Performance optimization and mechanical modeling of uniaxial piezoresistive microaccelerometers

The acceleration measurements in automotive, navigation, biomedical and consumer applications demand high-performance microaccelerometers. This paper presents an optimization model to maximize the bandwidth of uniaxial piezoresistive microaccelerometers based on cantilever-type beams. The proposed model provides a high sensitivity as well as normal stress levels lower than the material rupture stress of these microaccelerometers. This model uses the Rayleigh method to determine the objective function of the bandwidth and the maximum-normal-stress failure theory to obtain a stress constraint that guarantees safe operation for the microaccelerometer structure. The Box-Complex optimization method is used to solve the optimization model due to its easy programming algorithm. Finite element models (FE) are developed to determine the mechanical behavior of the optimized piezoresistive microaccelerometers. The results of the FE models agree well with those of the optimization model. The optimization model can be easily used by designers to find the optimum geometrical dimensions of piezoresistive microaccelerometers to maximize their performance.