ISO-dielectric separation: A new method for the continuous-flow screening of cells

We introduce the first implementation of a method for the continuous-flow sorting of cells based specifically upon differences in their electrical properties. The method, which we call iso-dielectric separation (IDS), uses the dielectrophoretic (DEP) force in a liquid of spatially varying conductivity to map any electrically distinguishable phenotype to a unique position along the width of a microfluidic channel. The method is analogous to iso-electric focusing, with dielectric properties replacing surface charge as the basis for separation. IDS leverages the correspondence between the physiological state of a cell and its electrical properties to separate cells based upon such characteristics as viability or production of biomolecules [1]. Because IDS selects cells according to their generic electrical differences, it is possible to screen for such production without regard to the specific molecule being produced.