Induced-Charge Electrophoresis

The electrokinetic motion of heterogeneous particles, having nonuniform composition and/or irregular shape, involves translation, rotation, and deformation due to the combined effects of electrophoresis, induced-charge electrophoresis, and dielectrophoresis. 

Nonlinear electrokinetic phenomena, such as the electrokinetic motion of polarizable particles, have only been studied for a few decades, and attention is just begiiming to be paid to the nonlinear motion of heterogeneous particles due to induced-charge electrophoresis [7-9]. Recent theoretical work has relaxed assumptions 1-3, but much remains to be done. Surprising new possibilities include particles that rotate continuously or translate perpendicular to a uniform AC field [9]. 

Electrokinetic Motion of Heterogeneous Particles, Fig. 3 Induced-charge electrophoresis of Janus particles, illustrated for the case of metal partially coated with insulating thin films, fiom [9]. (a) Stable orientation in a uniform field, showing induced-charge and slip... 

Yariv E (2005) Induced-charge electrophoresis of nonspherical particles. Phys Fluid 17 051702... 

Gangwal S, Cayre OJ, Bazant MZ, Velev OD (2007) Induced-charge electrophoresis of metallo-dielectric particles, http //arxiv.org/abs/0708.2417 (preprint)... 

The electrokinetic motion of polarizable particles results from electroosmotic flow (induced-charge electrophoresis) of the first of second kind, in addition to electrostatic forces ( dielectrophoresis). 

Since all materials are polarizable to some degree, the surface charge is generally not fixed. This leads to a broad class of nonlinear electrokinetic phenomena, where bulk electric fields interact with induced diffuse charge in solution to produce nonlinear electrophoretic motion, U = f(E). In electrolytes, such effects of induced-charge electrophoresis (ICEP) occur in addition to the purely electrostatic effect of... 

Saintillan D, Darve E, Shaqfeh ESG (2006) Hydrodynamic interactions in the induced-charge electrophoresis of colloidal rod suspensions. J Fluid Mech... 

In this canonical example, broken symmetries generally lead to fluid flow past the object, if it is held fixed, or motion by induced-charge electrophoresis (ICEP), if it is freely suspended [3, 10],... 

Induced-charge electrophoresis refers to the translational and rotational motion of a polarizable particle due to induced-charge electro-osmotic flow. 

It has recently been proposed to refer to this nonlinear correction as the Stotz- Wfien effect [14]. It can be understood as a phenomenon of induced-charge electrophoresis due to the nonlinear differential capacitance C(xlr) of the diffuse layer, as a function of its voltage drop xfr, given by = ( — 0surface)/(l + 3) for a constant compact-layer capacitance. In that case, for example, the coefficient of the leading nonlinear term in a weak electric field (Ea kT/e) is given by a = —9/8(d/d log C)f- for... 

Induced-Charge Electro-Osmosis Induced-Charge Electrophoresis... 

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