Current collection efficiency of micro- and nano-ring-recessed disk electrodes and of arrays of these electrodes

Diffusional transport theory for micro- and nano-ring-recessed disc microelectrodes has been developed using finite difference methods. The device is typically operated in generator–collector mode with the disc acting as generator and the ring as the collector. The collection efficiency, defined as the ratio of the detector to generator currents under diffusion controlled conditions, is shown to depend on the depth of the recession of the disc below the ring and the radius of the ring relative to the disc radius. The latter is also the inner radius of the ring. The theory shows that collection efficiencies in excess of 90% are possible with this geometry, which is larger than most conventional hydrodynamic systems. This level of efficiency is in the same range as interdigitated microband electrodes. The diffusion domain approach is used to extend the theory to arrays of such micro- and nano-ring-recessed disc systems.