Theoretical modelling of electrokinetic flow in microchannel networks

This work deals with the description of electrokinetic flow in microfluidic networks involving multiple channels intersections. A generalized one-dimensional modelling is carried out to predict flow rate and electric current in each branch of the network, as a function of applied electric potentials and pressure gradients. Mathematical derivations ground on thermodynamic formalisms for electrokinetic phenomena, and takes into account the characteristics of every channel and circulating fluid in the system. The coefficients that relate driving forces and conjugated flows are derived for both slit and cylindrical microchannels, with arbitrary values of surface potential and electric double layer thickness. Calculations are used to rationalize typical operations performed in analytical devices that consist of well-defined microchannel networks. The modelling suggested also provides an accurate basis to study fundamental aspects of electrokinetic phenomena in microfluidic systems. (C) 2007 Elsevier B.V. All rights reserved.