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MA: Fachverband Magnetismus

MA 38: Magnetic Nanoparticles

MA 38.7: Talk

Thursday, March 19, 2015, 11:15–11:30, H 0110

Magnetic trapping of a superparamagnetic particle by a single micro-ring conductor — •Benjamin Riedmüller, Meng Li, and Ulrich Herr — Institut für Mikro- und Nanomaterialien, Ulm, Deutschland

In this work we present a magnetic trap for superparamagnetic particles, consisting of a single ring-shaped current conductor, which allows to transport and trap magnetic particles to a defined position with an accuracy of ≈ 1 um. The functionality of the device can be understood on the magnetic force caused by the superposition of a magnetic field gradient (generated by a static current through the conductor ring) and a superimposed, homogeneous magnetic field perpendicular to the plane of the substrate. The tracking of a single trapped Dynabead M-280 particle allows to determine the viscosity of the surrounding medium (here water was used) with an accuracy of < 10 %. By applying the fluctuation-dissipation-theorem the stiffness constant of the trap, which is a measure for the remaining particle fluctuation around the energy minimum caused by Brownian motion, can be extracted. The stiffness constant is then systematically changed by applying different static currents and by changing the externally applied field. We find a good correlation between the experimentally extracted stiffness constants to the values which are predicted from numerically modeling the energy landscape near the energy minimum with a simple spring model.