Robust and Multifunctional Conductive Yarns for Biomedical Textile Computing

Performance and durability of conductive yarns are essential factors to consider in the development of smart garments for textile computing applications. Conductive yarns and materials are used in various consumer and industrial products, however, their performance after washing, which is present with smart garments, is an unconventional, yet important consideration. This study investigates the impact of domestic washing on conductive silver-plated nylon and carbon-containing nylon yarns knitted into different patterns, simulating the incorporation of the conductive yarns into smart textiles. Various factors such as conductive yarn materials, types of knitting machine, and conductive feature patterns were considered. The resistance of silver-based textile electrodes increased by 100-300% over 50 wash cycles. Sulfidation and mechanical abrasion are the two main reasons for silver yarn degradation. The resistance of carbon-based textile electrodes stabilized after about five laundry cycles, showing little to no change afterward. Finally, the best performing silver and carbon electrodes were compared with gold-standard hydrogel electrodes for skin-electrode impedance and electrocardiogram measurement before and after 35 times of laundering. The results obtained demonstrated that both of the textile electrodes performed comparably to hydrogel electrodes and can be considered for continuous monitoring of biopotential signals from the human body.