Electrowetting refers to the reduction in the contact angle of a sessile liquid drop on a surface, when a potential difference is
applied between the drop and an underlying electrode that is separated from it by a thin dielectric. Using this mechanism on a
lithographically-patterned electrode array, the drops can be moved onto sequentially activated electrodes rapidly and controllably. In
most implementations of electrowetting, the drops have to be confined by a top plate, which also serves to ground them electrically. We have been able to control droplet movement by
grounding it from the same surface as the activation electrodes,eliminating the need for a top plate. We have also implemented an
"on-demand" electrowetting platform in which the movement of microdrops are controlled using click-and-drag activation by a computer mouse. In this talk, we will describe the physics of
electrowetting and the fascinating dynamics of the actuated drops, as captured by high-speed video. [Collaborators: J.D. Sterling,
R. Miraghaie, and C. Cooney.]
Audio (MP3 File, Podcast Ready)
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