|
Dielectrophoresis is the phenomenon of movement of polarizable particles under the action of non-uniform AC electric field. The corresponding force acting because of this phenomenon is termed as the dielectrophoretic force. For a particle suspended in an aqueous medium the dielectrophoretic force depends on the gradient in electric field, the volume of the particle and on the effective polarizability of the particle. Dielectrophoresis has many promising biological applications: separating cancer cells from blood, enriching CD34+ cells in bone marrow samples and cell sorting during differentiation process. In conventional DEP an AC field is applied between the respective crossover frequencies of two dissimilar cell types. On the contrary if the dielectric properties of the different cell types are not significantly different, as in the case of many mammalian mixed cell systems, for example, their DEP crossover frequencies will be close. As a result of this complication, it has been found impractical to separate cells having less than 50% difference in their crossover frequencies using DEP differential affinity alone. Although traveling wave DEP is used to increase particle (cell) discrimination. In this work, we are presenting a new idea which is based on cell modification. The dielectrophoretic amplitude response of specific target cell is modulated by labeling cells with specific gold and silica particles that differ in polarization response. After cell labeling, cell mixtures will be interrogated in the DEP activated cell sorter, wherein the electric fields will be engineered to achieve efficient separation between dielectrophoretically labeled and unlabeled cells. The unique electrodes, designed and constructed to exploit the differences in dielectrophoretic response between unlabeled and bead labeled cells. As the cell mixture enters this region the labeled cells are selectively collected on the electrode edge. This technique may offer the potential for specific and rare cell sorting, high throughput and selectivity. |