Martinez-Pedrero F, Ortiz-Ambriz A, Pagonabarraga I, Tierno P. Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt.
PHYSICAL REVIEW LETTERS 2015;
115:138301. [PMID:
26451584 DOI:
10.1103/physrevlett.115.138301]
[Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 06/05/2023]
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.
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