Biological & Soft Matter Seminar: Predicting complex electrophoretic motions of unevenly charged colloids

Abstract:

Biology provides us many reproducible colloid-scale systems that have reproduceable but asymmetric charge distributions.  Such objects have complex tensor responses to an electric field.  They translate and rotate in directions that depend on both the field and their orientation.  We report a discrete particle simulation method aimed at predicting these tensor responses.  The discrete particles carry charge, countercharge and stokes drag.  They respect the conservation of momentum and angular momentum that distinguish the electrophoretic response.  Using two thousand of these discrete particles we reproduce the known motion of monopolar, dipolar and quadrupolar charges on a sphere to less than five percent.  Since this method does not rely on symmetries of the object, it can readily be generalized to arbitrary shapes.  We show nonintuitive motions arising from time-varying driving fields.

Seminar Organizer: Guy Yaacoby