Theory and computational study of electrophoretic ion separation and focusing in microfluidic channels

Abstract

In this work we describe the theory and 2D simulation of ion separation and focusing in a new concept of microfluidic separation device. The principle of the method of ion focusing is classical in the sense that it consists in opposing a hydrodynamic transport ensured by the solution flow to an electrophoretic driving force so that any ionic sample results poised within the microchannel at the point where the two forces equilibrate. The originality of the concept investigated here relies on the fact that thanks to the use of an ion-conducting membrane of variable thickness in electrical contact with the channel the electrophoretic force is varied continuously all along the channel length. Similarly, changing the geometric shape of the membrane allows a facile optimization of the device separation and focusing properties.

Effects of Fluid–Structure–Interaction and Surface Heterogeneity on the Electrophoresis of Microparticles

“…Figures a and b show the typical contours of fluid velocity ( u f ) and the electric field potential (ϕ 2 ) surrounding the particle when it is under a steady electrophoretic migration after the unsteady part is over. The contours clearly suggest that both of these parameters are rather asymmetrically distributed around the microparticle undergoing electrophoresis inside a microchannel, which is unlike most of the analytical models proposed so far. − In order to elaborate on this issue, Figure a shows different cut lines around the particle taken at different angles along which the variations in profiles of the fluid velocity ( u f ) and the electric field potential (ϕ 2 ) surrounding the particle has been plotted in Figures c and d.…”