Analysis and Design of Multistage Electrostatically-Actuated Micro Vacuum Pumps

Abstract

A new concept for a MEMS-fabricated micro vacuum pump is proposed. The pump is designed to operate in air and can be easily integrated into MEMS-fabricated micro fluidic systems. The pump consists of a series of pumping cavities with electrostatically actuated membranes interconnected by electrostatically actuated microvalves. A thermodynamic model of the micropump has been developed and used to determine the pump performance. It is shown that volume ratio plays an important role in the operation of the pump. For a fixed number of stages, at high volume ratio, pumping action is uniformly distributed among the stages. In contrast, at low volume ratio most of the pumping takes place in the latter stages of the pump. Detailed calculations of the flow through key components of the micropump are also reported. In particular the flow through a checkerboard microvalve and electrode perforations is discussed, and new correlations for the pressure loss in these components are proposed.