An Electrostatic Comb Excitation Resonant Pressure Sensor for High Pressure Applications

In order to meet growing attentions and demands in the high-accuracy and high-pressure applications of deep-sea sciences, petroleum exploration, special industrial manufacturing, a silicon resonant high-pressure sensor with the measurement range of 50 MPa was developed based on double resonators of dual electrostatic comb excitation and piezoresistive detection in this paper. When operating, the frequency shifts of the resonators suspended in a sensitive diaphragm were produced due to the deformation of the diaphragm by applied pressure. The sensor structures were investigated by adopting the finite element analysis to extend the pressure-sensitive range with focusing on sensitivities, strength and the amplitude of the output signal and were fabricated by bulk-micromachining processes. Besides, by adopting dual synthetic comb-driven-force in the resonator, the direct current biased voltage and the negative stiffness effect of the sensor were decreased. The developed sensor here exhibited a high Q-factor value of ~46000, a differential pressure sensitivity of ~66 Hz/MPa (~930 ppm/MPa) with a linear coefficient of 0.99999, a low differential temperature sensitivity of ~0.1 Hz/°C (~1.4 ppm/°C). Benefiting from aforementioned characteristics, fitting errors of the sensor were better than 0.01% full scale (gas pressure of 0.11 to 7 MPa) under temperature range (−30 to 80°C) by using a polynomial algorithm and measurement errors of the sensor were better than 0.018% full scale (gas pressure of 0.11 to 7 MPa) under temperature range (−10 to 80°C).