Electroosmotic flows with simultaneous spatio-temporal modulations in zeta potential: cases of thick electrical double layers beyond the Debye Hückel limit

Abstract

We devise a mathematical model for analyzing the effects of spatio-temporal perturbations in zeta potential on electroosmotic transport in narrow fluidic confinements, considering thick electrical double layer limits. The spatial perturbations in zeta potential may be attributed to surface charge patterning, either designed or manifested as a natural artifact of the surface inhomogeneities. The time-dependent variations in zeta potential, as considered in this work, may stem from the temporal perturbations in the bulk ionic concentrations in the end-channel reservoirs or 'wells'. Overcoming the simplifications routinely employed in the literature, we develop here an improved analytical formalism, without imposing any constraints on the magnitude of the zeta potential. Using these solutions, we highlight the possibilities of obtaining designed rotationalities in the flow structure with simultaneous spatial variations in the zeta potential and temporal variations in the well concentrations. We show that such combinations of spatial and temporal variations, in effect, render the flow system to be capable of shedding vortex structures that are not otherwise obtainable with spatial variations in zeta potential alone.

Electroosmosis‐modulated bio‐flow of nanofluid through a rectangular peristaltic pump induced by complex traveling wave with zeta potential and heat source

“…For instance, Towns and Regnier [19] inspected chemically modified capillaries for electrophoretic separations. The modification of zeta potential distributions can be achieved through the use of field-effect voltage control [20] or multiple capillary systems [21]. Some interesting results are shown over the years by defining nonuniform zeta potential [22][23][24][25].…”