Solar Thermal Textiles for On-Body Radiative Energy Collection Inspired by Polar Animals

Abstract

Humans use textiles to maintain thermal homeostasis amidst environmental extremes but known textiles have limited thermal windows. There is evidence that polar-dwelling animals have evolved a different mechanism of thermoregulation by using optical polymer materials to achieve an on-body “greenhouse” effect. Here, we design a bilayer textile to mimic these adaptations. Two ultralightweight fabrics with complementary optical functions, a polypropylene visible-transparent insulator and a nylon visible-absorber–infrared-reflector coated with a conjugated polymer, perform the same putative function as polar bear hair and skin, respectively. While retaining familiar textile qualities, these layers suppress dissipation of body heat and maximize radiative absorption of visible light. Under moderate illumination of 130 W/m2, the textile achieves a heating effect of +10 °C relative to a typical cotton T-shirt which is 30% heavier. Current approaches to personal radiative heating are limited to absorber/reflector layer optimization alone and fail to reproduce the thermoregulation afforded by the absorber–transmitter structure of polar animal pelts. With increasing pressures to adapt to a rapidly changing climate, our work leverages optical polymers to bridge this gap and evolve the basic function of textiles.

Adaptive cooling strategy via human hair: High optothermal conversion efficiency of solar radiation into thermal dissipation

“…Saharan silver ants ( 24 ) have triangular micro hairs with nano roughness on their hair for high efficiency of solar energy reflection. There is also evidence that polar bears’ fur has evolved a special way to absorb near-IR (NIR) radiation in solar energy by selective optical transmittance enabled hollow morphology inside its fur ( 25 , 26 ). Either of cases utilize the hierarchical structure for efficient optical scattering/extinction to adapt environment and survival.…”