Dielectrophoretic force: A comparison of theory and experiment

Abstract

Because of the increasing use of dieleetrophoresis in the dielectric characterization and sorting of living cells or their parts, it has become important to establish carefully the theoretical backgrounds for this effect. A comparison with experiment is made of the several versions of the theory for the dielectrophoretic force exerted by nonuniform electric fields upon a neutral object. The three fundamental approaches: the Maxwe11~ tensor) the effective dipole moment, and the 'Helmholtz' energy approach are presented along with the general solution given earlier by Pohl and Crane. These are found to agree closely with experiment in predicting the dieleetrophoretic force upon various rods hung in specially shaped (isomotive) field distributions. On the other hand, an alternative formulation based upon a debatable assignment of fields local to the dipoles gave a good fit to the experimental data only for materials of very low permittivity, and fitted poorly in the ease of highly polarizable materials.An improved derivation of the theory for stable dielectrophoretie levitation is also presented. This phenomenon is of particular interest in that it is based upon an apparent violation of the Earnshaw's theorem, and is useful in the study of the dielectric properties of individual living cells.

Electrical conduction and dielectric breakdown characteristics of alkyl ester dielectric fluids obtained from palm kernel oil

“…In addition, dielectrophoresis may cause uncharged particles to move to regions of high electric field further increasing the inhomogeneity and the additional electric field enhancement. If the particles have a higher ε r ' than the oil at the power frequency then the particles will move towards the higher field region, otherwise they will move away 10 . As ionic charge carriers, responsible for the dc electrical conductivity, drift and collide with liquid molecules, momentum is lost and energy is transferred to the fluid leading to electrohydrodynamic (EHD) motion of the liquid near breakdown 11 .…”

Electrokinetic trapping and surface enhanced Raman scattering detection of biomolecules using optofluidic device integrated with a microneedles array

“…As mentioned previously, there are two types of DEP motion which are induced by non-uniform electric field. 9 When the particles are more polarized than the medium, they move to the region with the highest electric field gradient (e.g., the edge of the electrodes) and this is called positive DEP (pDEP). On the other hand, when the particles a) Author to whom correspondence should be addressed.…”

Polymer composite based microbolometers

“…This effect is based on the particles' polarization in electrical fields and the resulting electrostatic force. In inhomogeneous electrical fields and under suitable conditions, the resultant force causes the desired formation of particle chains between the field-forming electrodes (Pohl et al, 1978;Nocke et al, 2009). The aim of such an alignment is the creation of a conductive network between appropriate electrodes at a preferably low filler loading (here: 0.1 wt.…”