Models of electroosmotic flow in micro and nanochannels
Abstract
Understanding electrooosmotic flow (EOF) is essential for developing efficient drug delivery and rapid biomolecular analysis devices given the extremely high pressure gradients required to drive flows through channels smaller than about 10 μ m. We consider fullydeveloped and steady EOF in one and twodimensional micro and nanochannel geometries. The fluid, which is assumed to behave as a continuum, is a mixture of a neutral solvent such as water and a salt where the ionic species are entirely dissociated. The model can be used to analyze EOF where the opposite channel walls are oppositely charged and EOF with arbitrary electric double layer thickness. Unlike most previous models which assume a wall ζ potential a priori, the model calculates the boundary conditions for the (wall) mole fractions using the equilibrium electrochemical potential in the upstream reservoir. We can therefore predict the wall ζ potential, and calculate EOF with spatially and temporally varying wall ζ potentials. The model results for electroosmotic mobility and volumetric flow rate are compared with those from three independent experimental datasets, and found to be in good agreement with all three sets of experimental data for channel sizes ranging from O(10 nm) to O(10 μ m). The limits of the continuum theory for EOF are discussed.
 Publication:

APS Division of Fluid Dynamics Meeting Abstracts
 Pub Date:
 November 2003
 Bibcode:
 2003APS..DFD.FD001Z