Core–Sheath Fiber-Based Triboelectric Nanogenerators for Energy Harvesting and Self-Powered Straight-Arm Sit-Up Sensing

[Image: see text] Fiber-based triboelectric nanogenerators (F-TENGs), a green and sustainable energy-harvesting and transformation technology, hold great potential in the areas of portable energy harvesters and smart wearable sensors. Herein, the core–sheath structure F-TENGs (CF-TENGs) are developed by using continuous production equipment. The CF-TENGs, consisting of an elastic conductive fiber (core layer) and silicone rubber (sheath layer), can simultaneously accomplish stable reversible strain and excellent electrical output performance. High outputs (an open-circuit voltage of 17.5 V and a short-circuit current of 0.1 μA at a frequency of 1 Hz) can be attained when the CF-TENGs (a length of 5 cm) are contacted with a nylon fabric. The CF-TENGs not only act as self-powered sensors for applications in motion monitoring but also efficiently transfer mechanical energy into electric energy. As self-powered wearable sensors, the CF-TENGs can accurately indicate various human physiological movements. Moreover, they can be applied on straight-arm sit-up sensing to achieve standardized sport testing. Importantly, a CF-TENG-based weaved fabric presents high electrical performance to meet requirements as an energy harvester. These CF-TENGs provide a significant insight to facilitate the development of fiber-based triboelectric applications.