Measurement of the dielectrophoretic enrichment of yeast on grid electrodes using image analysis

Dielectrophoresis using grid electrode structures offers many advantages for the abstraction and enrichment of cells in analytical microbiology. Modifications to the quantification method of a grid-based dielectrophoresis system are described, utilizing a more rapid and efficient image analysis technique. The grid electrode arrangement enabled dielectrophoretic enrichment of Saccharomyces cerevisiae, resulting in between 36.2 and 46.1% concentration of cells (by a single pass), relative to an identical control sample suspension analysed without an applied electric field. These enrichment factors compare favourably with previously obtained data using alternative measurement techniques. In addition, the image analysis technique is considerably less labour intensive and enables the continuous detection of cellular concentration and dielectrophoretic behaviour. Utilizing differences in frequency dependent cell responses, the system described could be suitable for highly selective pre-enrichment or cell separation on a large scale. Dielectrophoretic techniques, including enrichment, viable cell analysis and assessment of low microbial concentrations, could enhance or replace many existing methods for the analysis of micro-organisms and other cells.