EPFL flexible conductors

What are you looking at in the photo above? It’s a sheet of plastic with electrical conductors on its surface. These traces connect LEDs to a power source, and you can see that the electricity is reaching them because they are glowing green. So far, so what? Now, that sheet of plastic started off flat, and was inflated to create that bubble shape seen in the photo. And the plastic can be inflated and deflated repeatedly, and the LEDs keep on lighting up. You can’t do that with the copper wires typically used to carry electricity; they don’t stretch. In fact, we use metal wires to hold up things like suspension bridges precisely because they don’t stretch.

What is happening here? This image comes from a video made by scientists at EPFL (École polytechnique fédérale de Lausanne) in Switzerland, and it demonstrates new conductors that can stretch up to four times their original length and still function. The material has been tested by stretching it a million times, and it did not crack or lose its conductivity. How does it do it? Remember the shape-shifting android in “Terminator 2” that was made of a material that was a solid metal and a liquid metal at the same time? The Swiss scientists have created a metal film that is partly solid and partly liquid. A solid layer of gold keeps a liquid layer of gallium from separating into discrete droplets, thus maintaining a continuous electrical circuit.

Its flexible characteristics could be important for wearable Health Tech applications, from body sensors to feedback devices on prosthetic limbs. It also could be used in textiles to provide stretchable circuits for smart clothing. The new technology could make a range of new uses practical.