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Title: Counter-propagating dual-trap optical tweezers based on linear momentum conservation
Author: Ribezzi-Crivellari, M.
Huguet, J. M.
Ritort Farran, Fèlix
Keywords: Física estadística
Dispositius optoelectrònics
Feixos de làser
Aparells i instruments científics
Statistical physics
Optoelectronic devices
Laser beams
Scientific apparatus and instruments
Issue Date: 9-Apr-2013
Publisher: American Institute of Physics
Abstract: We present a dual-trap optical tweezers setup which directly measures forces using linear momentum conservation. The setup uses a counter-propagating geometry, which allows momentum measurement on each beam separately. The experimental advantages of this setup include low drift due to all-optical manipulation, and a robust calibration (independent of the features of the trapped object or buffer medium) due to the force measurement method. Although this design does not attain the high-resolution of some co-propagating setups, we show that it can be used to perform different single molecule measurements: fluctuation-based molecular stiffness characterization at different forces and hopping experiments on molecular hairpins. Remarkably, in our setup it is possible to manipulate very short tethers (such as molecular hairpins with short handles) down to the limit where beads are almost in contact. The setup is used to illustrate a novel method for measuring the stiffness of optical traps and tethers on the basis of equilibrium force fluctuations, i.e., without the need of measuring the force vs molecular extension curve. This method is of general interest for dual trap optical tweezers setups and can be extended to setups which do not directly measure forces.
Note: Reproducció del document publicat a:
It is part of: Review of Scientific Instruments, 2013, vol. 84, num. 4, p. 043104-1-043104-10
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ISSN: 0034-6748
Appears in Collections:Articles publicats en revistes (Física de la Matèria Condensada)

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