Development of a High-Performance Microaccelerometer With Position Independent Pure-Axial Stressed Piezoresistive Beams

It has been demonstrated that piezoresistive beams in a purely axial deformation state significantly enhance the performance of piezoresistive accelerometer. Current solution to realize purely axial deformation of piezoresistive beams for the high-performance microaccelerometer relies heavily on beam positions, which limits its design flexibility and the error tolerance in the fabrication process. In this article, a novel structure with position independent pure axially deformed piezoresistive beams is proposed. By controlling synchronous displacements at both ends of piezoresistive beams, the pure axially stress states of the piezoresistive beams can be easily realized at any beam position without tedious theoretical calculations. The theoretical model was developed to understand the relationship between the displacement and the axial stress of the piezoresistive beams, as well as the natural frequency of the whole structure. Then, the correctness of the theoretical model was verified by finite element simulation and experiments. The results demonstrated that the accelerometer had an extremely high sensitivity of 2.44 mV/g/5 V (without circuit amplification), and a high natural frequency of 11.4 kHz.