It is necessary to develop high performance microactuator in order to achieve it operating at a very low applied voltage. This paper describes the development of composite multi-layered PZT thin films for microactuator. The piezoelectric properties for 8 kinds of composite multi-layered PZT thin films are fabricated and studied. The ferroelectric polarization — electric (P-E) hysteresis loops of the films is also measured and discussed. According to the results of P-E hysteriesis loops, for these different composite films, most optimum composite form, i.e., sol-gel + sputter composite double-layered PZT thin films, which combined with conventional RF sputtering and sol-gel processing methods, exhibit excellent remnanent polarization and coercive fields of 14.87uC/cm² and 32.359KV/cm in 5V and 25.46uC/cm² and 41.94KV/cm in 7V, respectively. Moreover, as the applications of the composite double-layered PZT thin films, microactuators with different thickness diaphragm are developed using the most optimum piezoelectric property, i.e., sol-gel + sputter composite double-layered PZT thin films.

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This paper proposes a new method for improving an existing abnormality detection system for person who soaks in a bathtub. As the number of aged people increases year by year in Japan, bathing accident of the aged is growing at a rapid rate, especially in-bathtub drowning accident. Therefore, prompt detection of bather's abnormality such as dizziness and fainting is important to prevent in-bathtub drowning. In order to detect bather's abnormality promptly, an abnormality detection system using seven ultrasonic sensors has been proposed. The system uses the following two methods: posture detection and behavior detection, to detect bather's different state from normal before an accident occurs, and improves a delay of detection considered to be a serious problem heretofore. There was however plenty of room for improvement. In order to improve detection rate of the system, we propose a new detection method in this paper. The method uses two ultrasonic sensors to beam bather's head and neck, and detects the head height and swing speed of the head. Experimental results are superior to the accuracy of the existing system, which enables us to detect bather's abnormality more accurately.

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Crank-shaped and Y-shaped through-hole interconnections (THIs) filled with Au-Sn solder are demonstrated in this study. They are expected to realize more high-density Wafer Level Package (WLP) of electrical devices including MEMS (Micro Electro-Mechanical Systems) and MOEMS (Micro Optical Electro-Mechanical Systems) fields, compared with conventional WLP using THIs consist of strait through-holes. In this paper, formation techniques of Crank-shaped and Y-shaped THIs are reported. In order to make Crank-shaped and Y-shaped through-holes in a substrate, both femtosecond laser irradiation and wet chemical etching are used. Crank-shaped through-holes, having 80 μm opening and laterally 600 μm sifted, are successfully formed in silica, PYREX and sapphire substrates. Y-shaped through-holes, 80 μm opening and 400 μm in deep, are also achieved. Gold(Au)-Tin(Sn) solder was filled into the holes by Molten Metal Suction Method (MMSM). Airtightness of the THIs was examined by Helium leakage test and estimated leakage rate was smaller than 1.0×10^-9 Pa·m³/sec, which is enough to be used in the WLP applications.

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A practical and low cost instrument for accurately measuring small impact force is proposed. In the various industrial and research applications such as materials testing, the requirements for evaluating the mechanical characteristics of materials and structure have increased. In this paper, the mechanical characteristics of material against small impact force are determined by means of the newly developed pendulum mechanism that based on the levitation mass method (LMM). In this method, a pendulum mechanism is used as a substitute for expensive pneumatic linear bearing. A mass that is suspended using a newly developed pendulum mechanism with negligible friction and a stable restoring force, is made to collide with the object under test. A pendulum mechanism with 6 wires is used to realize the static motion of mass that is the swing part of pendulum. Mass is suspended by 3 triangles formed using 6 wires. The Doppler frequency shift of a laser beam reflecting on the mass is highly accurately measured using an optical interferometer. The velocity, position, acceleration and inertial force of the mass are calculated from the measured time-varying Doppler frequency shift. The performance of the proposed method is demonstrated by evaluating the viscoelasticity (i.e. hysteresis curve between force and displacement, curve between force and velocity) of a small silicon-gel block under an impact load.

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