CMUTs机电耦合系数解析式及其对功耗的影响  

Analytical Expressions for the Electromechanical Coupling Coefficient of Capacitive Micromachined Ultrasonic Transducers(CMUTs)and Its Effects on Power Consumption

作　　者：李支康 赵立波[1,2,3,4] 李杰[1,2,3,4] 赵一鹤 徐廷中 罗国希[1,2,3,4] 郭帅帅 刘子晨 蒋庄德 LI Zhikang;ZHAO Libo;LI Jie;ZHAO Yihe;XU Tingzhong;LUO Guoxi;GUO Shuaishuai;LIU Zichen;JIANG Zhuangde(State Key Laboratory for Manufacturing Systems Engineering,Xi’an 710049;International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies,Xi’an 710049;School of Mechanical Engineering,Xi’an Jiaotong University,Xi’an 710049;Suzhou Academy,Xi’an Jiaotong University,Suzhou 215123)

机构地区：[1]西安交通大学机械制造系统工程国家重点实验室,西安710049 [2]西安交通大学微纳制造与测试技术国际合作联合实验室,西安710049 [3]西安交通大学机械工程学院,西安710049 [4]西安交通大学苏州研究院,苏州215123

出　　处：《机械工程学报》2020年第17期173-181,共9页Journal of Mechanical Engineering

基　　金：国家重点研发计划(2016YFB1200100);国家自然科学基金(51805423、51875449、51890884、51421004、91748207);苏州市重点产业技术创新前瞻性应用研究(SYG201721);机械系统与振动国家重点实验室课题(MSV201809);中国博士后科学基金(2017M623160)资助项目。

摘　　要：电容式微加工超声换能器(CMUTs)在便携式超声成像与治疗、家庭超声诊断系统、基于超声波的非接触式人机接口等领域具有极其可观的应用前景。实现低功耗、高机电耦合系数CMUTs的研发是解决上述应用需求的关键,而这就需要对CMUTs机电耦合系数的变化规律及其对功耗的影响具有更深入的理解。针对圆形和方形薄膜CMUTs,利用基于固定电容和自由电容比值的原理建立了圆形和方形薄膜CMUTs的机电耦合系数解析式,同时利用有限元仿真和对已有CMUTs芯片机电耦合系数的试验测试来验证理论解析式的正确性;开展了机电耦合系数的参数化研究;建立了CMUTs功耗与偏置电压之间的函数关系。结果表明圆形和方形薄膜CMUTs的机电耦合系数解析式能在低于塌陷电压96%的偏置电压范围内准确分析不同偏置电压下的机电耦合系数。在相同偏置电压下,机电耦合系数随着空腔高度增加而降低,但随着薄膜半径增大而增加;在相同偏置电压/塌陷电压比下,具有不同结构参数的CMUTs机电耦合系数相同。此外,从功耗与机电耦合系数的内在关系研究中可知通过减小塌陷电压或提高在低偏置电压下的机电耦合系数则可实现低功耗和高机电耦合系数这两种相互制约的性能参数的协调设计。Capacitive micromachined ultrasonic transducers(CMUTs)are promising in applications such as portable ultrasonic imaging,ultrasonic therapy,ultrasonic diagnostic for homecare and ultrasound-based touchless human-machine interface.Development of CMUTs with low power consumption and high electromechanical coupling coefficient is the key to meeting the requirements from the aforementioned applications.The analytical expressions for the CMUTs with circular and square membranes based on the ratio of the fixed capacitance to free capacitance are established.The finite element simulation(FEM)and experiment testing on the fabricated CMUTs chips are carried out to validate the analytical expressions.Parametric studies using the proposed analytical expressions are done to study the effects of CMUTs parameters on the electromechanical coupling coefficient.The relationship between the power consumption of CMUTs and the bias voltage is established.The results show that the analytical expressions for the CMUTs with circular and square membranes can accurately predict the electromechanical coupling coefficients under the bias voltages lower than 96%of the corresponding collapsed voltages.The electromechanical coupling coefficients decrease with the increasing height of the CMUTs cavities,while increase with the increasing radius under the same bias voltages.CMUTs with different parameters have the same electromechanical coupling coefficient under the same ratios of bias voltages to collapse voltages.In addition,from the study on the relationship between the power consumption and electromechanical coupling coefficient,it can be concluded that the performance requirements for both low power consumption and high electromechanical coupling coefficient can be coordinately achieved through reducing the collapse voltages or increasing the electromechanical coupling coefficient under low bias voltages.

关 键 词：CMUTs 机电耦合系数 解析式 功耗 

分 类 号：TH77[机械工程—仪器科学与技术]