A double differential torsional micro-accelerometer based on V-shape beam

This paper reports the design, simulation, fabrication and measurement of a double differential torsional micro-accelerometer based on V-shape beam. The structure of conventional torsional micro-accelerometers is typically composed of two unbalanced proof masses and a torsional beam. This work develops a torsional micro-accelerometer with an optimized structure, which is composed of four proof masses splitting into two pairs. The two pairs of unbalanced masses have the opposite sensitivity to acceleration but the same sensitivity to off-acceleration input, and by using double differential arithmetic the sensitivity, environment robustness and bias stability can be improved. The accelerometer prototype is fabricated with the pre-buried mask wet-etching method and tested. The resonant frequency and quality factor are about 1485 Hz and 28.02 respectively. The sensitivity and nonlinearity of the measuring range ±15 g is 0.14 mV/g and 0.22% respectively. The x-axis and y-axis cross-axis errors are 0.04% and 0.69% respectively. The 1 g bias stability of the accelerometer is 0.11 mg for 1 h and the Allan deviation is 8.7 μg. In the full temperature range of −40 °C to +60 °C,the temperature sensitivity of the scale factor is 49.9 ppm/°C while the offset temperature coefficient is 0.22 mg/°C after temperature compensation.