Metal-hygroscopic polymer conductors that can secrete solders for connections in stretchable devices†
Wearable electronics have great potential to enable seamless human–machine interfaces and can dramatically improve the quality of life by using advanced monitoring and therapeutic devices. Despite great progress in wearable devices, very few wearable devices can be both highly integrable and stretchable (strain >100%) due to the lack of reliable connections between the soft conductors and rigid electronics. Here, we report highly stretchable metal-hygroscopic polymer conductors that can secrete solders for connections. Propelled by changing humidity, liquid metal particles within conductors will merge and erupt, providing electrical connections for electronics, while the coated adhesive can provide mechanical connections. Thus, rigid electronics can be stably connected on conductors by pressure, with no extra solder, solvent or heat being required. The stable connections and high stretchability of the conductors (105 S m−1 at a strain of 800%) allow integrated electronics to stretch to a strain of 150%. We have created a stretchable, integrated device that is double-sided and multi-layered and it can sense the oxygen saturation in blood, heart rate, strain and temperature.