Theoretical And Experimental Investigation Of Electrostatic Micropump With Flexible Membrane

Electrostatic micropumps have been studied extensively in the fields of chemical/biological fluid handling and thermal management of electronic components, because its advantages such as high energy density, fast response and low power consumption. Through the utilization of flexible membrane and cavity with continuous surface, the distance between the membrane and cavity is decreased, leading to increased electrostatic force and membrane deformation. As a result, the compression performance of the micrpump is improved. The present study focuses on the theoretical analysis, manufacture, encapsulation and experimental testing of electrostatic micropump with flexible membrane. The main works of this study are as following:(1) The analytical model for electrostatic micropumps with flexible membrane and cavity with continuous surface has been established by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The influence of design parameters on the pressure rise of the micrpump has been discussed. As a result, an electrostatic micropump with a relatively thin dielectric thickness, a cavity of comparatively small radius and depth, and a double cavity structure is preferred for the realization of high pressure rise.(2) The effect of electrostatically actuated flexible microvalves on the output performance of electrostatic micropumps has been analyzed. The existence of microvalves reduces the pressure rise and volumetric efficiency of micropumps. The flexible valve plate yields a reduced critical voltage for valve closing, enhancing the reliability of the pump.(3) Electrostatic micropump with double membrane for overflow has been designed by the introduction of overflow in small-scale rotor compressor. Both the volume efficiency and effective displacement of the pump with overflow are improved under the premise of little variation in the discharge pressure.(4) Cavity with continuous surface and membrane with several electrodes have been manufactured by integrating microfabrication and precision machining; electrostatic micropump has been encapsulated properly through the use of self-compound ATSP adhesion; the bonding of the periphery structure of the pump and microchannel heat exchanger has been realized by using AF 163-2K thermal-setting membrane.(5) A nonaxisymmetrical pull-in process between the membrane and cavity under electrostatic actuation has been observed, which is caused by the diameter deviation between the membrane electrode and the cavity.(6) The pressure performance of the micropump has been tested. The pressure difference between the inlet and outlet of the pump increases with the increasing of the actuation amplitude and frequency, which yields the same tendency of the calculation results. Moreover,the pressure waves filtered at the actuation frequencies appears to be like sine waves of the actuation frequencies,whose fluctuating amplitudes also increases with the enlargement of the actuation amplitude and frequency.