Electroosmotic pumping using porous anodic alumina membranes

This study demonstrated electroosmotic pumping with high flow rate per unit area at a rather low applied voltage through an alumina nano-porous membrane driven by Platinum mesh electrodes. The electrode was placed perpendicular to, and had direct contact with nano-channel inlet to reduce the electric voltage drop in the reservoir. The complete set of the Poisson-Nernst-Planck equations for electrical potential and ionic concentration, coupled with the Navier-Stokes equation were solved for the purpose of a full understanding of the ionic transport and flow characteristics of EOF in nano-fluidics capillaries. The measured flowrate versus electrolyte (KC1) concentration reveals that the flowrate is usually high in low concentration (10(-5) M similar to 10(-7) M) regime in which a maximum value also occurs. In addition, a remarkable surge of flow rate is observed when the concentration surpasses below 10(-4) M. The maximum flowrate achieved from this study is 0.09 mL min(-2)V(-1) cm(-2) and the energy transfer efficiency is 0.43% at an operation voltage of 20V. The flowrates investigated in this study are comparable to other existing results whereas the corresponding operation voltage used this study is about one to two order lower than most existing results. Numerical results exhibit correct trends for nano flows involving strong overlap of electrical double layers. Comparisons of numerical and experimental results were made and discussed.