Light actuation of liquid by optoelectrowetting

Optical actuation of liquid droplets has been experimentally demonstrated for the first time using a novel optoelectrowetting (OEW) principle. The optoelectrowetting surface is realized by integrating a photoconductive material underneath a two-dimensional array of electrowetting electrodes. Contact angle change as large as 30degrees has been achieved when illuminated by a light beam with an intensity of 65 mW/cm(2). A micro-liter droplet of dejonized water has been successfully transported by a 4 mW laser beam across a 1 cm x 1 cm OEW surface. The droplet speed is measured to be 7 mm/s. Light actuation enables complex microfluidic functions to be performed on a single chip without encountering the wiring bottleneck of two-dimensional array of electrowetting electrodes. Published by Elsevier Science B.V.