Hydrodynamic Voltammetry with Nanogap Electrodes

We study the influence of convective mass transport on faradaic currents detected under redox cycling conditions at nanogap electrodes embedded in a microchannel. We show that, unlike the case of microelectrodes, the limiting current in the nanofluidic device is not influenced by the sample flow rate in the microfluidic channel. This is due to both the hydraulic resistance of the nanochannel suppressing flow within the device and the inherently diffusion-based mass transport between microelectrodes separated by a 70 nm gap. These devices thus allow electrochemical measurements without the need for any flow velocity correction.