https://www.sciencedaily.com/releases/2018/06/180614213840.htm

"These are the first flexible electronics that are at once highly conductive and stretchable, fully biocompatible, and able to be fabricated conveniently across size scales with micro-feature precision," says senior author Xingyu Jiang, a professor at the National Center for Nanoscience and Technology. "We believe that they will have broad applications for both wearable electronics and implantable devices."

The material that the researchers fashioned is called a metal-polymer conductor (MPC), so called because it is a combination of two components with very different yet equally desirable properties. The metals in this case are not familiar conductive solids, such as copper, silver, or gold, but rather gallium and indium, which exist as thick, syrupy liquids that still permit electricity to flow. The researchers found that embedding globs of this liquid metal mixture within a supporting network of silicone-based polymer yielded mechanically resilient materials with enough conductivity to support functioning circuits.