RT Journal Article
SR Electronic
T1 The nonlinear electromigration of analytes into confined spaces
JF Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science
FD The Royal Society
DO 10.1098/rspa.2012.0221
A1 Chen, Zhen
A1 Ghosal, Sandip
YR 2012
UL http://rspa.royalsocietypublishing.org/content/early/2012/06/11/rspa.2012.0221.abstract
AB We consider the problem of electromigration of a sample ion (analyte) within a uniform background electrolyte when the confining channel undergoes a sudden contraction. One example of such a situation arises in microfluidics in the electrokinetic injection of the analyte into a micro-capillary from a reservoir of much larger size. Here, the sample concentration propagates as a wave driven by the electric field. The dynamics is governed by the Nerstâ€“Planckâ€“Poisson system of equations for ionic transport. A reduced one-dimensional nonlinear equation, describing the evolution of the sample concentration, is derived. We integrate this equation numerically to obtain the evolution of the wave shape and determine how the injected mass depends on the sample concentration in the reservoir. It is shown that due to the nonlinear coupling of the ionic concentrations and the electric field, the concentration of the injected sample could be substantially less than the concentration of the sample in the reservoir.