Vol. 9, Supplement B (1993)

Vol. 9, Supplement B (1993)

Proceedings of the East Asia Conference on Chemical Sensors
(Proceedings of the 17th Chemical Sensor Symposium)
October 12-13, 1993
Fukuoka Sun Palace, Fukuoka, Japan

Abstracts

[PL1]

Porous Ceramics For Sensor Applications

Yao Xi, Zhang Liang-Ying, Sun Hong-Tao, Wu Ming-Tang and Wang Sa-Sa

Electronic Materials Research Laboratory, Xi'an Jiaotong University
Xi'an 710049, China

In order to enhance the sensing effect and to improve the sensing behaviors, porous ceramic and porous silica are used to prepare chemical sensors. A porosifier has been introduced to prepare porous ceramics. The control of porosity and pore size of the ceramic as well as their effect on sensing behaviors are presented. Sol-gel technique has been used to prepare porous silica. The various ways of loading the porous silica with active sensing component are discussed.

[PL2]

Some New Advances In FET-Type Microbiosensor Technology

Byung-Ki Sohn

Sensor Technology Research Center, Kyungpook National University
Taegu 702-701, Korea

A new signal detecting circuit composed of only MOS devices for the FET type micro-biosensors and a H₂O₂ electrolytic technique for performance enhancement, useful for the enzyme micro-biosensors related to the H₂O₂ generating reaction in operation, have been described. The discussion is extended to the micro-miniaturization of reference electrode and an on-chip integration of sensor/reference electrode/signal processing circuit used the new signal processing circuit and the micro-miniaturizing reference electrode. Their performance characteristics and responses are so good that those technique can be widely adapted.

[PL3]

From Biocatalytic to Bioaffinity Sensors

Masuo Aizawa, Yohsihito Ikariyama, and Eiry Kobatake

Department of Bioengineering, Tokyo Institute of Technology
Nagatsuta, Midori-ku, Yokohama 227, Japan

Current development of bioaffinity sensors is presented with three examples; an optical immunosensor for homogeneous immunoassay, an electrochemiluminescent sensor for DNA-interacting antitumor and antiviral agents, and a bioluminescent sensor for environmental hazardous organic compounds.

[1A01]

Development of a High Performance Humidity Sensor

Chao-Nan Xu and Kazuhide Miyazaki

Department of Chemical Engineering, Faculty of Engineering, Fukuoka University
8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-01, Japan

The structure, oxidization properties, and humidity-sensitive characteristics under both ac and dc fields of MnO₂-Mn₃O₄ elements were studied. An correlation between the oxidizable ability and humidity sensitivity has been found. There are three types of Mn₃O₄-based humidity sensors in this respect. "Type I", very easy to be oxidized, can detect humidity over the whole relative humidity range, but lacks stability in the performance, probably due to its thermally unstable microstructure. "Type II", able to be oxidized by some oxidizing catalysts, produces the most stable sensing properties, can detect humidity over 0-100%RH with high sensitivity under both ac and dc field. "Type III", unable to be oxidized, is not sensitive to humidity below 50% RH, also showing small change in resistance over the range of 50-100%RH.

[1A02]

Humidity Sensor Durable at High Humidity Using Cross-linked Hydrophilic Polymers

Yoshiro Sakai, Masanobu Matsuguchi, Yoshihiko Sadaoka and Hiroki Sakai

Department of Applied Chemistry, Faculty of Engineering, Ehime University
3 Bunkyo-cho, Matsuyama 790, Japan

In order to prepare resistive type humidity sensors using hydrophilic polymers, several cross-linking methods were proposed to make the polymers insoluble in water. From the results of durability test in water, it was found that the simultaneous formation of hydrophilic site and cross-linking is the most promising method in view of simplicity of procedure as well as durability in water. The results obtained with the sensor composed of the film of poly (chloromethyl styrene) cross-linked with N,N,N',N'-tetramethyl-1,6-hexanediamine are shown as an example.

[1A03]

Humidity Sensing Characteristics of TiO₂/SnO₂ Prepared by Coprecipitation and Precipitation Methods

Ji-Won Joo, Jong-Heun Lee, Soon-Ja Park

Department of Inorganic Materials Engineering, Faculty of Engineering, Seoul National University
Shilim-dong, Kwanak-Gu, Seoul 151-742, Korea

The sensing characteristics of TiO₂/SnO₂ system show large differences between solid solutions and simple mixtures of TiO₂ and SnO₂. These differences are thought to be caused by different kinds of adsorbed water species on the surfaces which may be resulted from the formation of solid solutions. These observations are closely related to the humidity sensing characteristics of TiO₂ and SnO₂ each. The mixtures show the similar sensing tendencies to those of SnO₂ sensors, which strongly suggests that the physisorbed water on SnO₂ and the mixture sensor surfaces have important effects on the characteristics. The solid solutions seem to have similar tendencies to those of TiO₂ sensors. The data evidently show that the chemisorbed water controls the sensing characteristics in both TiO₂ and (Ti, Sn)O₂.

[1A04]

A New Potential-Type Sensor Using Metal/MnO_x/Metal Cell System

Chao-Nan Xu, Seiji Hieda and Kazuhide Miyazaki

Department of Chemical Engineering, Faculty of Engineering, Fukuoka University
8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-01, Japan

An approach for a new potential type sensor is to use the battery systems M₁/MnO_x/M₂ as the sensing elements, where M₁/M₂ are the two electrodes of different metals, and MnO_x samples act as the solid electrolyte. Systems consisting of some MnO₂ electrolytes with Pt/Cu electrodes are most favorable to give rise high electrical potentials in a high humidity ambient. Moreover, the humidity response characteristics of these systems can be greatly improved by mixing certain amount of Mn₃O₄ into the MnO₂ electrolyte materials. For all systems, the potential value produced between the couple of Pt/Cu tends to equal the sum of those produced between Pt/Ni and Cu/Ni. A simple model is proposed to interpret the phenomena.

[1A05]

Nonlinear Humidity Sensor from Porous Silica

Hong-Tao Sun, Liang-Ying Zhang and Xi Yao

Electronic Materials Research Laboratory, Xi'an Jiaotong University
Xi'an 710049, China

Porous silica coatings with 10% porosity and average pore radius of 20Ѓр were derived from sol-gel process. Capacitance and loss tangent of the coatings are sensitive to the changes in humidity. They are approximately constants below 60%RH, and increase by 1.6 and 2.7 times respectively, up to 100% RH. A capacitive sensor from the coating appears to be more durable and stable compared to the frequency-type one. Based on Kelvine equation of adsorbed and condensed water, and dielectric equation of composites, a theoretical description of the nonlinear property has been made.
[Key Words: humidity sensor, silica, capacitance, relative humidity]

[1A06]

Multi-Sensor Using a Limiting Current Type Plane Oxygen Sensor

Hideaki Yagi and Keiichi Ichikawa

Research and Development Center, NGK SPARK PLUG CO., LTD.
2808 Iwasaki Komaki Aichi 485, JAPAN

High temperature humidity sensor using a limiting current type plane oxygen sensor has been developed under ambient and normal air. However, when this sensor was used for a direct firing system, errors of humidity measurement are caused by the influence of changes of O₂ and CO₂ concentration. To solve above problems, the sensor element with plural pairs of electrodes on the surface was produced by using the advantage of a plane structure and this sensor can simultaneously measure O₂ concentration and water vapor pressure. We have investigated humidity sensing characteristics of this sensor changing O₂ and CO₂ concentration. As a result, the multi-sensor which is possible to use for the direct firing system has been developed.

[1A07]

Gas Sensing Characteristics of Multi-layer of Iron Oxide Thin Films

B. C. Chun Yu, S. Zhao, W. Zhang and J. Lu

Department of Chemistry, Shandong University
Jian, 250100, Shandong, China

Multi-layer metal-oxide of SnO₂, Fe₂O₃ thin films have been prepared by using Metal-Organic Chemical Vapor Deposition (MOCVD) technique. The crystal structure and morphology of multi-layer thin films was measured by X-ray diffraction analysis and Scanning Electronic Microscope respectively. The properties of multi-layer SnO₂, Fe₂O₃ thin films are sensitive to acetone with high sensitivity. The minimum concentration of acetone at 5 ppm can be detected and it also sensitivity to alcohol and LPG gases without any noble metal catalysts. Another, the selectivity was improved and the good stability was also obtained.

[1A08]

Organic Vapor Sensing Characteristics of Polypyrrole Thin Films

Hiroyasu Nagase, Hiroyuki Abe, Toshinobu Imanaka and Michio Matsumura^*

Department of Chemical Engineering, Faculty of Engineering Science, Osaka University
Toyonaka, Osaka 560, Japan
^* Research Center for Photoenergetics of Organic Materials, Osaka University
Toyonaka, Osaka 560, Japan

Polypyrrole films are potential sensing materials for various organic vapors. Polypyrrole films doped with BF₄^-, ClO₄^- or SO₄^2- and those doped with p-toluenesulfonate or poly(4-styrensulfonate) showed decreased and increased electric resistance, respectively, when exposed to methanol vapor. Poly-3-methylpyrrole showed similar behavior, while the response of poly-N-methylpyrrole to methanol was opposite to that of polypyrrole and poly-3-methylpyrrole. From XPS measurement, it is concluded that cationic (or oxidized) sites of polypyrrole films doped with small anions have strong electrostatic interaction with the anions. As a result, the positive charge is delocalized and resistance is lowered.

