Fully Stretchable Sandwich Structured Textile-Based Triboelectric Nanogenerator with a Crepe Paper-Induced Surface Microstructure

As various wearable devices are released, self-powered wearable energy harvesting technology is in the spotlight as a next-generation technology. Among them, research on triboelectric nanogenerator (TENG), which efficiently converts mechanical energy into electrical energy, is being actively conducted. In particular, the textile-based TENG is one of the most promising energy harvesters for realizing wearable devices and self-powered smart clothing. However, most of the existing textile-based TENGs generate energy only in the intentional vertical-contact mode, and have poor durability against twisting or bending deformation using metal materials.<br/>This study, we propose a sandwich structured textile-based TENG (STENG) with a stretchability and fully flexibility for wearable energy harvesting. One side of stretchable textile is coated with micropatterned EcoFlex and used as a negative triboelectric material. The performance of power generation was improved by patterning the EcoFlex surface based on the microstructure of the crepe paper surface. The other side, acetate cloth tape is attached to the stretchable textile as a serpentine structure, and is used as a positive triboelectric material. Since this is a serpentine structure, it is possible to expand and contract up to 50% in the lateral direction. The top of the acetate cloth is sewn with yarn to generation an air gap, which can generate energy even in stretching mode. That is, through friction between micropatterned EcoFlex and acetate, STENG harvests mechanical energy in the contact-separate, stretching, and rubbing modes. In addition, since all flexible materials are used, the structure is free from deformation. The output of 361.3 V and 58.2 μA in the contact-separate mode, the output of 166.1 V and 23 μA in the stretching mode, and the output voltages and currents of 119.5 V and 17 μA in the rubbing mode were observed. This is the result of 250% improvement in output performance compared to the flat EcoFlex-based STENG without nanopatterns. Finally, we successfully demonstrated the operation of the 135 LEDs using STENG's output without external power source. These findings could provide a textile-based power source with practical application in future e-textile and self-powered electronics.