# Confinement-controlled rectification in a geometric nanofluidic diode

## TL;DR

This paper presents a theoretical model explaining ionic current rectification in nanofluidic diodes, highlighting the role of surface-to-bulk conductivity ratio over double layer overlap in rectification efficiency.

## Contribution

It introduces a new theoretical framework that clarifies the physical mechanisms behind ionic current rectification in conical nanopores, emphasizing the importance of the Dukhin length.

## Key findings

- Rectification efficiency depends on surface-to-bulk conductivity ratio.
- Channel selectivity is influenced by the Dukhin length.
- The model explains experimental observations of rectified ionic currents.

## Abstract

Recent experiments with electrolytes driven through conical nanopores give evidence of strong rectified current response. In such devices, the asymmetry in the confinement is responsible of the non-Ohmic response, suggesting that the interplay of entropic and enthalpic forces plays a major role. Here we propose a theoretical model to shed light on the physical mechanism underlying ionic current rectification (ICR). By use of an effective description of the ionic dynamics we explore the system's response in different electrostatic regimes. We show that the rectification efficiency, as well as the channel selectivity, is driven by the surface-to-bulk conductivity ratio Dukhin length rather than the electrical double layer overlap.