Enhanced Sensitivity of an all Quartz Package Saw Pressure Sensor Incorporating Optimal Shapes of Diaphragms

The sensitivity of an all quartz package (AQP) surface acoustic wave (SAW) pressure sensor was enhanced by optimizing the shapes of diaphragms. A rectangular and an elliptical shaped sealed cavity were utilized and the pressure sensitivity was analyzed by using the finite element method (FEM) combining the perturbation theory. The effect of normal stress along the SAW propagation direction on the sensitivity was also investigated by calculating elliptical diaphragms with different orientation. The performance of the sensitivity analysis was confirmed by the measured responses from the AQP sensors with optimal elliptical and typical circular diaphragms. Experiments show the accuracy of theoretical analysis, and the sensitivity is improved by 25.5%.