Electrostatic actuated micro gripper using an amplification mechanism

This paper presents a microgripper using an amplification mechanism coupled to an electrostatic linear motor. The gripper design, particularly the principle of the amplification mechanism based on the combination of ground-links and moving pin-joints, is explained. The linear motor is composed of scratch drive actuator inducing the use of electrostatic forces to obtain quasi-static motion for high accuracy in micropositioning. To corroborate the design, the gripper mechanism has been modeled by finite elements method with different mesh elements via the simulator CASTEM 2000(TM). Then, the amplification ratio of displacement, the critical buckling load and the force applied to the grasped object are determined. Moreover, the fabrication process requiring four levels of polysilicon are presented and notices based on visual observations of the realized actuator are given. Based on video observations, kinematics characterization of different topologies of the microgripper is performed and a discussion concerning the comparison with the simulation results and the influence of the geometric shapes of jaws/arms on the kinematics parameters is done. Finally, reliability aspects are stated consisting in the determination of the brittleness areas. (C) 2003 Elsevier B.V. All rights reserved.