The Optimal Shape of MEMS Beam Under High-G Shock Based on a Probabilistic Fracture Model

MEMS designed for high-g shock environments tend to sacrifice their structural performance for reliability concerns. The size and shape of the micro-beam are critical for both the performance and reliability of MEMS. This paper proposes an optimization method that can exploit the structural performance of MEMS beams under mechanical overload. First, we proposed a reliability model to quantify the fracture probability of MEMS beam under shock. Secondly, a performance optimization problem was established based on the variable cross-section beam structure. Finally, the optimal shape of four typical types of MEMS beam was obtained numerically. Without sacrificing their reliability under high-g shock, the driving voltage and the structural sensitivity of the beam of optimal shape were improved by 13-49% and 32-79%, which is a practical optimization design by not changing the manufacturing process drastically.