Development of the Flexible Polymer-Based Capacitive Micromachined Ultrasound Transducer using Adhesive Technology

• Main Authors: Geng-Hong Lin, 林耿弘
• Other Authors: DA-CHEN PANG
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/47505001930977063047

碩士 === 國立高雄應用科技大學 === 機械與精密工程研究所 === 98 === In this research the adhesive technique is used to fabricate the flexible polymer-based capacitive micromachined ultrasonic transducer (CMUT). Because polymer-based CMUT can be made at low temperature and low cost it has wider applications comparing to high temperature and high cost of silicon-based counterpart. This fabrication method replaces the earlier sacrificial layer method of our group and it can reduce the number of processes with better yield. Each CMUT is designed with 472 hexagonal membranes, with the overall size of 3mm x 4mm. Each cell has a diameter of 143μm, sidewall thickness of 10μm, cavity height of 2μm and membrane thickness of 5μm. The resonance frequency is calculated as 0.89 MHz using ANSYS software. This study demonstrates the flexible polymer-based CMUT can be fabricated using adhesive technique on ITO-PET substrate. The ITO-PET substrate surface is first roughened before the SU-8 is coated and exposed to produce sidewall. The semi-adhesive SU-8 is separately prepared on removable transparent plastic. It is sealed on top of the sidewall and exposured to fabricate membrane. After removing plastic the gold is evaporated and etched to make top electrode layer. The CMUT is tested with DC bias voltage of 50V and AC voltage of 325V and has a resonance frequency of 0.87MHz. It can detect object at the distance up to 38mm. The laser Doppler interferometer is also used to measure the vibration of the membrane with resonance frequency of 0.92MHz and peak to peak amplitude of 170nm. Our flexible polymer-based CMUT can be used as proximity sensor. Since it is made with fewer processes and lower cost it is especially suited for large array sensor applications.