heat capacity causes small sensitivity. Therefore, we have formed the thermal separation structure and have obtained high sensitivity using thin-grinded thermistor membrane supported with posts to reduce heat capacity. We deposited Pt as catalyst material on the thermistor membrane, and confirmed sensing characteristics using hydrogen gas. As a result, we obtained the output voltage 1.5V, response time 1sec under the condition input voltage 3V, operation temperature 100 degree, hydrogen concentration 2.4%.

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車室内空質制御のための高感度においセンサの開発

エフアイエス

○小野　靖典、吉良　満治、村上　順一

DEVELOPMENT OF HIGHLY SENSITIVE ODOR SENDOR FOR AUTOMOTIVED

Kiyonori Ono, Mitsuharu Kira, Junichi Murakami

FiS inc., 3-36-3 Kitazono, Itami, Hyogo, 664-0891, Japan

Semiconductor gas sensors are commonly used in ventilation control systems in automobiles by detecting exhaust gases from other motor vehicles. In this application, in addition to the detection of exhaust gases, there has been a rise in demand recently for applications that detect bad odor from farm animals, domesticated livestock or garbage disposal facilities. Individual sensors are usually used for detecting different types of gases because specific conditions are required for each gas to be detected. We have developed a mini-bead type gas sensor which can detect both odor and exhaust gases. This unique sensor is achieved by employing an Au doped SnO₂ for sensing materials, creating it on a 0.3mmφ×0.5mmφ structure, and applying a cyclic temperature change with 0.9V×0.6 seconds and 0.4V×0.6 seconds for operation. Furthermore, by including an effective signal processing algorism for detecting different gases, we have developed a single sensor that is capable of detecting both gasoline and diesel exhaust gases and malodors with high sensitivity, accurate selectivity and quick response.

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半導体式ガスセンサの分析装置への応用展開

新コスモス電機株式会社

○久世 恭、神田奎千、伊藤達也

APPLICATION OF SEMICONDUCTOR TYPE GAS SENSOR TO PORTABLE GAS ANALYZER

Takashi Kuse, Keisen Kanda, Tatuya Ito

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

Gas analyzers using semiconductor type gas senor have been developed by authors. The gas analyzers (XG-100 series) can detect target gases at very low concentration at which the gases can not be detected by the conventional analyzers. The measurement of target gases is simply done by injecting only small amount of sample into the system and the concentration of each component is determined automatically with high accuracy.

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高輝度紫外線LEDを用いたホルムアルデヒド計測用生化学式ガスセンサ

東医歯大院 医歯学^a、東京都立産業技術研究センター^b、東医歯大 生体材料工学研究所^c

○鈴木祐貴^a、月精智子^a,b、髙橋大志^c、荒川貴博^c、工藤寛之^c、三林浩二^c

BIOCHEMICAL GAS SENSOR FOR FORMALDEHYDE MEASUREMENT USING HIGH INTENSITY UV-LED

Yuki SUZUKI ^a , Tomoko GESSEI ^a,b, Daishi TAKAHASHI ^c, Takahiro ARAKAWA ^c, Hiroyuki KUDO ^c and Kohji MITSUBAYASHI <sup>c

a</sup> Graduate School of Medical and Dental Science, Tokyo Medical and Dental University,
1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
^b Tokyo Metropolitan Industrial Technology Research Institute,
3-13-10 Nishigaoka, Kita-ku, Tokyo, 115-8586, Japan
^c Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University,
2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan

A fiber-optic biochemical gas sensor (bio-sniffer) for formaldehyde vapor was constructed and evaluated. The bio-sniffer measures formaldehyde as fluorescence of nicotinamide adenine dinucleotide (NADH) which is produced by formaldehyde dehydrogenase (FALDH) reaction. The bio-sniffer consists of a high intensity UV-LED (λ=335nm) based portable excitation system, a photomultiplier tube, and an optical fiber probe with a FALDH immobilized membrane. In order to maintain enzyme activity, phosphate buffer solution was circulated into a flow cell attached on the sensing region. Characterization of the bio-sniffer was carried out using a standard-gas generator. The calibration range of the bio-sniffer was from 2.5 to 10000ppb, including the maximum permissible concentration of formaldehyde in workplace (80ppb). The bio-sniffer showed high gas-selectivity (HCHO:CH₃CHO = 100:1.59) due to substrate specificity. Potential application of the bio-sniffer is continuous formaldehyde monitoring in residential atmosphere.

