Design and Simulation of Nanorod-Based SAW Gas Sensor to detect Hazardous Gases

The work presents the design, a 2D and 3D finite element method (FEM) simulation, analysis, and optimization of a surface acoustic wave (SAW) based gas sensor. The simulation of SAW gas sensors with and without the presence of nanorods is performed. Gas adsorption on a surface causes a change in the mass, modulus, and conductivity of the sensing layer, which can be accurately, detected using SAW-based gas sensors. The device is constructed using a YZ-cut lithium niobate as a substrate, which is covered by a 0.2 μm thick intermediate layer upon which ZnO nanorods are present operating at 4 μm wavelength. Simulations in COMSOL Multiphysics are performed using eigen frequency, time-dependent, and frequency domain analysis. The materials of the intermediate layer as well as interdigitated transducers (IDTs) and the height of the nanorods are varied for the optimization of the device. The frequency shift and total displacement were seen to be significantly improved for the nanorod-based SAW gas sensor device.