Spontaneously Synchronized Electrochemical Micro-oscillators with Nickel Electrodissolution

Abstract

We investigate the dynamical behavior of oscillatory electrodissolution of two nickel microwires in an on-chip integrated microfluidic flow cell. With equivalent circuit analysis, an equation is derived that shows that the electrical coupling strength between the electrodes can be intensified by increasing the distance from the downstream electrode to the reference/counter electrodes, increasing the electrode size, and decreasing the total resistance within the cell. Experiments and numerical simulations with an ordinary differential equation model show that by intensifying the coupling between the electrodes spontaneously synchronized oscillations occur due to large potential (IR) drop in the small flow channel. Experiments with different distances, electrode diameters, and total resistances confirm a correlation between the statistical entropy based synchrony index and the theoretically derived coupling strength formula. The findings thus show that dynamical features of the chemical reaction that have been previously seen with macroelectrodes with application of external coupling resistances can occur spontaneously with microwires. The delineation of coupling effects in the reaction system could facilitate kinetic and electroanalytical applications in design of microchip-based setups that require collector-generator multielectrode wires: the accuracy of the measurement can be improved by proper cell design that diminishes electrical cross talk.