Long-term and thermal shock stability of high-temperature pressure and force sensors

Abstract:
Conventional high-temperature force and pressure sensors often fail to meet all the requirements of high-temperature applications and tend to malfunction after a short period at elevated temperatures. This paper introduces silicon-based capacitive force and pressure sensors fabricated using gold-silicon (Au-Si) and aluminum-silicon (Al-Si) eutectic bond-ing. These sensors exhibit exceptional thermal stability, with a nonlinearity of inverse capacitance of 0.008% FS at 350 °C for Au-Si and 0.035% FS at 500 °C for Al-Si. The long-term stability of the sensors is demonstrated by subjecting them to temperatures of 300 °C and 500 °C for 72 and 52 hours, respectively. Despite repeated mechanical stress, the sensors show promising results, with a relative change in zero-point for the Au-Si sensor of less than -0.4% after 72 hours at 300 °C and for the Al-Si sensor of 1.5% after 52 hours at 500 °C.