Nanopores offer the potential for label-free analysis of individual proteins and low cost DNA sequencing. In order to design and evaluate nanopore devices, an understanding of nanopore electrokinetic transport is crucial. However, most studies of nanopore electrokinetic transport have neglected the effects of concentration polarization (CP) in the bulk fluid surrounding the pore. In this paper, we present a computational model which demonstrates the effects of CP on the background electrolyte in nanopore devices with tip diameters of 40–100 nm. We also present direct experimental observation of the distribution of an anionic dye in the vicinity of a conical nanopore. These results indicate that CP in a nanopore system can affect concentration distributions in the bulk solution tens of microns away from the pore, suggesting that typical boundary conditions used to model nanopore electrokinetic transport are incomplete.

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