Design of bone-like continuous gradient porous scaffold based on triply periodic minimal surfaces

In this work, we designed a new bone-like scaffold with a continuous porosity gradient change based on minimal surfaces. Three minimal surface structures (P (Primitive), G (Gyroid), and D (Diamond)) were chosen to design the scaffolds, and the scaffolds were successfully prepared by selective laser melting using a new Ni46.5Ti44.5Nb9 alloy. The re-sults show that the scaffolds have the matched low elastic modulus (1.5-3.4 GPa) and suitable strength (75-321 MPa) compared with human bone. The unit structure type has a considerable effect on mechanical properties and permeability, and the superiority order is P > G > D. The scaffold is more compact with lower porosity on the outside, where can bear more stress during compression, thus improving the mechanical properties of the scaf-folds. The high porosity in the inner facilitates the flow of liquid, thus improving the permeability of the scaffold. This work provides a new method to design porous scaffolds in medical applications.