Sweat-Resistant Parylene-C Encapsulated Conductive Textiles for Active Thermal Management

The development of electro-thermal textiles has attracted growing interest as a promising approach for active thermal management in wearable systems. Metallic-coated fabrics can efficiently generate heat through the Joule effect; however, their long-term performance and safety are severely limited under perspiration due to metal ion release and corrosion. To overcome these challenges, this study introduces a Parylene-C encapsulation strategy for copper-coated polyethylene terephthalate nonwovens (CuPET) using a chemical vapor deposition (CVD) process. The conformal, biocompatible Parylene-C films (thickness 4-16 μm) act as effective protective barriers while preserving the porous textile structure. Morphological and comfort analyses demonstrate a controlled reduction in air permeability from 3100 to 1100 L·m^-2·s^-1, maintaining acceptable breathability. Electro-thermal measurements reveal rapid and uniform heating, reaching 40-45 °C within 2 min at 2 V, and the addition of a thermal insulation layer further enhances the Joule heating efficiency, increasing the steady-state temperature by approximately 6 °C. ICP-OES results show an ≈80% reduction in copper ion release (from 28.34 mg·L^-1 to 5.80 mg·L^-1) after artificial sweat exposure. This work demonstrates a scalable encapsulation route that effectively balances sweat protection, electrical stability, and thermal performance, paving the way for safe, durable, and actively heated smart textiles for advanced thermal insulation applications.