Abstract

This paper reports a high accuracy oil-filled MEMS absolute pressure sensor based on quartz crystal double-ended tuning fork (DETF) resonator, which is suitable for application in ocean, petroleum, meteorological, aerospace and spacecraft field, etc. The pressure sensing unit is mainly composed of DETF resonator, diaphragm and back cavity structure. These pieces are all fabricated by quartz crystal using MEMS process, and are bonded together as ‘sandwich’ structure to form the absolute pressure sensing unit using glass frit under low temperature and vacuum condition. This process could effectively eliminate the thermal stress effect and form the reference vacuum cavity. The isolated packaged pressure sensor is composed of corrugated stainless steel diaphragm, silicone oil, pressure sensing unit and ceramic base package. The experimental results show that the accuracy is up to ±0.033% FS in the pressure range 0~300 kPa over the temperature range −20 °C~+45 °C.

Highlights

  • Resonant pressure sensors are more attractive than common piezoresistive or capacitive pressure sensors for its higher accuracy, higher stability, lower power consumption and inherently digital-type output

  • We report an oil-filled MEMS absolute pressure sensor based on quartz crystal double-ended tuning fork (DETF) resonator, quartz crystal diaphragm and quartz crystal back cavity structure

  • The pressure sensor which we report here is believed to be higher accuracy and stability than that using quartz resonator and silicon diaphragm, because the three main parts are all fabricated by quartz crystal with same orientation through MEMS

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Summary

Introduction

Resonant pressure sensors are more attractive than common piezoresistive or capacitive pressure sensors for its higher accuracy, higher stability, lower power consumption and inherently digital-type output. High accuracy resonant pressure sensors usually employ resonators such as resonant beams or tuning forks as resonant strain gauges to sense pressure-induced stresses in a diaphragm [1,2]. R.J. Cheng et al has reported a resonant pressure sensor by combination of DETF quartz resonator and silicon diaphragm [3]. The mismatch between quartz crystal and silicon could affect the accuracy and stability of the pressure sensor. We report an oil-filled MEMS absolute pressure sensor based on quartz crystal DETF resonator, quartz crystal diaphragm and quartz crystal back cavity structure. The pressure sensor which we report here is believed to be higher accuracy and stability than that using quartz resonator and silicon diaphragm, because the three main parts are all fabricated by quartz crystal with same orientation through MEMS process. The isolated packaging technology is used to protect the pressure sensing unit and improve the media compatibility of the sensor

Device Design
Fabrication
Results and Discussion
Conclusions
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