FEM simulation of SAW H2 gas sensor based on Pd/AlN/Si multilayer structure

The SAW (Surface Acoustic Wave) sensor for measuring H
2
gas is a type of sensor based on the phenomenon of changing surface acoustic wave velocity. In this study, we propose a Finite Element Method (FEM) simulation model of multilayer structure for SAW to measure H
2
gas based on a two-port delay line sensor. AlN/Si substrate was chosen due to its high surface velocity thus potentially increasing sensitivity. In addition, Pd was selected to combine with AlN/Si because of its high absorption of H
2
. The FEM simulation results show that the center frequency decreases from 127.41 MHz to 127.36 MHz, while the hydrogen ratio in palladium increases from 0.0 to 0.3. In the process of changing the temperature from $27^{\circ}\mathrm{C}$ to $107^{\circ}\mathrm{C}$, the center frequency of the H
2
SAW sensor decreases from 128.67 MHz to 128.54 MHz.