title: Passive trapping of rigid rods due to conformation-dependent electrophoretic mobility.
abstract: We present computer simulations of a rigid rod in a combination of an extensional fluid flow and extensional electric field. The electrophoretic mobility of the rod is different parallel or perpendicular to the rod. The dependence of the mobility on the conformation (orientation) leads to a new phenomenon where the rods can be passively trapped in all directions at the stagnation point. This contrasts with the behavior in either fluid flow or electric field alone, in which an object can be pushed towards the stagnation point along some directions but is pushed away in others. We have determined the state space where trapping occurs and have developed a model that describes the strength of trapping when it does occur. This new phenomenon could be used in the future to separate objects based on a coupling between their mobility and ability to be oriented.
authors.affiliation: Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, New York 12180, USA. underhill@rpi.edu.
authors.forename: Harsh
authors.initials: H
authors.lastname: Pandey
authors.affiliation: Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, New York 12180, USA. underhill@rpi.edu.
authors.forename: Sylvia A
authors.initials: SA
authors.lastname: Szafran
authors.affiliation: Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, New York 12180, USA. underhill@rpi.edu.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Underhill