Directed Motion of ColloidalParticles in a GalvanicMicroreactor.

The mechanisms leading to the deposition of colloidalparticlesin a copper–gold galvanic microreactor are investigated. Usingin situ current density measurements and particle velocimetry, weestablish correlations between the spatial arrangement and the geometryof the electrodes, current density distribution, and particle aggregationbehavior. Ionic transport phenomena are responsible for the occurrenceof strongly localized high current density at the edges and cornersof the copper electrodes at large electrode separation, leading toa preferential aggregation of colloidal particles at the electrodeedges. Preferential aggregation appears to be the result of a combinationof electrophoretic effects and changes in bulk electrolyte flow patterns.We demonstrate that electrolyte flow is most likely driven by electrochemicalpotential gradients of reaction products formed during the inhomogeneouscopper dissolution. [ABSTRACT FROM AUTHOR]