Printable superelastic conductors with extreme stretchability and robust cycling endurance enabled by liquid-metal particles

Stretchable conductors are vital and indispensable components in soft electronic systems. The development for stretchable conductors has been highly motivated with different approaches established to address the dilemma in the conductivity and stretchability trade-offs to some extent. Here, a new strategy to achieve superelastic conductors with high conductivity and stable electrical performance under stretching is reported. It is demonstrated that by electrically anchoring conductive fillers with eutectic gallium indium particles (EGaInPs), significant improvement in stretchability and durability can be achieved in stretchable conductors. Different from the strategy of modulating the chemical interactions between the conductive fillers and host polymers, the EGaInPs provide dynamic and robust electrical anchors between the conductive fillers. A superelastic conductor which can achieve a high stretchability with 1000% strain at initial conductivity of 8331 S cm-1 and excellent cycling durability with about eight times resistance change (compared to the initial resistance at 0% strain before stretching) after reversibly stretching to 800% strain for 10 000 times is demonstrated. Applications of the superelastic conductor in an interactive soft touch device and a stretchable light-emitting system are also demonstrated, featuring its promising applications in soft robotics or soft and interactive human-machine interfaces. National Research Foundation (NRF) The authors thank Dr. M. Lin, Dr. J. Xiong, Dr. P, Cui, Q. Kai, and X. Chen for their valuable discussions. This work was financially supported by the National Research Foundation Competitive Research Programme (Award No. NRF-CRP-13-2014-02), and the NRF Investigatorship (NRFI) (Award No. NRF-NRFI2016-05).