Influences of perforation ratio in characteristics of capacitive micromachined ultrasonic transducers in air |
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Authors: | Bu-Sang ChaSeung-Mok Lee Takeshi KanashimaMasanori Okuyama Tsunehisa Tanaka |
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Affiliation: | a Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan b Ingen MSL Inc., Ayumino 2-7-1, Izumi, Osaka 594-1157, Japan c Department of Information & Electronics, Technology Research Institute of Osaka Prefecture, Ayumino 2-7-1, Izumi, Osaka 594-1157, Japan |
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Abstract: | Capacitive micromachined ultrasonic transducers (CMUTs) with a perforated membrane have been fabricated and characterized in air. Two types of CMUT device have been fabricated having perforation ratio (area ratio of holes = AR) of 10% and 20%, and analyzed about electrical and mechanical characteristics. The perforation ratio (AR) of membrane substantially influences on the electrostatic force and mechanical restoring force of the device since it leads to the area variation of electrode and membrane, it subsequently influences on the sensitivity and frequency response of the CMUT device. The electrostatic force and mechanical restoring force were improved by decreasing the AR and increasing the DC bias voltage. The open-circuit sensitivity of a CMUT having AR 10% membrane, 8.45 μV/Pa, is larger than that of AR 20%, 4.07 μV/Pa at DC 15 V. Furthermore, the resonance behaviors were observed in the range of 60-80 kHz, and the resonance frequency could be changed by varying the applied DC voltage and AR. |
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Keywords: | Capacitive micromachined ultrasonic transducer Perforation ratio Sensitivity |
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