Micromotor operation in a liquid environment

The authors present the first account of successful electrical operation of electrostatic microactuators in a liquid environment. Successful operation of both the Range and center-pin harmonic (wobble) and salient-pole sidedrive micromotors in deionised water and silicone lubricating oil is achieved. In comparison with a gas environment, the minimum operating voltages are typically higher for operation in the liquids studied, while the maximum motor speeds possible are significantly lower. The motive torque is increased by the relative dielectric constant of the liquid, while the viscous drag torque is increased due to the high viscosity of the liquid. In contrast to operation in a gas environment, in a liquid, the gear ratio of the wobble micromotors is dependent on the excitation speed.<>