A new platform for manipulation and separation of oil-in-water emulsion droplets using optically induced dielectrophoresis

A new platform for manipulation and separation of oil-in-water emulsion droplets by using optically induced dielectrophoresis (ODEP) is reported. By utilizing different scanning speeds of a moving light beam, the oil-in-water emulsion droplets can be moved and separated with a high separation resolution. Several new applications such as pre-separation and fine separation of emulsion droplets were presented. Three different sized droplets (40~43 mum, 20~30 mum and 2~8 mum) can be roughly separated first, which demonstrates the capability of the developed method for pre-separation of emulsion droplets. The fine separation of droplets with a radius of 17.5 mum and 20 mum is then performed using a moving light beam with gradual gradient of moving speeds. To avoid the collision and overlapping of the droplets, a new approach with which individual moving track for each droplet can be achieved by using well-defined moving light pattern, is adopted. Accordingly, droplets with five sizes (30, 20, 10, 7.5, and 5 mum) are successfully separated.