Z cut α-quartz wafers were etched in saturated ammonium bifluoride solution at 87 degrees C. The side wall profiles were observed using the scanning electron microscopy (SEM) and plotted dependent on the polar direction. This research focused on investigating high aspect ratio trench and through-hole, which were dependent on the polar direction to the crystal axis. Aspect ratio in dependence on polar direction was also plotted and microchannels with aspect ratio > 3 could be achieved at the polar angle between 30° to 60°. The possibility of application for microcapillary was discussed, and the trench at 45° was considered best. Double-sided etching technique was used for manufacturing through-hole structures. Through-hole at 0° was demonstrated effective for fabrication of capacitive MEMS tilt sensor. Through-holes at 15° and 105° were proposed for fabrication of 90°-arranged two axis capactive tilt sensor, taking advantage of the twofold symmetry property around X axis and threefold symmetry property around Z axis.

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The laser-induced breakdown spectroscopy (LIBS) using micro-droplet sodium chloride solution is presented. Since the 1980s, many liquid miniaturizations of analytical technique for LIBS measurements were reported. The method we present allowed micronizing the sample in such a way that whole volume of a sample was confined in the laser beam spot area (minimum beam spot diameter 53.2μm, microdroplet diameter 50-60μm) and was separated from its surrounding condition. If the sample's physical state was liquid, the density of solution could be controlled as needed. In this paper, originally designed ink-jet system for sampling procedure was presented. According to the new method, improved sensitivity for drawing calibration curves with the aim of the LIBS quantitative measurement were obtained.

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In this paper, we present the optimization of the PZT diaphragm pump for application in gas gyroscope. A circular flow inside the sealed case is simulated in detail by utilizing 3D compressible flow with the interaction of fluid-solid phase and the transient analysis is employed. The working principle and the effect of the jet-pump integrated inside the sensor are explained and validated by experiments using anemometry technique. The results verified that configuration of the pump is optimized and the peak velocity of the flow at the sensing element is 3.5m/sec after starting the pump 3.6ms. A novel structure of the sensing element of the gas gyroscope, consists of thermistor and heater, is also reported. The thermistor is heated by a separate heater, whose power is supplied independently form that of thermistor. This design allows low voltage on the thermistor, therefore the noise is reduced. Both heater and thermistor are optimized in order to reduce the thermal induced stress which occurred in the old thermistors at working temperatures. The thermal stress appeared in p-type silicon thermistors reduced the performance of sensor by 7.5%, which is calculated and experimentally confirmed.

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Detecting technique of smoldering fire was examined using tin oxide gas sensors. Eight sensors were installed in a room. They were same type. Four kinds of materials were adopted as a fire-source material. The materials were cotton cloth, wallpaper, curtain cloth and woodchip, which were main smoldering fire-source materials in an indoor environment. The sensor outputs to gases evolved upon the smoldering fire of the materials were measured. The differential characteristic of the output was derived to analyze. As for the results, it became obvious that the sensor locating at higher position had a higher sensitivity and it could sense the fire instantaneously. It is thought that the generated gases rise up directly toward the ceiling and reflect downward. A small type of electric cooking stove was used as a fire-source. The surface temperature of the stove plate arrived at 340 °C. A bar was adopted to set the sensors freely. In this experiment, three bars were adopted and the heights of the sensor position were 50, 100, 150 and 200 cm from the floor. It is effective to locate the sensor at higher position in detecting a smoldering fire. The sensor characteristics were analyzed using principal component analysis (PCA). The system could discriminate source materials among wallpaper, woodchip and curtain for smoldering fire by utilizing the result of PCA. But, the smoldering fire of cotton cloth could not be distinguished from that of curtain by this system. Each fire could be identified in four minutes.

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We have developed multi-point bad-smell sensing system for monitoring living environment. Although there are a variety of gas sensors, it is difficult to detect ppb-order gas without interference. Our previous system was able to detect methyl mercaptan, hydrogen sulfide, propion aldehyde and toluene with the concentrations down to a few tens of ppb by using a gas detector tube combined with a CCD image sensor. A gas detector tube with color change caused by the chemical reaction between the analyte and the reagent system was implemented into our low cost wireless portable measurement system. This portable system called a sensor node consists of a gas detector tube, one-dimensional CCD image sensor, LVDS interface, microcomputer, and wireless LAN module. We report experiment on gas-distribution measurement under actual environments such as paint factories. It was found that the gas distibution around paint factories could be measured using this sensor network. Moreover, the dynamical change of gas distribution was clearly observed.

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