The wires have a liquid-metal core and polymer sheath and can reconnect at the molecular level after being severed. Like NCSU's earlier wires, the liquid core makes them stretchable, which makes them perfect for use in dangerous environments. (Or any environment where you don't want something to break.)
To make the wires, the researchers first dug out tiny tunnels from a self-healing polymer, then filled it with a liquid metal combination of indium and gallium. The core oxidizes when it's cut up, forming a barrier that keeps the liquid metal from falling out of the polymer sheath. But when the severed ends are put back together, it reconnects, giving you a functional wire.
Useful! A request: Put this in all of our gadgets so we can stop worrying about warranties.