Analysis and design for piezoresistive accelerometer geometry considering sensitivity, resonant frequency and cross-axis sensitivity

Presented in this paper is the geometrical analysis and design for piezoresistive accelerometers. An improved figure of merit (FOM), considering sensitivity, resonant frequency and cross-axis sensitivity, is established to evaluate the sensor characteristics. Three conventional geometries, including cantilever-beam, quad-beam and cross-beam, are investigated to explore the influence from sensor configurations on the FOM. Based on the obtained results, a multi-beam structure is developed to provide an available solution to the drawback of low FOM in normal geometries. The proposed design increases its resonant frequency at the cost of a slight loss in sensitivity, and declines the cross-axis sensitivity by the specific configuration, which is made possible by incorporating two tiny sensing beams into the quad-beam structure. The simulated FOM is about 5.5 times of the conditional structures. The fabricated prototype is characterized for static parameters and resonant frequency. Experimental results show that the measured FOM is about 4.85 × 10⁹ Hz², much higher than the existing designs in literatures or on the market.