video: This movie, accelerated 35x, shows the dynamics of the living crystals under an external magnetic field (B ~ 1mT). The field orientation is externally varied in time. Under the imposed magnetic field, the composite particle slightly tilts and the direction of self-propulsion aligns with the direction of the field. The direction of B is indicated in the movie by the white arrow and is changed externally in orthogonal directions. The use of the magnetic field allows us to steer the living crystals. Moreover, as visible on the movie, forcing the particles to go in the same direction suppresses the crystal breakup. This video relates to a paper that appeared in the Jan. 31, 2013, issue of Science Express, published by AAAS. The paper, by Jeremie Palacci at New York University in New York, N.Y., and colleagues was titled, “Living Crystals of Light-Activated Colloidal Surfers.” view more
Credit: [Video courtesy of <i>Science</i>/AAAS]