Separation of Micro Particles and Biological Cells Inside an Evaporating Droplet Using Dielectrophoresis

Micro particles or biological cells mixed in water solution was shown to be separated using the combined electrical force due to dielectrophoresis and mechanical one generated in an evaporating droplet. Micro patterned electrodes of Au were fabricated on the silicon dioxide layer and were used for generating dielectrophoresis. Polystyrene particles, red blood cells and E-coli were used for separating objects. Micro particles and biological cells were separated by adjusting the amplitude and frequency of the applied voltage. The mechanical force is enough to transport the particles to the boundary of the droplet, nevertheless it could not detach the particles trapped at the electrode. Based on this work, the micro particles and biological cells can be separated, controlled and sensed without liquid pumping unit.