Effects of discrete-electrode configuration on traveling-wave electrohydrodynamic pumping

Traveling-wave electrohydrodynamic (EHD) micropumps can be incorporated into the package of an integrated circuit chip to provide active cooling. They can also be used for fluid delivery in microdevices. The pump operates in the presence of a thermal gradient through the fluid layer such that a gradient in electrical conductivity is established allowing ions to be induced. These ions are driven by a traveling electric field. Such a traveling electric field can be realized in practice only via discrete electrodes upon which the required voltages are imposed. The impact of using discrete electrodes to create the traveling wave on the flow rates generated is explored through numerical modeling. The change in performance from an ideal sinusoidal voltage boundary condition is quantified. The model is used to explore the widths of electrodes and the intervening isolation regions that lead to optimized pumping. The influence of the choice of working fluid on the performance of the pump is determined using an analytical model.