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Proceedings Paper

Study of microparticles' anomalous diffusion in active bath using speckle light fields (Presentation Recording)
Author(s): Ercag Pince; Sabareesh K. P. Sabareesh; Giorgio Volpe; Sylvain Gigan; Giovanni S. Volpe

Paper Abstract

Particles undergoing a stochastic motion within a disordered medium is a ubiquitous physical and biological phenomenon. Examples can be given from organelles as molecular machines of cells performing physical tasks in a populated cytoplasm to human mobility in patchy environment at larger scales. Our recent results showed that it is possible to use the disordered landscape generated by speckle light fields to perform advanced manipulation tasks at the microscale. Here, we use speckle light fields to study the anomalous diffusion of micron size silica particles (5 μm) in the presence of active microswimmers. The microswimmers we used in the experiments are motile bacteria, Escherichia coli (E.coli). They constitute an active background constantly agitating passive silica particles within complex optical potentials. The speckle fields are generated by mode mixing inside a multimode optical fiber where a small amount of incident laser power (maximum power = 12 μW/μm2) is needed to obtain an effective random landscape pattern for the purpose of optical manipulation. We experimentally show how complex potentials contribute to the anomalous diffusion of silica particles undergoing collisions with swimming bacteria. We observed an enhanced diffusion of particles interacting with the active bath of E.coli inside speckle light fields: this effect can be tuned and controlled by varying the intensity and the statistical properties of the speckle pattern. Potentially, these results could be of interest for many technological applications, such as the manipulation of microparticles inside optically disordered media of biological interests.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9548, Optical Trapping and Optical Micromanipulation XII, 95481J (5 October 2015); doi: 10.1117/12.2186845
Show Author Affiliations
Ercag Pince, Bilkent Univ. (Turkey)
Sabareesh K. P. Sabareesh, Bilkent Univ. (Turkey)
Giorgio Volpe, Univ. College London (United Kingdom)
Sylvain Gigan, Univ. Pierre et Marie Curie (France)
Giovanni S. Volpe, Bilkent Univ. (Turkey)

Published in SPIE Proceedings Vol. 9548:
Optical Trapping and Optical Micromanipulation XII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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