Electrical signal transmission across electrolyte junctions separated by atomically-thin graphene

Signal transmission across membranes is usually mediated by the permeation of molecular species. Here we show that atomically thin graphene crystals, although impermeable to any ions or molecules, can transmit interfacial electrical potentials across electrolyte junctions without significant disruption. In monolayer graphene, applying an electrical potential at one graphene-electrolyte interface induces a similar responsive potential at the opposite side, with the magnitude governed by ionic sizes. By increasing the number of graphene layers, the response decays and vanishes at ~ 5 layers. Theoretical analysis attributes these observations to graphene’s tunable charge-carrier concentration combined with its extreme thinness. This capability of transmitting activation stimuli without mass transport may find its applications in artificial synapses and other neuromorphic junctions. This study shows that atomically thin graphene can transmit electrical signals between separated liquids without allowing ions or molecules to pass, enabling communication across otherwise impermeable membranes.