The motion of charged colloidal particles in electric fields

Abstract

General formulas are derived for the force and torque on a charged rigid macromolecule in electric fields. The theory is based on the Smoluchowski mean field approximation and yields the motion in terms of the electric potential and certain geometric quantities of the particle. If convection can be neglected in the ion conservation equations, the theory makes any further hydrodynamic considerations unnecessary. The formulas of Smoluchowski, Hückel, and Henry for electrophoretic mobility are obtained as simple consequences. Smoluchowski's formula is generalized to nonconstant surface potentials. The torque on an uncharged rod in moderately strong field is considered. © 1982 American Institute of Physics.