Table : Placement of the working electrode (WE); counter electrode (CE); reference electrode (RE); and two poles of the closed bipolar electrodes (BPE1 & BPE2). Set-up details can be seen in Figure . An illustration of the electrochemical set-up is shown in Figure . Electromagnetic noise was reduced by performing measurements inside a Faraday cage. This consisted of two parts: a copper lid; and a copper plate with a hole for a microscope objective, allowing observation of the fluorescence in the reporting cell, and a small opening for the potentiostat cables.