High efficient cell leading into microwell array by using positive dielectrophoresis

Positive dielectrophoresis was used to increase cell leading effect into microwells on the single cell based microwell array system. Cell suspension prepared with low conductivity buffer was applied to PDMS microwell array sheet which was put on an ITO electrode. Then it was covered with another ITO electrode across a silicone spacer and high frequency sinusoidal voltage was applied between the two ITO electrodes. The optimal condition for positive dielectrophoresis was 10MHz and 10V. Implanted ratio (ratio of cells in wells comparing with total cells in the measured area) and occupied ratio (ratio of wells filled with a cell in the measured area) were increased up to ca. 90%. By using positive dielectrophoresis, ca. 80% cells in a sample can be utilized for cell analysis. Comparing with negative dielectrophoresis (26%), efficiency of cell analysis could be extremely improved. Positive dielectrophoresis also contributes to release prevention of cells in microwells. The present method was successfully applied to two kinds of microwell-arrayed chemical sensors for single cell analysis.