Sensitivity Improvement of MEMS Resonant Accelerometers by Shape Optimization of Microlevers and Resonators

High-frequency sensitivity to external acceleration is crucial for improving the accuracy of MEMS resonant accelerometers. This study proposes utilizing shape optimization of microlevers and resonators to improve sensitivity. Initially, an optimization model for microlevers is established, considering the arm's shape and the dimensions of the pivots, outputs, inputs, and supported beams. Secondly, shape optimization for the resonant beam of the tuning fork resonators is implemented, utilizing a bi-objective function to maintain the fundamental frequency. Finally, the genetic algorithm is employed in both optimizations to search for the global optimal solution. The microlever optimization achieves a high sensitivity of 286.9 Hz/g, and the final trapezoidal arm shape offers the advantage of accommodating a larger proof mass within a given die area. Meanwhile, the resonator optimization improves the sensitivity to axial inertial force from 727 Hz/mN to 1338.5 Hz/mN while keeping the fundamental frequency at approximately 20,000 Hz. Integrating the optimized microlevers and resonators yields a very high sensitivity of 480.2 Hz/g, and the sensitivity per proof mass area is significantly higher than that reported in previous studies.