Monolithic structures, in which the photodetectors are combined with signal multiplexers without bump bonding technology, are beneficial in order to manufacture high resolution infrared focal plane arrays and reduce their production cost. The GeSi/Si heterojunction photodetector can be easily integrated monolithically on Si multiplexers and is one of the most promising infrared detectors for high resolution focal plane arrays detecting the infrared irnage in the 10-μm spectral band. We have fabricated GeSi/Si heterojunction photodetectors by MBE technology and evaluated their photoresponse and dark current, and investigated the feasibility of the GeSi/Si heterojunction infrared focal plane array. The quantum efficiency has a maximum value at a GeSi thickness of 20nm and the cutoff wavelength can be tailored by the composition of the GeSi film. It was confirmed that the cutoff wavelength can also be controlled by the impurity concentration in the GeSi film. The dark current exhibited an ideal thermionic emission characteristic in a wide temperature range. The performance obtained in the preliminary experiments indicates that the GeSi/Si heterojunction technology has sufficient capability in realizing focal plane arrays with full TV resolution for the 10-μm infrared spectral band.

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In this paper, damping characteristics of piezoresistive integrated silicon accelerometers, in which a micromachined seismic mass is suspended by four narrow beams from the surrounding frame that incorporates peripheral circuitry and squeeze film damping effect is provided by a single-side air gap under the seismic mass, were analyzed and numerically calculated. The output waveforms for applied sinusoidal accelerations are different from those of accelerometers with symmetrical air-gap structure when subject to large accelerations. The calculated results are compared with measured characteristics of the fabricated devices.

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Electromagnetic tachometers are applied to many industry products. The magnetic field analysis is required for these performance evaluation. In this paper, we propose an electromotive force (emf) calculation method for an electromagnetic tachometer system which corrects vector potentials calculated from 2D finite element method in a focused area. The calculated and the measured emf are in agreement with 70%. And tendency of calculated emfs agrees with that of measured emfs. Therefore, the present method has advantages for design and evaluation of an electromagnetic tachometer systems.

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This paper presents high-resolution micro fluxgate magnetic sensor interface circuits using 2nd-order ΔΣ modulation. The fluxgate sensing element is placed in modulation loop in order to reduce the instability due to the use of ferromagnetic core. As one of the integrators, a continuous-time integrator is used, and that is also used for the anti-aliasing filter for phase sensitive detector output. The oversampling A/D conversion using the 2nd-order ΔΣ modulation is useful for the high-precision detection of extremely weak magnetic field in the order of nanotesla. The interface LSI chip using ΔΣ modulation is designed and fabricated. The magnetic field measurement is successfully performed using the fabricated interface LSI chip and a fluxgate sensing element.

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Impedance changes in lipid membranes by basic taste substances were measured. A multichannel taste sensor developed by us is based on potentiometry, then sensitivity to nonelectrolytes and weak electrolytes is lower than that to strong electrolytes. There is a possibility to detect nonelectrolytes as increase of membrane resistance because of adsorption of chemicals to the membrane by performing the impedance measurement which is represented by a combination of resistance and capacitance. In this work, sucrose, a nonionic taste substance, could be detected as increase of membrane resistance and capacitance. Therefore, taste sensing based on impedance measurement will be effective for detection of taste substances of nonelectrolytes, and the highly efficient, humanlike taste-sensing system will be realized by combination with the conventional taste sensor.

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Photovoltaic effects of semiconductor were examined for chemical sensing. Light induced potential change influences surface electrical polarity through lighy generated carriers, then characteristics of electrode changes and the electrode respond to various chemicals. Odor and taste substances have various electrical property and affect the light induced potential change. We can detect very sensitively electrolyte or nonelectrolyte, such as sucrose, ethanol and mono sodium glutamate by changes of photo voltage. The results suggest that characteristics of the transducer can be controlled and information of chemicals multiplexed in a signal from a single transducer.

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The applicability of an optical fiber sensor to the monitoring of SF6 gas condition in gas insulated equipments in power transmission line was investigated. Two different designs of an optical fiber sensor were suggested and tested. The float type sensor was shown to be appropriate for a sudden pressure relay, whereas the diaphragm type sensor was applicable to a sudden pressure relay as well as a gas detection relay. Both sensors exhibited almost linear responses with pressure changes. Unlike the existing sudden pressure relays and gas detection relays, fiber sensors generate analog output signals which improve monitoring capability of the system. Non-contact and noise immune natures of the fiber sensors increase system reliability.

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A quartz core microcantilever fabricated from an optical fiber tip can be utilized for monitoring of deposition thickness. Dynamic monitoring of deposition thickness was performed without influence of electrical noise in an ion sputtering apparatus. Resonance frequencies were measured as a function of deposition time of Au and Ag. Resonance frequency decreased from 11.52kHz to 10.89kHz during a deposition time of 60 minutes which corresponded to a thickness of 360nm in case of Au.

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Damping control for packaged micro mechanical devices, such as an accelerometer, is desired to achieve wide frequency range by preventing the overdamping and suppressing the resonance. For capacitive detection type devices, which have narrow gap in a sealed cavity, the control of the cavity pressure is required for the damping control. We developed a novel cavity pressure control method using non-evaporable getters (NEG) and inert gas in anodically bonded glass-silicon structure. From the experiments using deflection of thin silicon diaphragm, the cavity pressure could be controlled at 120 and 5900Pa as designed. In application to the accelerometer, vibration behavior of seismic mass was studied experimentally and simulated by using Molecular Gas film Lubrication (MGL) equation. The result indicates that the critical damping under controlled pressure can be well designed to achieve wide frequency range.

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