Stretchy circuits will make for better wearables and robots

Liquid-metal electronics can be stretched up to four times their original length.

Smart clothing and robots alike might soon get better thanks to a breakthrough from a team of Swiss researchers. They created relatively thin electronic circuits that can be stretched like rubber up to four times their original length in any direction. In addition, it can be cycled that way nearly a million times without cracking or losing conductivity. That makes it perfect for biological sensors, artificial skin, prosthetics or for electronics that can easily be sewn into fabrics.

The hybrid material is based on both liquid metal and solid metal alloys. The team first created a film using silicone-based substrate called polydimethylsiloxane (PDMS). They then formed a metallic bi-layer by evaporating gallium onto a sputtered gold film a mere 60 nanometers thick. When the solid part of the gold alloy is stretched, cracks can form, but they're quickly filled by the liquid gallium, which has a melting point of 29.8 degrees Celcius (85.6 degrees F). Best of all, the final material can be lithographed onto any surface in complex patterns just like regular electronic circuits.

Without the need to print circuits on a board, the team has dreamed up all kinds of usage scenarios. "We can integrate conventional electronics into assemblies that stretch and carry power, we can use it in soft robotics and smart clothing... but we can also use it to construct actuators that give tactile feedback," says graduate student Arthur Hirsch. In other words, electronics can finally work with our squishy human bodies or help researchers create more life-like robots with liquid metal circuits. Hm, wait a second ...