Doctoral Defense

Electromechanics of Suspensions

Mr. Tirumani N. Swaminathan
Ph.D. Candidate
Advisor: Professor Howard H. Hu
Department of Mechanical Engineering
University of Pennsylvania

Abstract

Electrokinetic forces are becoming an increasing popular choice for the manipulation of tiny particles in microfluidic devices. Several electrokinetic phenomena, including electrothermal forces, electroosmosis, AC electroosmosis, electrowetting, electrophoresis and dielectrophoresis, are being exploited for these purposes. Currently, experimental exploration outpaces the theoretical understanding of these phenomena. In this work, the theoretical aspects of three of these phenomena, namely electrophoresis, dielectrophoresis and AC electroosmosis have been examined. A finite element based numerical scheme has been developed to analyze these complex phenomena which can not otherwise be analytically solved for. Simulations of these three phenomena reveal interesting results of interactions between electromechanical and hydrodynamic forces in such systems. Inertial forces are seen to bunch up particles undergoing electrophoresis. Under dielectrophoresis, dipole-dipole interactions are seen to chain particles together along the direction of the electric field. Futhermore, in ionic solutions, the double layer formation due to induced surface charges is seen to effect particle motion in AC electric fields as opposed to the fixed charge electrophoresis case wherein the double layer causes no motion in AC fields.

Friday, April 7th
10 AM, 229-C Towne Bldg.