Bio-Inspired Stretchable Selective Emitters Based on Corrugated Nickel for Personal Thermal Management

While dynamic photonic materials have attracted much attention and there are well-known examples of color-changing species in nature, dynamic thermal control via modulation of optical properties has made relatively little progress. By replicating unique properties of desert ants and chameleons, here we present a stretchable selective emitter based on corrugated nickel that can modulate the emissivity to provide dynamic thermal control on human bodies. By evaporating nickel on a pre-strained polymer, we create 700-nm periodic corrugations that increase the nickel absorptivity from 0.3 to 0.7 in 0.2–2.5 µm wavelengths due to multiple scattering, as supported by spectroscopy and computations. The optical change is reversible and accompanies ambient surface temperature variations in 305–315 K. We demonstrate a wearable system, and the corrugated nickel on a human body at 309 K allows a heat flux of 62 Wm−2 out of the skin when stretched and 79 Wm−2 into the skin when released.