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ナノ孔ガラスと赤外分光を用いたベンゼン・トルエン・キシレンセンサの検討

城西大理^a，国立環境研^b，ソナック^c

○犬塚 俊介^a，紺野 東一^a，尾崎 裕^a，内山 政弘^b，長澤 浩^{c *}

A STUDY ON SENSORS FOR BENZENE, TOLUENE AND XYLENE BY USE OF
POROUS GLASS AND IR SPECTROSCOPY

Shunsuke INUDZUKA ^a, Toichi KONNO ^a, Yasushi OZAKI ^a, Masahiro Utiyama ^b and Hiroshi Nagasawa ^c,*

^a Faculty of Science, Josai University, Sakado-shi, Saitama 350-0295
^b National Institute for Environmental Studies, Tsukuba-shi, Ibaraki 305-0053
^c SONAC Inc., Minato-ku, Tokyo 105-0003

In order to develop a portable device for the measurement of VOC (Volatile Organic Compounds) concentrations, near-infrared (near-IR) spectroscopy and nano porous glass are used in this research. First, since peak intensities in the near-IR region are generally only 1％of those in the mid-IR region, the intensities in the spectrum of toluene absorbed in the nano porous glass, pores of which are covered by Si-OH, are investigated. As a result, it was found that the intensity of the peak at 1685 nm, which was assigned to the first overtone of aromatic CH stretching mode of toluene in porous glass, is about 10 times larger than that of the corresponding peak of liquid toluene. This indicates that the nano porous glass enhances the sensitivity to toluene not only by condensation but also by the larger transition probability. Second, the concentrations of toluene absorbed in nano porous glasses with pores covered by Si-OH, Si-O-Si and Si(CH₃)₃ in 50-800 ppm toluene air were measured as a function of elapsed time by use of the absorbance of the 1685 nm peak. Consequently, it was found that toluene was strongly absorbed in the glass with pores covered by Si(CH₃)₃. *Present address: NITTA Corp., Tokyo Branch, Chuou-ku, Tokyo 104-0061.

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インターロック用途を目指した電気化学式エタノールセンサの開発

フィガロ技研株式会社

○山本　吉弘、竹原　浩美、井澤　邦之、石橋　昇、兼安　一成

DEVELOPMENT OF ELECTROCHEMICAL Ethanol SENSOR FOR INTERLOCK USE

Yoshihiro YAMAMOTO, Hiromi TAKEHARA, Kuniyuki IZAWA, Noboru ISHIBASHI, Kazunari KANEYASU

Figaro Engineering Inc.,1-5-11 Senba-nishi, Mino, Osaka 562-8505, Japan

Alcohol Ignition Interlock System (AIIS) is one of the promising methods to prevent traffic accidents caused by drunk drivers. AIIS measures the breath alcohol concentration (BrAC) of a driver. If driver's BrAC is over a predetermined limit, AIIS prevents the engine from being started. Electrochemical sensor is used for AIIS because AIIS requires high accuracy to measure alcohol concentration and good selectivity to interference gases. Moreover, AIIS use alveolar air to accurately measure BrAC and the alveolar air in breath is sucked into the sensor with a pump. We report various characteristics of the sensor measured through sucking gas into the sensor with a pump. The sensor shows excellent linear relationship between C₂H₅OH concentration in sample gas and its of measurement concentration in the range of 0.00～0.75 mg/ℓ. The sensitivity of interference gases is much lower than sensitivity of C₂H₅OH 0.10mg/ℓ. These characterizations pass the test of CENELEC₁₎ established EN50436-1 standard.

