Pressure sensor based on surface acoustic wave resonators

In this work we present a pressure sensor based on surface acoustic waves (SAWs) resonators and operating in the pressure range from 0 bar to 3 bar. The achieved high resolution values (3.5 Pa), are obtained making use of 2-ports SAW resonators working at approximately 393 MHz on a quartz membrane. The membrane deformations under the hydrostatic pressure, have been studied by finite element methods (FEM), using the elastic constants of the anisotropic ST-cut quartz and considering vacuum as reference pressure on the other side of the membrane. The implemented sensor is an hybrid structure where the quartz membrane is placed between two glass ceramic elements; the first to implement an hermetically closed cavity, the other to define the diaphragm. A differential configuration has been designed to reduce parasitic phenomena due to temperature variations. The response curve of the sensor is reported.