Spatial Measurement of Spurious Forces With Optical Tweezers
Staforelli, J. P.
Proceedings of SPIE - The International Society for Optical Engineering
1 - 7
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The study of diffusion in a crowded and complex environment, such as inside a cell or within a porous medium, is of fundamental importance for science and technology. Combining blinking holographic optical tweezers and sub-pixel video microscopy permits one to study Brownian motion in confined geometries. In this work, in particular, we have studied the Brownian motion of two colloidal particles interacting hydrodynamically with each other. The proximity between the two microspheres induces a space-dependence in the particles diffusion coefficient and, therefore, a spurious drift. We measure this drift and evaluate the magnitude of the spurious force associated with it. We present the optoelectronic tools employed in the experiment and we discuss the experimental results.
KeywordsBlinking optical tweezers
Digital video microscopy
Holographic optical tweezers
Stochastic differential equations