Graphene-Based Adaptive Thermal Camouflage

Abstract

In nature, adaptive coloration has been effectively utilized for concealment and signaling. Various biological mechanisms have evolved to tune the reflectivity for visible and ultraviolet light. These examples inspire many artificial systems for mimicking adaptive coloration to match the visual appearance to their surroundings. Thermal camouflage, however, has been an outstanding challenge which requires an ability to control the emitted thermal radiation from the surface. Here we report a new class of active thermal surfaces capable of efficient real-time electrical-control of thermal emission over the full infrared (IR) spectrum without changing the temperature of the surface. Our approach relies on electro-modulation of IR absorptivity and emissivity of multilayer graphene via reversible intercalation of nonvolatile ionic liquids. The demonstrated devices are light (30 g/m), thin (<50 μm), and ultraflexible, which can conformably coat their environment. In addition, by combining active thermal surfaces with a feedback mechanism, we demonstrate realization of an adaptive thermal camouflage system which can reconfigure its thermal appearance and blend itself with the varying thermal background in a few seconds. Furthermore, we show that these devices can disguise hot objects as cold and cold ones as hot in a thermal imaging system. We anticipate that, the electrical control of thermal radiation would impact on a variety of new technologies ranging from adaptive IR optics to heat management for outer space applications.

Micro/Nanostructures for Far-Field Thermal Emission Control: An Overview

“…For graphene-based thermal camouflage devices (see Fig. 11(c)) has also been designed by introducing intercalation of a nonvolatile ionic liquid 187 into graphene layers using porous substrate. This type of tunable camouflage can work at full mid-infrared region, and electrical control of thermal emissivity (0.3 -0.8) can be achieved in real-time, exhibiting outstand adaptive camouflage functions by disguising hot surface as 188 cold one and vice versa.…”

High-temperature infrared camouflage with efficient thermal management

“…To control the surface emittance, nanostructure-based surfaces (e.g., metasurfaces 3,8 and metallic-dielectric nanowires 9 ) or films (metal 10 , semiconductor 11,12 , and multilayer films [13][14][15][16][17] ) are demonstrated with low-surface emittance over the whole IR range, and yet the radiative heat transfer is blocked, causing severe heat instability 18 . Wavelength-selective emitters [19][20][21][22][23][24][25] with radiative cooling [26][27][28][29][30][31] in the non-atmospheric window (5-8 μm) 18,20,32 are adopted to mitigate the heat instability without influencing the IR camouflage.…”

Multispectral camouflage for infrared, visible, lasers and microwave with radiative cooling

“…Conventionally, camou age is only con ned in a particular spectral range e.g. visible 3,6 , midinfrared (MIR) [7][8][9][10][11][12][13] , or microwave 14 . However, a combination of advanced detectors operating in different wavelength bands developed in recent years entails for a compatible camou age among different spectral bands, i.e.…”