[1A09]

High Sensitive Ca Ion Doped SnO₂ Thick Film Methane Sensor

Young-Ho Hong, Wan-Young Chung^*, Jae-Hyun Lee, Duk-Dong Lee

Department of Electronics, Kyungpook National University
1370 Sangyeok-dong, Buk-gu, Taegu 702-701, Korea
^* Department of Electronic Engineering, Semyung University
Shinwul-dong, Jecheon, Choongpuk 390-230, Korea

High sensitive SnO₂-based thick film methane gas sensors were fabricated using fine particle Ca ion-doped tin oxide powder and the electrical and sensing characteristics were investigated. By Ca addition, the crystal growth of SnO₂ was suppressed during calcining and sintering, and the sensitivity of SnO₂ to methane gas was enhanced.

[1A10]

Characteristics of Pulse Drive Semiconductor Gas Sensor

Maki Kitora, Taro Amamoto, Yoshinobu Matsuura and Yoshihisa Kajiyama

Advanced Materials Research Dept., Figaro Engineering Inc.
1-5-3 Senbanishi, Minoo City, Osaka 562, Japan

A pulse drive gas sensor was developed to lower power consumption. The sensor element has a multilayer structure which was formed by a printing process on an alumina substrate. The SnO₂ layer was heated by the RuO₂ heater pulsatively. In the case of a duty ratio of 8/1000 every 1 sec, the effective power consumption was about 14 mW. The sensor showed good selectivity to CO and H₂ by using a charcoal filter, and showed good characteristics for gas response, temperature and humidity dependency, durability and long-term stability.

[1A11]

Effect of Doping Methods on the Gas Sensing Properties of ѓї-Fe₂O₃

Jiaqiang Xu, Zhizhuang Tian and Wenhui Zhu

Department of Chemical Engineering, Zhengzkou Institute of Light Industry
Zhengzhou 450002, China

SnO₂ doped ѓї-Fe₂O₃ gas sensing materials were made by hydrolysis and chemical coprecipitation from the solution of Fe(III) ions mixed with Sn(IV) ions, respectively. The microstructure of the materials were analyzed with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The resistance change of the sensors made from the above materials were measured in different atmosphere and heating power. 2wt%SnO₂ doped ѓї-Fe₂O₃ (hydrolysis) sensor has several features, such as fine particle (40 nm), high sensitivity (R_a/R_g=18, 2000 ppm C₄H₁₀), low resistance (10⁵-10⁶ѓ¶), low power (0.5-0.7 W) and good stability.

[1A12]

Recognition of Human-life Behavior by Gas Sensor Using a Production System

Takashi Oyabu, Haruhiko Kimura^*, Yoshinobu Matsuura^** and Shozo Ishizaka

Toyama University of International Studies, Department of Sociology
Oyama-cho, Toyama 930-12, Japan
^* Kanazawa University, Department of Electrical and Computer Engineering
Kodatsuno, Kanazawa 920, Japan
^** Figaro Engineering
Senbanishi, Minoo-shi, Osaka 562, Japan

Awakening and sleeping are recognized by a sensor system composed of a tin oxide gas sensor and OPS5. Daily indoor air-pollution is detected precisely by recognizing various human-life behaviors, e. g. awakening and sleeping. The recognitions are done using daily output-patterns of the gas sensor and the patterns are very similar to each other. Indoor air pollution can be detected accurately by laying an awakening hour of a daily periodical pattern on top of another awakening hour. OPS5, which is one of the production systems, is used in recognizing. Rete match algorithm is also adopted in order to match the patterns and the inference of the recognition is done at a high rate.

[1A13]
Smoke-Detector Signal Processing Circuits

Aroutiounian V. M., Adamian Z. N., Panossian M. S., Barsegyan A. A., Abovian H. V.

Yerevan State University
1 Manoukian Str., Yerevan 375049, Republic of Armenia

It is reported about two new possibilities of smoke-sensors connection, the circuits operating principal. Proposed by us sensor (US Patent invention No. 07/943, 071) is high sensitive to smoke and does not require additional preheating during operation.
One type of signal processing circuits included the operational amplifier, second type of processing circuits is logical integral circuit made by complementary metal-oxide-semiconductor field-effect-transistors technology. Microcircuit includes logical NAND and OR-AND cells with two inputs each. It is discussed merits and deficiencies of those processing circuits.
Smoke detectors signal processing circuits reported allows to consume extremely low power (consumed current in the waiting mode was less than 2 nA at nominal voltage 7-15 V) with high sensitivity (responsitivity less than 4% per foot), quick response in time (tenth parts of second), high accuracy and reliability.

[1B01]

Electrochemical Behaviors of Benzoquinone and Ferrocene Monocarboxylic Acid at a Polyaniline Coated Platinum Electrode and Its Applications in Biosensor Research

Zong-Rang Zhang, Wei-Fang Bao, Chung-Chuin Liu^*

Department of Chemistry, Shanghai Teacher's University
10 Guilin Road, Shanghai 200234, CHINA
^* Electronics Design Center, and Edison Sensor Technology Center, Case Western Reserve University
Cleveland, OH 44106, USA.

A Polyaniline coated platinum electrode is prepared by potentiostalic polymerization in acidic solution and it shows electroactivity in a weak acidic medium. The polyaniline layer on this modified electrode can be used as the substrate for glucose oxidase entrapment. The electrochemical behaviors of benzoquinone and ferrocene monocarboxylic acid, which can be used as mediators for enzymatic reaction at a polyaniline modified electrode, are studied. Significant enhancement of the reaction rate and the reversibility of benzoquinone/hydroquinone couple is observed. Benzoquinone and ferrocene monocarboxylic acid are used in the catalytic cycle of a glucose oxidase-glucose system. A polyaniline based glucose oxidase sensor with soluble benzoquinone or ferrocene monocarboxylic acid in test solution displays a good response to the concentration of glucose.

[1B02]

Optimal Blood Glucose Regulations in Ambulatory Diabetic Patients with Wearable Artificial Endocrine Pancreas
- Application of Newly Designed Biocompatible Membrane -

Michiharu Sakakida, Kenro Nishida, Yasuhiro Hashiguchi, Motoaki Shichiri, Kazuhiko Ishihara^* and Nobuo Nakabayashi^*

Department of Metabolic Medicine, Kumamoto University School of Medicine
1-1-1 Honjo, Kumamoto 860, Japan
^* Institute for Medical and Dental Engineering, Tokyo Medical and Dental University
2-3-10 Surugadai, Kanda, Chiyoda-ku, Tokyo 101, Japan

To prepare the long-life and stable glucose sensor, a newly designed biocompatible membrane, 2-metahcryloyloxyethyl phosphorylcholine (MPC) membrane, has been developed and its characteristics in vitro and in vivo were examined. 1. A ferrocene-mediated needle-type glucose sensor covered with MPC membrane possessed excellent characteristics in vitro experiments. 2. With this sensor, subcutaneous tissue glucose concentrations could be monitored and followed nicely to the changes in blood glucose concentrations for up to 7days without any in vivo calibrations. 3. In ambulatory diabetic patients, physiological glycemic control could be obtained by the application of wearable artificial endocrine with ferrocene-mediated needle-type glucose sensor covered with MPC membrane for longer-period by replacing the sensor every 7th days. We therefor concluded that ferrocene-mediated needle-type glucose sensor covered with MPC membrane was stable and reliable, and could be applied for continuous glucose monitoring and for glycemic regulations with wearable artificial endocrine pancreas in diabetic patients for longer-period.

[1B03]

Preparation and Characterization of N-Substituted Polypyrrole/Nafion Thin Film Electrode Having Immobilized Glucose Oxidase

Mikito Yasuzawa, Hiroshi Sasaki and Akira Kunugi and Hiromu Satake^*

Department of Chemical Science and Technology, Faculty of Engineering, University of Tokushima
^* Center for Cooperative Research, University of Tokushima
2-1 Minami Josanjima, Tokushima 770, Japan

Glucose sensors having immobilized glucose oxidase (GOD) with a layer of cation exchange film, Nafion, were prepared by two processes; (1) the Nafion film coating process and (2) the GOD immobilizing process (electropolymerization of 1-pyrrole propionic acid (PPA) in the presence of GOD). After the introduction of the Nafion film inside the GOD immobilizing layer, the interference of uric acid on the glucose response was significantly inhibited without reducing its sensitivity. However, ascorbic acid interference still slightly occurred. This sensor also exhibits good selectivity against common interference except for the exogenous drug acetaminophen.

[1B04]

Thin Film Electrode Based on TCNQ Complex and Immobilized Enzyme for Glucose Sensor

Yoshihisa Kishimoto

Advanced Technology Research Laboratories, Sumitomo Metal Industries, Ltd.
1-8 Fuso-cho, Amagasaki-shi, Hyogo 660, Japan

Thin film of TCNQ (tctracyanoquinodimethane) complex and immobilized glucose oxidase (GOD) was prepared as a new type enzyme electrode, and evaluated for an amperometric glucose sensor application. This enzyme electrode was coated with two layers. The inner layer was TCNQ charge transfer complex, which was prepared by the spontaneous electrolysis of Ag substrate in TCNQ solution. The outer layer was consist of GOD and electron mediator (dimethylferrocene, DMFe) which were dispersed uniformly in the polymer matrix. A glucose sensing system was constructed by placing the counter electrode near the enzyme electrode. This system showed a rapid current response to a drop of glucose solution and a linear relationship between the response current and the glucose concentration by applying low potential. Therefore the system was applied to the human serum containing up to 25 mM glucose without preliminary treatment (diluting or mixing the sample).

