Dual electrochemical modulation of reflectivity and luminescence on plasmonic gratings investigated by fluorescence microscopy coupled to electrochemistry

By coupling fluorescence microscopy and electrochemistry at plasmonic electrodes, a first example of simultaneous dual electrochemical modulation of reflected light and luminescence is demonstrated through two examples of fluorophores: one switching by electrochemical reduction (tetrazine derivative) and the other switching by electrochemical oxidation (iridium complex). Opposite behaviors are observed: in the first case, reflected light interacting with plasmons is electrochemically tuned in the reverse way compared to luminescence, while in the latter case, both modulations go in the same direction. Discrimination between reflected light and fluorescence is obtained using an adequate set of excitation filters and backside optical detection. This dual modulation is observed either in direct (epifluorescence) or in total internal reflection (TIRF) excitation configurations.