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Proceedings Paper

Hydrodynamic assisted barrier escape
Author(s): Arran Curran; Michael P. Lee; Roberto Di Leonardo; Miles J. Padgett
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Paper Abstract

We present experimental evidence of hydrodynamic assisted escape from a potential well. Holographic optical tweezers are used to landscape a bistable system composed of two optical traps, separated by 400nm as seen by a Si colloid of radius 400nm. We observe thermally activated transitions between the two metastable states in the system with transition rates that are in agreement with Kramers theory. Introducing a second bistable system into our experiment allows us to study the behaviour of thermally activated transitions in the presence of hydrodynamic interactions. The two bistable systems are placed in a line separated by a few micrometers. Using camera tracking technologies we track each of the two beads as they hop back and forth within their respective system. The escape events are recorded and any correlation between the two systems are then computed. We consistently find that the number of observed correlations are as expected and that the number of correlations having a positive coefficient are greater than the number of correlations having a negative coefficient. The hydrodynamic interactions assist in the escape from a metastable potential. Our results are particularly relevant in the context of concentrated colloidal suspensions where hydrodynamic interactions could lead to the formation of higher mobility paths along which it is easier to overcome barriers to structural rearrangement.

Paper Details

Date Published: 9 September 2011
PDF: 7 pages
Proc. SPIE 8097, Optical Trapping and Optical Micromanipulation VIII, 80970Q (9 September 2011); doi: 10.1117/12.894610
Show Author Affiliations
Arran Curran, Univ. of Glasgow (United Kingdom)
Michael P. Lee, Univ. of Glasgow (United Kingdom)
Roberto Di Leonardo, Univ. degli Studi di Roma La Sapienza (Italy)
Miles J. Padgett, Univ. of Glasgow (United Kingdom)

Published in SPIE Proceedings Vol. 8097:
Optical Trapping and Optical Micromanipulation VIII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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