[1B05]

Electrocatalysis of Tetracyanoquinodimethane (TCNQ) Modified Electrode for NADH Oxidation

A. Surya, N. Murthy, Anita and R. L. Gupta

Department of Chemistry, Indian Institute o Technology
New Delhi-110 016, India

A TCNQ-modified edge-plane pyrolytic graphite electrode, prepared by dip coating and electrodeposition procedures shows electrocatalytic activity for NADH oxidation in phosphate butter solutions (pH 7.0). The modified electrode is stable and shows linear calibration for NADH in the concentration range 0-10 mM. The modified electrode is potentially useful to function as sensor for dehydrogenase enzyme based substrates.

[1B06]

The Mechanism of Blood-Compatibility of Some Materials Used in Biomedical Sensors

A. S. Poghossian

State Engineering University of Armenia, Department of Design and production of Radio Apparatus
Terian Str. 105, 375009, Yerevan, Armenia

Blood clotting is the most obvious indications of the biological incompatibility of materials, being in contact with blood. At present no one of the proposed mechanisms of interaction blood with foreign body don't completely explain the antithrombogenic properties of the materials. The most important factors, defining the antithrombogenic properties of materials are the surface state charges and electrochemical phenomena, take place at the solid state-blood interface. In this paper are presented the results of the investigation of blood clotting time for 13 various materials, which are widely used in biomedical chemical sensors technology, in particular for production ISFETs, ISFET-based gas and biosensors, humidity sensors, etc. Amongst of these materials silicon wafers; SiO₂, Si₃N₄, Ta₂O₅, Al₂O₃ films; PVC and Teflon films; others packages and polymers. The highest blood compatibility (to say nothing of Teflon) have Si₃N₄ and Ta₂O₅ films, which allows to use them as membranes in biomedical pH sensitive ISFETs for endurable in vivo measurements. The least blood compatibility have glass, Si and SiO₂ films.
Using the site-binding model we suggest a mechanism, which allows to explain the high antithrombogenic properties of Si₃N₄ and Ta₂O₅ films. It is known, that the surface to these films contains hydroxyl groups, the dissociation degree of which depends on the solution pH. At pH>pH_p.z.c. (p.z.c. = point of zero charge) the surface is charged negatively, which just takes place when the above mentioned films contact with blood. The negative surface charge prevents from adsorption stimulating thrombosis formation of the negatively charged proteins of blood plasma. The higher concentration of the surface hydroxyl groups, correspondingly the more surface negative charge of the materials at pH>pH_p.z.c, perhaps, call forth their high antitrombogenic properties.

[1B07]
Electrodeposition of BSA Film on the Electrode and Its Application to Enzyme Sensor

Jun-ichi Anzai, Bei Guo, Tomonori Hoshi and Tetsuo Osa

Pharmaceutical Institute, Tohoku University
Aobayama, Sendai 980, Japan

A thin film composed of bovine serum albumin (BSA) was prepared on the surface of platinum electrode by applying a constant potential to the electrode in the BSA solution. The BSA film was further modified with enzymes (glucose oxidase and lactate oxidase) to construct amperometric enzyme sensors. The BSA film-based enzyme sensor showed a satisfactory response to glucose or lactate. The experimental conditions such as electrode potential and electrolysis time in the electrodeposition of BSA film were systematically studied.

[1B08]
The Response Characteristics of Enzyme Embodied Electrode in Flow Injection Analysis

Masashi Yaoita, Yoshihito Ikariyama^*, Shigeru Yamauchi

Research Institute of National Rehabilitation Center for the Disabled
4-1 Namiki, Tokorozawa, Saitama 356, Japan
^* Dept. of Bioengineering, Tokyo Institute of Technology
4259 Nagatsuda, Midoriku, Yokohama 227, Japan

An enzyme-embodied electrode (EEE) fabricated by direct immobilization of enzyme on a platinized platinum (platinum black) electrode was adopted as a working electrode for glucose sensing in a flow injection analysis (FIA). We have reported that the peak current decreases with the increase in the flow rate, whereas the peak current of an electrochemical detector normally increases with a thin layer cell in FIA.
Cathodic reduction of potassium ferricyanide at a platinum black electrode in a flow cell was carried out to investigate the response behaviors EEE sensor. In FIA experiment, the peak current of a platinum black electrode decreased in spite of the increase in absorbance of ferricyanide. At high flow rate, we observed a delayed current response of ca. 0.2 s. The delayed time coincided with the time constant is obtained in a pulse voltammetric operation of EEE glucose sensor. These results indicate that diffusion process in an EEE sensor plays a very important role. We conclude that the anomalous behaviors of EEE in FIA are caused by the mass diffusion in porous electrode material.

[1B09]

High Sensitive LAP Biosensor Using a New Differential Measurement Method

Yasuyuki Kanai, Hidekazu Uchida, Masaaki Shimizu, Hitoshi Maekawa and Teruaki Katsube

Department of Information and Computer Science, Faculty of Engineering, Saitama University
255 Shimo-Okubo, Urawa, 338 Japan

A new differential measurement method applicable to a LAP (Light Adressable Potentiometric) sensor was proposed and it was applied to construct an integrated enzyme sensor. Major advantage of this system is that highly stabilized sensing response was expected by the noise compensation effect of the differential measurement. Miniaturization of the LAP sensor was also attained by using small size metal pseudo reference electrode instead of a robust glass electrode.

[1B10]

Glucose Sensitivity of Gold Electrodes Having Immobilized Glucose Oxidase and 2-Aminoethylferrocene

Takeshi Okamoto, Yoshio Kajiya and Hiroshi Yoneyama

Department of Applied Chemistry, Faculty of Engineering, Osaka University
2-1 Yamada-oka, Suita, Osaka 565, Japan

A novel amperometric glucose sensor was fabricated in which glucose oxidase and 2-aminoethylferrocene as an electron mediator were chemically bound to self-assembled 4-aminothiophenol monolayers on gold electrode with use of glutaraldehyde bridges. The glucose sensor prepared under optimal conditions showed remarkable amperometric sensitivities to glucose of more than 30ѓКA cm^-2 for 20 mM of glucose.

[1B12]

Glucose-Sensor Electrode Based on Carbon Paste Containing Polyethylene Glycol-Modified Enzyme and Cobalt Phthalocyanine

Fumio Mizutani and Soichi Yabuki

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

An amperometric glucose-sensing electrode was prepared by incorporating a PEG-modified GOD and CoPc into CP. The modification of GOD was effective for enhancing the enzyme activity in the hydrophobic CP matrix, which resulted in a much higher activity of the modified enzyme than the native enzyme in the matrix. The low electrocatalytic activity of CP for oxidizing hydrogen peroxide was solved by introducing a catalyst, CoPc. The resulting enzyme electrode exhibited high performance characteristics such as rapid response (100% response, less than 5 s) and high sensitivity (detection limit, 2ѓКM).

[1B13]

Chemically Modified Screen-Printed Carbon Strip Electrodes

Jun Hu

Beijing Yi-Cheng Bioelectronics Technology Co., Ltd.
4/F, Building 214, Gao-Jia-Yuan Xiao Qu, Beijing 100015, People's Republic of China

The aim of this work was to develop a simple method situated to the mass production of disposable, chemically modified carbon-based strip electrodes printed on a special support material to meet the needs of Chinese huge clinical and biological research. The work attempts to our investigations with particular emphasis on details for glucose strip sensor construction and their subsequent evaluation in blood glucose determination and other biomedical and biological interest.

[2A01]

LaAlO₃-CaTiO₃-Solid Solution - A New Gas-Sensitivity Material

Zaven N. Adamian, Vladimir M. Aroutiounian, Ara A. Barsegyan, Manuk S. Panossian

Department of Semiconductors and Dielectrics Physics
Yerevan375049, Armenia

It is established that LaAlO₃-CaTiO₃ solid solution materials used for preparing capacitors can be promising sensitive materials for gas-detectors. Influence of smoke on the such a ceramics was investigated. Measurings of dependence of active resistance and tgѓВ on concentration of smoke in air at room temperature were carried out. The resistance was dropped from 10¹² Ohm up to 10⁹ Ohm, tgѓВ was increased up one order of magnitude at 10-15% of smoke in air.
It is established that tgѓВ does not depend on frequency in range 1 Hz-1 MHz, except the region 300-500 Hz, where the minimum of tgѓВ is observed. In point of minimum(Ѓ`400 Hz) tgѓВ was affected up to four orders of magnitude with measuring of smoke concentration.
Smoke detector with high sensitivity and small using power was created on the base above-mentioned new sensitive to smoke material.

