Human bones are amazing. But up until recently, it's been hard to engineer a synthetic material that replicates the super-strong structure of the real thing. Now, scientists in Germany are using a 3D printer to do just that—and it could mean a breakthrough for how we build everything from architecture to spacecraft.
A new study published in The Proceedings of the National Academy of Sciences looks at a fundamental problem with material sciences: the trade-off between weight and strength. Generally, materials that are very strong tend to be very heavy—like steel—while lighter materials are less stable.
Organic material, like our bones, are an exception to this rule; they form structures made of collagen and hydroxyapatite at a microscopic scale—almost like tiny columns and floor plates filled with air. They are both light and strong. Here's how lead author Jens Bauer explains the concept:
Technical foams are very light, but compared with bulk materials, their strength is quite low because of their random structure. Natural lightweight materials, such as bone, are cellular solids with optimised architecture. They are structured hierarchically and actually consist of tiny nanometre building blocks, providing a benefit from mechanical size effects.
Recreating that concept at such a tiny scale has always been a challenge, not only from a design standpoint, but from a fabrication standpoint; 3D printers simply weren't advanced enough to recreate these microscope patterns until recently. While carbon fibre and graphene operate on similarly nano-scales, the research focused on bone due to its naturally occurring structure.
Using 3D laser lithography, Bauer's team printed nano-scale structures using ceramic polymer, the same basic stuff of our own bones. Basing different models on different structural organisations—shell versus microtruss, for example—they were able to test the compressive strength of synthetic bone at the same scale as the real thing.
So, why is this so cool? Well, as we saw with an MIT study from last summer that 3D-printed similar structures, this work is pointing the way towards lighter, stronger materials for our buildings and bridges. But it could also be critical for space travel, since every gram of weight counts when a spacecraft is launched. As the LA Times suggests, these ideas could even be applied to bone-based spacecraft and off-world structures. [The Proceedings of the National Academy of Sciences; LATimes]
Lead image: Mopic/Shutterstock.