A new strategy for eliminating interference from EC′ mechanism during analytical measurements based on plane-band-recessed microdisk array electrodes

Theory of Microwell Arrays Performing as Generators–Collectors Based on a Single Bipolar Plane Electrode

“…The response of the microelectrode array was simulated taking into account the symmetry of the ordered array; hence, only a single unit cell (or diffusion domain) was simulated (shown in Figure b) . Although in the arrays used in our previous experiments the unit cells had a square shape (see Figure a), in our simulations we considered a cylindrical unit cell with radius r c (its value being adjustable in order to yield the same surface area as for the corresponding square or hexagonal unit cell). Indeed, we demonstrated recently that this does not introduce any significant bias in predicting the responses of arrays under any of the conditions considered here.…”

“…When the microdisk potential reaches sufficiently positive values, the oxidized species Ox generated at the disk electrode diffuses towards the top of the microwell where it undergoes reduction at the top‐plane electrode. This creates a “generator–collector” amplifying redox cycle taking advantage of the positive diffusional feedback created between the two electrodes (Figure b) . An interesting observation was that under certain conditions, when the top‐plane electrode was left floating (i.e., was not connected to a potential source), the system could perform almost as efficiently as in the generator–collector case just described.…”

“…The self‐induced opposite polarization of the electrode edges is generally brought by one of the two following ways: 1) through establishing a high voltage across the cell solution, parallel to the unbiased electrode, see for example, Ref. , or 2) through building up local concentration gradients of redox species along the conductor length, for example, as in arrays of microelectrodes or in scanning electrochemical microscopy (SECM) at conducting unbiased substrates …”

“…In this work, we focus on the bipolar behavior induced by a concentration polarization in the context of analytical devices consisting of recessed microdisk arrays . The sketch of these devices, as well as their operating principle, is shown in Figure .…”

“…Although the general mechanism underpinning bipolar electrochemistry is well understood, here we would like to contribute with a more specific and detailed picture by visualizing and rationalizing simulated potentials and current densities underlying the bipolar phenomena occurring under the conditions we just described . We would also like to theoretically investigate the conditions defining the experimental range of such efficient activity as well as to draw some mechanistic insights relative to the bipolar electrode operation.…”