| Summary: | 碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 92 === Abstract
The device of novel capacitive ultrasonic transducers were developed with the concept of capacitance, small signal model and electro-mechanical transformer theorem. They offer performance advantages of wide bandwidth.
The thesis describes the design and fabrication of the capacitive ultrasonic transducer. The basic electro-mechanic-acoustical analogous circuits are presented. The vibration equation is derived from Mason’s theory. We have been fabricated the capacitive ultrasonic transducer and tested. In the study, we use the Surface micromachined technique, such as sacrificial layer, photo lithography, etching technique and thin film deposition to fabricate vibration membrane, chamber, vacuum sealing and metal layer form sequentially. The effects of the thin film with different deposition methods and KOH etching problem are discussed.
In the thesis, the resonant frequency of the capacitive ultrasonic transducer is observed by HP4192A Impedance Analyzer in air at about 11MHz with 67ohm. The impedance measured data shows that the characteristic of theoretical simulation and tested data are match. The Pulse-echo experiment has been established. The experimental results exhibit the capacitive ultrasonic transducer can be transmitter or receiver to launch or detect signal.
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