A curved electrode electrostatic actuator designed for large displacement and force in an underwater environment

There is a need for the development of large displacement (O (10−6) m) and force (O (10−6) N) electrostatic actuators with low actuation voltages (< ±8 V) for underwater bio-MEMS applications. In this paper, we present the design, fabrication, and characterization of a curved electrode electrostatic actuator in a clamped–clamped beam configuration meant to operate in an underwater environment. Our curved electrode actuator is unique in that it operates in a stable manner past the pull-in instability. Models based on the Rayleigh–Ritz method accurately predict the onset of static instability and the displacement versus voltage function, as validated by quasistatic experiments. We demonstrate that the actuator is capable of achieving a large peak-to-peak displacement of 19.5 µm and force of 43 µN for a low actuation voltage of less than ±8 V and is thus appropriate for underwater bio-MEMS applications.