Thermally comfortable epidermal bioelectrodes based on ultrastretchable and passive radiative cooling e-textiles

On-skin electronics with excellent passive cooling performance are highly favorable in improving human thermal comfort and reducing cooling energy consumption, which has received less research attention recently. Herein, a permeable and skin-conformable electronic textile (e-textile) with remarkable passive radiative cooling (PRC) performance is developed for all-day multi-environment passive cooling and human electrophysiological monitoring. The excellent passive cooling performance is attributed to the evenly encapsulated Al2O3 microparticles and thermally-fused nano/micropores in the nonwoven styrene-ethylene-butylene-styrene (SEBS) elastomeric microfibers, thus high emissivity (maximum emissivity>97%) and efficient backscattering of ultraviolet-visible-near infrared radiation (sunlight reflectivity>90%) can be realized simultaneously, resulting in the superior radiative cooling capability at daytime (10.5 °C and 11.3 °C for sunny and cloudy weather, compared with the ambient environment) and at nighttime (7.0 °C compared to pure SEBS textiles). Moreover, the obtained PRC e-textiles printed with liquid metal can serve as thermally comfortable and skin-mountable bioelectrodes for monitoring high-fidelity electrophysiological signals (including electrocardiograph (ECG), surface electromyogram (sEMG), and electroencephalograph (EEG) signals even underwater). Thus, this ultrastretchable PRC e-textile provides a promising alternative for zero-energy cooling in health monitoring epidermal electronics.