Design, analysis and fabrication of a novel hybrid electrothermal microgripper in microassembly cell

The methods of actuating, grasping, assembling and transporting microelectromechanical systems (MEMS) have been studied extensively. This paper has introduced a microassembly cell for positioning and gripping micro parts using normally closed hybrid microgrippers consisting of U-shaped and V-shaped microactuators. Most of the actuators presented in the articles have been designed and fabricated to grip fixed dimensions but this paper has presented a novel design of normally closed hybrid electrothermal microgrippers that, with applying the potential difference to its anchors, the micro parts can be positioned, maintained and transported in the 110 to 160-μm dimension ranges. Each microgripper design includes four V-shaped electrothermal actuator attached to a shuttle at the bottom and two U-shaped microactuators at the top. Finally, two microgrippers have been positioned in a single assembly cell to simultaneously grip two pieces. The whole design has been considered on a rotary table to excite the piezoelectric system to move the micro parts toward the gripping site. After determining the design parameters using the introduced model, the behavior of this microgripper has been simulated in COMSOL MULTIPHYSICS® finite element software and the displacement of the gripper arms and the heat generated by the actuator have been calculated. Finally, the design has been fabricated following the necessary modifications to make fabrication feasible according to existing facilities using silicon microfabrication processes. After the fabrication of the microgripper, the necessary tests have been performed on the fabricated sample and the results of the measurements are compared with the numerical outputs. The comparison have shown good agreement with the experminetal results associated with the fabricated sample.