[2A02]

Sensing Properties of LnMO₃/SnO₂ (Ln = Rare Earth, M = Transition Metal) Having a Heterojunction

Tomohiro Nagata, Osamu Makimoto and Tsuyoshi Arakawa

Department of Industrial Chemistry, Faculty of Engineering, Kinki University in Kyushu
Iizuka, Fukuoka 820, Japan

The I-V characteristics and sensing properties are investigated for a SmCo_1-xMn_xO₃/SnO₂ (x=0.2, 0.5, 0.7) element prepared by mechanically contacting two sintered pellets. SmCo_0.8Mn_0.2O₃ shown the strong rectification effect. It was found that the activity of these elements was correlated the magnitude of the activation energy (E_t) of trap level for SmCo_1-xMn_xO₃.

[2A03]

The Design and Characteristics of A Porphyrin LB Film ChemFET Gas Sensor

Changzhi Gu, Liangyan Sun^* and Tong Zhang^*

Institute of Atomic and Molecular Physics, Jilin University
130023 Changchun, P. R. China
^* Department of Electronics Science, Jilin University
130023 Changchun, P. R. China

Some new kinds of metal porphyrin derivatives were designed and synthesized. LB multilayer films of metal porphyrin derivatives were deposited on FET designed specially. The process of the interaction between the device and ambient gases such as NO₂, NH₃, CO and H₂S was studied at appropriate heating power. The results are showing that only cobalt porphyrin was sensitive to NO₂, and the length of aliphatic chains will effect the sensitivity, responsibility and stability.

[2A04]

Mechanism of Hydrogen Sensing by MIS Tunneling Diodes

Hikaru Kobayashi, Yasutaka Kogetsu and Yoshihiro Nakato

Research Center for Photoenergetics of Organic Materials, and Department of Chemistry, Faculty of Engineering Science, Osaka University
Toyonaka, Osaka 560, Japan

The mechanism of hydrogen sensing by Pt/silicon oxide/Si tunneling diodes has been investigated by the measurements of current-voltage (I-V) and conductance-voltage characteristics. It is concluded from the detailed analysis of the shifts of the I-V curves induced by hydrogen that the shifts are caused by the following three factors: i) the decrease of the Pt work function, ii) the internal filed-assisted movement of hydrogen ions in the silicon oxide layer, and iii) the formation of interface states. Due to factor i, the barrier height in the n-Si is lowered, while that in the p-Si is increased. Factor ii causes the dependence of the bias voltage at which a constant current flows on the voltage applied during the intervals of the measurement of the I-V curve. The formation of the interface states by hydrogen (factor iii) is evident from an increase in the electrode conductance.

[2A05]

A Study of I-V Characteristics of Hydrogen Switching Device with a Pd-Si Tunnel MIS Structure

Shinji Nakagomi and Tatsuo Yamamoto

Department of Electronic Materials, Faculty of Science and Engineering, Ishinomaki Senshu University
Minamisakai, Ishinomaki-shi, Miyagi 986, Japan

I-V characteristics of hydrogen switching devices with a Pd-Si tunnel MIS structure was studied. As tunneling layers, polycrystalline silicon prepared by plasma CVD was used. This device has a negative resistance switching property. Moreover threshold voltage of switching is sensitive to hydrogen gas concentration. The variation of I-V characteristics with a change in temperature was measured in some atmosphere. Measuring the dependence of the current in "off state" on temperature, it was clarified that the work function of surface varies with a change of atmosphere in condition.

[2A06]

A Surface Adsorption Based Model for an Integrated MOS Gas Sensor

Roy C. C. Li, Philip C. H. Chan, Peter W. Cheung

Department of Electrical and Electronic Engineering, Hong Kong University of Science and Technology
Clear Water Bay, Hong Kong

This paper presents a surface chemistry based circuit model which describes the performance of a MOS gas sensor. This model indicated that the heat of adsorption, q_ads, of the sensing gas, governs the adsorption behaviour and hence the sensitivity of the sensor. We have applied our model to three sensor systems, namely adsorption of H₂ on Pd/Pt gate, adsorption of NH₃ on platinum gate and adsorption of CO on palladium gate using data published in the literature. We found that the model correctly describes each sensor system. This model can easily be incorporated into the popular SPICE circuit analysis program. The performance of an integrated gas sensor, which comprises the front-end sensor and the signal-conditioning circuitry, can therefore be analyzed in the same manner as conventional integrated circuits.

[2A07]

Possibility of Galvanic Cell Type Hydrocarbon Sensor without Reference Materials

Takashi Hibino, Hiroyasu Iwahara and Tamotsu Yajima^*
Synthetic Crystal Research Laboratory, School of Engineering, Nagoya University
Furo-Cho, Chikusa-ku, Nagoya 464-01, Japan
^* TRK Corporation, Research and Development Center
3-1 Ohbata-cho, Tajimi 507, Japan

A galvanic-cell-type hydrocarbon sensor, which does not need any reference material, has been fabricated using a high-temperature-type proton conductor as a solid electrolyte. The test cell, La_0.6Ba_0.4CoO₃ | CaZr_0.9In_0.1O_3-ѓї | Au, gives rise to the stable EMFs for hydrocarbons (CH₄, C₂H₆ and C₃H₈) in air at 700ЃЋ. The linear relationship between EMF and hydrocarbon content is obtained, and the order of the sensitivity is given as C₃H₈Ѓ„C₂H₆Ѓ„CH₄. The sensing mechanism of the test cell is based on a steam concentration cell, which results from the difference in combustion activity for hydrocarbons between two electrode materials.

[2A08]

New Type NO_x Sensor Based on Capacitance Change

Tatsumi Ishihara, Shinobu Sato and Yusaku Takita

Department of Applied Chemistry, Faculty of Engineering, Oita University
Dannoharu 700, Oita 870-11, Japan

The effects of nitrogen oxide on the capacitance of the binary oxides generally contains WO₃ were investigated in this study. It is found that the capacitance of the mixed oxides are usable as a NO_x sensor based on the capacitance change. In particular, NiO-WO₃ element with Ag electrode exhibits the extremely high sensitivity to NO_x, but rather a long period was required to recover the original level after checking the NO introduction. On the other hand, mixed oxide of WO₃-ZnO exhibits the height sensitivity to NO_x and its capacitance increased with increases in the NO_x concentration up to 300 ppm. Although the sensitivity was decreased, application of Pt for the sensor electrode is effective for shortening the recover time and the almost a constant sensitivity to 100 ppm NO_x was obtained over 2 days.

[2A09]

Room Temperature Oxygen Sensor Using Lanthanum Fluoride as Solid Electrolyte

N. C. Chang^*, P. P. Tsai and W. H Chang*

Industrial Technology Research Institute, Materials Research Laboratories
195-5 Chung-hsing Rd., Set 4, Chutung, Hsinchu 31015, Taiwan, R. O. C.
^*Department of Biomedical Engineering, Chung Yuan Christian University
Chung Li 32023, Taiwan, R. O. C

Electrochemical solid state oxygen sensing element were fabricated using lanthanum fluoride (LaF₃) pressed pellet as solid electrolyte, platinum paste as working electrode, and tin and tin fluoride (SnF₂) sintered mixture as reference electrode. Copper wire as lead was attached to each electrode with silver paste. Studies of sensor response with respect to the oxygen partial pressure from 0 to 1 atm were undertaken at 25ЃЋ. The effect of humidity and temperature on the sensor response were also studied. The voltage response decreased almost linearly with respect to humidity from 30 to 90%RH at 25ЃЋ. The voltage decreased from 25ЃЋ to 100ЃЋ under constant humidity at 55%RH. Stable readings were obtained during the one-month rest in the atmosphere. AC impedance study of lanthanum fluoride solid electrolyte were also carried out.

[2A10]

Amperometric CO₂ Gas Sensor Based on Electrochemical Reduction of Platinum Oxide Formed on a PTFE Membrane

Toru Ishiji, Yoshikazu Shibasaki and Katsuo Takahashi^*

RIKEN KEIKI Co. Ltd.
2-7-6 Azusawa, Itabashi-ku, Tokyo 174, Japan
^* The Institute of Physical and Chemical Research (RIKEN)
Wako-shi, Saitama 351-01, Japan

An amperometric sensor for the detection of carbon dioxide (CO₂)was developed by utilizing the reduction of platinum oxide (PtO). The gas sensor consisting of a gas permeable PtO electrode and aqueous electrolytic solution was evaluated for CO₂ detection by controlled potential method. The sensor could measure the CO₂ concentration in the atmosphere without the interference of oxygen reduction. The sensor showed good response and stability for practical use.

[2A11]

Sensing Mechanism of Solid Electrolyte CO₂ Sensor Using NASICON and Metal-Carbonate Auxiliary Phase

Sachio Hosohara, Youichi Shimizu^*, Sheng Yao, Norio Miura and Noboru Yamazoe

Department of Materials Science and Technology, Graduate School of Engineering Sciences, Kyushu University
Kasuga, Fukuoka 816, Japan
^* Present address; Department of Chemistry, Faculty Engineering, Kyushu Institute of Technology
Tabata, Kitakyushu 804, Japan

In order to understand the working mechanism of a conventional solid electrolyte CO₂ sensor, three types of NASICON (Na₃Zr₂Si₂PO₁₂)-based devices attached with or without Na₂CO₃ were investigated for their EMF behavior upon variations in partial pressure of CO₂ or O₂ under various conditions. The results show that the EMF behavior of the conventional device coinciding with a 2-electron reduction of CO₂ (n=2) regardless of coexistent O₂ at 550ЃЋ is ascribable to the carbonate-sensing electrode interface, whereas the NASICON-sensing electrode interface dominates at 270ЃЋ, giving rise to complex EMF behavior.

