Colloidal Deposition on Remotely Controlled Charged Micropatterned Surfaces in a Parallel-Plate Flow Chamber

This article describes a method to influence colloid deposition by varying the zeta potential at microelectrodes with remotely applied electric potentials. Deposition experiments were conducted in a parallel-plate flow chamber for bulk substrates of glass, indium tin oxide (ITO), and ITO-coated glass microelectrodes in 10 and 60 mM potassium chloride solutions. Colloid deposition was found to be a function of solution chemistry and the small locally delivered electric surface potentials. Electric fields and physical surface heterogeneity can be ruled out as cause of the observed deposition. Results are reported using experimentally determined Sherwood numbers and compared to the predictions of a previously developed patch model. Minor deviations between predicted and experimental Sherwood numbers imply that physical and chemical interactions occur. Specifically, we propose that colloidal particles respond to local variations in surface potential through electrostatic interactions, altering particle streamlines flowing along the surface and ultimately the extent of deposition.