Towards the measurement of the spatial correlation among multiple optically trapped magnetic particles

Abstract

Optical Tweezers are a powerful tool that, using a strongly focused laser beam, allow us to generate optical forces for the manipulation of micro and nano-metric objects. They have a wide variety of applications in the fields of chemistry, biology, and physics. In this thesis we address the issue of a few-body system of a geometric configuration of optically trapped spheres in water and their hydrodynamic and magnetic correlations as they exhibit Brownian motion. Starting from the Oseen solution to the Stokes equation, a method to find the correlation displacement functions that characterize the hydrodynamic and magnetic interactions among optically trapped magnetic micro-beads immerse in a fluid in the low Reynolds number is elaborated. We report the correlation functions and how they are found for three different geometric configurations with multiple trapped spheres, following a procedure that can be replicated for different geometric layouts and a greater amount of trapped particles. Some results of measurements already carried out with the current Optical Tweezers setup are presented, in addition to further proposed experiments to compute the correlation displacements functions that were found. Understanding and characterizing magnetic micro-systems is a topic of great interest, given the multiple applications they have, for instance, in medicine.