# Optimal transport and colossal ionic mechano-conductance in graphene crown ethers

## TL;DR

This study demonstrates that applying small mechanical strains to graphene crown ether pores dramatically enhances ion conductance and selectivity, providing a tunable platform for investigating optimal ion transport mechanisms.

## Contribution

The paper introduces a novel graphene-based platform with mechanically tunable ion transport properties, revealing colossal conductance changes and insights into biological ion channel function.

## Key findings

- Small pore strains induce 100% increase in conductance.
- Transport operates mainly in a diffusive, barrierless regime.
- Mechanical modulation reveals local electrostatic conditions.

## Abstract

Biological ion channels balance electrostatic and dehydration effects to yield large ion selectivities alongside high transport rates. These macromolecular systems are often interrogated through point mutations of their pore domain, limiting the scope of mechanistic studies. In contrast, we demonstrate that graphene crown ether pores afford a simple platform to directly investigate optimal ion transport conditions, i.e., maximum current densities and selectivity. Crown ethers are known for selective ion adsorption. When embedded in graphene, however, transport rates lie below the drift-diffusion limit. We show that small pore strains -- 1 % -- give rise to a colossal -- 100 % -- change in conductance. This process is electromechanically tunable, with optimal transport in a primarily diffusive regime, tending toward barrierless transport, as opposed to a knock-on mechanism. Measurements of mechanical current modulation will yield direct information on the local electrostatic conditions of the pore. These observations suggest a novel setup for nanofluidic devices while giving insight into the physical foundation of evolutionarily--optimized ion transport in biological pores.