Large displacement low voltage multistable micro actuator

This paper presents the modeling, design, fabrication and characterization of electrostatic large displacement multistable micro actuators. The device incorporates multiple serially connected bistable elements realized as shallow curved beams of slightly varying length. Loaded by an increasing force provided by an electrostatic comb drive transducer, the device undergoes a sequence of snap-through events and exhibits multiple stable equilibrium configurations at the same voltage. A Reduced Order (RO) model built using the Rayleigh-Ritz procedure as well as a nonlinear Finite Element (FE) analysis were used in order to predict the actuator behavior and evaluate design parameters. Devices of four different configurations were fabricated by a Deep Reactive Ion Etching (DRIE) based process using silicon on insulator (SOI) wafers. Experimental results demonstrate that the multistable devices exhibit stable displacement of 90μm while four snap-through and snap-back events take place during loading and unloading respectively. Experimental results are found to be in good agreement with the theoretical predictions.