Electrostatically Actuated Surface Micromachined Offset Planetary Gear Pump Design

An offset planetary pump fabricated in five-level polysilicon surface micromachining is introduced. The pump consists of a ring gear enclosing two planetary gears and an offset sun gear, which generates pumping due to its eccentric rotation. The pump is driven by an electrostatically actuated comb-drive microengine and mechanical power is transmitted to the ring gear through a micro gear train. The paper presents a derivation of pump capacity and the detailed design of its mechanical elements, demonstrating the implementation of relatively advanced mechanical functions in multi-level surface micromachining, including axial roller bearing support, fluidic seal and planetary gear transmission.