Optimized Surface Acoustic Wave-based Pressure Sensor Using Equivalent Circuit Model

This paper presents an optimized design on surface acoustic wave (SAW)-based pressure sensor, which is composed of a broadband reflective delay line and a bond substrate underneath the diaphragm. Using the equivalent circuit model (ECM), the SAW device was simulated, and the effect of inter-digital transducer structure, acoustic aperture and number of finger pairs on the performance of the system was studied. To determine the geometry and configuration of the sensor, Finite Element Method (FEM) was used to calculate the diaphragm bending and stress/strain distribution. From the ECM simulation and FEM analysis, the optimal design parameters were determined, and a new 440 MHz reflective delay line on 41deg YX LiNbO₃ was developed, the measured reflection coefficient S₁₁ results in time domain shows a good agreement with simulated one, low loss, sharp reflected peaks and high dynamic separation between the peaks were observed. The SAW device was successfully applied to pressure measurement, and the experiment results approve it is working satisfactorily