Pressure-driven electrokinetic slip-flow in planar microchannels

This paper presents an analytical solution for pressure-driven electrokinetic flows in planar microchannels with velocity slip at the walls. The Navier-Stokes equations for an incompressible viscous fluid have been solved along with the Poisson-Boltzmann equation for the electric double layer. Analytical expressions for the velocity profile, average electrical conductivity, and induced voltage are presented without invoking the Debye-Hückel approximation. It is known that an increase in the zeta-potential leads to an increase in the flow-induced voltage; however, it is demonstrated that the induced voltage reaches a maximum value at a certain zeta-potential depending on the slip coefficient and the Debye-Hückel parameter, while decreasing rapidly at higher zeta-potentials. The present parametric study indicates that liquid slip at the walls can increase the maximum induced voltage very significantly.