电容式微机械超声传感器设计与仿真

Design and Simulation of Capacitive Micromachined Ultrasonic Transducer

建立电容式微机械超声传感器(CMUT)微元三维有限元模型,经过分析CMUT微元不同结构对CMUT性能的影响,得到CMUT结构参数。设定工作频率范围1~2 MHz,工作电压Vdc<100V,首先,利用有限元模型进行模态分析研究薄膜参数与一阶频率的关系,以此确定薄膜参数;然后,在阐述相关理论和静态分析的基础上,仿真、分析空腔对CMUT性能的影响,进而确定空腔高度;最后,通过静电-机械耦合分析和计算机电耦合系数优化电极参数。对所设计的CMUT结构进行仿真验证,工作频率为1.65 MHz,塌陷电压为68 V,满足应用要求。

The three-dimensional model of CMUT unit was established to study the effects of different structures of CMUT unit on the performance of CMUT and the CMUT structure parameters was obtained.The operating frequency range of 1-2 MHz and working voltage of Vdc100V were set.First,the membrane parameters were determined by using the finite element model for the modal analysis to study the relationship between the membrane parameters and first order frequency.Then,the effect of the gap on the performance of CMUT was simulated and analyzed based on the explanation theories and static analysis and the gap thickness was determined.Finally,the electrode parameters were optimized through the electrostatic-mechanical coupling analysis and the calculation of the electromechanical coupling coefficient.The simulation verification of the proposed CMUT structure was carried out through COMSOL Multiphysics.The result showed that the working frequency was 1.65 MHz and collapse voltage was 68 V,which met the requirements of design.