电容式MEMS超声传感器设计与分析

Design and analysis of capacitive MEMS ultrasonic sensor

目前电容式MEMS超声传感器(CMUS)多为收发一体结构,但二种工作模式对传感器结构要求存在很大差异,设计时为了兼顾收发性能往往不能使传感器性能达到最优;此外,传统的电容式MEMS超声传感器还存在寄生电容大的缺点。针对以上问题,基于收发分离的思想,设计了一种专用作超声接收的MEMS电容式传感器,结构上采用上下电极引线互错,单元间电极联线交错的方式来减小寄生电容。通过理论分析和ANSYS仿真得到所设计传感器的最佳工作电压为586V,灵敏度为174.2fF/Pa,满足现有超声接收传感器的应用要求。

At present, most of capacitive MEMS ultrasonic sensor （CMUS） are used for both transmission and receiving,but there is a big difference on structure of the two operating modes, so the performance cannot obtain optimal under consideration of transmitting and receiving properties in structure design. Moreover, parasitic capacitance of traditional CMUS is relatively big. In order to solve these problems, based on the idea of transmitreceive separate mode, design a CMUS which is only used for ultrasonic receiving. The leads of top and bottom electrodes are stagger with each other and the connecting line between inter cells are in a cross stagger manner to reduce the parasitic capacitance. Theoretical analysis and ANSYS simulation show that the best working voltage is 586 V and sensitivity is 174.2 fF/Pa,which meets the requirements of current ultrasonic receiving sensor.