Design, modeling and simulation of electrothermally actuated Microgripper with integrated capacitive contact sensor

This paper presents a detailed overview of modeling and simulation of an electro-thermally actuated Microgripper with integrated capacitive contact sensor. The Microgripper is actuated by chevron-shaped thermal actuator and a transverse type capacitive sensor is integrated with the actuator to sense the microgripper jaw position. The Microgripper is designed for standard MetalMUMPs process with 20 um thick Nickel as structural layer. The finite element analysis (FEA) is carried out in Intellisuite. A total displacement of 79 μm is achieved at a voltage Of 0.7 volts at the tip of the jaws. The normal jaw opening is 100 μm. The gripper can manipulate objects in size range between 21 μm to 100 μm. Model analysis of the microgripper is performed for first six modes to investigate natural frequencies and mode shapes for drive direction. The natural frequency of the model in drive mode is 11.12 KHz. The FEA analysis of capacitive sensor indicates a differential capacitance of 1055.9 fF at maximum displacement of 9 μm. The sensitivity of the capacitive sensor is 117.3f F/μm. The total size of the Microgripper is 4.58 mm×2.233 mm.