title: Motion of Optically Heated Spheres at the Water-Air Interface.
abstract: A micrometer-sized spherical particle classically equilibrates at the water-air interface in partial wetting configuration, causing about no deformation to the interface. In condition of thermal equilibrium, the particle just undergoes faint Brownian motion, well visible under a microscope. We report experimental observations when the particle is made of a light-absorbing material and is heated up by a vertical laser beam. We show that, at small laser power, the particle is trapped in on-axis configuration, similarly to 2-dimensional trapping of a transparent sphere by optical forces. Conversely, on-axis trapping becomes unstable at higher power. The particle escapes off the laser axis and starts orbiting around the axis. We show that the laser-heated particle behaves as a microswimmer with velocities on the order of several 100 μm/s with just a few milliwatts of laser power.
authors.affiliation: Université de Bordeaux , Centre de recherche Paul-Pascal (CRPP), 33600 Pessac, France.|Université de Bordeaux , Laboratoire Ondes et Matière d'Aquitaine (LOMA), 33400 Talence, France.
authors.forename: A
authors.initials: A
authors.lastname: Girot
authors.affiliation: Université de Bordeaux , Centre de recherche Paul-Pascal (CRPP), 33600 Pessac, France.|Université de Bordeaux , Laboratoire Ondes et Matière d'Aquitaine (LOMA), 33400 Talence, France.
authors.forename: N
authors.initials: N
authors.lastname: Danné
authors.affiliation: Université de Bordeaux , Laboratoire Ondes et Matière d'Aquitaine (LOMA), 33400 Talence, France.
authors.forename: A
authors.initials: A
authors.lastname: Würger
authors.affiliation: Université de Bordeaux , Laboratoire Ondes et Matière d'Aquitaine (LOMA), 33400 Talence, France.
authors.forename: T
authors.initials: T
authors.lastname: Bickel
authors.affiliation: CORIA-UMR6614, Normandie Université, CNRS, Université et INSA de Rouen , Avenue de l'Université, 76800 Saint Etienne du Rouvray, France.
authors.forename: F
authors.initials: F
authors.lastname: Ren
authors.affiliation: Université de Bordeaux , Centre de recherche Paul-Pascal (CRPP), 33600 Pessac, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Loudet
authors.affiliation: Université de Bordeaux , Centre de recherche Paul-Pascal (CRPP), 33600 Pessac, France.
authors.forename: B
authors.initials: B
authors.lastname: Pouligny