'Lissajous-like' trajectories in optical tweezers

0467069 - ÚPT 2017 RIV US eng J - Journal Article
Hay, R. F. - Gibson, G. M. - Simpson, Stephen Hugh - Padgett, M. J. - Phillips, D. B.
'Lissajous-like' trajectories in optical tweezers.
Optics Express. Roč. 23, č. 25 (2015), s. 31716-31727. ISSN 1094-4087
Institutional support: RVO:68081731
Keywords : low Reynolds number * particles * force
Subject RIV: BH - Optics, Masers, Lasers
Impact factor: 3.148, year: 2015

When a microscopic particle moves through a low Reynolds number fluid, it creates a flow-field which exerts hydrodynamic forces on surrounding particles. In this work we study the 'Lissajous-like' trajectories of an optically trapped 'probe' microsphere as it is subjected to time-arying oscillatory hydrodynamic flow-fields created by a nearby moving particle (the 'actuator'). We show a breaking of time-reversal symmetry in the motion of the probe when the driving motion of the actuator is itself time-reversal symmetric. This symmetry breaking results in a fluid-pumping effect, which arises due to the action of both a time-dependent hydrodynamic flow and a position-dependent optical restoring force, which together determine the trajectory of the probe particle. We study this situation experimentally, and show that the form of the trajectories observed is in good agreement with Stokesian dynamics simulations. Our results are related to the techniques of active micro-rheology and flow measurement, and also highlight how the mere presence of an optical trap can perturb the environment it is in place to measure.
Permanent Link: http://hdl.handle.net/11104/0265211