Omnidirectionally stretchable electrodes based on wrinkled silver nanowires through the shrinkage of electrospun polymer fibers

Abstract

Stretchable electrodes have attracted great attention for developing next generation wearable and flexible electronics. However, the fabrication of stretchable electrodes with high electrical stability, especially high omnidirectional stretchability, remains challenging. Here, we proposed a scheme for making stretchable electrodes based on wrinkled silver nanowires (Ag NWs) through the shrinkage of electrospun polymer fibers. The Ag NWs were vacuum filtered on electrospun fluoroelastomer fiber mats, and then they formed isotropic wrinkles on the scale of several micrometers after the thermal induced shrinkage of the fibers. An ∼80% areal shrinkage was achieved in the composite fiber mat under the conditions of 7 kV applied voltage during electrospinning and 120 °C thermal treatment temperature. The co-shrunk Ag NW electrodes reached high stretchability of up to 500%. The resistance increased only by a factor of ∼0.65 under 100% strain and ∼0.1 under 50% strain. These random wrinkles endow the electrodes with high omnidirectional stretchability, no significant variation of resistance change was observed along the hexagonal stretched directions at ∼80% strain. In addition, the stretchable electrodes demonstrated good electrical stability, with only <0.15 resistance change after 1000 stretching/recovering cycles at 50% strain. Finally, the electrodes were successfully used in omnidirectional stretchable electroluminescence device and electrocardiogram (ECG) recording, showing great potential in future stretchable and wearable electronics.