[2A12]

A Proto-Type Carbon Dioxide Gas Sensor Based on Lithium and Oxide Ionic Conductors

Nobuhito Imanaka, Yohei Hirota and Gin-ya Adachi

Department of Applied Chemistry Faculty of Engineering, Osaka University
2-1 Yamadaoka, Suita Osaka 565, Japan

A proto-type carbon dioxide gas sensor, was set up by the combination of a LiTi₂(PO₄)₃ + 0.2 Li₃PO₄ sintered solid electrolyte and an oxide ionic conductor with a heating element. Because one surface of the Li⁺ conducting electrolyte was sealed with the oxide conductor, the sensor became compact and possible to insert in the atmosphere to detect. A linear relation was obtained between the sensor output and the CO₂ content from 250 ppm to 2% at 650ЃЋ. The slope of the line was in good agreement with the value obtained from the Nernst equation. A nitrogen dioxide existence (500 ppm) had little influence on the gas sensing. No interference was observed for the CO₂ detection from 500 ppm to 2% at the water vapor concentration of 0.86%. The proto-type sensor has a noticeable merit to detect the CO₂ gas with a continuous and accurate operation even on condition that the oxygen content and the ambient temperature are changing.

[2A13]

CH₃CN Gas Sensitivity of Think Film SnO₂ Sensors Added with SiO₂

Hyo-Derk Park, Jong-Pack Sohn^*, Duk-Dong Lee^**, Wu-Il Lee^**

Center for Advanced Materials Research, Korea Electronics Technology Institute
Seoul 135-080, Korea
^*Department of Industrial Chemistry, Kyungpook National University, Taegu 702-701, Korea
^**Department of Electronics, Kyungpook National University
Taegu 702-701, Korea

The highly selective CH₃CN gas sensor were fabricated by the screen printing and dipping method, and the sensing characteristics to CH₃CN gas was investigated. As one of the researches to examine closely the role of additives (Nb₂O₅ and SiO₂) in the SnO₂-based thick film devices, we analyzed the products of CH₃CN by the FT-IR method using the gas reaction cell, and investigated the sensing characteristics. The thick film devices showed high selectivity to CH₃CN gas and negative sensitivity by oxidizing agents (NO_x) produced during the reaction of CH₃CN vapor on the thick film.

[2A14]

NH₃ Selective Gas Sensor Using Sintered SnO₂ Semiconductor

Tadashi Takada and Hiromasa Tanjou

New Cosmos Electric Co., Ltd.
2-5-4 Misuya-naka, Yodogawa-ku, Osaka 532, Japan

The NH₃ selective gas sensor was examined by addition of Pd catalyst on a SnO₂ semiconductor. The sensor, in which Pd catalyst was distributed to be 6.3% of Pd atomic ratio to Sn on the sensor surface and 0.4% in the interior side of the sensor, had a high NH₃ selectivity in the presence of interfering inflammable gases. The sensitivity to 30 ppm NH₃ was higher than those to 500 ppm H₂, 1000 ppm CH₃OH, 500 ppm C₂H₅OH, 1000 ppm CH₃COCH₃, 3000 ppm C₇H₈ and so on. The long term stabilities in both the NH₃ sensitivity and the selectivity had been confirmed for over 1 year.

[2A15]

The Role of Catalysts in Ammonia Sensing Characteristics of Semiconductor Gas Sensor with Double-Layered Structure

Kenichi Miyazaki, Yuji Takao, Yasuhiro Shimizu and Makoto Egashira

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

To clarify the role of catalyst layers in semiconductor NH₃ gas sensors with double-layered structure, catalytic activity for NH₃ oxidation of the specimens used for the sensor has been investigated. The response behavior of the sensors could be well explained by the activity of the catalysts as well as the sensing material, In₂O₃-MgO(5 mol%). It was revealed that high performance of the sensor with a 0.5Ir/TiO₂ catalyst layer and interface electrodes could be ascribed to the lower activity of the catalyst for producing NO₂ and to the reduced interference from NO₂ generating in the sensing layer.

[2A16]

Improvement of NO Sensitivity of WO₃ Element with Pt-Loaded Zeolite Catalyst

Jun Tamaki, Hua-Min Zhang, Tatsuro Harada, Norio Miura and Noboru Yamazoe

Department of Materiaks Science and Technology, Graduate School of Engineering Sciences, Kyushu University
Kasuga-shi, Fukuoka 816, Japan

It was tried to improve the NO sensitivity of a WO₃ element with the addition of Pt-loaded zeolite catalysts. The zeolite (ferrierite) catalyst loaded with a small amount of Pt (1.6 wt%), which was active for oxidizing NO into NO₂, was found to enhance the NO sensitivity to the same level as that of the NO₂ sensitivity when NO concentration was below 10 ppm. It was estimated that the Pt particles in this case were accommodated inside the zeolite, being well separated off the WO₃ particles. This separation seemed to enable one to utilize the catalytic of Pt to improve the NO sensitivity of the element without suffering from an unfavorable electronic interaction between Pt and WO₃.

[2A17]

Gas Sensing Characteristics and Impedance Spectra of the SnO₂-Based Thin-Film Gas Sensor

Kwang Soo Yoo, Han Sang Song and Hyung Jin Jung

Division of Ceramics, Korea Institute of Science and Technology
P. O. Box 131, Cheongryang, Seoul, Korea

Pd-doped SnO₂ gas sensors which can be used commercially were fabricated by thermal oxidation process of Sn thin films. The thickness of SnO₂ thin films as a sensing layer was approximately 1800 A. Pd thin films with 30 A as a catalyst were evaporated on the surface of SnO₂ films. Sensitivities of SnO₂ thin films to H₂, CO, and CH₄ gases were measured. Impedance measurements of SnO₂ thin films were newly performed at various temperatures. As a result of impedance analysis, the conduction mechanism of SnO₂ thin films was due to the bulk conduction.

[2A18]

Thermal Analysis of Integrated Gas Sensor Chip Using Finite Element Method

Samuel K. H. Fung and Philip C. H. Chan

Department of Electrical and Electronic Engineering, The Hong Kong University of Science and Technology
Clear Water Bay, Hong Kong

One of the trends in solid-state gas sensor is to integrate heater and electronics on the sensor chip and to use an array of sensor to improve selectivity. This requires good thermal management on the chip. Commercially available three dimensional finite element software packages were used to perform the steady-state thermal analysis of integrated silicon gas sensor chips. Analysis was performed on four integrated gas sensor structures. This paper will present the simulation methodology and results.

[2A19]

Gas Response of Semiconductor Sensors

Vladimir M. Aroutiounian

Yerevan State University
1 Manoukian Str., Yerevan 375049, Republic of Armenia

In assumption that the binding energy of chemical sorption changes linear with the concentration of adsorbed particles it was received expressions for nonlinear dependence of excess concentration particles on gas pressure.

[2A20]

SnO₂ Thin Film Sensor to Detect Smouldering Odor

Yoshiaki Okayama, Koji Ueno, Michiharu Kobayashi, and Atushi Koide

Laboratory, Nohmi Bosai LTD
5058 Menuma, Menuma, Osato-gun, Saitama 360-02, Japan

In early stage of smouldering fires, odor generates from heated stuff before smoke particles are released. It indicates that an odor sensor is capable of detecting smouldering fires earlier than a smoke sensor detects them. We made SnO₂ thin film sensors by electron beam evaporation method to detect smouldering odor and investigated characteristics of sensor to odor from various smouldering stuff. The sensor's sensitivity to smouldering odor from cellulosic stuff and epoxy resin is high but that to hydrocarbon gases is low. It became cleat that odor give out from smouldering cellulosic stuff as levoglucosan (C₆H₁₂0₅) by electrospray mass spectrometer analysis. The sensor seems to be sensitive to levoglucosan, but so far the mechanism of adsorption has not yet been clear.

[2A21]

Highly Selective and Sensitive Alcohol Sensors Based on Doped SnO₂ Thick Films

Zhimei Qi, Yaohua Zhang, Honglin Tang, Mingqiang Li, Jinhuai Liu

Hefei Institute of Intelligent Mechines, Academia Sinica
Hefei Anhui 230031, China

SnO₂ thick film(TF) sensors doped with M (where M=Ca, Sr, Ba) and Sb elements were prepared by means of the screen print technique using doped SnO₂ powder produced by the sol-gel method. Crystallization of amorphous doped SnO₂ powder was investigated by XRD and DT analyses. The average crystallite sizes of SnO₂ after the power obtained by drying the sol calcinated at various temperature were 6.2 nm to 8.9 nm. The effects of the sintering temperature to electrical resistance and gas sensitive properties of elements were examined and analysed. The minimum resistance of TF was obtained after sintering at 700ЃЋ. The experimental results indicated that the rise in sintering temperature from 600 to 800ЃЋ decreased the sensitivity of elements and enhanced their resolution to alcohol from gasoline.

