Design and Simulation of Saw based Gas Sensor

Abstract

There has been a great interest in Surface Acoustic Wave (SAW) based gas sensors in recent years. SAW based gas sensors can efficiently detect the change in mass, modulus and conductivity of the sensing layer due to the adsorption of gas over the surface. Piezoelectric effect is used as the working principle in the operation of SAW based gas sensors. The advantages of SAW based gas sensors include small size, robustness, low cost, high sensitivity, portability and high accuracy. In the present thesis work, different geometries of SAW based gas sensors are studied, designed and simulated for sensing hydrogen (H2) gas. COMSOL Multiphysics software is used to design and simulate the proposed models of the gas sensor. Different parameter selections, boundary conditions, study settings etc are identified and optimised from the outcomes of the study based on literature review. Various design parameters of the gas sensor are optimized. The electrode thickness is optimized to 200nm and electrode material is selected as aluminium as per simulation results optimizations. The thickness of intermediate layer is optimized to be 0.6 µm, with maximum displacement shown by the gas sensor and hence the sensing results. The thesis is concluded with few fabrication steps that are performed in the laboratory.