Stretchable Cables: Fact or Fantasy?

If researchers in North Carolina have their way, Santa will have to stop at North Carolina State University next Chrismas to pack his giant Santa sack full of the stretchable wires being developed there. And with any luck good old Rudolph will guide his sleigh to my house where Santa can dump a heap of them under my prewired LED-lit artificial tree. (They don’t even have to be giftwrapped.) Really, Santa, I’ll be good. I want some of those wires! Imagine having headphone cords or HDMI interconnects or USB cables that can stretch up to eight times their original length. On my Christmas list, that’s about as close to the top as it can get. In fact, it’s written just below “world peace”, “utility bills paid for life”, and “make new episodes of Max Headroom”.

Unfortunately, you can’t buy any of these super-stretchy wires yet. They’re still vaporwire. Actually, they’re liquid wire—or, more correctly, wires made with liquid metal. To date, most of the work on elastic wires has involved embedding metals or other electrical conductors in a stretchy substance. While this composite approach might be good enough for other researchers, the NC State folks make their wires by taking a really, really thin tube made of a really, really elastic polymer and then pour in (using a really, really tiny funnel, I presume) a tasty dose of a liquid metal alloy consisting of gallium and indium. Aside from being awesome because it’s “liquid metal”, the alloy is also a very efficient conductor of electricity.

According to Dr. Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of the thrillingly titled article “Ultrastretchable Fibers with Metallic Conductivity Using a Liquid Metal Alloy Core”,

“Increasing the amount of metal improves the conductivity of the composite, but diminishes its elasticity. Our approach keeps the materials separate, so you have maximum conductivity without impairing elasticity. In short, our wires are orders of magnitude more stretchable than the most conductive wires, and at least an order of magnitude more conductive than the most stretchable wires currently in the literature.”

Here’s a short, tantalizing video of a a one-inch piece of headphone cord being stretched about six inches. I assume that the music playing in the background is from the earbuds, but it might have been mixed in for effect.

Don’t get me wrong. In my electronic dream world, everything is wireless but everything is wireless in a way that works. Not in the wild wireless wilderness I currently live in. Not in the way Verizon can’t seem to figure out why my iPhone 4S only intermittently functions as a wireless hotspot. And that’s even after they replaced the first iPhone 4S. (It’s okay, though. I like paying $20/month for a service I can only use maybe one out of eight times I try.) And not in the way that I’m currently only getting the equivalent of dialup download speeds from my satellite internet service. And not in the way my Apple Airport Extreme router will sometimes not play nice with various Wi-Fi devices on the network. And—oh, hell, just give me a bunch of those stretchy wires. It’ll seem a bit like going back to the days of using a couple of tin cans and a string to communicate, but until Santa can bring some ultra-reliable wireless connectivity, I’d be more than happy to have some ultra-stretchable wires instead.