SEPARATION OF ERYTHROCYTES AND LATEX BEADS BY DIELECTROPHORETIC LEVITATION AND HYPERLAYER FIELD-FLOW FRACTIONATION

A model system consisting of a mixture of latex beads and erythrocytes has been investigated to demonstrate the practical feasibility of par ticle separation by means of the combined application of negative diel ectrophoresis and hyperlayer held-how fractionation. The dielectrophor etic levitation of latex beads is demonstrated by energizing interdigi tated electrodes, of widths and separation ranging from 5 to 40 mu m, with AC signals of 0-10 V (rms) in the frequency range 1 kHz-10 MHz. M aximum levitation was attained at 1 MHz, at which frequency levitation is relatively independent of the suspending medium conductivity. Levi tation was also independent of particle size, but dependent on particl e density and dielectric properties. At 1 MHz the erythrocytes were at tracted to the electrodes by positive dielectrophoresis, and so could be separated from the latex beads by fluid flow. The electric held and held gradient above the electrodes were also computer modelled, and t his information was used to design the electrode and chamber geometrie s for optimum DEP-field-flow fractionation. (C) 1998 Elsevier Science B.V. All rights reserved.