A Resonant High-pressure Sensor Based on Integrated Resonator-diaphragm Structure

Accurate measurements of high-pressure are demanded urgently in the fields of ocean sciences, industrial controls, and oil explorations. However, conventional piezoresistive high-pressure sensors suffer from serious temperature drifts and eventually result in compromised accuracies. Herein, this paper presents a resonant high-pressure sensor with the pressure range of 30 MPa. This sensor composes of a glass wafer for vacuum package and an SOI wafer with integrated dual resonators and diaphragm structures to alleviate the temperature effect on sensor. High-pressure under measurement bends the pressure sensitive diaphragm, producing frequency shifts of suspended resonators. Finite element analyses were conducted to promote the structural strength of the sensor and optimize the pressure sensitivities and the temperature sensitivities to improve the accuracy of the sensor. Fabrication of the sensor was realized using the SOI-MEMS process. Characterization results showed the pressure sensitivities of the resonators were quantified as 0.43 kHz/MPa and 0.16 kHz/MPa with linear coefficients of 0.9999, respectively. The temperature sensitivities of the resonators were reduced from 44 Hz/°C to -1 Hz/°C. In addition, the accuracy of the sensor was higher than 0.02 %FS in the temperature range of -10°C to 60°C and the pressure range of 0.11 MPa to 5 MPa by using a polynomial algorithm. Simulative and experimental results indicate that the sensor may be a potential candidate in the field of high-pressure sensing.