FEM-Based Analysis of Delay-Line SAW Resonator Sensors for Volatile Organic Compound Detection

Abstract

Surface Acoustic Wave (SAW) resonator sensors have high sensitivity and selectivity in sensing Volatile Organic  Compounds (VOCs) using mass-loading effects on the sensing layer. This paper describes the design and Finite Element  Method (FEM)-based analysis of a delay-line SAW resonator for VOC sensing, focusing on PCE detection using  polyisobutylene (PIB) as the active sensing layer. The analysis begins by describing the basic properties, applications, and  limitations of SAW filters, together with a categorization scheme for acoustic devices. A detailed discussion about the  optimization of SAW sensors is provided through the piezoelectric substrate, material properties, and fine-tuning of the IDT.  Further optimization extended to multiple types of IDTs, including selection of materials, delay length to improve the  performance of the SAW device. The frequency domain analysis has been performed to obtain S11 and displacement plot.  The optimized SAW resonator used for VOC detection into the dynamic behavior of the filter. The proposed sensor was  exposed to six organic gases, with their concentrations varying from 0 to 400 ppm. The frequency downshift of the SAW  sensor was linear with the 400 ppm concentration of PCE gas, with a frequency shift (∆f) of 270 kHz and a calculated 
sensitivity of 0.67 kHz/ppm. The structure under consideration has simulated high selectivity for PCE gas, the sensor is designed for 158 MHz range. These important findings of the study make work highly useful for optimization or application in diversified technological domains to benefit researchers and engineers in this field.