声表面波气体传感器叉指换能器的结构优化

Interdigital transducer structure optimization of SAW gas sensor

为降低声表面波气体传感器在传播声波时所产生的插入损耗,分析了常规高损耗型双向叉指换能器的结构形状,设计了一种低损耗型浮动电极单向换能器的结构,采用COMSOL有限元软件建立双向和单向叉指换能器的仿真模型,通过添加固体力学和静电物理场,对比分析两种结构输出端的插损。结果表明:双向叉指换能器两个输出端产生的插损十分接近,说明声波具有双向性传播,未能起到降低插损的作用;浮动电极单向换能器每个周期6个不同电极的的特殊设计,使其具有单向传播性,可以降低声表面波气体传感器4 dB的插入损耗,提高了传感器的敏感特性。

This paper intends to to reduce the insertion loss of SAW gas sensor as propagating sound wave.The study involves analyzingthe structure of conventional high loss bi-directional interdigital transducer;designing a structure of low loss floating electrode unidirectional transducer;establishing simulation models of bi-directional and unidirectional interdigital transducerseparately using COMSOL finite element software;comparing and analyzing the different insertion losses at two outputs by adding solid mechanics and electrostatic physical fields.The results show that the insertion losses produced by the two outputs of the bidirectional interdigital transducer are approximately the same,which indicates that the sound wave exhibiting bidirectional propagation can not reduce the insertion loss;the special design of the floating electrode unidirectional transducer with six different electrodes in each cycle provides unidirectional propagation,in a way which can reduce the insertion loss of the SAW gas sensor 4 dB and improve the sensitivity of the sensor.