Active camouflage artificial skin in visible-to-infrared range

Phys.org  December 2, 2020 Researchers in South Korea have developed a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with active cooling and heating. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt […]

Asymmetric optical camouflage: Tunable reflective color accompanied by optical Janus effect

Phys.org  October 20, 2020 Going beyond an improved colour gamut, an asymmetric colour contrast, which depends on the viewing direction, and its ability to readily deliver information could create opportunities for a wide range of applications, such as next-generation optical switches, colour displays, and security features in anti-counterfeiting devices. Researchers in South Korea propose a simple Fabry–Perot etalon architecture capable of generating viewing-direction-sensitive colour contrasts and encrypting pre-inscribed information upon immersion in particular solvents. Based on the experimental verification of the theoretical modelling, they have discovered a completely new and exotic optical phenomenon involving a tunable colour switch for viewing-direction-dependent […]

Researchers create surface coating that can create false infrared images

UC Berkeley  July 23, 2020 At certain temperature tungsten-doped vanadium dioxide can phase shift from an insulator to a metal. An international team of researchers (US Berkeley, Singapore, China) created special structures made from delicately engineered thin films of tungsten-doped vanadium dioxide. With judicious engineering of the doping profile, the insulator-metal phase transition can even out, allowing the substance to emit a constant level of thermal radiation over wide range of temperature variations (15-70 degrees Celsius). This state of equilibrium prevents a camera from detecting the true infrared signals that an object normally emits around room temperature. The coatings can […]

This wearable device camouflages its wearer no matter the weather

Phys.org  March 3, 2020 An international team of researchers (USA -UC San Diego, Singapore) has developed a proof-of-concept device that has a surface that cools down or heats up to match ambient temperatures, camouflaging the wearer’s body heat. The surface can go from 10 to 38 degrees Celsius (50 to 100.5 degrees Fahrenheit) in less than a minute. They used phase-changing material that’s like wax but with more complex properties. The melting point of the material is 30 degrees Celsius (roughly 86 degrees F), the same temperature as the surface temperature of human skin. The outside layer of the device […]

Hiding images and information in plain sight

Science Daily  December 17, 2018 Researchers at the University of Central Florida created a three-level, layered, “plasmonic” system that sandwiches a polymer layer imprinted with nanoscale holes, between a gold mirror at the bottom and a gold layer at the top with holes that match the polymer layer. Images can be imprinted on top of the “plasmonic sandwich,” and aspects of the holes, such as size and depth, help dictate which infrared band the image can be seen in. Varying the pattern characteristics allows the researchers to control the electron plasma resonance created when light hits the device. By controlling […]

Thermal camouflage disguises hot and cold

Nanowerk  June 27, 2018 Thermal camouflage requires an ability to control the emitted thermal radiation from the surface. An international team of researchers (Turkey, USA – MIT, UK) used electro-modulation of IR absorptivity and emissivity of multilayer graphene via reversible intercalation of nonvolatile ionic liquids. The new surfaces are thin, ultraflexible and they can conformably coat their environment. By combining active thermal surfaces with a feedback mechanism, they demonstrated an adaptive thermal camouflage system which can reconfigure its thermal appearance and blend itself with the varying thermal background in a few seconds. These devices can disguise hot objects as cold […]