A Resonant Pressure Microsensor with the Measurement Range of 1 MPa Based on Sensitivities Balanced Dual Resonators

Abstract

This paper presents a resonant pressure microsensor with the measurement range of 1 MPa suitable for the soaring demands of industrial gas pressure calibration equipment. The proposed microsensor consists of an SOI layer as a sensing element and a glass cap for vacuum packaging. The sensing elements include a pressure-sensitive diaphragm and two resonators embedded in the diaphragm by anchor structures. The resonators are excited by a convenient Lorentz force and detected by electromagnetic induction, which can maintain high signal outputs. In operation, the pressure under measurement bends the pressure-sensitive diaphragm of the microsensor, producing frequency shifts of the two underlining resonators. The microsensor structures were designed and optimized using finite element analyses and a 4” SOI wafer was employed in fabrications, which requires only one photolithographic step. Experimental results indicate that the Q-factors of the resonators are higher than 25,000 with a differential temperature sensitivity of 0.22 Hz/°C, pressure sensitivities of 6.6 Hz/kPa, and −6.5 Hz/kPa, which match the simulation results of differential temperature sensitivity of 0.2 Hz/°C and pressure sensitivities of ±6.5 Hz/kPa. In addition, characterizations based on a closed-loop manner indicate that the presented sensor demonstrates low fitting errors within 0.01% FS, high accuracy of 0.01% FS in the pressure range of 20 kPa to 1 MPa and temperature range of −55 to 85 °C, and the long-term stability within 0.01% FS in a 156-day period under the room temperature.

Highly sensitive and wide-range resonant pressure sensor based on the veering phenomenon

“…Pressure microsensors have been explored for various potential applications, such as industrial control, healthcare, medical testing, aerospace, meteorology, and environmental monitoring [9][10] [11]. Different sensing mechanisms and designs have been used for the detection of air-pressure, such as capacitive, piezoelectric, piezoresistive, and resonant [12] [13] [14][15] [16]. Resonant pressure micro-sensors have the advantage of digital frequency output, which can be measured with high precision using simple electronic circuits.…”

Novel resonant pressure sensor based on piezoresistive detection and symmetrical in-plane mode vibration

“…4d. The dimension of the resonant pressure sensor chip is only 4.7 mm × 5.7 mm, which is much smaller than the reported resonant pressure sensors 6,14 , in Fig. 4e.…”

“…These capacitive detection-based resonant pressure sensors showed that the change in the detection capacitance was extremely small, requiring a signal amplifier circuit with an extremely large amplification factor; meanwhile, the crosstalk between an excitation comb and capacitance detection comb was hard to eliminate 12 . Electromagnetic detection-based resonant pressure sensors have been comprehensively researched by Li et al 11 and Lu et al 14 ; these sensors have a total accuracy that is >0.01% FS. However, external magnets must be mounted on the sensors, and thus the sensors have large package sizes and poor temperature sensitivity.…”

A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

“…The reported data showed that the sensitivity was 1.8 Hz/kPa under a measurement range of 10 kPa to 1 MPa. Furthermore, our previous studies focused on several types of resonant pressure sensors with pressure measurement ranges over 500 kPa, such as Lu (2019) [ 32 ], Yan (2019) [ 33 ] and Xiang (2020) [ 34 ], with s maximal value of 2 MPa.…”