title: Double-layer polarization of a non-conducting particle in an alternating current field with applications to dielectrophoresis.
abstract: Dielectrophoresis is becoming one of the most important techniques in particle manipulation including particle separation, particle assembly, and biomolecule characterization. Understanding dielectrophoretic properties of particles is a key step toward effective and efficient particle manipulation. Theoretical studies of polarization of a particle can help to understand experimental observations and also go beyond to develop a predictive theory to guide the experimental design. This article discusses recent theoretical advances in the polarization of a dielectric particle, in particular, the polarization of the electric double layer. The double-layer polarization is critical to determine particle dynamics in dielectrophoresis. The dipole moment characterizing the strength of this polarization depends on the double-layer thickness, the electric field frequency, the particle's surface charge, and other surface's properties (Pohl, H. A., Dielectrophoresis, Cambridge University Press, New York 1978). After a brief review of the mathematical model, the focus is on the following problems: (i) the polarization of a spherical particle; (ii) the polarization of an elongated cylindrical particle; (iii) the effect of the slip on the polarization of a particle. The double-layer polarization is examined here in the context of high-frequency and low-frequency dispersions induced by surface conduction and diffusion, respectively.
authors.affiliation: Department of Mechanical Engineering, University of Nevada, Las Vegas, NV 89154, USA. hui.zhao@unlv.edu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
mesh_terms: D004574:Electromagnetic Fields; D004586:Electrophoresis; D008962:Models, Theoretical; D053758:Nanoparticles