Textile-Based Wearable Electrothermal Pad Using Woven AgNW/EG-PEDOT:PSS Heaters and PS/PEDOT:PSS Thermistor Yarns

Wearable thermal management devices are gaining increasing attention for healthcare, rehabilitation, and personal comfort applications. Here, we present a textile-based wearable electrothermal pad that integrates a woven heater with a yarn temperature sensor on a flexible, breathable fabric platform. The heater element was fabricated using cotton yarn coated with silver nanowires (AgNW) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) doped with ethylene glycol (EG-PEDOT:PSS), enabling uniform heat distribution, washability, and low-voltage operation. The AgNW/EG-PEDOT:PSS yarn heater rapidly reached 45 °C within 60 s at an applied voltage of 1.5 V and demonstrated good thermal stability and repeatability over 2,000 stretching-releasing cycles. The temperature sensor, based on polystyrene-coated PEDOT:PSS (PS/PEDOT:PSS) yarn, exhibited thermistor behavior with resistance decreasing as the temperature increases. It showed a negative temperature coefficient of resistance of 0.25%°C^-1 and a response time of less than 130 s. The yarn temperature sensor also maintained resistance stability under bending and stretching-releasing conditions. To demonstrate a wearable electrotherapy platform, the PS/PEDOT:PSS yarn temperature sensor was integrated with a woven AgNW/EG-PEDOT:PSS heater to enable closed-loop feedback for thermal regulation. Programmable, on-demand thermotherapy and real-time thermal management could be wirelessly controlled via a smartphone. This custom-designed electrothermal pad offers a promising solution for wearable thermotherapy and smart clothing applications.