Due to the increasingly serious environmental pollution and the extreme shortage of energy resources, harvesting clean and sustainable random energy from the environment is a scientific, effective, and necessary solution in the coming intelligent era. Such random and disorder energy, like that from human motion and textile-related movement, can be obtained via textile-based triboelectric nanogenerators (TENGs). However, research related to textile-based TENGs with mature, high-efficiency, and economical manufacturing techniques is limited. Here, by using a high-speed ring spinning method, negative Poisson's ratio yarn (NPRY) with a composite structure is designed and fabricated as a variety of intelligent device. Based on the special negative Poisson's ratio effect, NPRY combined with TENG can be used as a foundation structure to form diverse flexible textile-based electronic devices, such as an energy harvesting fabric, a self-counting yoga elastic band, and a self-powered pre-alarm cable. At the same time, NPRY-TENGs with different structures and structural parameters are systematically investigated to optimize the output performance in this work. This special, low-cost, and highly efficient NPRY as a foundation structure material has promising applications in the manufacture of all kinds of textile-based TENGs and harvesting a lot of random energy from the environment, where the random energy can be used by other electronic devices or those textile-based TENGs themselves as self-powered sensors.

The main content dealt with in the paper is to make a theoretical analysis of the contour diameter of auxetic yarn under tension, which expands transversely under axial tension. The auxetic yarn is designed by two components, that is, a core filament and a wrap filament. Compared with the wrap filament, the core filament is thicker, softer and much more extensible. In the initial status, the core filament is straight in the center of the auxetic yarn and the wrap filament wraps the core filament helically in a certain helical angle. Based on theoretical analysis, the formula of negative Poisson’s ratio of stretched auxetic yarn is obtained. It is found that the value of Poisson’s ratio is related to axial strain, helical angle and the diameter ratio of the core filament to the wrap filament. An applied example is presented to verify the Poisson’s ratio value-strain curve of auxetic yarn. In order to better investigate effects on negative Poisson’s ratio, the effect of different parameters of yarn, including mesh size, diameter ratio, tensile modulus and helical angle of the wrap filament, is investigated using finite element analysis based on ABAQUS software to analyze the negative Poisson’s ratio of auxetic yarn when stretched. It verified that yarn spun by two different components produced a negative Poisson’s ratio effect under tension and structure parameters of auxetic yarn significantly affected negative Poisson's ratio values. It is expected that this study could help us understanding the deformation mechanism of auxetic yarn under axial tension load.

The main content dealt with in the paper is to present a kind of weft-knitted spacer fabric with high porosity. It is a kind of three-dimensional textile fabric with a sandwich structure that consists of a middle layer of multifilament and two outer layers of plain-knitted fabric. Compared with traditional warp-knitted spacer fabric as cushion mats, weft-knitted spacer fabric is well used as apparel for good softness, thermal/moisture comfort, and air permeability. Therefore, three structures were designed and nine samples were prepared by choosing plain-knitted fabric as the outer layers and selecting soft and thin multifilament as a middle layer. Experimental results show that this kind of weft-knitted spacer fabrics has high porosity, greater than 86%, and also demonstrate that the weft-knitted spacer fabric is suitable for comfortable apparel based on experimental results of air permeability, compression properties, stiffness, and thermal insulation properties.