Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Fluid dynamics I

DY 16.11: Talk

Wednesday, March 25, 2009, 17:30–17:45, ZEU 255

Observation of the Interaction of Magnetic Particles in a Rotational Magnetic Field — •Simone Herth, Alexander Weddemann, and Andreas Hütten — Fakultät für Physik, Universität Bielefeld, Germany

The manipulation of magnetic particles on chip gained interest in the field of microfluidic systems, medical physics, such as hyperthermia, or nanobiotechnology in general. Especially, the advantages of magnetic particles include their possibility to be manipulated by an external magnetic field, detected by magnetoresistive sensors, and their easy handling.

If magnetic particles are under the influence of a rotational magnetic field, their interaction strongly depends on the frequency of the rotation. Starting with a low frequency of an applied rotational magnetic field, which arranges the particles in chains, the particles will finally not be influenced by the magnetic field at all at very high frequency. However, numerical simulations show that there is a critical frequency, which leads to a repulsive force between the particles (see abstract titled ”Interactions of Magnetic Particles in Non-Magnetic Liquids”). The critical frequency depends on the particle size, the saturation magnetisation as well as the applied field and can be analysed by microscopic observations.

The talk will analyse the videos taken of moving particles in a rotational magnetic field at various frequencies, compare the results with simulations, and discuss some applications.