Two-directional switching of bistable curved micro beams by fringing electrostatic fields

In this work we investigate the feasibility of two-directional switching of a pre-buckled electrostatically actuated micro beam operated by a single electrode fabricated from the same structural layer. The distributed electrostatic force, which is engendered by the asymmetry of the fringing fields in the deformed state, acts in the direction opposite to the deflection of the beam and is of a restoring nature. The reduced order model was built using the Galerkin decomposition and verified using the results of the numerical solution of the differential equation. The actuating force was approximated by fitting the results of the numerical solution of the electrostatic problem. Static stability analysis reveals that the presence of the restoring electrostatic force may result in the suppression of the snap-through instability. We show that two-directional switching of a pre-buckled beam between two stable configurations and bistability cannot be achieved using quasistatic loading but are possible through dynamic instability mechanism. We demonstrate that switching associated with the dynamic snap-through takes place within certain interval of actuation voltages and pulse durations. Theoretical results illustrate the feasibility of the suggested operational principle as an efficient mechanism with application to nonvolatile mechanical memory devices.