Liquid Metal Self-Healing Wire Invented That Reconnects After Cut

Self-healing polymers already exist and can be bought for various purposes - now researchers from North Carolina State University invented a new application by adding a special liquid-metal alloy to combine both to form elastic, self-healing wires in which both the liquid-metal core and the polymer sheath reconnect at the molecular level after being severed.

"Because we're using liquid metal, these wires have excellent conductive properties," says Dr. Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper on the work. "And because the wires are also elastic and self-healing, they have a lot of potential for use in technologies that could be exposed to high-stress environments."

To achieve this, Dickey's team just drilled tiny tunnels, known as microfluidic channels, in the polymer using solid wire. Now add the secret ingredient, liquid-metal -- which is actually an alloy of indium and gallium -- to fill the microchannel. Since the wire is not a solid thread, it cannot be torn apart, and instead be stretched along with the polymer sheath.

But what if you severe or even cut the cable with a scissor? Then the liquid metal oxidizes - forming a "skin" that prevents it from leaking out of its sheath. But the most fascinating feature can be observed when the severed edges of the wire are placed back together: The liquid metal actually reconnects and the sheath re-forms its molecular bonds.

Dickey says that one of the handy features of their inventions could be to "allow us to create more complex circuits and rewire existing circuits using nothing more than a pair of scissors by cutting and reconfiguring the wires so that they connect in different ways."

Paper: "Self-Healing Stretchable Wires for Reconfigurable Circuit Wiring and 3D Microfluidics," published online in Advanced Materials.