  This fluid dynamics video showcases how optically induced electrokinetic
forces can be used to drive three-dimensional micro-vortices. The strong
microfluidic vortices are used constructively in conjunction with other
electrokinetic forces to dynamically and rapidly aggregate particle groups.
Particle manipulation is achieved on the surface of a parallel-plate
gold/indium tin oxide (ITO) electrode that is illuminated with near-infrared
(1064 nm) optical patterns and biased with a low frequency ($<$ 100 kHz)
alternating current (AC) signal. The fluid dynamics video shows how
electrokinetically driven flows in the microdomain can be used for non-invasive
particle manipulation.
