Spatially Distributed Current Oscillations with Electrochemical Reactions in Microfluidic Flow Cells

Abstract

The formation of spatiotemporal patterns is investigated by using a chemical reaction on the surface of a high-aspect-ratio metal electrode positioned in a flow channel. A partial differential equation model is formulated for nickel dissolution in sulfuric acid in a microfluidic flow channel. The model simulations predict oscillatory patterns that are spatially distributed on the electrode surface; the downstream portion of the metal surface exhibits large-amplitude, nonlinear oscillations of dissolution rates, whereas the upstream portion displays small-amplitude, harmonic oscillations with a phase delay. The features of the dynamical response can be interpreted by the dependence of local dynamics on the widely varying surface conditions and the presence of strong coupling. The patterns can be observed for both contiguous and segmented metal surfaces. The existence of spatially distributed current oscillations is confirmed in experiments with Ni electrodissolution in a microfluidic device. The results show the impact of a widely heterogeneous environment on the types of patterns of chemical reaction rates.

Decoding Network Structure in On-Chip Integrated Flow Cells with Synchronization of Electrochemical Oscillators

“…In other words, we assume that Ohm’s Law is obeyed for the potential drop in the cell. This assumption was validated in numerical simulations and experimental measurements of the resistance of the flow channel2527. Note that such assumption is valid when the quasi-one-dimensinal flow channels are much longer than the size of the electrode; the approximation is usually acceptable in a typical flow channel length of few mm and electrode sizes in the few μ m range.…”

Electrochemical Oscillations during Electro-oxidation of Copper Anode in Phosphoric Acid Solution

“…Electrochemical oscillations (EOs) occur in electrodissolution, electropolishing, electrodeposition, and electro-catalytic oxidation of Cu, Fe, Zn, and other metals and their corresponding oxides in electrochemical systems. [1][2][3][4] Nonlinear elementary reaction steps form in electrochemical systems. As the field gradually drives the system from the equilibrium, the effect of nonlinear terms becomes significant, resulting in EOs and other spatiotemporal phenomena.…”

Dynamical modes of two almost identical chemical oscillators connected via both pulsatile and diffusive coupling

“…Dynamical regimes of coupled oscillators with different connectivities have attracted the attention of many scientists 1,2 due to the importance of this issue in such fields as neural networks, 3 electrochemical oscillators, 3,4 or collective behaviour of living organisms or active particles, [5][6][7] due to new patterns (like chimera 8,9 ) that can be and are found in such complex systems as coupled oscillators, and due to many unresolved theoretical problems. 10,11 The study of coupled chemical oscillators probably started with the work by Marek and Stuchl.…”