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電気化学式NH₃センサの応答改良

光明理化学工業株式会社

○中村　仁

RESPONSE TIME IMPROVEMENT OF AMPEROMETRIC NH₃ GAS SENSOR

Hitoshi NAKAMURA

Komyo Rikagaku Kogyo K.K.
1-8-28 Shimonoge, Takatsu-ku, Kawasaki-City 213-0006

One of the important technical problems of a conventional amperometric NH₃ gas sensor is slow response time, especially when the sensor is used under high temperature and high humidity conditions. We found that the response time of the sensor was faster with a decreased amount of the working electrode catalyst. We succeeded in getting the sensor which had a fast response time by controlling the working electrode catalyst.

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ペロブスカイト型酸化物を検知極に用いた電流検出型ジルコニアセンサのNOx応答特性

（財）ファインセラミックスセンター

○上田太郎、永野孝幸、大川元、高橋誠治

NOx SENSING CHARACTERISTICS OF ZIRCONIA-BASED
AMPEROMETRIC-TYPE SENSOR USING PEROVSKITE-TYPE OXIDE SENSING-ELECTRODE

Taro UEDA, Takayuki NAGANO, Hajime OKAWA, Seiji TAKAHASHI

Japan Fine Ceramic Center
2-4-1 Mutsuno, Atuta-ku, Nagoya, 456-8587

Sensing characteristics of the zirconia-based amperometric-type NOx sensor using yttria-stabilized zirconia (YSZ) and perovskite oxide sensing electrode (SE) were examined. We focused on using La-Sr based perovskite as SEs because these oxides have a property to decompose NO on a pair of adjacent oxide ion vacancies. As a result, the sensor using La_0.6Sr_0.4Co_0.98Mn_0.02O₃ showed high sensitivity as well as good selectivity to NO₂ at 600℃. The sensitivity was almost linear to NO₂ concentration in the range between 50 to 800 ppm, and a 90% response and recovery time to 400 ppm NO₂ were less than 20 s. Though the NO₂ response of the sensor was slightly affected by the changes in O₂ concentrations, it showed still high sensitivity in the examined range of 5 - 21 vol%.

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燃料電池作動型COセンサ膜と電極触媒の影響

静岡大院^a、静岡大工^b、東京ガス^c、矢崎資源^d

○望月　計^a,d、山本　新^b、菊池　貴之^b、須藤　雅夫^a,b、
堀米　宏規^c、石黒　義昭^d、鈴木　隆之^d

EFFECTS OF MEMBRANE AND ELECTRODE CATALYST ON FUEL CELL TYPE CO SENSOR

Kei Mochizuki^a,d, Arata Yamamoto^b, Takayuki Kikuchi^b, Masao Sudoh^a,b,
Hironori Horikome^c, Yoshiaki Ishiguro^d and Takayuki Suzuki^d

^a Graduate School of Science and Technology, Shizuoka University,
^b Department of Materials Science and Chemical Engineering, Shizuoka University,
Hamamatsu, Shizuoka 432-8561 Japan
}^c Product Development Department, Tokyo Gas Co., Ltd.
Minamisenju, Arakawa-Ku, Tokyo 116-0003 Japan
^d Gas Equipment Development Center , Yazaki Resources Co.Ltd.
Hamamatsu, Shizuoka 431-3393 Japan

With the progress in the airtight of modern structures and the increasing use of various gases appliances within concentrated areas, a serious carbon monoxide (CO) poisoning occurs more possibly. Such a situation makes it become increasingly important to detect low concentration CO caused by incomplete combustion within combustor or fire. In order to improve these problems we have developed new amperometric sensor based on proton-conducting membranes for sensing CO of exhaust gases. The sensor performance was affected by loading change in cathode catalyst rather than anode catalyst.

