压电微机械超声换能器仿真与结构优化

Simulation and Structure Optimization of Piezoelectric Micromachined Ultrasonic Transducer

压电微机械超声换能器(PMUT)在医疗阵列成像、手势识别、内窥成像、指纹识别等领域有着重要的应用,而灵敏度等性能是影响其成像质量的主要因素。该文对基于PMN-PT圆形压电复合振动膜的压电微机械超声换能器等效电路模型进行分析,并通过有限元法研究了压电层PMN-PT厚度对PMUT的发射电压响应、接收灵敏度的影响。仿真结果表明,当压电层厚度为4.5μm(厚度为基底厚度的90%)时,换能器的发射电压响应级最大,达到191.6 dB,接收灵敏度级随厚度的增加基本呈线性上升趋势;当压电层厚度为5.1μm(厚度为基底厚度的102%)时,回路增益(损耗)最大,达到-64.50 dB。

The piezoelectric micromachined ultrasonic transducer(PMUT)has important applications in medical imaging,gesture recognition,endoscopy imaging,fingerprint recognition and other fields,and its performance such as sensitivity are the main factors affecting the imaging quality.This paper analyzes the equivalent circuit model of PMUT based on Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-PT)circular piezoelectric composite vibration film,and then investigates the influence of PMN-PT film thickness on the transmitting voltage response and receiving sensitivity of PMUT by finite element method.The simulation results show that when the thickness of the piezoelectric layer is 4.5μm(90%of the thickness of the substrate),the value of the transmitter voltage response level of the transducer is the maximum,reaching 191.6 dB.The receiving sensitivity basically increases linearly with the increase of thickness.When the thickness of the piezoelectric layer is 5.1μm(102%of the thickness of the substrate),the number of loop gain(loss)is the maximum,reaching-64.50 dB.