This paper presents a novel microdevice for droplet transportation using a wettability gradient surface that is generated by EWOD (Electrowetting-on-dielectric). Velocity of a droplet on this device can be controlled by changing the frequency of a square-wave voltage that is applied between two interdigitated and wedge-shaped electrodes. When a square wave voltage of 50 V and 10 Hz was applied, the transportation velocity of a 5 μl deionized (DI) water droplet was 3.9 mm/s. Also, we succeeded in transporting not only DI water but also organic solution (dimethyl sulphoxide, DMSO) and electrolyte solution (KCl and phosphate bufferd saline, PBS), and investigated the relationship between their transportation velocities and voltage frequencies.

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A wireless intra-oral device has been fabricated to measure the temperature in a mouth. It contains a silicon CMOS chip attached printed circuit board and a button battery. A ring oscillator on the chip generates continuous wave which frequency depends on ambient temperature. The frequency shift is detected by a short wave radio wirelessly at the distance of 30 cm. The circuit draws 51 μA from a 1.55 V silver-oxide button battery for watches and it gives more than ten days running time.

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We have developed a practical urea monitor based on a chemiluminescent (CL) reaction of urea and hypobromous acid produced by electrolysis of sodium bromide (NaBr) for measuring urea concentration in spent dialysate at set intervals. A reagent containing 4×10^-2 M hypobromous acid is produced by electrolysis of an electrolyte containing 5.9 M NaBr and 0.2 M sodium hydroxide (NaOH). Chemiluminescence is emitted by injection of spent hemodialysis fluid (0.11 ml) into the reagent, and the CL-intensity is measured by a photomultiplier tube using the photon counting technique. The CL-intensity is proportional to the 0.9th power of the urea concentration between 7×10^-4 and 2×10^-2 M. The urea monitor can determine the urea concentration in spent dialysate samples collected from the waste line of a dialyzer, and the time for the intermittent measurements including the cleaning cycle of the reaction chamber is 3 min. The urea concentrations measured by the monitor are in close agreement with those measured by the conventional enzyme colorimetric method using urease for the spent dialysate collected during a hemodialysis treatment, and the correlation coefficient is 0.93.

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In this paper, we propose a real-time vibration amplitude/phase imaging technique for out-of-plane mechanical vibration detection and dynamic characterization of micro-structures. It is based on the white-light interferometry and the heterodyne detection scheme. Continuous motion is given to the interference fringe by scanning the reference mirror. The vibration generates beat frequencies between the modulation frequency by the scanning and the vibration frequency. A newly developed multiple channel correlation image sensor enables us to obtain sufficient number of frequency components to demodulate uniquely the vibration amplitude and phase two-dimetionally simultaneously. We show the system realizes a real-time observation of vibration modes of micro-structures at 45 frame per second with 320×256 spatial resolution.

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A new sensor to detect a smile of a person is proposed in this paper. When a person smiles, the shape of cheeks changes. The change is used for the detection of the smile. The sensor consists of a infrared LED, a photodiode and a few electronic parts. When the sensor detects a smile, at first infrared light is irradiated on a cheek. Then the sensor detects the smile by using the strength of light reflected from the cheek. As a result, the sensor is simple and can detect a smile.

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