Structural optimisation of silver-plated yarn knitted electrothermal fabric and its application in an electric heating neck wrap

Conventional neck-warming devices often suffer from limitations in flexibility, heating efficiency, and wearing comfort. In this study, an electric heating neck wrap was developed using optimised knitted structures incorporating silver-plated yarns. Six knitted electrothermal fabrics were fabricated by combining three knitting structures with two periodic alternating arrangements of conductive and conventional yarns. Their temperature-rise behaviour, temperature uniformity, and thermal stability were systematically evaluated. Results indicated that the 1 × 1 rib structure exhibited the best heating performance, while the single-course alternating arrangement achieved higher steady-state temperatures and more uniform heat distribution. The 1 × 1 rib fabric was ultimately selected as the heating element for the neck wrap, reaching 46.8 °C within 30 min under 7 V at (20 ± 5) °C, with a resistance variation below 5%. The integrated neck wrap increased the local neck temperature to 38 °C within 10 min, demonstrating uniform heat distribution and favourable wearing comfort. This study provides valuable insights into the structural optimisation and practical application of flexible knitted electrothermal fabrics for wearable heat therapy devices.