Biological ion channels balance electrostatics and hydration, yielding 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 transport conditions. Crown ethers are known for selective ion adsorption. When embedded in graphene, however, transport rates lie below the 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 majority diffusive regime -- veering toward barrierless transport as opposed to a knock--on mechanism. Its measurement will yield direct information on the local electrostatic conditions of the pore. These observations suggest a novel setup for biomimetic devices while giving insight into the physical foundation of evolutionarily--optimized ion transport.
Ion transport, Nanopores, Ion channels, Crown ether