Abstract: The functional reconstruction of critical-sized bone defects poses a significant challenge in orthopedic surgery. Traditional manufacturing techniques often struggle to produce implants with hierarchical porosity and precisely tailored mechanical properties that mimic natural bone. This study presents a novel approach utilizing a camphene-based metal ink for direct ink writing (DIW) to fabricate hierarchical porous titanium (Ti) scaffolds with controlled cross-scale porosity for enhanced biocompatibility. Macroscale pores are defined by the DIW process, while microscale and nanoscale pores are generated through camphene dendrite coarsening, organic additive removal, and incomplete sintering, respectively. The resulting 3D-printed scaffolds exhibit a porosity of 53 %-75 %, compressive strength of 68-289 MPa, and elastic modulus of 3.8-11.9 GPa, closely matching the mechanical properties of cortical bone and effectively mitigating stress shielding. The hierarchical porous architecture promotes energy dissipation through columnar collapse and plastic micro-buckling, leading to superior energy absorption. Furthermore, the pore network provides a favorable environment for cell adhesion, proliferation, and apatite nucleation, enhancing biocompatibility and biofunctionalization. This approach to fabricating hierarchical porous Ti scaffolds holds immense promise for bone tissue engineering applications, offering a pathway to develop biomimetic implants with exceptional mechanical and biological performance.

Key words: Camphene-based metallic ink, 3D printing, Hierarchical pore, Compressive strength, Bone tissue engineering