Analysis of electrokinetic flow in microfluidic networks

Abstract

A general model for electrokinetic flow in a one-to-multi-branch microchannel system is developed. This model can be extended to more complex microfluidic networks. The liquid flow may be generated by applying pressure gradients (pressure-driven flow) or electric fields (electro-osmotic flow) to the microchannels. Phenomenological coefficients in non-equilibrium thermodynamics are employed to describe the effects of channel size and surface electrokinetic properties on microfluidic characteristics. Analytical solutions of the flow rate and the streaming potential (for pressure-driven flow) or the electric current (for electro-osmotic flow) are obtained for each branch-channel, in addition to the distributions of pressure and electric potential. The flow behaviors in such a microchannel network can thus be predicted by these analytical solutions. As examples, a two-section heterogeneous microchannel and a one-to-two-branch microchannel system are analyzed using the derived model.