[2A22]

A Hydrogen Sensor Employing Zinc Oxide Varistors

Feng-Cang Lin, Yuji Takao, Yasuhiro Shimizu and Makoto Egashira

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

Current(I)-voltage(V) characteristics of ZnO varistors have been investigated under different H₂ concentration in air. In the temperature range 400ЃЋ-600ЃЋ, the breakdown voltage shifted to a lower electric field and the magnitude of the shift increased with an increase in H₂ concentration for all varistors tasted. Thus, it was found that a new type H₂ sensor can be developed by employing varistors. The highest H₂ sensitivity was achieved at 400ЃЋ with the ZnO varistor doped with 1.0 mol% Bi₂O₃ and 10 mol% Cr₂O₃ simultaneously.

[2A23]

The Effect of Laser Beams on the Surface Structure and Sensing Gas Properties of SnO₂ Ultrafine Particle Films

Xiaoren Pan, Yuancheng Lu, Hui Lu, Yongmei Li and Shanding Shi

Department of Physics, East China University of Chemical Technology
Shanghai 200237, P. R. China

The properties of SnO₂ ultrafine particle films used as gas sensors have a bearing on preparing conditions and post-treatment. In obtaining various properties of the film, we used a pulsed laser to irradiate SnO₂ ultrafine particle films. The surface analyses by SEM and XRD show that the surface morphologies of the films greatly changed and the crystal grains in the films aggregated and selectively grew in SnO₂(112) and SnO(102). The sensitivity of the irradiated film to C₂H₅OH decreased and the optimum operating temperature of sensing C₂H₅OH increased. Meanwhile, the sensitivity to gasoline gas increased and the optimum operating temperature of sensing gasoline gas decreased. This result was similar to that of the SnO₂ film with large-area crystal, which had been deposited on SiO₂(110) substrate.

[2A24]

High Sensitive Smoke Sensor Operated at Room Temperature

A. S. Poghossian, H. V. Abovian and V. M. Haroutunian

State Engineering University of Armenia, Department of Design and Production of Radio Apparatus
Terian Str. 105, 375009, Yerevan, Armenia

The search of new gas sensitive materials, having fast response and high sensitivity at room temperature without heating element is one of the basic research activities in the field of semiconductor gas sensors. In this paper the results of an experimental investigation of the characteristics of ceramic smoke sensor based on Bi₄Fe₂O₉, are presented. The smoke-sensitive elements are ceramic pellets with electrodes. The composition Bi₄Fe₂O₉ was synthesized by both the furnace method and a method of self-developing high-temperature synthesis(SHS). In comparison with conventional methods the SHS method is ecologically clean, wasteless, energy saving and highly productive. The phase composition of the synthesized material were all checked by X-ray diffraction analysis. The Bi₄Fe₂O₉ represented a double-phase mixture of the BiFeO₃ and Bi₂O₃ compositions. The double-phase character of Bi₄Fe₂O₉ was also confirmed by electron microscopic analysis, which showed that Bi₂O₃ formed a thin layer on the surface of BiFeO₃ grains.
D.c. electrical resistance measurements of the smoke sensitive elements were carried out at room temperature in the range of smoke concentration in air from 0 to 80 vol.%. Bi₄Fe₂O₉ samples show high sensitivity to smoke (under Ѓ`80 vol.% smoke concentration in air the sensitive element resistance is changed more than by a factor of 10³), fast response (the 90% response and recovery times are Ѓ`10s). The most advantage of Bi₄Fe₂O₉ based smoke sensor is its operation at room temperature without heating element. The mechanism of low temperature smoke sensitivity of Bi₄Fe₂O₉ are discussed. The obtained results shows the potential of using Bi₄Fe₂O₉ based smoke sensors in the devices of fire signalling, as well as for the control of environment pollution.

[2B01]

Self-Driven Sensor Based on Electromotive Force Induced by Sample Addition

Shunichi Uchiyama, Yasushi Hasebe, Seiji Maeda and Shuichi Suzuki

Department of Environmental Engineering, Faculity of Engineering Saitama Institute of Technology,
1690 Fusaiji, Okabe, Saitama 369-02, Japan

If the substance in the sample solution is to be oxidized (reduced) without external electric power supply, the redox potential of the sample solution must be sufficiently lower (higher) than the redox potential of the counter electrode solution. In contrast to the consumption of current during electrolysis, in this case, the current is generated from the added sample. Electrochemical method based on the integration of cell current generated by the electromotive force of the cell is named a self-driven sensor. This concept has been realized by using a coulometric cell with a carbon felt electrode impregnated with electrolyte not containing an electroactive species and counter carbon felt electrode impregnated with hexacyanoferrate(III) ion solution. The absolute determinations of L-ascorbic acid and NADH were carried out with nearly 100% discharging efficiencies and it was demonstrated that self driven coulometry exhibited the same properties as compared to conventional electrolytic coulometry using an external electric power supply.

[2B02]

Fabrication and Characterization of ISFET-based Sucrose Sensor

Soo-Keun Lee, Byung-Woog Cho, Chang-Soo Kim and Byung-Ki Sohn

Sensor Technology Research Cener, Kyungpook National University
Taegu, 702-701, Korea.

Sucrose sensors have been developed by using an enzyme co-immobilized pH-ISFET. The small dissociation constant of the gluconic acid, however, results in low sensitivity and slow response time of the conventional sucrose sensors. In order to solve these problems, an ISFET-based sucrose sensor containing a platinum electrode was fabricated. The sensitivity of the ISFET-based sucrose sensor with a platinum electrode was much increased, up to 35 mV/decade, due to the additional production of hydrogen ion through the electrolysis of hydrogen peroxide, while the response time was a little reduced.

[2B03]

Preparation of Hydrogen Peroxide Microsensor by Immobilization of Horseradish Peroxidase in Redox Hydrogels

Hideki Sakai, Ryo Baba, Kazuhito Hashimoto, Akira Fujishima and Adam Heller^*

Department of Synthetic Chemistry, Faculty of Engineering, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan
^* Department of Chemical Engineering, The University of Texas at Austin
Austin, Texas 78712-1062, USA

A hydrogen peroxide microsensor has been fabricated with horseradish peroxidase immobilized in poly[(vinylpyridine)Os(bipyridine)₂Cl] derivative-based redox hydrogel on a beveled carbon fiber microdisk (7ѓКm diameter) electrode. In the resulting sensor, the steady state H₂O₂ reduction current was 0.17 mA cm^-2 (for 0.1 mM H₂O₂) and the dynamic range of the sensor was from 5Ѓ~10^-7 M to 1Ѓ~10^-4 M. The current density at the microsensor was 10 times higher than that of a macroelectrode (3 mm) made with the same hydrogel. This higher current density is attributed to the radial diffusion of the electron through the redox hydrogel. Finally, this micro H₂O₂ sensor was applied for two dimensional mapping of H₂O₂ formed by the photocatalytic water cleavage reaction at the surface of a TiO₂-ITO composite film.

[2B04]

A Study of Cholesterol Oxidase Biosensor Based on Glassy Carbon Electrode Modified with Nafion and Methyl Viologen

Jin Litong, Zhao Guizhu, Fang Yuzhi and Jin Jiye

Department of Chemistry, East China Normal University
3663 Zhong Shan Road(N), Shanghai 200062, P. R. China

Determination of cholesterol is very useful in clinical diagnosis. Among various techniques for cholesterol analysis, enzyme electrode has received widespread attention. The conventional enzyme electrodes are based on noble metal electrodes which have slow response time and inferior resistance to interferences. In this paper, a cholesterol oxidase biosensor is constructed by using bovine serum albumin and glutarldehyde as cross linker to immobilize cholesterol oxidase and cholesterol esterase on glassy carbon electrode modified with Nafion and methyl viologen (MV). Cholesterol ester is converted to free cholesterol in the presence of cholesterol esterase and free cholesterol is converted to ketone and hydrogen peroxide in the presence of cholesterol oxidase. This results in a decrease in the concentration of dissolved oxygen and can be detected by the decrease of electrocatalytic redution current of DO at Nafion-MV modified electrode. The biosensor is used to determine total cholesterol in blood by cathodic scan voltammetry and the results are in good agreement with those by spectrophotometric method. The linear range of detection is 2.5Ѓ~10^-7 to 1.0Ѓ~10^-4 mol/L and the detection limit is 5.0Ѓ~10^-8 mol/L. The response time is 12 s. The life time of the present biosensor is 17 days. However, its response value decreases by about 2.5% for every 50 times of measurements. This biosensor has the advantage of high sensitivity, fast response time and superior resistance to interferences and therefore, will provide a good alternative for the determination of cholesterol in clinical analysis. In addition, thanks to the low detection limits obtained in this method, it is particularly useful when the usual volume of blood sample is difficult to get (e.g., in pediatric work) as only 0.1 ml of serum sample is required for the determination.

[2B05]

Development of Conductivity-Based Immunosensor for Sensitive Detection of Methamphetamine (Stimulant Drug) in Human Urine

Kaoru Yagiuda, Akihide Hemmi, Satoshi Ito, Yasukazu Asano, Yoshito Fushinuki^*, Chien-Yuan Chen^** and Isao Karube^**

DKK Corporation
4-13-14 Kichijoji Kitamachi, Musashino-shi, Tokyo 180, Japan
^* Scientific Investigation Research Laboratory, Kagoshima Pref. Police H. Q.
13-1 Yamashita-cho, Kagoshima-shi, Kagoshima 892
^** Research Center for Advanced Science and Technology, The University of Tokyo
4-6-1 Komaba, Meguro-ku, Tokyo 153

A portable immunosensor based on a conductivity detector was developed for determination of methamphetamine (MA, stimulant drug) in liquids. Anti-MA antibody was immobilized onto the surface of a pair of platinum electrodes. The reaction of MA with the antibody causes on increase in conductivity of the immobilized antibody. The conductivity of the electrode increased with the increment of MA concentration. A linear relationship was obtained between the conductivity and MA concentration in the range of 1-100ѓКg/ml. However, this relationship was found only in water solution. This detection system provided good selectivity and reproducibility.

