Electrokinetic forces

The potential between the Helmholtz double layer of a charged particle. Important for assessing the suitability of polyelectrolyte chemicals because it can be easily measured, unlike some other electrokinetic forces. 

Dielectrophoresis is the translational motion of neutral matter owing to polarization effects in a non-uniform electric field. Depending on matter or electric parameters, different particle populations can exhibit different behavior, e.g. following attractive or repulsive forces. DEP can be used for mixing of charged or polarizable particles by electrokinetic forces [48], In particular, dielectric particles are mixed by dielectrophoretic forces induced by AC electric fields, which are periodically switched on and off. 

Phenomena that arise in these materials include conduction processes, mass transport by convection, potential field effects, electron or ion disorder, ion exchange, adsorption, interfacial and colloidal activity, sintering, dendrite growth, wetting, membrane transport, passivity, electrocatalysis, electrokinetic forces, bubble evolution, gaseous discharge (plasma) effects, and many others. 

In the presence of non-uniform AC electric field, colloidal particles suspended in an aqueous medium experience electrokinetic forces including electrophoresis (EP), dielectrophoresis (DEP), and hydrodynamic drag force due... 

In the following, we present a simple particle displacement analysis for various AC electrokinetic effects. Assuming co-planar parallel interdigitated electrodes, the electric field between two electrodes can be assumed as half-circular lines near the electrode surface. Various electrokinetic forces can be represented in simple analytical forms using this simplified electric field distribution. 

Abstract. Programmable manipulation of particles or cells plays an important role in many biological and medical applications. Here a new programmable micro manipulator, named lab-on-a-display, in which particles are manipulated by optically induced electrokinetic forces generated from an optoelectronic tweezers on a liquid crystal display, is introduced. This optoelectrofluidic platform has been utilized to manipulate various kinds of cells such as blood cells, oocytes, and motile bacteria for several biotechnological applications. 

Tseng, W.L., et al.. Nanoparticle-filled capillary electrophoresis for the separation of long DNA molecules in the presence of hydrodynamic and electrokinetic forces. Electrophoresis, 26, 3069, 2005. 

This dielectric force pushes particles toward regirms of high field density or low field density depending on whether the Clausius-Mossotti factor is positive or negative, respectively. In other words, if Op < ct then negative dielectrophoretic motion away from sharp points in electrodes or insulator obstacles is observed the converse is true for positive dielectrophoresis, which is rarely observed in DC-DEP due to other electrokinetic forces. For a truly insulating particle, Op = 0, the Clausius-Mossotti factor is simply 1/2, and motion away from high field... 

Liao KT, Tsegaye M, Chaurey V, Chou CF, Swami NS (2012) Nano-constriction device for rapid protein preconcentration in physiological media through a balance of electrokinetic forces. Electrophoresis 33 1958-1966... 

Biological macromolecules are often handled through microfluidic systems, in which these molecules can transport and react. A common driving force behind such microfluidic transport processes is the electrokinetic force, which originates as a consequence of interaction between the electric double-layer potential distribution and the applied electric field. This entry discusses some of the important features of the biochemical reactions in such microfiuidic systems. 

At the lower end of the mixing scale we are within the micro-fluidics regime as discussed in Chapters 3 and 10. The application of active enhancanent methods to increase or improve mixing at these scales can, of course, be fruitful. These may include ultrasound and electrokinetic forces. As with any flows at the small scale, particularly if multiple phases are involved, the possible adverse effect of thermophoresis and electrophoresis may work against mixing. 

The electrokinetic force in the double layer (Spielman and Cukor, 1973) is given by... 

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