Wireless, direct pressure sensing with saw devices at elevated temperatures

Process control in industrial applications often demands to precisely measure pressure. SAW based pressure sensors can significantly decrease the effort of the sensor installation as they can be subjected to high process temperatures and allow for wireless readout. While the SAW sensing elements are well understood and have proven their sensitivity for pressure reading, a successful sensor implementation still demands a comprehensive system design approach, accounting for the SAW element itself, the sensor's housing, the antenna and the reader. This report focusses on a SAW element for pressure and temperature reading, based on Lithiumniobate, operating at 2.45 GHz. The design features a metal housing allowing for a direct contact with the measurand over a wide temperature range. For temperature stabilization reasons, we banned any organic material from the sensor element. The devices were tested in a climate chamber under pressure and temperature loads and exhibited both a good sensitivity and stability. In addition, the performance in wireless reading was investigated.