Fig. 1. Working principle model of triboelectric nanogenerator^[21]. (a) Triboelectric nanogenerator in vertical contact-separation mode; (b) lateral sliding mode triboelectric nanogenerator; (c) single-electrode mode triboelectric nanogenerator; (d) triboelectric nanogenerator with freestanding triboelectric-layer mode

Fig. 2. Fiber/yarn-based TENG prepared by textile technology. (a) A core-shell triboelectric nanogenerator with polyurethane fiber and stainless steel fiber^[26]; (b) triboelectric nanogenerators made by winding silk or teflon fibres around bundles of stainless steel fibres^[29]; (c) hollow braided tubular yarn using nylon and PDMS as triboelectric materials^[30]; (d) electrospinning PVDF nanofibers on carbon nanotube yarn lines^[14]

Fig. 3. Fiber/yarn-based TENG prepared by coating method. (a) Using silvered polyamide composite yarn coated with silicone rubber to weave double rib fabric^[34]; (b) a fibrous TENG made of spandex fiber is coated with AgNWs, CNT, and PDMS^[35]

Fig. 4. Preparation of fiber/yarn-based TENG by injection, extrusion, and hot drawing. (a) Stretchable fibrous TENG with liquid metal as electrode^[36]; (b) polymer solution was injected into the gel electrode fiber TENG in the hollow fiber^[37]; (c) fibrous TENG with core-skin structure prepared by coaxial wet spinning process^[38]; (d) fabrication of a fibrous TENG with a patterned surface by thermal stretching^[40]

Fig. 5. Integration strategies of various fiber/yarn-based TENG. (a) Fabrics with different weaves woven using woven processes^[43];(b) scaly TENG woven using knitting process^[44]; (c) TENG fabrics with different patterns prepared using embroidery process^[45]; (d) TENG of three-dimensional five-way braided structure^[46]