Microresonant accelerometer composed of silicon substrate and quartz double-ended tuning fork with temperature isolator

A microresonant accelerometer which consists of silicon substrate and a quartz double-ended tuning fork (DETF) is described. A temperature isolator structure on the silicon substrate is designed to decrease the influence of thermal stress on the DETF´s tines. Two stiff ends of the quartz DETF are mounted on the proof mass and temperature isolator, respectively. When acceleration is applied, the proof mass will move, inducing the variation of axial stress on the DETF´s tines. The resonance frequency of the DETF´s tines will change corresponding to the stress, so acceleration can be measured. The DETF is excited by the inherent piezoelectric property of quartz based on the anti-phase in-plane bending model. Both the silicon substrate and the DETF are fabricated by micromachining. The sensor is analysed by finite-element simulation. According to the simulation, the temperature isolator decreases thermal stress by 30.2%. Experimental results show that the resonance frequency of the sensor is 35.2563 kHz and the sensitivity is 8.55 Hz/g, which is in good agreement with analytical calculation.