A light-induced dielectrophoretic droplet manipulation platform.

We report on a light-actuated, droplet based microfluidic platform enabling two-dimensional (2D) droplet manipulation on an open chamber with a single-side, featureless photoconductive surface. The droplet actuation mechanism is based on recently demonstrated floating electrode optoelectronic tweezers (FEOET), which enable light-induced dielectrophoretic forces to manipulate aqueous droplets immersed in electrically nonconductive oil, with a light intensity as low as 400 microW/cm2. In this paper, we study the shape effect of optical patterns for 2D droplet actuation, and demonstrate light-actuated droplet manipulation functions including 2D droplet transport, merging, mixing, and multidroplet processing, for up to 16 droplets in parallel. Such an open chamber platform also permits easy interfacing and integration with other microfluidic structures, such as wells and close-channel based droplet devices to increase its versatility for biochemical analyses.