Complete control and strengthening over iron oxide porous structures freeze cast under oscillating magnetic fields

Porous scaffolds can be utilized in a variety of biomedical as well as mechanical applications. The process of freeze casting is a successful method to fabricate these porous structures but with ideal characteristics in only one direction (the ice-growth direction). The application of magnetic fields led to an increase in both the microstructural control and mechanical strength in an additional orthogonal direction. The application of these weak, uniform fields (<= 20 mT), in particular oscillating fields from a Helmholtz coils setup, has led to increases in mechanical strength through microstructural alignment in multiple material types. However, structures fabricated from these uniform fields have primarily been compared to each other, with little research comparing them to structures fabricated under strong, non-uniform fields from permanent magnet setups. Therefore, iron-oxide scaffolds were fabricated under weak, uniform fields (<= 20 mT) as well as strong, non-uniform fields (>= 20 mT), and their mechanical and microstructural properties were compared to one another. The application of weak, uniform fields led to superior mechanical properties compared to those produced from the application of strong, non-uniform fields, no distortions in the physical structure of the freeze-cast scaffold, and the best microstructural alignment ever seen in freeze-cast structures.