Sensitivity Analysis of a LFE Acoustic Wave Gas Sensor with Finite Element Method

In the last decade, there are increasing investigations on lateral field excited (LFE) acoustic wave sensors in biochemical liquid sensing applications due to their high sensitivity and simple fabrication. However, the research on this kind of sensor for gas detection is still awaited. Therefore, we adopted finite element method (FEM) to analyze a LFE acoustic wave gas sensor, and further calculate its sensitivity to the variations of mass density and electrical conductivity of a selective film caused from gas concentration. In the meantime, quartz crystal microbalance (QCM) was also analyzed for comparison. Finally, the geometry of the LFE gas sensor was discussed and optimized to obtain a better sensing sensitivity. Results show that the LFE sensor exhibits larger sensing range and higher sensitivity than the QCM. This is because no shielding electrode exists on sensing surface of the LFE sensor, and hence the electric field can penetrate into the selective film. According to the simulation results, we conclude that a LFE acoustic wave sensor is very suitable to apply for gas detection.