Design and statistical optimization of inlay-knitted joule heating textiles for wearable heat therapy

Abstract

This study presents the design, fabrication, and optimization of an inlay-knitted heating textile intended for wearable heat therapy. A low-twisted cotton sheath encapsulating stainless-steel conductive yarn was engineered into a core-sheath configuration and integrated into a rib-knit fabric via inlay knitting. A Box–Behnken Design (BBD) was employed to systematically investigate the effects of applied voltage, number of conductive yarn plies, and heating zone spacing on the surface temperature. Experimental results revealed that increasing yarn plies significantly reduced electrical resistance, thereby enhancing thermal output. The developed regression model exhibited high accuracy (R² = 0.9902), with ANOVA confirming the statistical significance of process parameters. Optimized fabrication conditions were identified to maintain a therapeutic surface temperature of 40 °C while minimizing power consumption, verified experimentally with strong agreement to model predictions. The resultant textile demonstrated uniform, stable heating and excellent flexibility, comfort, and safety, validating its suitability for localized musculoskeletal pain relief. This approach offers a scalable pathway for producing energy-efficient, comfortable, and safe knitted heating fabrics for wearable thermal therapy.