Frequency Output Pressure Sensors Based on an Application of Surface Acoustic Wave Technology

A new type of frequency output pressure sensor is described which utilizes a novel application of Surface Acoustic Wave (SAW technology. Variations in SAW velocity over a miniature pressure dependent diaphragm are used to control the frequency of an electronic feedback oscillator. Prototype SAW pressure sensors have been built which provide a frequency output that varies almost linearly with applied pressure and is accurate to better than 0.2 percent of full scale. The high precision, digital compatibility, and mass producible integrated circuit form of these sensors makes them potentially very attractive for automotive applications.