Fiber-shaped stretchable triboelectric nanogenerator with a novel synergistic structure of opposite Poisson's ratios

The rapid advancement of flexible and stretchable electronics has attracted intensive attention in recent decades. However, challenges still remain in developing wearable and sustainable power sources with comparable portability and stretchability. Here, a novel type of stretchable fiber-shaped triboelectric nanogenerator (AXFTENG) was fabricated by inserting a negative Poisson-ratio auxetic fiber into a positive Poisson-ratio hollow circular sleeve, forming a synergistic structured TENG composed of opposite Poisson's ratios. Owing to the advanced structural designs, the inner auxetic fiber would expand in all directions to more effectively contact with the shrunk outer steel wire sleeve under stretching. The peak-to-peak voltage and transfer charge of composite based AXF-TENG could reach up to 42 V and 12.5 nC, respectively. The fabricated AXF-TENG can be used as a self-powered multifunctional sensor to detect human motions and be woven into an energy-harvesting fabric to scavenge biomechanical energy. With open-circuit voltage of 46 V and maximum instantaneous power density of 52.36 mW/m2, the AXF-TENG fabric was capable of lighting up 20 light emitting diodes (LEDs), charging commercial capacitors, powering an electronic watch and a calculator. All of these merits of the proposed AXF-TENGs suggest their promising potentials for versatile applications in biomechanical energy harvesting and self-powered sensing.