Experimental and Finite Element Analysis approach for torque assessment in CSFH-based microgrippers with different geometries

Microgrippers are MEMS devices capable of precise manipulation of objects on a micrometer scale. Few studies in the literature have focused on the dynamic characteristics of microgrippers with capacitive actuators. This work aims to the development of a novel approach that combines experimental measurements with finite element analysis to evaluate the torque exerted by microgrippers characterized by three different geometries. The investigated devices are composed of electrostatic rotary comb-drives and conjugated surface flexure hinges. The microactuators’ rotation has been measured by means of an image analysis technique developed by the Authors, employing videos captured by optical microscope equipped with a high-resolution camera, while the hinge stiffness is estimated through numerical simulations. The experimental results of the different geometries confirm the effectiveness of the proposed approach in assessing the torque output of microgrippers’ actuators. The results showed a quadratic trend for the torque as a function of the supply voltage, and that doubling the number of comb-drives results in double the torque. Furthermore, the results also validated the numerical model, allowing the implementation of a phy-digital twin of the device that can be used to simulate the behavior of a microgripper under different conditions and empowering their optimization and design refinement.