A coupled field study on the non-linear dynamic characteristics of an electrostatic micropump

In this paper, a micropump actuated by electrostatic forces is dynamically analyzed. Coupled electromechanical effects are considered in the evaluation of the performance of the electrostatic micropump. The boundary element method is employed here to solve the quasi 3-D Laplace equation that the potential difference satisfies in order to obtain the surface charge density and corresponding electrostatic force. First order shear deformation theory is used to model the electrode membrane of the pump. Geometric nonlinearity arises due to the inclusion of von Karman strains. The finite element method is employed to discretize the governing equations and Newton's iteration method is employed to solve the discretized equations. With the electro-mechanical coupling effects considered within the framework of linear plate theory, i.e., ignoring the von Karman strains, similar response trends are obtained for the 2-D plate analysis as that of I-D analysis found in open literature. The present study is extended to non-linear analysis with von Karman strains included and non-linear load-deflection relationship is demonstrated. Variation of the amplitude and frequency of the potential difference applied across the two electrodes are investigated and responses are compared with those of linear analysis. Qualitatively different responses are observed. Also, the effects of the length-to-thickness ratio of the electrode plate are examined in detail. (C) 2003 Published by Elsevier Ltd.