Analysis of preconcentration patterns in microfluidic ion concentration polarization devices

Abstract

The analysis of governing parameters on the preconcentration of charged analytes is of utmost importance for ion concentration polarization-based devices. The interaction between applied voltage and microchannel length, i.e., the electric field, can be used to obtain optimum operation of ion concentration polarization (ICP) in terms of enrichment factor. In this paper, the affecting parameters of ICP were studied numerically and experimentally to investigate the preconcentrating behavior of analytes upon applying voltage. We showed that applying different electric fields changes the accumulation patterns of the preconcentrated analytes. We classified the patterns for the first time based on the range of electric fields as no preconcentration, dispersed, protruded, and focused preconcentration. In addition, the analysis of the effect of buffer concentration on enrichment factor revealed that unlike the electric field, the buffer concentration only affects the enrichment factor without influencing the preconcentrated analyte pattern. The results demonstrated that by decreasing the buffer concentration, the enrichment factor is increased. The comparison of the experimental findings with the numerical results, obtained from COMSOL Multiphysics®, manifested acceptable correspondence. The findings of this study can be used for further optimization, to develop high-performance ICP devices in biomedical and analytical applications.