Negative Poisson’s ratio lattice for designing vertebral biomaterials

This work designs and experimentally validates a novel bone-mimicking biomaterial for human cancellous bone vertebral implants. The lattice architecture here proposed consists of a 3D printed titanium auxetic meta-biomaterial, with a complex micro-structure resembling vertebral trabeculae, and exhibiting a negative Poisson’s ratio. Through finite element analysis, the work finds the optimal geometrical parameters of the unit cells of the lattice and performs the shape optimization of the trabeculae. This leads to a meta-biomaterial with a Poisson’s ratio up to -0.64, and a Young’s modulus of 128.3 MPa, close to that of human vertebral cancellous bones, as the experimental validation confirms. The work demonstrates the great potential of additively manufactured hybrid titanium auxetic metamaterials, which can be designed to obtain peculiar mechanical properties that improve bone tissue regeneration while prevent stress-shielding phenomena.