A team of researchers from the North Carolina State University has engineered fiber that has the toughness of metal, but with the flexibility and stretch of rubber.

They believe that their creation has various applications, including soft robotics, packaging materials, and, of course, the next generation of textiles.

The team published a paper titled "Toughening stretchable fibers via serial fracturing of a metallic core" in the journal Science Advances.

A New Type Of Fiber

"A rubber band can stretch very far, but it doesn't take much force to stretch it," explained Michael Dickey, a professor at the North Carolina State University and an author of the study. "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."

They claim that the fiber they have developed addresses both concerns.

To develop the stretchy but tough material, the researchers used gallium metalcore encased in an elastic polymer sheath. When under stress, the fiber has the strength of the metal core. When the metalcore breaks, the polymer sheath stretches, bridging the gap, absorbing the strain, and transferring the stress back to the metal core.

This mechanism allows the fiber to stretch slowly under heavy load. Dickey said that the fiber has the capacity to stretch up to seven times its original length before failure.

"To think of it another way, the fiber won't snap and drop a heavy weight," he added. "Instead, by releasing energy repeatedly through internal breaks, the fiber lowers the weight slowly and steadily."

The Next Generation Fiber

The fiber, right now, is still just a proof of concept, but the researchers can imagine a variety of uses for the material. Dickey said that there is a demand for an engineering material that behaves like human skin. Their creation not only mimics but surpasses the toughness and elasticity of the human skin.

The researchers also said that the fiber can be altered by using different materials at the core and the shell.

Moreover, the fiber can be reused over and over again by melting the metal cores back together.