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Mimicking termites to generate new materials

Inspired by the way termites build their nests, researchers at Caltech have developed a framework to design new materials that mimics the fundamental rules hidden in nature's growth patterns. The investigators showed that, using these rules, it is possible to create materials designed with specific programmable properties.

The U.S. National Science Foundation-supported study, led by Chiara Daraio, was published in the journal Science. "Termites are only a few millimeters in length, but their nests can stand as high as four meters — the equivalent of a human constructing a house the height of California's Mount Whitney," says Daraio.

If you peer inside a termite nest you see a network of asymmetrical, interconnected structures, like the interior of a loaf of bread or a sponge. Made of sand grains, dust, dirt, saliva and dung, this disordered, irregular structure appears arbitrary, but a termite nest is optimized for stability and ventilation.

"We thought that by understanding how a termite contributes to the nest's fabrication, we could define simple rules for designing architected materials with unique mechanical properties," says Daraio.

Architected materials are foam-like or composite solids that comprise the building blocks that are then organized into 3D structures, from the nano- to the micrometer scale. Until now, the field of architected materials has primarily focused on periodic architectures — such architectures contain uniform geometry unit cells, like octahedrons or cubes, that are repeated to form a lattice structure. However, focusing on ordered structures has limited the functionalities and use of architected materials.

"We want to understand the fundamental rules of materials' design to then create materials that have superior performances compared to the ones we currently use in engineering," says Daraio. "For example, we envision the creation of materials that are more lightweight but also more resistant to fracture or better at absorbing mechanical impacts and vibrations."