DIELECTROPHORETIC SEPARATION OF CELLS - CONTINUOUS SEPARATION

Dielectrophoresis is the movement of particles in nonuniform alternati ng and direct current (AC, DC) electric fields, When nonuniform electr ic fields are created between microelectrodes, cells will redistribute themselves around the electrodes, the force holding the cells in plac e depending on the local electric field and on the electrical properti es of the cells themselves and the suspending medium. Steric drag forc es produced by a gentle fluid flow in the chamber can be used to separ ate cells by selectively lifting cells from potential energy wells pro duced by the electric field. The technique is demonstrated in the batc h separation-of bacteria, yeast cells, and plant cells, Continuous sep aration and extraction of two cell types can be achieved by repeated r eversing of the fluid flow direction in phase with the switching on an d off of the applied voltage, and the efficacy of the technique is dem onstrated for viable and nonviable (heat-treated) yeast cells. (C) 199 5 John Wiley and Sons, Inc.