Beyond the Continuum Theory: Conductance Scaling and Correlated Imaging in Atom-Scale Artificial Ion Channels.

Ion transport in artificial channels that mimic biological ion channel behavior can enable advances in neuromorphic computing and biomolecular sensing. We fabricate atom-scale artificial ion channels in multilayer hexagonal boron nitride (hBN), with dimensions comparable to biological ion channels, and demonstrate a distinct regime of ion transport. Channels ranging from 0.5 to 1.5 nm in diameter reveal unconventional ion transport under conditions of extreme confinement: the conductance G remains approximately constant regardless of bulk ion concentration c and is significantly enhanced as c decreases. Molecular dynamics simulations support this G versus c relationship, suggesting a single-file ion transport mechanism without dehydration. A comprehensive theoretical analysis attributes the breakdown of conductance scaling to the combined effects of confinement and surface charge. Postmeasurement characterization shows the stability of our hBN channels, ensuring experimental reliability and direct diameter measurements. These findings further the understanding of ion transport phenomena in artificial ion channels at the atomic scale.