Simulation of 1D and 2D Electrophoretic Separations in Microfluidics Chips

Abstract

Electrophoretic separations comprise a group of analytical techniques such as capillary zone electrophoresis (CZE), isoelectric focusing (IEF), isotachophoresis (ITP) and free flow electrophoresis (FFE). In all cases, separation is based on the dissimilar mobility of ionic species under the action of an external electric field. These techniques, which are widely used in chemical and biochemical analysis, have been miniaturized in the last years and now represent one of the most important applications of the lab-on-a-chip technology. In a previous work, a generalized numerical model of electrophoresis on microfluidic devices was presented. The model is based on the set of equations that governs electrical phenomena (Poisson equation), fluid dynamics (Navier-Stokes equations), mass transport (Nerst-Planck equation) and chemical reactions. Also the relationship between the buffer characteristics (ionic strength, pH) and surface potential of channel walls is taken into consideration. In this work, three application examples are presented: (a) an IEF assay with immobilized pH gradient (IPG) including the influence of electro-osmotic flow on its performance, (b) an IEF assay involving ampholyte-based pH gradient, and (c) a 2D electrophoresis, involving FFIEF plus CZE. The numerical simulation is carried out by using PETSc-FEM (Portable Extensible Toolkit for Scientific Computation - Finite Elements Method), in a Python environment developed at CIMEC using high performance parallel computing and solving techniques based on domain decomposition methods.