Impact experiment analysis of MEMS ultra-high G piezoresistive shock accelerometer

A novel ultra-high g shock micro accelerometer with four self-supporting piezoresistive micro beams was proposed to simultaneously enhance the sensor performance of sensitivity and frequency response. The finite element method (FEM) simulations indicated that the pure axial deformations could occur on self-supporting piezoresistive micro beams via optimizing structure dimensions. And the average stress distribution in piezoresistive beams was 81.5 MPa, the natural frequency of sensor was about 505.00 kHz. To verify the sensitivity and natural frequency of fabricated shock accelerometer, impact tests were carried out using Hopkinson pressure bar under impact loads of 100,000 g. The results were obtained in the form of response curves of a shock signal. Then, the average sensitivity was calculated as 1.586 μV/g/3V, and the natural frequency was obtained as 445 kHz by fast Fourier transform. The experimental results agreed well with the FEM simulations except for a slight mismatch in natural frequency which was probably resulted from the errors of device fabrication and package processes. The experiment results reliably demonstrate that the proposed shock accelerometer, with high natural frequency and high sensitivity, is capable of measuring ultra-high g loading shock.