Modeling and performance evaluation of 2.4GHz SAW-based pressure sensor

This paper presents a pressure sensor based on 2.4 GHz surface acoustic wave (SAW) reflective delay line on a 41deg YX LiNbO₃ substrate. Coupling of modes (COM) modeling and finite element method (FEM) were used to extract the optimal design parameters. Based on the simulation results, the SAW device with bar type reflectors was fabricated by electron bean lithography, and characterized wirelessly using the network analyzer. Three sharp peaks with high S/N ratio and few spurious signals were observed from three reflectors. A good agreement was observed between the simulated and measured reflection coefficient S₁₁. Newly employed metal ground shielding covered all over the bonding substrate reduced a coupling loss of propagating SAW to the surrounding atmosphere. Depending on the amount of applied mechanical compression force, the phase angle was modulated. The sensitivity was evaluated as about 2.9deg/kPa.