Freeze casting of iron oxide subject to a tri-axial nested Helmholtz-coils driven uniform magnetic field for tailored porous scaffolds

In this research, Fe3O4 particles were magnetically manipulated to create porous scaffolds using a tri-axial nested Helmholtz coils-based freeze-casting setup. This novel setup allowed for a uniform magnetic field to be applied in any direction and for it to effectively change directions at any time. Applying a uniform low magnetic field of 7.8 mT in various directions was investigated to fabricate a variety of tailored microstructures and mechanical properties in the resultant scaffolds. It was observed that using the magnetic field aligned up to 81% of the lamellar walls and also altered the area and shape of the pores of the resultant scaffolds. This lamellar wall alignment occurred at every applied magnetic field direction due to the Fe3O4 particles aligning during the freeze-casting process. As a result of this alignment, increases in the mechanical properties of up to 4.1× were observed. The results provide a novel experimental technique for the fabrication of user-defined microstructures in Fe3O4-based freeze-cast materials that provides significant advantages over previous experimental setups for magnetic freeze casting.