title: Active motion of a Janus particle by self-thermophoresis in a defocused laser beam.
abstract: We study self-propulsion of a half-metal coated colloidal particle under laser irradiation. The motion is caused by self-thermophoresis: i.e., absorption of a laser at the metal-coated side of the particle creates local temperature gradient which in turn drives the particle by thermophoresis. To clarify the mechanism, temperature distribution and a thermal slip flow field around a microscale Janus particle are measured for the first time. With measured temperature drop across the particle, the speed of self-propulsion is corroborated with the prediction based on accessible parameters. As an application for driving a micromachine, a microrotor is demonstrated.
authors.affiliation: Department of Physics, The University of Tokyo, Tokyo, Japan.
authors.forename: Hong-Ren
authors.initials: HR
authors.lastname: Jiang
authors.forename: Natsuhiko
authors.initials: N
authors.lastname: Yoshinaga
authors.forename: Masaki
authors.initials: M
authors.lastname: Sano
mesh_terms: D003102:Colloids / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D007834:Lasers; D008853:Microscopy; D009038:Motion; D012399:Rotation; D013696:Temperature
chemical_list: D003102:Colloids; D005456:Fluorescent Dyes