A hybrid meta-biomaterial that promotes bone growth is not something you will find in nature, but it can be created using a 3-D printer and existing biomaterials. TU Delft researchers have developed a meta-implant that combines a conventional meta-biomaterial with an auxetic meta-biomaterial. Unlike natural materials, auxetics have a negative Poisson’s ratio—when stretched, they become thicker perpendicular to the applied force. The material may therefore be used in hip implants to ensure their long-term fixation. The TU Delft researchers published their findings in the scientific journal Materials Horizons on 2 January 2018.