High-efficiency self-charging smart bracelet for portable electronics

Highlights: • High efficiency self-charging smart bracelet consists of F-TENG, D-MSC and PMM among the same substrate. • With double-sided layout, the stretchable MSC is based on the CNT-PDMS conductive elastomer with electrochemical stability. • Utilizing FPCB technique, the F-TENG and PMM are fabricated together to harvest mechanical energy effectively and efficiently. • The self-charging smart bracelet could scavenge walking motion energy and sustainably drive portable electronics. -- Abstract: The rapid advancements of lightweight, customized electronics have imposed a significant challenge on sustainable and maintenance-free micro-energy systems. For the sake of solving the limited power supply and low integration, it seems urgent to develop the flexible energy devices through structure design and performance optimization. Here, a high-efficiency self-charging smart bracelet is proposed by seamlessly combining flexible freestanding triboelectric nanogenerator, power management module with stretchable double-sided micro-supercapacitors. For energy-generating component, the FPCB-based freestanding triboelectric nanogenerator and power management module are adopted with excellent output performance, which obtains peak voltage of 305 V, and maximum power efficiency of 69.3%. Additionally, the double-sided micro-supercapacitors based on CNT-PDMS elastomer are designed to work stably and reliably as the stretchable energy-storing component, the capacitance of which maintains more than 96.87% even under 20% stretching strain. During human normal motions, this smart bracelet could be utilized for scavenging random motion movements and then simultaneously storing in the energy storage device through the high-efficiency power management module to develop a self-powered system for portable devices. As an effective and efficient power supply solution, this proposed self-charging smart bracelet demonstrates admirable potential to power a temperature-humidity meter or pedometer, which owns huge potentials in micro-energy wearable electronics and lays the solid foundation on the smart appliance.