Thermally-excited SiN beam resonant pressure sensor
Chen D., Cui D., Yu Z., Wang L., Cui Z., Xia S.
A new type pressure sensor based upon an electro-thermally driven and piezo-resistively sensed SiN-beam resonator is presented. A finite element analysis (FEA) method is involved to analyze the relationship between the excitation power, thermal stress, applied pressure and the resonant frequencies of the beam. The sensor is fabricated using silicon micro-machined technology and fusion bonding. Measurements yield a fundamental frequency of about 85kHz and Q-factor of 1000 in air at atmospheric pressure, rising to over 40000 in high vacuum(<0.01Pa). A special close-loop detecting technology is employed to measure the response of the resonant frequency at different applied pressure loads. A 0 - 400kPa sensor has a good linear frequency/pressure relationship. The span is about 10kHz over the full pressure sweep, and the pressure sensitivity is about 23.8 Hz/kPa.