Optical counting of trapped bacteria in dielectrophoretic device with pillar array

The development of rapid, accurate and simple screening system is essential in actual processes for large-volume water treatment from a standpoint of recent strict regulations. In the present work, we newly produced a dielectrophoretic device with three dimensional microstructures and sophisticated microchannel to trap and detect bacteria efficiently. We measured the luminous area and intensity of stained bacteria in the gap between electrodes, and estimated the number of trapped bacteria quantitatively. The dependence of the trapping efficiency of bacteria on flow velocity was also discussed.