[2B06]

Long-Term Use of the Immobilized Alkaline Phosphatase Column an a Recognition Element for Heavy Metal Ions

Ikuo Satoh, Yukihiro Tokoro, Keiichi Suzuki and Yutaka Yamada

Department of Chemical Technology, Faculty of Engineering, Kanazawa Institute of Technology
1030 Shimo-Ogino, Atsugi 243-02, Japan

Alkaline phosphatase immobilized onto oxirane-acrylic beads was packed in a small polymer column and then, used as a receptor element for zinc(II) ions. The flow-injection biosensing system was assembled with the column and a u.v./visible spectrophotometer mounting a quartz flow-through cell for monitoring the enzyme activity. The immobilized enzyme beads were readily regenerated by pumping 2,6-pyridine dicarboxylate solution (pH 6.0) as the cofactor-complexing agent for removing the metal ions in the active site of the enzyme molecules. Zinc(II) ions were thus, photometrically determined in submicromolar levels through its activation of the immobilized apoenzyme column. The system could be repeatedly used over 840 times during 2 years of operation at ambient temperature.

[2B07]

Electrochemical Evaluation of the Surface Structures of Self-Assembling Promoter-Modified Electrodes for Protein Electrochemistry

Isao Taniguchi, Mamoru Kajiwara, Toru Kai, Ryo Muraguchi, Koji Tonemura and Katsuhiko Nishiyama

Department of Applied Chemistry, Faculty of Engineering, Kumamoto University
2-39-1, Kurokami, Kumamoto 860, Japan

The surface structures of promoter modified electrodes have been evaluated by using the redox behavior of cytochrome c as a monitor reaction. The cyclic voltammogram of cytochrome c became better-defined with increasing the coverage of the promoter, such as bis(4-pyridyl)disulfide (PySSPy). By using a simulation technique on the basis of a microelectrode assembling model for electroactive (or promoter modified) sites, the observed voltammograms were analyzed. On the basis of the present procedure, the diameter of the active site became smaller to be more uniform with increasing the coverage, and each active site of less than ca. 2ѓКm in diameter is suggested at higher coverages. Similar results were also obtained for other promoter modified electrodes, suggesting that an electrochemical technique is useful as a conventional sensing method sensing method for evaluating various functionalized electrode surfaces.

[2B08]

Selective Detection of Food Allergen Using Rat Basophilic Leukemia (RBL-1) Cells

Shizuko Kumazawa, Koji Sode and Tadashi Matsunaga

Department of Biotechnology, Tokyo University of Agriculture and Technology
2-24-16 Naka-cho, Koganei, Tokyo 184, Japan

We have investigated the electrochemical detection of the allergic reaction using rat basophilic leukemia(RBL-1)cells by applying cyclic voltammetry. When the applied potential was in the range of 0-1.0 V vs. saturated calomel electrode (SCE), an anodic peak current appeared at around 0.34 V vs. SCE. This peak current was due to intracellular serotonin. After addition of model allergen (DNP-BSA), this peak current increased with time and a maximum current was obtained after 20 min. On the other hand, the current was constant when DNP-BSA was not added. This current increase was attributed to localization of the intracellular serotonin and was allergen specific. Therefore, based on this reaction, sensitive and rapid detection of food allergen was achieved. When RBL-1 cells were sensitized with serum of a rat which was allergic of wheat, wheat allergen could be detected 25 min after allergen addition. The peak current increased linearly with the increasing concentration of wheat protein in the range of 10^-2 to 5Ѓ~10^-1ѓКg/ml. These results suggest that the concentration of protein bringing about allergic reaction can be determined by cyclic voltammetry within 20 min after the addition of food allergen.

[2B09]

Theoretical Studies on a Liquid-immersed AT-cut Quartz Resonator

Hong-Tao Sun and Xi Yao

Electronic Materials Research Laboratory, Xi'an Jiaotong University
Xi'an 710049, China

Theoretical studies on an AT-cut quartz resonator immersed in a liquid have been made. Based on piezoelectric matrix equations, complex impedance spectra of the resonator are associated with the viscoelastic and dielectric properties of the liquid as well as the piezoelectric effect of the resonator. This analysis directly relates the impedance spectrum to the liquid properties. Furthermore, an experiment is carried out for identifying the analysis. This work shows that there are several ways other than frequency shift can be used to analyze the sensing behavior of the liquid-immersed quartz resonator.
[Key Words: quartz, resonator, liquid, viscoelasticity, dielectricity, peizoelectricity]

[2B10]

Admittance Characteristics of Electrode-Separated Piezoelectric Quartz Crystal

Noboru Oyama, Kazutake Takada, Tetsu Tatsuma and Toshiaki Nomura ^*

Department of Applied Chemistry, Faculty of Technology, Tokyo University of Agriculture and Technology
2-24-16 Nakamachi, Koganei, Tokyo 184, Japan
^*
Department of Chemistry, Faculty of Science, Shinshu University
3-1-1 Asahi, Matsumoto, Nagano 390, Japan

The admittance characteristics of the electrode-separated piezoelectric quartz crystal (PQC), whose gaps between the electrodes and a crystal plate were filled with various liquids, were studied. The electrical equivalent circuit parameters were estimated and compared with those of the normal type PQC. It was found that the electrode-separated PQC could measure the conductivity and the permittivity of liquid more sensitively than the normal type PQC.

[2B11]

Construction of Fiber Optic Immunosensor Based on Enhanced Chemiluminescence to Determine Different Antigens

N. F. Starodub, V. A. Berezin^* and P. J. Arenkov^*

Institute of Morecular Biology and Genetics, Ukraine Academy of Sciences
150 Zabolotnogo Str., 252143 Kiev-143, Ukraine
^* State university
Dnepropetrovsk, Ukraine

In this report the main scheme of cell measuring as well as itself sensor devices, the analyze conduction and the results of quantitative determination of several different antigens are presented. Especially attention is paid to one of the immunocomponents immobilized on the fiber optics surface. In this case three approaches are investigated: a) covalent binding of immunocomponents with the help of glutaraldehyde to preliminary treated by aminopropilethoxysilane surface; b) direct binding of immunocomponents to silicon oxide surface by BrCN; c) usage of a special membrane closely contacted to fiber optics. It is established that the level of immobilized biomolecules may be achieved etwa two fold more by second approach in comparison with first one. Good results may be received by the usage of the special membrane too. The immunocomponents were immobilized on the butt-end of fiber optics, inner side of the special capillaries. The measurements were fulfilled in stationary and flow regime. Thyroxyne, estradiole-17, ѓї-2-interfern, chorionic honadotropine, cell of Salmonella Typkimurium are used as analyte. The investigations shown that sensitivity of the fiber optics immunosensors intended for determination of above mentioned substances is comparable with one made by ELISA-method. But in all cases the rate of analysis which are carried out with the help of immunosensors is much more higher (5 and more fold) than one fulfilled by ELISA-method. The advantages and disadvantages of this immunosensors type in practical usage are discussed.

[2B12]

Differential Systems of Insulated Gate Chemical Sensor

Yoshitaka Ito

Research and Development Center NO. 01, Shindengen Kogyo Co., LTD.
10-13 Minamicho, Hanno-shi, Saitama-ken 357, Japan

Conductor-insulator-semiconductor(CIS) structure can be two or three electric terminal devices in which there are the C-V method of CIS diode (two terminal) and the chemical sensitive field effect transistor (three terminal). A dual gate FET on one chip, with the same W to L ratios, is designed for ion and gas sensors in a differential system and tested in instability of its characteristics. A dual gate FET gas sensor is formed with different metals and a pseudo-reference metal electrode on the same chip. For the ISFET a new method of a temperature compensation is proposed, the temperature coefficient of the differential output voltage can be achieved lower than 0.5 mV/ЃЋ. It is also described that more recently the Light-Addressable Potentiometric (LAP) sensor is also added to the CIS devise, in which the different region of the back of a wafer is illuminated. The LAP sensors can be easy a large scale integrated sensor like a CCD.

[2B13]

PVA Gel Reference Combined pH Glass Electrode

Jishou Xu, Weizhen Xu and Changdong Feng

Shanghai Institute of Ceramics, Chinese Academy of Science

pH sensors applicable to on-line determination should be endurable to pressure changes and high temperature. Gel reference combined pH glass electrode is prepared to meet this need. Reference solution is immobilized with PVA gel. Both the PVA gel reference and the glass electrode have high stability at the temperature 5-95ЃЋ and are endurable to high temperature sterilization at 130ЃЋ. Their potential are reproducible. The combined electrode responds linearly at pH 1-12, PTS>95%, at the temperature 5-95ЃЋ and sterilizable at 130ЃЋ. With simple structure, it is endurable to on-line conditions. Preparation of the gel electrode and glass electrode is discussed.

