Automotive Pressure Sensors Based on New Piezoresistive Sense Mechanism

To date, nearly all automotive pressure sensors share a common design: They have a mechanical diaphragm that either converts pressure into in-plane strain (piezoresistive sensors) or acts as one side of a variable capacitor in capacitive designs. In both cases, the diaphragm is the limiting design element for accuracy and reliability. CTS has developed a pressure sensor that converts pressure directly to a resistance change without any kind of intervening diaphragm. The sensor is based on thick film resistors that have been modified to respond directly to changes in pressure. In this paper, we share results of sensors designed for common rail diesel fuel pressure measurement. These sensors must withstand over 3000bar and have total errors of less than 1% over the full temperature and pressure range. Data is included on performance over temperature, thermal shock, corrosive fuel exposure, burst pressure, and pressure fatigue cycle testing.