Dielectrophoresis particle sorting

Another electrokinetic effect is based on polarization of particles within an oscillating electrical field or field gradient (dielectrophoresis), as depicted in Fig. 13c. Dielectrophoresis is applied in many fields, e.g. for the controlled separation and trapping of submicron bioparticles [245], for the fusion and transport of cells [246], or the separation of metallic from semiconducting carbon nanotubes [13, 247-249]. Other applications are cell sorting [250, 251] and apoptosis of cells [252, 253]. 

AC Dielectrophoresis Lab-on-Chip Devices, Fig. 5 An illustration of a dielectrophoretic microsystem that can selectively sort particles (top view). Recall that the electrodes are on the top and bottom surfaces of the microchannel and to not mechanically manipulate the particles... 

Curvature-Induced Dielectrophoresis, Fig. 5 Application of C-iDEP in a serpentine microchaimel to continuous sorting of yeast cells liom 3 pm particles in 1 mM phosphate buffer under an average DC electric field of 10 kV/m The left column shows the snapshot (al) and composite (hi) images of cell/particle focusing at the entrance of the serpentine section the middle column... 

Curvature-Induced Dielectrophoresis, Fig. 6 Application of C-iDEP in a double-spiral microchaimel (a) to continuous sorting of nonfluorescent 5 pm (gray), nonfluorescent 10 pm (dark), and fluorescent 10 pm (bright) particles in 0.1 mM phosphate buffer snapshot image (b) at the entrance of the spiral, composite image... 

Let us mention that dielectrophoresis has also found wide application in manipulation and sorting of particles and biological cells. Together with standard electrophoresis, it is perhaps the most often used electrokinetic phenomenon with practical applications in mind. Even particle separation can be achieved by using microelectrode arrays [55]. Based on the dielectrophoresis phenomenon, a new technique has recently become available for particle or cell separation, namely the dielectrophoresis/gravitational field-flow fractionation (DEP/G-FFF). In DEP/ G-FFF, the relative positions and velocities of unequal particles or cells are controlled by the dielectric properties of the colloid and the frequency of the applied field. The method has been applied to model polystyrene beads, but, most interestingly, to suspensions of different biological cells [56]. 

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