覆盖聚合物敏感膜的水平剪切型声表面波气体传感器机理分析

Theoretical Analysis on Response Mechanism of Polymer-Coated ShearHorizontal Surface Acoustic Wave Gas Sensor

采用微扰理论分析了覆盖聚合物敏感膜的水平剪切型声表面波气体传感器(SH-SAW)的响应机理。以针对有机磷毒剂具有良好选择性的含氟多羟基聚硅氧烷(FPOL)膜材料为例,分析了聚合物膜厚以及传感器工作频率在敏感膜吸附气体时对传感器响应的影响。计算结果表明,SH-SAW气体传感器对于不同浓度的甲基磷酸二甲酯(DMMP)气体响应随FPOL膜厚和传感器工作频率的改变呈现非线性变化。为了获得线性特性的传感器响应及较小的声波衰减,在一定的DMMP气体浓度检测范围内,通过理论计算提取出了优化的FPOL敏感膜膜厚和传感器工作频率等参数。

The response mechanism of polymer-coated shear horizontal surface acoustic wave （SH-SAW）sensor was analyzed based on the perturbation approach. Using fluoropolyol （FPOL）as the sensitive detector for organophosphorus agents,the sensor response of the gas adsorption was analyzed as a function of the thickness of the polymer and the operating frequency of SH-SAW device. Calculation results indicate that the SH-SAW gas sensor has non-linear response for various concentrations of dimethyl methylphosphonate （DMMP）with different FPOL thickness and operating frequency. To obtain a monotone gas sensor response and low acoustic attenuation, the optimal parameters including the FPOL thickness and the operating frequency were determined theoretically.