Flexible Janus Functional Film for Adaptive Thermal Camouflage

Abstract

With the increasing development of infrared (IR) detection technologies for both military and civil applications, IR anti‐detection technologies, also known as thermal camouflage technologies, have attracted great attention in recent years. Decreasing the surface emissivity may be effective for high‐temperature targets, but fails for adaptive thermal camouflage in dynamic scenes where the background temperature varies. In this work, we demonstrate a flexible Janus functional film (JFF) for adaptive thermal camouflage. The JFF consists of a low emissivity (low‐ε) layer and a high heat capacity (high‐C) layer. The low‐ε layer can effectively suppress the IR radiation of the objects, thus reducing the temperature of the objects in IR camera, while the high‐C layer can make similar thermal response as the background. According to different environmental conditions, different surfaces of JFF can be selected as camouflage surface to achieve static or dynamic thermal camouflage effect. What's more, the substrate materials of JFF (i.e., high‐density polyethylene (HDPE), silica gel (SG)) enable the film with good flexibility and realize the encapsulation of the functional filler, thus improving its reliability of resisting water and oxygen. Such flexible JFF with high reliability, easy scalability, and low cost may hold great promise for broad applications in adaptive thermal camouflage.

Mass Diffusion Metamaterials with “Plug and Switch” Modules for Ion Cloaking, Concentrating, and Selection: Design and Experiments

“…where D is the diffusion coefficient of the outer layer of the bilayer cloak (Module 1), D′ r and D′ 𝜃 is the radical and tangential mass diffusion coefficient of the concentrator (Module 2). Equation (10) illustrates well the conditions for the integration of the cloak and the concentrator.…”

“…It controls the path of electromagnetic wave transport to achieve invisibility through an inhomogeneous medium artificially designed by the theories of transformation optics [ 1 ] (TO) by Pendry and SC [ 2 ] by Engheta. In addition to the ideal cloaking proposed by theory and demonstrated by experiments, the design is further extended to metamaterials with diversified functions such as concentrators, [ 3 , 4 ] rotators, [ 5 , 6 ] illusion metamaterials, [ 7 , 8 ] encryption, [ 9 ] camouflage, [ 10 , 11 ] encoding [ 12 ] and diode. [ 13 , 14 ] After great success in manipulating electromagnetic waves, [ 15 , 16 , 17 , 18 , 19 , 20 ] TO and SC were also proven to be powerful tools to manipulate not only other wave‐based fields like acoustic waves [ 21 , 22 , 23 ] and water waves [ 24 , 25 , 26 ] but also diffusion fields such as thermal flux, [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] electric fields, [ 41 , 42 , 43 , 44 ...…”

High-index-contrast photonic structures: a versatile platform for photon manipulation

“…Mid-infrared (5–30 µm) photonics have inspired a surge of applications, including quantum cascade lasers 76 , molecule sensors 77 , thermal camouflage 78 – 82 and radiative coolers 83 – 86 . In particular, research on RCs has attracted significant interest because it facilitates effective and passive (i.e.…”

Broadband hyperbolic thermal metasurfaces based on the plasmonic phase-change material In3SbTe2

“…[1][2][3] Structural designs based on nanophotonic engineering, such as photonic crystals and metamaterials, have enabled the flexible modulation of the emissivity in a variety of applications such as infrared detection, 4 radiative cooling [5][6][7][8][9][10][11] and thermal camouflage. [12][13][14][15][16][17][18] By incorporating materials for varying the emissivity by external voltage, strain, or temperature, a dynamic thermal radiation modulation has been achieved. [19][20][21][22] In recent years, phase change materials (PCMs) have gained particular interest for the dynamic modulation of thermal radiation because of their distinct optical properties in amorphous and crystalline phases and their switchability, either thermally or optically, between these two states.…”