Toward 3D double-electrode textile triboelectric nanogenerators for wearable biomechanical energy harvesting and sensing

Textile-based triboelectric nanogenerators (T-TENGs) have attracted much attention nowadays because of their excellent flexibility and wearability in biomechanical energy harvesting and sensing. However, T-TENGs prepared by current methods of layer-by-layer stacking, stitching, or coating on the surface of fabric still have some problems such as poor comfort, complicated preparation processes, and easy peeling of coating materials. Herein, a 3D double-electrode and machine-knittable fabric TENG (3D-FTENG) with integrated positive and negative triboelectric materials and electrode materials is proposed by coated core-spun yarn and programmable spacer fabric technologies. The triboelectric materials and electrodes of 3D-FTENG are made of thermoplastic polyurethane (TPU) coated and polydimethylsiloxane (PDMS) coated Ag-cotton core-spun yarns. With structural design, three 3D-FTENGs with the same surface structures but different intermediate structures are designed and prepared, and the influence of intermediate structures on performance of 3D-FTENG is further studied. The power density of 3D-FTENG with the crisscross structure as intermediate layer reach up to 200.93 mW/m2. The 3D-FTENG is also soft, comfortable, high air permeable and washable. The output electric performance can be maintained after washing cycles and 50,000 cyclic tests. The 3D-FTENG can not only power small electronic products but also monitor human motions, demonstrating good potentials in wearable electronics.