A novel electrochemical sensor using a gold thin-film electrode formed on a carbon-fluorocarbon membrane was developed for the detection of toxic gas such as arsine. The sensor shows a good linearity and long term stability. The output current of the sensor using a carbon-fluorocarbon membrane was not affected by ozone gas. These results indicate that the sensor is more useful in practical field.

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In this study, ultrasonic wave acoustic properties of mixed taste solutions were investigated, and the possibility of taste sensing based on the acoustical properties obtained was examined. In previous studies, properties of solutions were discriminated based on sound velocity, amplitude and frequency characteristics of ultrasonic waves propagating through the five basic taste solutions and marketed beverages. However, to make this method applicable to beverages that contain many taste substances, further studies are required. In this paper, the waveform of an ultrasonic wave with frequency of approximately 5 MHz propagating through mixed solutions composed of sweet and salty substance was measured. As a result, differences among solutions were clearly observed as differences in their properties. Furthermore, these mixed solutions were discriminated by a self-organizing neural network. The ratio of volume in their mixed solutions was estimated by a distance-type fuzzy reasoning method. Therefore, the possibility of taste sensing was shown by using ultrasonic wave acoustic properties and the soft computing, such as the self-organizing neural network and the distance-type fuzzy reasoning method.

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In this paper, we propose the new detection system for discriminating water in oil. The detection method adopts the difference in each temperature characteristic of propagation time of an ultrasonic wave in water and in oil. When water and oil are heated, those propagation times show a completely reverse change. For this reason, this detection system does not need to provide any previous absolute value database as references. We tried to detect the water in the electric oil transformer container. By this experiment result, we found the possibility of discrimination of water in oil, by using the proposed method.

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In this study, three methods are experimentally examined to improve the gas selectivity of semiconductor thin-film gas sensors. They include (1) opposition of an alumina substrate, (2) deposition of a catalytic metal on the opposing substrate, and (3) application of a perpendicular electric field. The sensing film has a double layer structure; the lower layer is a thin-film composed of Fe₂O₃+TiO₂ (5mol%) +MgO (4mol%) and the upper layer is a thin-film composed of WO₃+TiO₂ (10mol%). It is deposited on an alumina substrate. When the substrate and another alumina substrate are opposed in parallel at a close distance by inserting a couple of Au wires between them, the selectivity to reducing gases is improved. When a catalytic metal(Pt or Pd) is deposited on the opposing alumina substrate, the selectivity to i-C₄H₁₀ is enhanced. When a dc electric field is applied perpendicularly to the surface of the sensing film, the gas selectivity to reducing or oxidizing gases is controlled depending on the direction of the applied electric field.

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The mixed-potential-type NOx sensing cells using yttria-stabilized zirconia and metal-oxide sensing electrode were fabricated and examined for an evaluation of NOx detection performance. It has been found that Cr₂O₃ electrode gives the highest sensitivity among metal oxides examined. Furthermore, ZrO₂-laminated-type NOx sensor using Cr₂O₃ electrode was fabricated and evaluated. This type of sensor has showed excellent performances of detecting low NOx concentration of 10 ppm and little interference by HC and CO. The results indicate that the sensor has great possibility of being utilized as an on-board NOx sensor.

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This paper presents an approach for the liquid level and the concentration measurement of the solution using a single sensor at the same time. For achieving this proposal, a parallel-plate capacitor sensor with simple structure is made. One of the electrodes is segmented into two parts, and two capacitances between the every part of this electrode and another electrode are measured. In experiment process, two theoretical formulas for calculating the liquid level and the concentration are deduced based on defined conditions; and then the sensor is calibrated using sample solutions with known liquid levels and concentrations; and finally unknown liquid levels and concentrations of the sample solution are estimated using the two theoretical formulas. Experiment results prove that this approach is possible to detect the liquid level and the concentration at the same time and valuable as a process sensor in industry field.

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