Analytic theory of nonlinearly coupled electrokinetics in nanochannels

Yuki Uematsu

doi:10.1063/5.0131481

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arXiv · 2305.15714

Analytic theory of nonlinearly coupled electrokinetics in nanochannels

Yuki Uematsu

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Abstract

The nonlinear electrokinetic response of ionic solutions is important in nanofluidics. However, quantitatively understanding the mechanisms is still a challenging problem because of a lack of analytic approaches. Here, a general framework for calculating the nonlinear electrokinetic coefficients of strongly confined electrolytes is constructed using a perturbation scheme of the pressure and voltage differences across a nanochannel. The theory is applied to an electrically neutral nanochannel filled with electrolytes, and analytic expressions for the first- and third-order electrokinetic coefficients are obtained. We demonstrate that the combination of high hydrodynamic permeability and ion-wall friction plays an essential role in nonlinear electrokinetics. Furthermore, we analytically demonstrate that the external flow induces uniform excess charge inside the nanochannel.

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Yuki Uematsu. 2023-05-25. Analytic theory of nonlinearly coupled electrokinetics in nanochannels. https://doi.org/10.1063/5.0131481

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