Engineering materials inspired by nature

Magnetic field aligned freeze casting is a novel method to fabricate porous, anisotropic ceramic scaffolds with a hierarchy of architectural alignment in multiple directions. This concept was inspired by the structure of trabecular bone and the spiraling nature of the narwhal tusk. A weak rotating magnetic field applied normal to the ice growth direction in a uniaxial freezing apparatus allowed the manipulation of magnetic nanoparticles to create different pore structures and channels with long-range order in directions parallel and perpendicular to the freezing direction. Porous scaffolds consisting of different host ceramics as particles or platelets (hydroxyapatite (HA), ZrO2, Al2O3, or TiO2) mixed with varying concentrations of Fe3O4 nanoparticles were fabricated by freeze casting under no magnetic field, a static or rotating magnetic field. In the magnetic field direction, the compressive strength and stiffness of the scaffolds containing was doubled.