Dielectrophoretic separators

Li, H. B., and Bashir, R. (2002). Dielectrophoretic separation and manipulation of live and heat-treated cells of Listeria on microfabricated devices with interdigitated electrodes. Sens. Actuators B Chem. 86, 215-221. 

Most dielectrophoretic separations of cells to date have used steric-DEP-FFF. The cells are usually effectively immobilized in potential energy minima [282] near the electrodes by a combination of gravity and electrical field forces. Afterwards, the applied hydrodynamic flow forces transport those particles that are held less strongly at the electrodes. 

An early comparison of US and dielectrophoretic separations revealed the lower size limits of microparticles (0.65 pm for single particles and 14 nm for particle ensembles) manipulated by dielectrophoresis to be similar to those for ultrasonic fields (0.25 pm in intermediate volume suspensions to 40 nm in microchamber assemblies). Unlike US-assisted separations, dielectrophoretic separations require either very low volumes to avoid heating in salt-containing suspensions or desalination prior to separation in the field [111]. 

P. R. C. Gascoyne, Y. Huang, R. Pethig, J. Vykoukal and F. F. Becker, Dielectrophoretic separation of mammalian cells studied by computerized image analysis, Meas. Sci. TechnoL, 3, 439-445 (1992). 

M. S. Pommer, Y. Zhang, N. Keerthi, D. Chert, J. A. Thomsott, C. D. Meinhart and H. T. Soh, Dielectrophoretic separation of platelets from diluted whole blood in microfluidic chatmels, Electrophoresis, 29, 1213-1218 (2008). 

Markx, G.H., Dyda, P.A., Pethig, R., 1996. Dielectrophoretic separation of bacteria using a conductivity gradient. J. Biotechnol. 51, 175—180. 

Hughes MP (2002) Strategies for dielectrophoretic separation in laboratory-on-a-chip systems. Electrophoresis 23 2569-2582... 

Zhu J, Tzeng TJ, Xuan X (2010) Continuous dielectrophoretic separation of particles in a spiral mierochaimel. Electrophoresis 31 1382—1388... 

Dielectrophoretic separators utilise 10-25 kV non-uniform DC and AC electric fields to remove particles from dilute, generally non-aqueous suspensions. Particles moving through the electric field are polarised by redistribution of... 

Figure 1.57 The concept of a high gradient dielectrophoretic separator.

Green, N. and Morgan, H. (1997), Dielectrophoretic separation of nano-particles, Journal of Physics D Applied Physics 30, L41-L44. 

Dielectrophoretic separation of Bacillus subtilis spores from environmental diesel particles. Journal of Environmental Monitoring 9(1), 87-90. 

Figure 7.3.6. Continuous dielectrophoretic separation of apartide mixture in microfluidic channel flow. (After KralJ et aL (2006) channel height 28 pm, channel width 500 pm.) (a) Cutaway view of the dumnel in the (rt,7.)-plane showing the inlets of particle suspension, particle-free solution, bulk liquid flow, two liquid outlets for two particle fractions and slanted electrodes, (b) Cross-sectional view at the A-A plane of (a), showing electrodes on the channel floor, laiger and smaller particles separated in the x-direction (c) Value ofE of the voltage variation in the periodic array of electrodes at a distance 3 pm from the channel top. (d) Behavior of x(t) per equation (7.3.24) and a plot of x against t per equation (7.3.27). (e) x-coordinate position of particles of different Tp normalized with channel width of 500 pm against time L...

Capillary electrophoresis (Section 6.3.1.2) of live and dead bacteria show identical retention times their electrophoretic mobilities (ji ) are indistinguishable (Armstrong and He, 2001). However, the electrical conductivity of the cell membrane of a live bacteria is around 10 pS/mm, whereas that of the cell s interior is much higher, around 10 pS/mm due to many ions. When a bacterium dies, the conductivity of the cell membrane (which becomes permeable) becomes much higher (around IpS/mm). If dead bacteria and live bacteria are suspended in deionized water having a conductivity of 2.2 pS/mm, and if dielectrophoresis is employed, describe what kind of dielectrophoretic separation can be achieved. What would be the observed separation behavior of a plastic particle of radius 0.5 pm if its conductivity is 18.5 pS/mm ... 

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