Stretchy but tough fibres have potential for robotics and textiles

Engineers at North Carolina State University have developed a fibre that combines the elasticity of rubber with the strength of a metal, creating a material that could be incorporated into soft robotics or super-tough textiles. Capable of stretching up to 7 times its length without breaking, the fibre can absorb a great deal of energy as it deforms, becoming tougher than both the materials in its composition.

Developed by a team led by Michael Dickey, Alcoa Prof of chemical and biomolecular engineering at NC State, the fibre consists of a gallium metal core surrounded by a sheath of poly (styrene-ethylene butylene-styrene) (SEBS). In a paper in Science Advances, the team explained that the fibre mimics the behaviour of tough biological materials such as collagen or titin, the giant protein which acts as a molecular spring in muscle. "A good way of explaining the material is to think of rubber bands and metal wires," said Dickey. "A rubber band can stretch very far, but it doesn't take much force to stretch it. A metal wire requires a lot of force to stretch it, but it can't take much strain - it breaks before you can stretch it very far. Our fibres have the best of both worlds.”