Carbon nanotubes (CNT) have been extensively used to produce electrodes of enhanced performance but only very recently exploited in microfluidic devices. In these cases, CNT-electrodes had to be produced previous to device assembly, which might damage the CNT layer. Here, we show a fast and simple method for the reversible nanostructuration of microfluidic electrode devices in-situ. The procedure is based on attachment of single walled CNT (SWCNT) onto the surface of magnetic particles (MP) and magnetic confinement of the MP/SWCNT composite onto the sensor in a two-step process that provided homogeneous coating. As it is shown, subsequent magnet removal allows MP/SWCNT release and electrode reutilization. Compared to most previously described methods, ours is faster, simpler and also reversible.