Numerical Simulation of Field Amplified Sample Stacking in Microfluidic System

摘要

When an external electric field is applied to a system in which the conductivity in the sample zone is lower than that of running buffer, one establishes a protocol, namely field amplified sample stacking (FASS). The physical process of this pre-concentration technique is quite complex because of the interaction of convection, diffusion, electrophoresis and electroosmosis. We have developed a numerical simulation method that solves the transport phenomenon associated with sample stacking in microchip-based separation system. The model is based on thin double layer approximation where the electrostatic force is only salient in a very thin double layer adjacent to the charged surfaces. The electrokinetic equations describing the electrophoresis as well as electroosmosis are solved numerically in conjunction with fluid flow and electrostatics. Results for some typical sample stacking with one or two interfaces in the presence of electroosmosis are presented and compared with experiments.