video: Organization of the particles in a diverging flow. A diverging flow is created from the nozzle of a pulled micropipette, placed a few microns above the substrate. Under activation by the light, the self-propelled particles migrate and form a circle around the nozzle at a finite distance from the tip, given by the stagnation point. Turning off the light, the particles are immediately flushed away by the flow. Reactivated by the blue light, the particle reposition at the same distance from the tip. The drift of the tip of the pipette is due to a mechanical drift of the micromanipulator. Real time x10. This material relates to a paper that appeared in the May 1, 2015, issue of Science, published by AAAS. The paper, by J. Palacci at New York University in New York, NY, and colleagues was titled, 'Artificial rheotaxis.' view more
Credit: [Credit: Palacci <i>et al.</i> Sci. Adv. 2015;1:e1400214]