An electrothermally actuated high amplification MEMS microgripper with integrated capacitive sensing for micromanipulation

The significant challenges in the development of Microelectromechanical Systems (MEMS) microgrippers are scalability, power efficiency and seamless integration. In this research paper, a MEMS microgripper is presented, which uses electrothermal actuation and capacitive sensing to address these challenges. A two–stage displacement amplification is incorporated to achieve a high amplification ratio of 14.2. The novel design effectively overcomes the challenge of achieving high jaw displacement for a low input voltage, enabling seamless integration of the device into practical applications. For the optimization of the design of microgripper, Finite Element Method (FEM) is carried out using COMSOL Multiphysics. The simulation results are employed to determine the maximum allowable actuation voltage of 12 V, for which the microgripper stays within its temperature and fracture limits. Furthermore, experimental validation of the microgripper’s performance is carried out using microprobes and a microscope equipped with a camera system. The experimental results indicate a maximum jaw displacement of 51.32 µm for the maximum actuation voltage of 12 V. Additionally, the capacitive sensor is calibrated for displacement measurement, offering a resolution of 0.041 pF/µm. An analytical gripping force model is developed to estimate the gripping force at the jaws. The microgripper can generate a maximum gripping force of 0.72 µN. The microgripper has successfully performed a microwire gripping task to demonstrate its versatility in micromanipulation and biomedical applications.