A Topology-Optimized Compliant Microgripper With Replaceable Modular Tools for Cross-Scale Microassembly

Enhancing the operational capabilities within a limited workspace for the assembly of microobjects with different shapes and dimensions is a prominent objective in microgripper development. In response to the challenge, this article develops a novel microgripper equipped with replaceable modular tools. The design process involves an integrated topology optimization method for compliant mechanisms and piezoelectric actuators to achieve high compactness. This method employs a geometric representation scheme incorporating explicit and implicit topology descriptions to drive the layout evolution of actuators and compliant mechanisms. The extended finite element method (XFEM) is utilized to capture the displacement field in the design domain to enhance the accuracy of the structural response and sensitivity analysis. Moreover, the output compliance and minimum length scale control are considered in the optimization model to ensure the manufacturability of the results. Furthermore, the microgripper is equipped with replaceable modular tools, enabling an expanded clamping range and adaptability to microobjects of varying shapes and feature dimensions. Numerical simulations and experiments validate the efficacy of the design method and demonstrate the high area efficiency and application potential of the proposed microgripper. Notably, the microgripper has proven successful in clamping objects with feature dimensions ranging from 25 $\mu$ m to 3.8 mm and assembling micro silicon wafers and miniature planetary gears.