Electrochemical tunnelling sensors and their potential applications

The quantum-mechanical tunnelling effect allows charge transport across nanometre-scale gaps between conducting electrodes. Application of a voltage between these electrodes leads to a measurable tunnelling current, which is highly sensitive to the gap size, the voltage applied and the medium in the gap. Applied to liquid environments, this offers interesting prospects of using tunnelling currents as a sensitive tool to study fundamental interfacial processes, to probe chemical reactions at the single-molecule level and to analyse the composition of biopolymers such as DNA, RNA or proteins. This offers the possibility of a new class of sensor devices with unique capabilities.