Berlin 2012 – scientific programme
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BP: Fachverband Biologische Physik
BP 17: Posters: Physics of Cells
BP 17.12: Poster
Wednesday, March 28, 2012, 17:30–19:30, Poster A
Ferromagnetic guidance of paramagnetic microspheres and magnetically marked cells — •Thorsten Grassmann1, Yuri Koval1, Ben Fabry2, and Paul Müller1 — 1Dpt. of Physics and Interdisciplinary Center for Molecular Materials, Universität Erlangen-Nürnberg, Germany — 2Dpt. of Physics and Center for Medical Physics and Technology, Universität Erlangen-Nürnberg, Germany
We investigated thin film stripes of a ferromagnetic Permendur alloy with a high saturation magnetization aligned in a zig-zag geometry. This setup shows highly localized and permanent magnetic field gradients, both attractive and repulsive, located at the stripes' kinks. External out-of-plane magnetic fields are used to simultaneously alter depth and height of the magnetic field gradients. An external in-plane magnetic field is used to create an asymmetry in the gradient, selecting a preferred direction. This device allows the controlled motion of paramagnetic microspheres and magnetically marked biological cells along the stripes in a liquid environment, floating from kink to kink. The force acting on the paramagnets shows an inverse square-law behavior. A hardware setup with a computer-controlled vector magnet for programmable control of the field gradients and a video camera for measuring the microspheres' positions and speed was developed. The forces acting on the microspheres were measured directly via Stokes' drag. The possibility to move single living biological entities has been verified using living mouse liver cells incorporating magnetic microspheres. It is shown that the acting forces are in a range useful for rheological studies of living cells.