Ion Dynamics and Polarizations in Simulated Nanopore under Alternating Current Controls

A fundamental investigation of ion transport through nanopores offers a central basis in advancing the design of ionic or mo-lecular sensors. This report develops a new approach with the continuum modeling method to investigate the competition be-tween a surface-charge dominated electromigration process under an altering-current field induced dynamic ion distribution at controls of the field frequency. We highlight a size-dependent transition from a surface-charge-dominated ion distribution, where electric double layer (EDL) impacts prevail, to a bulk-like ion dynamics as pore dimensions approach to a microscale. Results reveal a rapid electromigration dominates ion distribution at a millisecond timescale, generating transient, non-equilibrium concentration profiles. In contrast, lower frequency perturbations enable diffusion to equilibrate ion distributions within each cycle, establishing periodic quasi-steady states. Findings from this work highlight the interplay of the ion selectivity and distribution by exploiting the dynamic competition between electromigration and diffusion.