Study on the impact resistance of silicon-based MEMS structures based on crystallographic orientation

Silicon-based micro-electro-mechanical systems (MEMS) have broad application prospects in aerospace, defense, and automotive electronics owing to their advantages in miniaturization, integration, and intelligence. However, under severe service conditions such as impact, vibration, and high overload, silicon-based MEMS devices are prone to structural damage or even failure due to the brittleness, anisotropy, and local stress concentration effects of single-crystal silicon (SCS). In this study, a new cantilever design scheme is proposed, and the influence of SCS anisotropy and fillet parameters on the impact resistance of silicon-based MEMS cantilever structures is systematically investigated. First, the tensile strengths of SCS (100) wafers along different crystallographic orientations were measured by the Brazilian disk splitting test. On this basis, an orthotropic material model for SCS was established. Numerical simulations were then performed to analyze the stress distribution characteristics of a silicon-based MEMS cantilever under impact loading, with particular emphasis on the effects of fillet radius on stress distribution, crystallographic orientation strength, and factor of safety. The results show that increasing the fillet radius effectively reduces local stress concentration and improves the stress-field distribution. Moreover, fillet optimization not only decreases the local stress level but also improves the matching relationship between the principal stress direction and the crystallographic orientation, thereby jointly enhancing structural safety. This study provides a theoretical basis for the impact-resistant reliability design and structural optimization of silicon-based MEMS components.