Precisely 3D printing of ultrastrong architected carbon with a bio-inspired superstructure

Reducing defect is a critical challenge for developing strong metamaterials that are greatly demanded in multiple fields. Herein, we show a precisely 3D-printed ultrastrong architected carbon with a superstructure in the skeletal structure of knobby starfish. This superstructure could function as a shrinkage-adaptive structure with isotropic uniformity stress distribution to significantly reduce the defects. By pyrolyzing polymer templates that were 3D-printed using two-photon lithography, the nano-architected carbon was precisely prepared under a 99% volume shrinkage. It had a compressive strength achieving the theoretical limit of 7.23GPa, a specific strength of 10.33 GPa g ^− 1 cm ³ , and a fracture strain as high as 66%. It might be the strongest in specific strength among the known mechanical metamaterials. The architected carbon scaffolds, with the strength-to-weight ratio exceeding 1000000:1, were customized for bone repair. The scaffold exhibited high strength and modulus comparable to cortical bone. Animal experiments indicated that the implant could effectively repair critical-sized bone defects by inducing osteogenesis in vivo , showing great promise as a future implant for clinical bone repair. This work highlights a bio-inspired structure design cue to address the challenge of precisely fabricating strong metamaterials with little defects.