Dielectrophoretic Cell Sorting
Living cells can be sorted with the aid of dielectrophoresis (DEP). The method depends upon the natural differences in the effective dielectric constants of the several types (species, physiological states, etc.) being handled. The use of additive stains or chemical modifiers or other tagging agents is not usually required. In the apparatus to be described, streams of cells can be subjected to DEP forces and their deflection into or out of the region of most intense electric field can be measured to provide dielectric relaxation spectra and comparisons of cell types or cell abnormalities. Moreover, since an actual physical force is exerted upon the cells, and a real displacement results, such an apparatus is readily arranged to provide continuous cell sorting base upon the intrinsic dielectric properties of the passing cells. Since there is much need for means to sort and to characterize living cells, we have focused upon how DEP should be applied to these desired ends. Our aim has been to devise a dual-purpose instrument capable of sorting cells and of characterizing them by their unique dielectric polarizability spectra. Early models succeeded in providing manual operation indicating an ability to make exquisitely delicate distinctions between cells, and to make actual separations, once the DEP spectra were determined. More recently, we have begun the redesign to obtain automation of the spectrometer mode of operation. Early tests show it to function successfully so as to provide simple spectra of a given cell type introduced into the instrument. The theory will be presented for the operation, and for the interpretation of the DEP spectra of cells. The experimental results for several cellular systems will also be presented.
KeywordsNeutral Particle Nonuniform Electric Field Effective Dielectric Constant Complex Dielectric Constant Intense Electric Field
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