Light Actuated Microfluidic Devices

A light-actuated microfluidic device has been successfully fabricated to inject, move, separate, and merge liquid droplets with nano-liter volumes. Light actuation is realized by sandwiching the liquid droplets between two photosensitive surfaces whose wettability can he changed by light. By integrating a photoconductor with an electrowetting electrode, the surface tension at the liquidsolid interface above the electrode can he modified by shining an optical beam on the photoconductor. The surface tension change is reversible and has a fast response time (millisecond). The liquid droplets follow the optical beam path up to a speed of 78 “,‘sec. All optical actuation for complete liquid droplet functions has been achieved. Simultaneous manipulation of multiple droplets is also demonstrated.