title: Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt.
abstract: We study propulsion arising from microscopic colloidal rotors dynamically assembled and driven in a viscous fluid upon application of an elliptically polarized rotating magnetic field. Close to a confining plate, the motion of this self-assembled microscopic worm results from the cooperative flow generated by the spinning particles which act as a hydrodynamic "conveyor belt." Chains of rotors propel faster than individual ones, until reaching a saturation speed at distances where induced-flow additivity vanishes. By combining experiments and theoretical arguments, we elucidate the mechanism of motion and fully characterize the propulsion speed in terms of the field parameters.
authors.affiliation: Estructura i Constituents de la Matèria, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Martinez-Pedrero
authors.affiliation: Estructura i Constituents de la Matèria, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Ortiz-Ambriz
authors.affiliation: Departament de Física Fonamental, Universitat de Barcelona, 08028 Barcelona, Spain.|Institut de Nanociència i Nanotecnologia, IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Pagonabarraga
authors.affiliation: Estructura i Constituents de la Matèria, Universitat de Barcelona, 08028 Barcelona, Spain.|Institut de Nanociència i Nanotecnologia, IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Pietro
authors.initials: P
authors.lastname: Tierno