Light Enabled Droplet Manipulations

Abstract

This fluid dynamics video showcases how optically induced electrowetting can be used to manipulate liquid droplets in open space and particulate phases inside the droplet. A photoconductive layer is added to a conventional electrowetting-on-dielectric (EWOD) structure to generate light enabled virtual electrodes, hence resulting in an eletrowetting action. Coplanar electrodes deployed alternately on a substrate enable open droplet manipulations differentiating from a sandwiched configuration. An integration with an optoelectric method shows dynamic and rapid particle handling by strong micro fluidic vortices in conjunction with other electrokinetic forces inside a droplet. The droplet manipulations are realized with visible illumination and powered at 150 volts peat-to-peak with a low frequency (100 Hz-800 Hz). The particle concentration is achieved on the surface of the same chip but illuminated with a near-infrared (1064 nm) light source and biased with a high frequency (24 kHz) AC signal.