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単結晶YSZ上に形成したAu検知極のガス応答特性

九大炭素資源センター ^a、九大院総理工 ^b、九大産学連携センター ^c

○ブラディミル プラシニツァ^a、藤尾 侑輝^b、三浦 則雄^c

GAS SENSING PROPERTIES OF Au-SENSINIG ELECTRODE FORMED ON SINGLE-CRYSTAL YSZ

○Vladimir V. PLASHNITSA^a, Yuki FUJIO^b, Norio MIURA^c

^a Research and Education Center of Carbon Resources, Kyushu University,
Kasuga-shi, Fukuoka 816-8580
^b Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,
Kasuga-shi, Fukuoka 816-8580
^c Art, Science and Technology Center for Cooperative Research, Kyushu University,
Kasuga-shi, Fukuoka 816-8580

The nano-structured gold sensing electrodes (SEs) were fabricated on single-crystal (sc; (100) and (111)) yttria-stabilized zirconia (YSZ) plates by using a colloidal gold solution of 5 nm. The divergence in surface profile of the blank sc-YSZ plates as well as the high-temperature treatment of Au colloids resulted in obtaining the different morphologies of Au-SEs; large square-like Au domains (ca. 5×5 μm) on YSZ(100) and triangular-like Au domains with the size of 2-3 μm on YSZ(111). The fabricated sc-YSZ-based sensors using nano-Au SEs of the different shape was found to give a large discrepancy in their gas sensing characteristics. While the sensor based on YSZ(100) treated with Au gave high emf responses to non-methane hydrocarbons (HCs) at 700℃ under the wet (5 vol.% H₂O) condition, the sensor based on YSZ(111) showed high sensitivity and selectivity to NH₃.

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3価のアルミニウムイオン伝導体を用いたアンモニアガスセンサ

阪大院工^a、学振^b

○永井つかさ^a,b、田村真治^a、今中信人^a

A NOVEL AMMONIA GAS SENSOR BASED ON
TRIVALENT ALUMINUM CATION CONDUCTING SOLID ELECTROLYTE

Tsukasa NAGAI ^a,b, Shinji TAMURA ^a, Nobuhito IMANAKA ^a

^a Department of Applied Chemistry, Faculty of Engineering, Osaka University,
2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
^b Japan Sosiety for the Promotion of Science,
1-8 Chiyoda-ku, Tokyo 102-8472, Japan

Ammonia gas is one of the useful gas species in the industrial field. However, ammonia gas is very toxic, and the ammonia gas sensor showing the exact gas detection with a rapid response is greatly requested for prevening the serious accidents. In this work, we fabricated a new solid electrolyte type ammonia gas sensor by the combination of the trivalent aluminum ion conducting solid electrolyte (Al_0.2Zr_0.8)_20/19Nb(PO₄)₃ with La₂O₂SO₄-(NH₄)₂HPO₄ as an auxiliary sensing electrode, and its ammonia gas sensing performance was investigated. Since the present sensor shows a superior sensing performance of continuous and reproducible response with obeying the theoretical Nernst relationship between sensor EMF output and logarithm of the NH₃ gas concentration even under humidified condition, it is greatly expected to be a practical NH₃ gas detecting tool.

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ジルコニアを用いた濃淡電池型VOCセンサ —Pt電極をAuでコートすることによる特性の改善—

愛媛大院理工

森　雅美、○定岡芳彦

POTENTIOMETRIC VOC DETECTION USING 8YSZ BASED OXYGEN SENSOR MODIFIED WITH Au

Masami MORI and Yoshihiko SADAOKA

Graduate School of Science and Engineering, Ehime University,
3 Bunkyo-cho, Matsuyama 790-8577

Potentiometric oxygen sensor was fabricated and applied to detect several volatile organic compounds (VOCs) at sub-ppm levels in the temperature range of 400-500 oC. For the sensor in which two platinum electrodes formed on the surface of 8YSZ sheet and one side Pt electrode was covered with Au layer, EMF was responded to contamination of ambient with several VOCs (acetic acid, methylethylketone, ethanol, benzene, toluene, o-xylene, p-xylene). The electromotive force (EMF) linearly changed with an increase in the concentration of VOCs. The sensing characteristics for all the VOCs examined in this study were enhanced, while the response and recovery times were prolonged b the coating of Pt electrode with Au. These phenomena are due to the change of the activity of oxygen ion at the three-phase boundary composed with gas-Pt-YSZ. The obtained results showed that the Au layer formed onto the Pt electrode depressed the diffusion of oxygen from the surface of the Au layer to the three-phase boundary when the air contaminated with VOCs was exposed to the device.

