Micro-magnetic imprinting of high field gradient magnetic flux sources

We report here on the fabrication of hard magnetic powder based micro-flux sources using micro-patterned hard magnetic films as templates or master structures. The micro-magnetic imprinting (mu MI) process is simple and the constituent materials of the final structures, commercial hard magnetic powders and polymer, are inexpensive. The structures may be transparent, and either flexible or rigid, depending on the choice of polymer matrix used. The peak-to-peak intensity of the z-component of the stray magnetic field measured above a test mu MI structure made with spherical NdFeB particles of average particle size 16 mu m is in good agreement with simulated field values (150mT at 5 mu m). Simulations indicate magnetic field gradients of up to 5 x 10(5) T/m at the surface of such mu MI structures. The trapping of cells functionalised with superparamagnetic beads by these structures has been demonstrated. The mu MI fabrication technique has much potential for the development of high field gradient magnetic flux sources for applications in biology and beyond. (C) 2014 AIP Publishing LLC.