Pull–Push Interaction between Ions and Synthetic Polymers in All-Fiber Triboelectric Nanogenerators for Wireless Healthcare Applications

Enhancing the charge density output at the molecular scale within confined tribolayer regions is a promising strategy for optimizing triboelectric nanogenerator (TENG) performance. This study explores the molecular-level enhancement of charge density in TENGs through ion-ion and polymer-ion interactions achieved by incorporating KCl into Nylon66 in varying ratios via electrospinning. Energy-dispersive X-ray spectroscopy (EDS) confirmed the uniform distribution of KCl both inside and on the surface of the Nylon66 nanofibers. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses revealed that KCl disrupts hydrogen bonding in Nylon66, facilitating its integration into the polymer's molecular chains. Kelvin probe force microscopy (KPFM) demonstrated that pure Nylon66 exhibits a relatively low static potential. Within a certain range, increasing the KCl content led to a significant rise in the surface positive potential of Nylon66, thereby markedly enhancing its triboelectric performance. However, when the KCl content was excessive (Nylon66:KCl = 2400:4), KCl particles gradually accumulated on the nanofiber surface. Due to its hygroscopic nature, KCl can slowly absorb moisture from the air, which increases surface conductivity and accelerates charge dissipation, ultimately resulting in a deterioration of the triboelectric performance. The optimized KCl ratio resulted in a significant enhancement, with output voltage and current density increasing by 121.7% and 135.3%, respectively. Additionally, instead of using a conventional metal film electrode, a breathable, flexible, and antibacterial electrode was developed by coating the tribolayer surfaces with silver nanowires (AgNWs). Ultimately, the improved TENG was seamlessly integrated into wireless healthcare systems, offering an innovative communication solution for individuals with speech impairments or mobility limitations. This functionality highlights its potential as a transformative innovation for personalized and accessible healthcare solutions.