Ionic conductance oscillations in sub-nanometer pores probed by optoelectronic control

TL;DR

This study experimentally observed ionic conductance oscillations in sub-nanometer MoS2 pores under optoelectronic control, revealing multi-ion interactions and Coulomb blockade effects crucial for nanofluidic and biological ion channel understanding.

Contribution

It provides the first experimental evidence of ionic conductance oscillations in atomically thin nanopores with active surface charge tuning, supported by theoretical analysis and simulations.

Findings

Observed multiple ionic current peaks under charge control.

Identified multi-ion interactions as the origin of conductance oscillations.

Enhanced understanding of ionic Coulomb blockade in nanoconfined environments.

Abstract

Ionic Coulomb blockade is one of the mesoscopic effects in ion transport revealing the quantized nature of ionic charges, which is of crucial importance to our understanding of the sub-continuum transport in nanofluidics and the mechanism of biological ion channels. Herein, we report an experimental observation and plausible theoretical reasoning of ionic conduction oscillations. Our experiment was performed under strong confinement in single sub-nanometer MoS2 pores with optoelectronic control enabled for active tuning of pore surface charges. Under this charge control, we measured the ionic current at fixed voltages and observed multiple current peaks. Our analytical discussions and molecular dynamics simulations further reveal that the conductance oscillations in atomically thin nanopores may originate from the multi-ion interaction at the pore entry, particularly the electrostatic repulsion of ions external to the pore by ions bound inside the pore. Our work adds a further understanding of ionic Coulomb blockade effect under extreme confinement in atomically thin nanopores and paves the way for developing advanced ionic machineries.