Design and characterization of temperature-robust piezoresistive micro-pressure sensor with double-Wheatstone-bridge structure

This study presents a silicon-based micro-pressure sensor in which the piezoresistive patches on the polysilicon membrane are configured in the form of two concentric Wheatstone bridge circuits. The sensors in the central circuit measure the membrane deflection caused by the combined effects of the pressure and the ambient temperature, respectively, while those in the outer circuit measure the deflection induced by the ambient temperature alone. Thus, by comparing the output signals of the two circuits, a reliable indication of the sensed pressure is obtained. ANSYS simulations are performed to establish the optimal positions on the membrane surface of the piezoresistors within the two Wheatstone bridge circuits. The sensor is then fabricated using micro-electro-mechanical systems (MEMS) techniques, and its sensing performance is compared with that of a micro-pressure sensor with a single-Wheatstone bridge configuration at pressures ranging from 0~150 psi and temperatures in the range -10degC to 75degC. Moreover, the results confirm that the double-Wheatstone bridge sensor is significantly more robust to variations in the external temperature than the single-Wheatstone bridge sensor at all values of the considered pressure range.