[2B14]

Performance Determining Factors for Ion Selective Electrode with Metal Sulfide Membrane

Cheol-Whan Yi, Won-Il Cho, Jeh-Beck Ju^* and Kyung-Suk Yun

Electrochem. Lab., KIST
P. O. Box 131, Cheongryang, Seoul, Korea
^* Dept. of Chem. Eng., Hong Ik University
72-1 Sangsoo, Mapo, Seoul, Korea

The effects of mould-pressure and the chemical composition on the detection performance of copper(II) ion selective electrode (ISE) consisted of mixed copper sulfide-silver sulfide membranes have been examined. An electrode fabricated at the mould pressure of 11.56 ton/cm² with the chemical composition of 1/9 molar ratio of CuS/Ag₂S has provided the best performance. The detection limit was about 10^-7 M (6.35 ppb) of Cu(II) ion concentration and it gave the linear Nernst behavior within the concentration ranges of 5Ѓ~10^-6-10^-1 M. The presence of jalpaite (Ag_1.55Cu_0.45S) in the copper membrane was also identified by X-ray diffraction analysis. The presence of jalpaite affect the performance of Cu(II) ISE, but there were no significant changes when the content of jalpaite increased. The effect of chloride ions on the performance of ISE was also examined for various electrode membranes.

[2B15]

Potassium Ion-Selective Liquid Membrane Electrode Based on 15-Crown-5 Derivatives with Charge Transfer Interaction

Toshihiko Imato, Yukiou Honkawa, Eva Mecs Kocsis and Totaro Imasaka

Department of Chemical Science and Technology, Faculty of Engineering, Kyushu University Hakozaki, Higashiku, Fukuoka, 812 Japan

A potassium ion-selective liquid membrane electrode was fabricated by using 15-crown-5-derivatives, which have moieties of electron accepting and electron donating properties, and its performance was evaluated with respect to potassium ion selectivity. Effects of the concentration of the crown ether in the membrane and mixing two crown ethers having an electron accepting moiety and an electron donating moiety on potassium ion selectivity were studied in this work. The selectivity coefficient of the crown ether in the membrane for most crown ethers examined, which indicated that the crown ethers form a 2:1 complex with potassium ion and a 1:1 complex with sodium ion in the electrode membrane. The mixing two crown ethers having a moiety of naphthoquinone and dihydroxynaphthalene was found to increase potassium ion selectivity of the electrode, compared with the membrane containing each crown ether separately. This enhanced potassium ion selectivity was estimated to may be due to an increase in stability of the 2:1 complex through a charge transfer interaction between two crown ethers.

[2B16]
Highly Sensitive Phosphate Ion Sensor for Environmental Monitoring

Masayasu Suzuki, Yohsihiro Inoue, Hironobu Kurata, Hiroyuki Yamamoto^*, Izumi Kubo^** and Isao Karube^***

Faculty of Information Science & Systems Engineering, Kyushu Institute of Technology
680-4 Kawazu, Iizuka, Fukuoka 230, Japan
^* The Turumi Seiki Co. Ltd.
Turumi, Yokohama 230, Japan
^** Faculty of Engineering, Soka University
Hachioji, Tokyo 192, Japan
^*** Research Center for Advanced Science & Technology, University of Tokyo
Meguro-ku, Tokyo 153, Japan

Phosphate ion sensor was developed by the use of recombinant pyruvate oxidase (PyOD) from Lactobacillus plantarum, which needs no addition of thiamine pyrophosphate and flavine adenine dinucleotide for reaction, and electrochemical detector. This system could detect 2 nM hydrogen peroxide. Response time for phosphate ion was 80 s and total measurement time for one sample was 3 min. Citrate buffer solution (pH 6.3) was most suitable for the measurement and optimum flow rate was 0.6 ml/min. Under these optimum conditions, minimum detection limit of phosphate ion was 15 nM, which was enough for the determination of phosphate ion in dam-lake.

[2B17]

The Deposition and Structure Study of Valinomycin-Cd Arachidate Langmuir Blodgett Films

Dafu Cui, Xinxia Cai, Jinghong Han and Yating Li

Institute of Electronics, Academia Sinica
Beijing 100080, (people's Republic of China)

The deposition and structure of Y-type mixed Langmuir Blodgett films of the ionophore valinomycin and Cd arachidic acid are described. An order layer structure of the multilayers assemblies have been investigated using the Small Angle X-ray (SAX) diffraction technique. The SAX diffraction exhibits 9(001) Bragg peaks in the range of 1.5-15 degree; The long spacing d =5.5 nm was detected.

[2B18]

Optochemical Gas Sensors

Yoshihiko Sadaoka
Department of Applied Chemistry, Faculty of Engineering, Ehime University
Bunkyo-cho, Matsuyama, Ehime 790, Japan

There has been an increasing interest in optical sensors to detect gas species in the atmosphere such as H₂O, NH₃, NO₂, organic vapors. Chemical sensors based on optical fibres offer several advantages, i.e., the sensors are electrically safe, their signals are not influenced by electrical disturbances, and the separation of the sensor element and actuators is easy. The sensing characteristics of optochemical humidity and ammonia gas sensors using absorbance- and fluorescence-based indicators examined in our group are reviewed.

[2B19]

An Optical Fiber pH Sensor Based on Dual Wavelength Measurement by Flow Injection Analysis

Qi Ren, Songyu Huang and Weimin Wang

Department of Physics, East Chian University of Chemical Technology
130 Mei Long Road, 200237, Shanghai, P. R. China

An optical fiber pH sensor for continuous, on line process analysis which uses a two-wavelength demultiplexed measurement system with a computer is demonstrated. The sensor involves the use of a reversible pH indicator dye immobilized on a porous cellulose polymer film to detect the pH values by a flow injection analysis (FIA) technique. The ratio of reflectance intensities at 493 nm and 607 nm, which are sensitive to the change of the appropriated pH, can be quantified pH values. Using a computer detecting technique, dark current and intensity of the two light signals are measured almost simultaneously; as a result, the effect of drift is negligible, and the overall system performance such as dynamite range, stability, accuracy and lifetime are improved. This sensor has the characteristics of high sensitivity, extended range, fine durability and rapid response time (0.03 min.).

[2B20]

Luminescence-Based Monitoring of Chemical Pollutants in Environment -an Approach toward the Monitoring of Hardly Decomposable Chemicals in Environment

Yoshihito Ikariyama, Eiry Kobatake and Masuo Aizawa

Department of Bioengineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology
Nagatsuta 4259, Yokohama 227, Japan

TOL plasmid of Pseudomonas putida mt-2 encodes the enzymes for degradation of benzene and its derivatives. The expression of these enzymes is induced in the presence of these chemicals. The structural gene of firefly luciferase, as a reporter enzyme, was fused to the promoter region of TOL plasmid. The obtained plasmid, pTSN316, was used for transformaing Eschelichia coli. This recombinant microorganism was applied to the environmental monitoring of benzene derivatives. The luciferase was significantly induced in the bacteria, depending on the pollutant concentration. The lower detection limit was a few ppm for m-xylene, although the induction effect of each derivative was different one by one. A luminescene biomonitoring system was fabricated by immobilizing the transformed microorganism at one end of a fiber optic. The biomonitoring device offers a rapid and sensitive detection technique for environmental protection from industrial pollutants.

[2B21]

Spectroscopic and Kinetic Studies on Superoxide Ion Electrogenerated in Acetonitrile

Takeo Ohsaka, Manabu Tsushima and Koichi Tokuda

Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology
4259 Nagatsuta, Midori-ku, Yokohama 227, Japan

The ultraviolet absorption spectra of superoxide ion (O₂^-), which is prepared by the electrochemical reduction of O₂ in acetonitrile (ACN) solutions containing an excess of H₂O relative to O₂^-, have been measured as a function of the elapse of time after the electrolysis in order to make clear the kinetics of the disproportionation of O₂^- initiated by H₂O as proton donor and to obtain its spectral parameters.

[2B22]

Surface Plasmon Resonance Study for the Detection of Some Chemical Species

Eiji Namira, Kazuhiko Ideta and Tsuyoshi Arakawa

Department of Industrial Chemistry, Faculty of Engineering, Kinki University in Kyushu
Iizuka, Fukuoka 820, Japan

An optical chemical sensor based on laser excited surface plasma resonance has been developed for detecting some chemical species. When the medium outside a silver thin film was changed from air to a squalane thin film, the resonance angle changed from 42.3 to 22.9 degree. Moreover, as a squalane thin film was exposed some gas-adsorbing organic materials (ethane, propane etc.), the angle of incidence was varied.

[2B23]

Optical Gas Sensor With Photoelectric Detector in Feedback Circuit

B. O. Semerdjian, V. M. Aroutiounian and Z. N. Adamian

Department of Physics of Semiconductors, Yerevan State University
1 Alec Manookian Str., Yerevan 375049, Armenia

There has been investigated a concept for the optical gas sensors (OGS) based on gas molecules concentration modulation spectroscopy with photoelectric detectors (PD) in feedback circuit. There was described one of the ways of the OGS' precision increase by modulating the transparence modulation of the investigating gas in the cell. The main attention was more focused on optimal choice and systematic questions of middle infrared (MIR) detector's applications working at 0

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