Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 39: Magnetic Particles / Clusters

MA 39.1: Talk

Friday, September 9, 2022, 09:30–09:45, H47

Direct determination of magnetic properties from energy lansdscapes around trapped magnetic beads — Florian Ostermaier, Moritz Quincke, Benjamin Riedmüller, Meng Li, Manuel Herschel, and •Ulrich Herr — Institut für Funktionelle Nanosyteme, Universität Ulm

Many Lab-on-Chip applications make use of micrometer sized polystyrene beads containing superparamagnetic iron oxide nanoparticles. Precise knowledge of magnetic properties is important for well-controlled manipulation by magnetic fields. We present a study of pairs of magnetic beads trapped in a current-carrying micro ring structure combined with a superimposed homogeneous field [1]. The trapped particles interact via repulsive dipole-dipole interaction. From analysis of the Brownian motion of the trapped particles we can extract information about the trap stiffness as well as the magnetic moments of the beads. The trap stiffness obtained in this way is compared to analytical and numerical calculations of the magnetic field distribution in the vicinity of the micro ring structure. We find that the restricted movement of the two interacting beads in the trap structure leads to a faster and more accurate measurement of the beads compared to observations made on single beads trapped in the same structure.

[1] F. Ostermaier, M. Quincke, B. Riedmüller, M. Li, M. Herschel, U. Herr, J. Phys. Chem. C 2022, 126, 7272-7280, DOI 10.1021/acs.jpcc.2c00759