Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 46: Magnetic particles and clusters

MA 46.2: Talk

Thursday, April 4, 2019, 11:45–12:00, H52

Testing energy landscapes with trapped magnetic beads — •Florian Ostermaier, Isiaka Lukman, Benjamin Riedmüller, and Ulrich Herr — Institut für Mikro- und Nanomaterialien, Universität Ulm, Ulm, Deutschland

Optical tweezers have been established as a powerful tool for passive microrheology of living cells and single molecule stretching. Magnetic tweezers offer a similar range of achievable force and particle localization, but may also be used in strongly absorbing environment. In addition, perspective Lab-on-Chip applications may benefit from the lack of requirement of high power Laser light.

We have already demonstrated successful trapping of single commercially available magnetic beads using a combination of the field gradient produced by a micro structured ring conductor and a superimposed homogeneous magnetic field.

Here we present studies of two magnetic beads simultaneously trapped in the same ring structure which are coupled via magnetic dipole-dipole interaction. The equilibrium distance between both beads depends on bead magnetization and the magnetic field gradient produced by the ring, and can therefore be tuned by varying the ring current. From the dynamics of the motion of the coupled beads in the trap potential, we extract information about the magnetic energy landscape formed by the combination of trap field and bead magnetization. In addition, interactions with the liquid environment and the walls of the trap can be extracted from analysis of the dynamics. We discuss possible applications in passive microrheology.