Modal analysis of a four-bar linkage MEMS microgripper with cooperative electrostatic actuation

MEMS-Technology based microgrippers have been recently used in different fields of applications. These microsystems can be actuated by means of electrostatic actuators, such as linear or rotary comb drives, but the robustness and feasibility of such components in static and as well as dynamic conditions still raises some concerns. In order to contribute to fill this gap, the dynamic properties of a MEMS-Techology Based silicon microgripper, based on four-bar linkage, with co-operative comb-drives, are here numerically analysed. The analysis of the vibrations is essential in many MEMS applications since vibrations may lead to significant positioning errors or undesirable contacts between the anchored and floating fingers of the comb-drives. The present investigation aims to assess the critical modes of a MEMS microgripper in order to ascertain the possibility of impact between the fixed and moving fingers of the comb-drives. The relative displacements between the anchored and the floating fingers are tolerable only if the center of the relative rotation is coincident with the center of the conjugate profiles. Hence, the nature of the relative motion for the first vibration modes has been assessed by means of Finite Element Analysis (FEA) in order to avoid operational issues.