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Proceedings Paper

Study of constrained Brownian motion of nanoparticles near an interface using optical tweezers
Author(s): Hui Yang; Matteo Cornaglia; Raphaël Trouillon; Thomas Lehnert; Martin A. M. Gijs
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Paper Abstract

We demonstrate a method to determine the Brownian motion and the diffusion coefficient of a nanoparticle in water in a plane that is parallel to a solid boundary and as function of the distance normal to that boundary by using an optical tweezers instrument. A solution of 190 nm-diameter fluorescent polystyrene nanoparticles in de-ionized (DI) water is introduced in a micro-chamber built from two thin glass substrates. A single particle is trapped by the tweezers and optically moved in the z-direction normal to a substrate. By analyzing a scatter plot of the time-dependent positions of the nanoparticle in the x-y plane in a histogram, the diffusion coefficient parallel to the substrate of the Brownian particle constrained by the substrate is determined as a function of the distance between the substrate and the nanoparticle. The experimental results indicate the increased drag effect on the nanoparticle when it is close to the substrate, as evidenced by an experimental diffusion coefficient nearby the substrate that is about half of that of the particle in the bulk fluid.

Paper Details

Date Published: 10 March 2015
PDF: 7 pages
Proc. SPIE 9379, Complex Light and Optical Forces IX, 93790W (10 March 2015); doi: 10.1117/12.2078341
Show Author Affiliations
Hui Yang, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Matteo Cornaglia, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Raphaël Trouillon, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Thomas Lehnert, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Martin A. M. Gijs, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

Published in SPIE Proceedings Vol. 9379:
Complex Light and Optical Forces IX
Enrique J. Galvez; Jesper Glückstad; David L. Andrews, Editor(s)

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