Washability Testing of Wearable E-Textiles for Robustness in Daily Use

Widespread adoption of wearable e-textiles requires their robustness in daily use, including reliable performance after machine laundering, defined as washability. However, the field of e-textile washability has not yet adopted an established testing procedure representative of household environment. Thus, a method for reproducible washability testing suitable for e-textiles was developed, with a gentle washing cycle applied 25 times. Washability testing was conducted for conductive yarns, fabrics and elastic fibers, and capacitive strain sensors (parallel plate strain sensor and helical auxetic yarn strain sensor (HACS)) constructed from these materials. Resistance and capacitance were measured for materials and sensors, respectively. Additionally, the effectiveness of encapsulation of functional elements in non-functional textile in improving washability was tested. Strain testing was applied to sensors to evaluate the effect of laundering on their response. Protection methods were not consistently effective in improving washability. Parallel plate sensors experienced changes in sensitivity, most likely due to geometrical changes, but retained their sensing functionality with laundering. HACS, when stabilized by encapsulation, proved the most robust to laundering. These results allow identification of key research areas to assess and improve e-textile washability.