Synchronization Patterns of Oscillatory Nickel Dissolution in Microfluidic Flow Cell with Branched Channel

Branched microfluidic channels are interconnected to allow for the solution to flow in different streams at different times, which is very attractive for creating complex structures that can be used in analysis, separation, and reaction kinetics. In electrochemical systems, branched flow channels can be used in control networks of chemical reactions and obtain time-resolved measurements of species. In this contribution, we simulate the oscillatory chemical reaction of nickel electrodissolution to explore the interactions through potential drop affecting the temporal variation of current. Mathematical equations were developed for the variation of the dynamical evolution of the electrode potentials and the surface coverage of electroactive species. The synchronization patterns were analyzed through change of coupling strength (k) and placement of electrodes. For each configuration, with increase of coupling strength, a transition from no synchrony through partial synchrony to full synchrony was observed. Close placement of the downstream electrodes to the branching point induces global coupling; under these conditions partial synchronization does not show specific spatial orientation. On the contrary, placement of the downstream electrodes far from branching point induces localized coupling between the upstream electrode and the electrodes in the branched channels. In this case, partial synchronization occurs between the upstream electrode and one of the electrodes in the branched channels. A phase diagram was successfully drawn to predict the synchrony patterns in different geometries. The result has significance in the design of branched microfluidic channel for analytical devices as it shows the extent and type of coupling through potential drop in the electrolyte.