A 70 MPa silicon resonant pressure microsensor with resonators supported by micro beams based on volume compressed sensing.

Meeting the growing demands for accuracy, resolution and response time of high-pressure microsensors applicated in ocean science and petroleum industry, this paper developed a silicon resonant high pressure microsensor based on volume compressed sensing with dual resonators supported by micro beams. In operation, the frequency of resonators shifts while the volume of microsensor compressed under high pressure. A couple of micro beams were introduced to support resonators and protect resonators from buckling in high pressure. At the meanwhile, the theoretical model of micro beams was established. Based on the expression between geometric parameters of micro beams and pressure sensitivity of resonators, the micro beams of the two resonators were modified that results in different pressure sensitivities of two resonators, which effectively performed temperature self-compensation. An eutectic bonding is adopted for wafer vacuum packaged. Dealing with potentially complex hydraulic measurement, the microsensors were surrounded by silicone oil and sealed with a corrugated diaphragm and a base. The pressure sensitivities of fabricated microsensors were quantified as 0.003 kHz/MPa ( ~ 30 ppm/MPa) of Resonator I and -0.118 kHz/MPa (~-1311 ppm/MPa) of Resonator II under 20 °C, which match with theoretical analysis. Finally, the accuracy of this microsensors is better than 0.01% FS with temperature self-compensation under the pressure range of 0.1~70 MPa from -10 °C to 50 °C, along with a response time better than 10 ms and a resolution of 100 Pa. This paper provided an effective structure of micro beams for resonant high-pressure microsensors combined with volume compressed sensing, derived the quantitative relationship between key structural parameters and sensitivity, and performed a possibility of high accuracy and high resolution measurements of a much wider pressure range.