Fabrication of a twisted sensing yarn for multifunctional wearable applications

Nanofibers are ideal for the fabrication of fiber-based sensors owing to the wide applicability of such sensors in various fields. However, achieving high sensitivity and excellent tensile properties while maintaining high electrical conductivity in such sensors is difficult. This study proposes a simple fabrication method for a helical conductive yarn, core-sheath helical yarn (CSHY), in which the electrospun thermoplastic polyurethane (TPU) /boron nitride (BN) film is used as the fibrous material and coated with a liquid metal (LM), EGaIn. The fiber is then stretched and twisted to obtain the CSHY with high sensitivity, tensile stability, and durability as well as fast response and recovery. Experimental results show that the sensor fabricated by weaving the CSHY has a water contact angle of 143.2 degrees, indicating that it can be used for human motion monitoring and underwater applications. In addition, the LM has excellent electrical conductivity and thermal conductivity and exhibits a synergistic effect with BN that is uniformly arranged along the fiber length. Thus, the fabric-based sensor exhibits excellent heat-dissipation, temperature-sensing, and electric-heating performances. Consequently, the proposed multifunctional smart yarn exhibits excellent strain sensing, self-controlled thermal management, and hydrophobic performance, with potential applications in future wearable electronics.