A Multilayer Film Based Selective Thermal Emitter for Infrared Stealth Technology

Abstract

Engineering the radiation characteristics for the design of selective thermal emitters has been a hot topic for decades and is of great value in the fields of thermophotovoltaic systems, radiative cooling, and infrared stealth. In this paper, a Ag/Ge multilayer film based selective emitter for infrared stealth is demonstrated using an ultrathin metal film and impedance matching to tune the radiation characteristics. Herein, a novel approach for infrared stealth that relies on the combination of emissivity (ε) reduction in the atmospheric windows (3–5 and 8–14 µm) and radiative cooling in a nonatmospheric window (5–8 µm) is proposed. The fabricated selective emitter has low emissivity (ε3‐5 µm = 0.18; ε8‐14 µm = 0.31) in the atmospheric windows for infrared “invisibility” and high emissivity (ε5‐8 µm = 0.82) outside the atmospheric window for radiative cooling and functions from ambient temperature to 200 °C. Compared with low‐emissivity materials, the selective emitter exhibits higher radiative cooling efficiency in vacuum and practical environments and presents lower apparent temperatures on infrared cameras. Moreover, the proposed selective emitter, with a planar and simple structure, is scalable, allowing flexible large‐area fabrication. The work demonstrates that selective emissive materials have promising applications in infrared stealth technology.

Research Progress of Bionic Adaptive Camouflage Materials

“…Furthermore, these devices can be easily multiplexed, enlarged, applied to rough and flexible substrates, or colored, demonstrating their multiple adaptive camouflaging capabilities (Li et al, 2020). Peng et al (2018) proposed a novel approach for infrared stealth that relies on the combination of emissivity (ε) reduction in the atmospheric windows (3-5 and 8-14 µm) and radiative cooling in a non-atmospheric window (5-8 µm). The fabricated selective emitter has low emissivity (ε 3−5µm = 0.18; ε 8−14µm = 0.31) in the atmospheric windows for infrared "invisibility" and high emissivity (ε 5−8µm = 0.82) outside the atmospheric window for radiative cooling and functions from ambient temperature to 200 • C. This work shows that selective emissive materials have promising application prospects and provide a more effective solution for infrared stealth technology (Peng et al, 2018).…”

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. However, they cannot operate at high temperature (<523 K) 18,20,32 .…”

“…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. However, they cannot operate at high temperature (<523 K) 18,20,32 . To control the surface temperature, thermal insulators 33 , phasechange materials 33 , and transformation thermotics [34][35][36][37] have been proposed.…”

Nanotreatment and Nanodiagnosis of Prostate Cancer: Recent Updates

“…Stealthing results in the increased reaching capability of nanoformulation into tumor site with enhanced circulation time in the blood stream via coating of hydrophilic polymers which results in the induction of strong stealth effects [ 38 ]. The mechanistic approach beside stealthing is the evading the path of nanoparticles from mononuclear phagocytic system trap and preventing the early elimination [ 39 ]. In reference to prostate cancer, poly(ethylene glycol) (PEG) coated pegylated nanoparticles were accompanied with immense accumulation of nanoparticles at tumor site as compared to un-modified non-stealth nanoparticles [ 40 ].…”