The fiber, which is composed of carbon nanotube sheets wrapped around a rubber core, may one day also find use in morphing aircraft, stretchy charger cords and exoskeleton limbs, along connecting cables for a wealth of other devices.

Unlike previous carbon nanotube fibers, which emphasized rigid strength that could be applied to bulletproof vests or offer an alternative to traditional carbon fiber, or that combined strength, flexibility, and conductivity, this new fiber is super stretchy.

The nanotube sheets are wrapped around the rubber while it is stretched, which results in buckling when the wrapped rubber relaxes – kind of like an accordion. Unlike an accordion, however, the fiber buckles in two dimensions – not only along its length, but also around its circumference, because stretching causes the rubber to shrink in diameter.