A Multi-strand Yarn with Integrated Sensing and Addressable Display Fabricated via “Lock-Knot”

Abstract

Smart fibers/yarns have attracted significant attention due to their highly potential applications in healthcare, astronautics, and human–machine interfaces. However, the fabrication of multifunctional smart fibers/yarns is very challenging, especially while keeping the good flexibility and durability of traditional ones. Herein, inspired by the multi-strand structure of traditional yarns, we developed a multifunctional yarn with integrated sensing (such as strain and temperature) and real-time addressable display units interconnected using a lock-knot joint technique, which enables adjustable positioning of different units. The strain sensing fibers have good elasticity and high sensitivity (gauge factors over 11 for strain within 0–39%), enabling monitoring of most human body deformations. The temperature sensing unit has a sensitivity of 0.27%/°C within 28–38 °C, suitable for monitoring body temperature. Blue, green, and yellow electroluminescent units with a size of 2 mm² and luminance values of 0.2, 0.8, and 0.1 cd/m² are integrated with the sensing units in one yarn, enabling sensing and displaying external stimuli in a real-time and addressable manner. The lock-knot yarn exhibits good flexibility, weavability, and washability, facilitating its practical applications. By integrating the smart yarn into clothes, we demonstrated its application in hunchback detection, running position tracking, “clothing climate” warning, and sports training guidance.