Laminated Fibrous Membrane Inspired by Polar Bear Pelt for Outdoor Personal Radiation Management

Outdoor cold stress often causes an undesired threat to public health, but devising an efficient strategy to achieve localized outdoor warming of the human body is still a great challenge. Polar bear pelt can absorb sunlight and reflect thermal radiation generated inside the body, which helps in adapting to the cold environment. Inspired by the radiation control strategy of the polar bear pelt, this study reports a porous Ag/cellulose/carbon nanotube (CNT)-laminated nanofiber membrane, in which one side of the cellulose basement membrane is coated with CNTs using a foam finishing process and the Ag layer is deposited on the other side by magnetron sputtering. Based on the high solar radiation absorptivity from CNT coating and the high infrared radiation reflectivity from Ag coating, the biomimetic membrane provides radiation warming by maximizing the heat input from the sun and minimizing the human radiation heat output. Because of excellent electrical conductivity, the Ag layer can work as a wearable heater to induce fast thermal response and uniform electroheating for extra warmth under a low supplied voltage. Moreover, the biomimetic membrane possesses porosity, hydrophilicity, breathability, flexibility, and mechanical stability, suggesting its huge potential for outdoor personal thermal management. Because of their versatility, the applications of the biomimetic membranes may be extended to wearable electronics, smart garments, and thermal control materials.