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金属酸化物で修飾した混成電位式アンモニアセンサにおける焼成温度と酸塩基性効果

名古屋大^a、日本特殊陶業^b

○片桐誠^a、清水研一^a、柿元志郎^b、菅谷聡^b、松谷渉^b、薩摩篤^a

EFFECTS OF CALCINATION TEMPERATURE AND ACID-BASE ON MIXED
POTENTIAL AMMONIA SENSOR MODIFIED BY METAL OXIDE

Makoto KATAGIRI^a, Kenichi SHIMIZU^a, Shirou KAKIMOTO^b,
Satoshi SUGAYA^b, Wataru MATSUTANI^b, Atsushi SATSUMA^a

^a Department of Molecular Design and Engineering, Nagoya University,
Nagoya-city, Aichi 464-0814
^b R&D Center, Engineering R&D Group, NGK Spark Plug Co.Ltd,
Komaki-city, Aichi 485-8510

For mixed potential sensors comoposed of yttria-stabilized zirconia (YSZ) as a solid electrolyte, a reference electrode, and a sensing electrode which is a mixture of Au and various metal oxides, the effects of calcination temperature and acid-base property of metal oxides are examined. The selective sensing of NH₃ was achieved by modification of sensing electrode by MoO₃, Bi₂O₃ and V₂O₅, while that by CuO, WO₃, Nb₂O₅ and MgO was not effective. The dependence of the relative sensitivity to NH₃ on calcination temperature suggested that the selective detection of NH₃ is affected by both melting point and acidity of metal oxides.

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安定化ジルコニアとNiO系検知極を用いた混成電位型プロペンセンサ

九大院総理工^a、九大炭素資源センター^b、九大産学連携センター^c

○藤尾 侑輝^a、V. V. プラシニツァ^b、P. エルマレイ^c、三浦 則雄^c

MIXED-POTENTIAL-TYPE PROPYLENE SENSOR USING YSZ AND NiO-BASED OXIDE

○Yuki FUJIO ^a、Vladimir V. PLASHNITSA ^b、Perumal ELUMALAI ^c、Norio MIURA ^c

^a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,
Kasuga-shi, Fukuoka 816-8580
^b Research and Education Center of Carbon Resources, Kyushu University,
Kasuga-shi, Fukuoka, 816-8580
^c Art, Science and Technology Center for Cooperative Research, Kyushu University,
Kasuga-shi, Fukuoka 816-8580

The yttria-stabilized zirconia (YSZ)-based sensor using oxide sensing-electrode (SE) was fabricated and examined its sensing characteristics to propylene (C₃H₆), one of representative hydrocarbons (HCs). Among various oxide-SEs examined, NiO-SE was found to give the highest sensitivity to C₃H₆ at 600℃ under the wet condition (5 vol.% H₂O), but the selectivity to C₃H₆ was poor. Thus, to improve the sensing performance, NiO-SE was further mixed with each of several oxides (50 mol.%) by ball-milling method. As a result, the sensor attached with NiO (+ 50 mol% TiO₂)-SE exhibited highly selective and sensitive response to C₃H₆ at 650℃. In this case, it was confirmed that the SE was composed of NiTiO₃. The 90% response and 90% recovery time to 100 ppm C₃H₆ was as relatively short as ca. 10 s and ca. 20 s, respectively. In addition, the electromotive force (emf) response of the present sensor varied almost linearly with the logarithm of C₃H₆ concentration in the examined range of 10 - 800 ppm.

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