A numerical study of sample preconcentration using ion concentration polarization in single microfluidic channels with dual ion-selective membranes

In this work, we investigated three single straight microchannel designs for the microfluidic biomolecule concentration device, including one traditional single channel and two innovative channels. These microchannels utilized the ion concentration polarization (ICP) phenomenon to preconcentrate very dilute sample biomolecules. By numerically solving coupled equations, Nernst-Planck, Poisson, and Navier-Stokes with appropriate boundary conditions, we provide insight into the ICP phenomenon and the preconcentration mechanism. From the detailed modeling results, we clarify the influence of important working parameters, including electric potentials, the ion-selective membrane dimensions, the channel dimensions, and the ionic strength of buffer solution on the formation of ICP and the enrichment rate of the charged biomolecules. These modeling results for various working conditions of the preconcentration systems highlight the advantage of generating a stronger electric field to preconcentrate biomolecules of two innovative channel designs over the conventional one. The findings are useful tips for the design and optimization of preconcentration microfluidic devices.