title: Trochoidal trajectories of self-propelled Janus particles in a diverging laser beam.
abstract: We describe colloidal Janus particles with metallic and dielectric faces that swim vigorously when illuminated by defocused optical tweezers without consuming any chemical fuel. Rather than wandering randomly, these optically-activated colloidal swimmers circulate back and forth through the beam of light, tracing out sinuous rosette patterns. We propose a model for this mode of light-activated transport that accounts for the observed behavior through a combination of self-thermophoresis and optically-induced torque. In the deterministic limit, this model yields trajectories that resemble rosette curves known as hypotrochoids.
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, New York, NY 10003, USA. david.grier@nyu.edu.
authors.forename: Henrique
authors.initials: H
authors.lastname: Moyses
authors.forename: Jérémie
authors.initials: J
authors.lastname: Palacci
authors.forename: Stefano
authors.initials: S
authors.lastname: Sacanna
authors.forename: David G
authors.initials: DG
authors.lastname: Grier