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Abstract
Dielectrophoresis, the movement of particles in non-uniform AC electric fields, was
used to rapidly separate viable and non-viable yeast cells with good efficiency. Known
mixtures of viable and heat-treated cells of Saccharomyces cerevisiae were separated
and selectively isolated using positive and negative dielectrophoretic forces generated
by microelectrodes in a small chamber. Good correlations with the initial known relative
compositions were obtained by direct microscopic counting of cells at the electrodes
after initial dielectrophoretic separation (r = 0.995), from methylene blue staining
(r = 0.992) and by optical absorption measurements (r = 0.980) of the effluent after
selectively flushing out the viable and non-viable cells from the chamber. Through
measurement of cell viability by staining with methylene blue and plate counts, for
an initial suspension of approx. 1.4 x 10(7) cells per ml containing 60% non-viable
cells, the dielectrophoretically separated non-viable fraction contained 3% viable
cells and the viable fraction 8% dead cells. The separation efficiency is increased
by dilution of the initial suspension or by repeat operation(s). Cell viability was
not affected by the separation procedure.