Constructing highly tribopositive elastic yarn through interfacial design and assembly for efficient energy harvesting and human-interactive sensing

Fibers/yarns with superior triboelectrification and robust stretchability are considered indispensable building blocks for booming fiber-shaped wearable electronics. Here, a new class of highly tribopositive elastic yarn is developed through an interfacial design and assembly using polyethylene oxide/waterborne polyurethane/alliin composite as stretchable tribomaterial and polyethyleneimine/multiwalled carbon nanotubes/phytic acid polyionic nanomaterial as electrode. The contact triboelectrification and mechanical stretch behaviors of yarn are separately modulated by multiple functional groups coordination and hydrogen bond crosslinking/electrostatic interactions, realizing efficient charge transfer/accumulation capability and stretchable robustness. The optimized yarn TENG with single-electrode mode can deliver a high voltage of 137 V and power density of 2.25 mW/m by varying content of alliin and controlling the thickness of tribocomposite, which is superior to fiber-shaped TENGs reported thus far. Importantly, the device exhibits good electrical output stability and durability in multiple dynamic deformations or long-term service. The yarn can be easily integrated into the stretchable fabric for motion energy harvesting and can also be used as pressure/strain sensor to realize whole-body physiological signals detection and human-interactive sensing in virtual reality space. This work provides feasible proposal for the design of stretchable high-performance fiber TENGs and greatly promotes the advancement in wearable energy/sensing/interactive systems.