High-Throughput Production of Electrically Conductive Yarn (E-Yarn) for Smart Textiles

Electrically conductive yarn is essential for developing smart textiles, combining advanced functionalities with the desirable mechanical properties of traditional yarn. This study introduces an innovative method for manufacturing Nylon yarn coated with an electrically conductive, thermoplastic polymer layer. The method is based on the classical wire coating process, thus enabling rapid scale-up. The feasibility of the new approach is demonstrated by coating a Nylon yarn 250 µm in diameter with a 20 µm thermoplastic coating layer consisting of a polyamide (Platamid M1276 F, melting temperature 110–120 °C) matrix including 20 vol% silver flakes (d₅₀ 2.5 µm). The resultant resistivity of the coated yarn is ≈7.5 Ω cm⁻¹, and essentially kept constant even after multiple bending and washing cycles simulating typical stresses during textile utilization. Additionally, the yarn is used to fabricate a pressure sensor, demonstrating a pressure sensitivity range of 1–20 kPa, a sensitivity of 10⁻³ kPa⁻¹, and a response time of 224 ms. This study showcases a versatile manufacturing process for electrically conductive yarn suitable for smart textile applications. It emphasizes the potential for integrating these yarns into functional textile systems and highlights the feasibility of using existing industrial-scale coating equipment, thus facilitating rapid market integration.