The diffusion domain approach is a general framework for the understanding, interpretation and prediction of the response of microelectrode arrays. This work exposes some of its limitations, particularly when dealing with nanoelectrode arrays of a few microns in size. This article provides an overview of the principles and assumptions underpinning the diffusion domain approach, and then applies it to the study of nanoelectrode arrays. The apparent disagreement between theory and experimental data, due to the importance of radial diffusion to nanoelectrode arrays compared to microelectrode arrays, is explained using simulations and experiments. The principle that an array of micro- or nano-electrodes eventually behaves as if the entire array were a single electrode of the size of the array, with its corresponding properties, applies always. However, while microelectrode arrays tend to behave as macroelectrodes, nanoelectrode arrays on the other hand may behave as microelectrodes. For the case of arrays of small numbers of electrodes, or array sizes of microns or less in size, this compromises one of the key assumptions of the diffusion domain approach, namely that inner electrodes in an array are equivalent, which may lead the unaware to erroneous conclusions.

Peer reviewed