Ac electrokinetics: a survey of sub-micrometre particle dynamics

Abstract

Abstract. Particles suspended in fluid exhibit motion when subjected to ac electric fields. The applied field results in forces on both the particles and the fluid, the study of which is referred to as ac electrokinetics. The ac electrokinetic techniques can be used for the controlled manipulation and characterization of particles, and the separation of mixtures. For sub-micrometre particles, Brownian motion is important and strong electric fields are required to overcome these effects. Planar micro-electrode arrays, fabricated using semiconductor manufacturing processes, can generate electric fields of the required strength from low potentials over a wide range of frequencies. This paper reviews and discusses sub-micrometre particle dynamics under the influence of dielectrophoretic and electrohydrodynamic forces. New experimental observations of the movement of sub-micrometre particles are also presented.

Influence of alternating current electrokinetic forces and torque on the elongation of immobilized DNA

“…3 The applied ac electric field can also lead to fluid flow, which in turn can result in movement of the molecule. 3,5,6 The manipulation of small particles using dielectrophoresis and ac electrokinetic techniques in general has recently received considerable attention as an alternative to optical tweezers 7,8 or scanning probe techniques, 9,10 and is becoming a useful tool in molecular biology and biotechnology. Dielectrophoretic forces have been used to separate and manipulate cells, 2,11 bacteria, 12,13 viruses, 14 and submicron latex spheres.…”

The Influence of Stern Layer Conductance on the Dielectrophoretic Behavior of Latex Nanospheres

“…1, with fluorescent latex spheres suspended in KCl on a quadrupole electrode structure (3,4). At low frequencies, the spheres are attracted to regions of high field at the edges of electrodes and between adjacent electrodes.…”

“…At low frequencies, the spheres are attracted to regions of high field at the edges of electrodes and between adjacent electrodes. At high frequencies the particles are repelled to the local low field region at the center of the electrode array (3).…”

“…[1], using Eqs. [3] and [4] to describe the particle conductivity, are also shown. Relative permittivities for the suspending electrolyte and particle, of 78 and 2.55, respectively, were assumed.…”

Design and Coupled Electro-Fluidic Simulation of a Novel Dielectrophoretic Microfilter

“…Reported DEP microfilters use castellated [8], interdigitated [1], or polynomial microelectrode arrays [9,10]. In such microfilters, the fluid flow with particles in the separation channels of DEP microfilters is described using the Navier-Stokes equation system, but the equations are applied to fluid media properties, without taking into account the presence of particles.…”