Advised by Dennis C. Prieve and Paul J. Sides
The motion of colloidal particles near an electrode under normally directed ac electric fields is currently being investigated for applications in mesoscale surface patterning, novel colloidal phase formation, optical devices, and cell manipulation. The typical boundary condition on the electrode used for the calculations of single and multi-particle motion near the electrode is the uniform electrical potential condition. However, a uniform potential is unlikely to be the correct boundary condition if there is a chemical reaction at the electrode in addition to the presence of the dielectric particle. Given parameters typical of our common electrolytes, a potential dependent electrode reaction will move the distribution of electrical current away from uniform potential distribution, and towards uniform current flux at the electrode surface. This work demonstrates that the electrical potential distribution on the electrode, combined with a phase difference between the electric field in solution and the electrode potential, can account for the experimentally observed vertical motion of single particles in ac electric fields.