Fluidic nanochannels are often fabricated on Si/SiO2 substrates, using methods similar to those in microchip manufacturing. While such approach is very convenient and allows for a substantial reduction in the channel size, a potential problem stems from the fact that the deposited SiO2 layer becomes conductive when in contact with aqueous solutions. Hence if electroosmosis/electrophoresis is attempted in such channels, a significant part of the current could leak across the SiO2 layer into the Si substrate instead of being transported along the channel by the electrolyte solution. The effect of such current leakage is that the electric field in the fluidic channel becomes non uniform, which will inevitably affect also the transport of fluid and analytes.

We present an analysis of the system Si/SiO2/Electrolyte solution based on numerical solution of transient Maxwell electrodynamics equations. Our model allows developing strategies for eliminating the current leaks or alternatively how to utilize them to modify the field shape in the fluidic nanochannel. For example it is possible to create local minima or maxima in the potential distribution along the channel which could be used for controlled analyte transport or focusing and separation.