Our first report on recording the nanoscale optical contrast of the electric double layer

Our first manuscript using the restructuring of the Electric Double Layer as an optical contrast mechanism is online. In this collaboration with the group of Philipp Kukura (Oxford) and Marc Koper (Leiden), we experimentally demonstrate that restructuring of the EDL at the nanoscale can be detected by dark-field scattering microscopy. Temporal and spatial characterization of the scattering signal demonstrates that the potentiodynamic optical contrast is proportional to the accumulated charge of polarisable ions at the interface and its time derivative represents the nanoscale ionic current. The material-specificity of the EDL formation is used in our work as a label-free contrast mechanism to image nanostructures and perform spatially-resolved cyclic voltametry on ion current density of a few attoamperes, corresponding to the exchange of only a few hundred ions.