Multifunctional Helical Coaxial Fiber Platform Enabling Energy Autonomy and Intelligent Sensing

Multifunctional self-powered fibers demonstrate significant potential for applications in wearable flexible electronics, human-machine interfaces, and Internet of Things (IoT) systems. A critical challenge in this field is achieving the effective integration and versatile application of various functional fibers. This study presents a novel multifunctional coaxial energy fiber capable of simultaneous energy harvesting, storage, and utilization. The fiber features a coaxial architecture that integrates an inner fiber-shaped zinc-ion supercapacitor (F-ZnSC) for energy storage and an outer spiral-yarn triboelectric nanogenerator (TENG) for energy harvesting and self-powered pressure sensor. The F-ZnSC comprises MXene-modified spiral yarn electrodes, a zinc wire anode, and a Gelatin/ZnSO₄ gel electrolyte, achieving a high specific capacitance of 455 mF cm⁻¹ along with excellent rate capability and cycling stability (e.g., ~96.6% capacitance retention after 5,000 cycles). The outer spiral-yarn TENG exhibits a high pressure sensitivity of 8 V kPa⁻¹, enabling effective and real-time monitoring of finger motions. Combining with a deep learning algorithm, the system recognizes five distinct hand gestures with an accuracy of 96.25%, demonstrating its utility in advanced game control and human-machine interaction. Furthermore, the encapsulation layer shared by the TENG and the F-ZnSC forms an additional contact-separation mode energy harvester. Ten such devices connected in parallel yield an output power of 177.1 μW, sufficient to power small electronics such as watches and calculators. This work highlights the promise of the coaxial energy fiber as a versatile platform for adaptive wearable energy systems, self-powered interfaces, and intelligent sensing.