Structural Design and Performance Study of Knitted “Liquid Diodes” for Sweat Trapping and Directional Movement

Humans perspire significantly after exposure to high temperatures or intense exercise, which can lead to discomfort and promote bacterial growth. In this study, a BN/ZnO/PDMS@N/S-20 yarn and two types of 'liquid diode' elastic fabrics (S3, S4) are developed knitted on a V-bed flat knitting machine to improve the fabric's liquid directional transport and antimicrobial properties. The results demonstrated that an increased number of successive loops of BN/ZnO/PDMS@N/S-20 yarns resulted in the fabric more effectively capturing sweat from the skin's surface. 5 µL of artificial sweat moved the farthest distance along the oblique direction on the S4 surface (stretched 1.5 times), reaching up to 2.2 cm, which is 3.4 times the transverse distance. The fabric's 'liquid diode' structure, formed on the surface due to the presence of tucks, generates Laplace force that drives the directional movement of sweat. This structure also serves as a bridge, connecting two adjacent rows of cotton yarns to ensure path interoperability. Additionally, the fabric exhibits excellent air and moisture permeability, with rates of 1728 mm s^-1 and 207 g m^{- 2}h^-1, respectively. When exposed to sunlight for 4 s, the surface temperature of the fabric is 7.1 °C lower than that of cotton knitted fabrics.