4222 パリレンを用いた静電容量型マイクロ超音波センサの開発(J24-2 生産機械のマイクロ化(2))

概要

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The final goal of this research is to develop a condenser type micro ultrasonic sensor, which would be used as both receiver and transmitter. Polymer diaphragm is flexible and non-brittle, allowing good sensitivity and durability. Besides that, Parylene has good C-MOS compatibility, since it can be deposited at room temperature. Based on the FEM simulation results on the resonant frequency under tensile stress of Parylene, the diaphragm radius of 500〜1200μm is employed to realize the bandwidth up to ultrasonic range of 40〜100kHz. The influence of the number and the radius of acoustic holes on damping ratio is investigated by FEM simulation, in order to achieve a moderate damping of the diaphragm. Practical sensor devices are fabricated. They can receive an impulsive ultrasonic pulse transmitted by a spark discharge. The open-circuit sensitivity is 0.3mV/Pa, in reference to B&K 4138 microphone. The ranging system using this sensor can detect the distance up to 1m with the error less than 1mm. The developed sensor can be approximated to be non-directional.
社団法人日本機械学会の論文
2007-09-07