The cities of the future may be built with synthetic bone, according to some researchers at Cambridge. It’s a far more sustainable alternative to today’s concrete and steel, which makes up for a tenth of worldwide carbon emissions.
Looking to nature for solutions, bioengineers found that the protein and mineral composition of bones make them particularly tough. They’re even trying to recreate the natural ability of bones to self-heal. This is the essence of biomimetics, a scientific field in which human-made systems imitate ones found in nature.
A prominent concern about technology is that it distances us from nature. Biomimetics shows that listening to nature may be a crucial part of stepping into the future.
Whereas some researchers are investigating ways of producing steel and concrete in more energy-efficient ways, or finding ways of using less, Oyen would rather turn the tables completely, and create new building materials that are strong, sustainable and take their inspiration from nature.
“What we’re trying to do is to rethink the way that we make things,” says Oyen. “Engineers tend to throw energy at problems, whereas nature throws information at problems – they fundamentally do things differently.”
Oyen works in the field of biomimetics – literally ‘copying life.’ In her lab, with funding support from the U.S. Army Corps of Engineers, she constructs small samples of artificial bone and eggshell, which could be used as medical implants, or even be scaled up and used as low-carbon building materials.
Like the real things, artificial bone and eggshell are composites of proteins and minerals. In bone, the proportions of protein and mineral are roughly equal – the mineral gives bone stiffness and hardness, while the protein gives it toughness or resistance to fracture. While bones can break, it is relatively rare, and they have the benefit of being self-healing – another feature that engineers are trying to bring to biomimetic materials.
In eggshell, the ratios are different: about 95 percent mineral to five percent protein, but even this small amount of protein makes eggshell remarkably tough considering how thin it is.
When making the artificial bone and eggshell, the mineral components are ‘templated’ directly onto collagen, which is the most abundant protein in the animal world.
“One of the interesting things is that the minerals that make up bone deposit along the collagen, and eggshell deposits outwards from the collagen, perpendicular to it,” says Oyen. “So it might even be the case that these two composites could be combined to make a lattice-type structure, which would be even stronger – there’s some interesting science there that we’d like to look into.”