A stretchable, self-healing and semi-transparent nanogenerator for energy harvesting and sensing

Triboelectric nanogenerators (TENGs) with an ability to harvest mechanical energy from natural and human activities, have shown tremendous potential to realise self-powered electronic devices and sensors. However, in order for optimum utilization of biomechanical energy, TENGs need to have body or tissue mimicking properties without compromising performance. Herein, a new hydrogel based all-soft, self-healing and stretchable TENG is introduced which exhibits outstanding power generation capability surpassing existing competitors. This unique TENG is realized by using gold nanoparticles doped semi-transparent hydrogel as an electrode and Ecoflex as the triboelectric layer which integrates multifunctional properties including rapid self-healing in < 2 min, 900% stretchability, high conductivity, transparency and excellent biocompatibility with human dermal fibroblasts. The use of a gel electrode with both ionic and electronic conductivities underlines the importance of gold nanoparticles in enhancing the performance of soft TENGs. A 5 cm2 device exhibits a prodigious power density of 1680 mWm−2 with an energy conversion efficiency of ≈ 26%, which is the highest achieved so far in contemporary hydrogel based TENGs. The moldable components allow easy fabrication of devices with tunable shapes and sizes that conforms to the human body and can power multiple electrical devices directly from body movements thus opening up possibilities for next generation self-powered wearable or implanted devices.