Abstract:

Objective The triboelectric nanogenerator (TENG) is capable of efficiently converting mechanical energy into electrical energy, showing immense potential in the field of self-powered wearable smart materials. The single-electrode mode, in particular, simplifies the system design and reduces the integration complexity, thereby demonstrating broad applicability across diverse scenarios. However, the conventional fabrication of TENG fibers with a core-sheath structure faces challenges due to the complexity of the preparation process. This study employed microfluidic spinning technology to fabricate single-electrode poly(vinylidene fluoride-hexafluoropropylene)-fibroin ionic liquid triboelectric nanogenerator fibers (PSE-TENG fibers) in a one-step process, using high-dielectric constant poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as the sheath material and fibroin ionic liquid (SE) solution as the conductive core material.
Method This study explored an innovative method using microfluidic spinning technology to achieve the one-step fabrication of single-electrode PSE-TENG fibers. PVDF-HFP, known for its high dielectric constant, was used as the sheath material, and a silk protein ionic liquid solution, noted for excellent conductivity, stability, and mechanical flexibility, was taken as the core material. The morphology, structure, and mechanical properties of the PSE-TENG fibers were characterized using scanning electron microscopy and a universal mechanical testing machine. A fatigue tester was adopted to simulate motion, and an oscilloscope was employed to collect the electrical output signals of the PSE-TENG fibers. The influences of spinning parameters on the structure of PSE-TENG fibers were thoroughly investigated, their mechanical properties were systematically evaluated, and their output performance and long-term stability under different mechanical motion conditions were explored.
Results SEM images confirmed a well-defined and continuous core-sheath geometry. The core diameter could be tuned by adjusting the flow-rate ratio in the microfluidic spinneret. PSE-TENG fibers exhibited a tensile strength of (3.32±0.19) MPa and an elongation at break of (176.83±27.14) %, indicating excellent flexibility and robustness suitable for textile processing. Under contact-separation motions of different frequencies, the peak open-circuit voltage increased monotonically with frequency, demonstrating a clear correlation between mechanical excitation rate and electrical output. Even after more than 20,000 contact-separation cycles, the voltage signals showed negligible degradation, proving outstanding operational durability.
Conclusion The results validate a facile, scalable microfluidic spinning approach for producing mechanically resilient, high-output PSE-TENG fibers in a single step, thereby eliminating the complexity of conventional layer-by-layer or post-coating techniques. The fibers unite 1) a stable core-sheath architecture, 2) high tensile strength and large elongation, 3) frequency-responsive voltage generation, and 4) long-term cycling reliability exceeding 20 000 operations. These attributes translate into superior energy-conversion efficiency and mechanical robustness, making the PSE-TENG fiber an attractive self-powered component for next-generation wearable electronics, smart textiles, and other portable or deformable devices that demand continuous, reliable, and efficient energy harvesting.

Key words: triboelectric nanogenerator, core-sheath structure fiber, microfluidic technology, fibroin ionic liquid, poly(vinylidene fluoride-hexafluoropropylene), spinning parameter