  In this investigation, the numerical simulation of electrohydrodynamic (EHD)
ion-drag micropumps with micropillar electrode geometries have been performed.
The effect of micropillar height and electrode spacing on the performance of
the micropumps was investigated. The performance of the EHD micropump improved
with increased applied voltage and decreased electrode spacing. The optimum
micropillar height for the micropump with electrode spacing of 40$\mu$m and
channel height of 100$\mu$m at 200V was 40$\mu$m, where a maximum mass flow
rate of 0.18g/min was predicted. Compared to that of planar electrodes, the 3D
micropillar electrode geometry enhanced the overall performance of the EHD
micropumps.
