Stretchy fiber keeps electrons flowing

A carbon-wrapped rubber rope keeps electrical current flowing even when stretched, twisted and bent. The flexible fiber, reported in the July 24 Science, could inspire flexible electronic displays, improved pacemaker leads and stretchable power cords.

Elasticity and current-carrying prowess don’t usually go together: Conventional wires have little give, while adjustable fibers tend to lose electrical conductance as they stretch. Zunfeng Liu, a materials scientist at the University of Texas at Dallas, and colleagues stretched a 2-millimeter-diameter rubber fiber to about 15 times its original length and wrapped it in conductive sheets of carbon nanotubes. When the rubber returned to its relaxed state, the carbon sheets buckled but didn’t break, creating an accordion-like coating. The fiber maintained its conductance as it was elongated to 11 times its initial length, and it didn’t wear down even when stretched and relaxed thousands of times.