Science Daily March 10, 2020 Recently, it has been shown that animals such as jumping spiders, birds, and butterflies have evolved ultra-black coloration comparable to the blackest synthetic materials. Researchers at Duke University examined a phylogenetically diverse set of butterflies and found considerable interspecific variation in the geometry of the holes in the structures reduce reflectance up to 16-fold. They produce ultra-black by creating a sparse material with high surface area to increase absorption and minimize surface reflection. They hypothesized that butterflies use ultra-black to increase the contrast of color signals. The findings could help engineers design thinner ultra-black coatings […]
Tag Archives: Camouflage
Camouflage made of quantum material could hide you from infrared cameras
Phys.org December 17, 2019 For most solids, the thermally emitted power increases monotonically with temperature in a one-to-one relationship that enables applications such as infrared imaging and noncontact thermometry. A team of researchers in the US (University of Wisconsin, Harvard University, Purdue University, MIT, Brookhaven National Laboratory) has shown that ultrathin samarium nickel oxide undergoes a fully reversible, temperature-driven solid-state phase transition. Its smooth transition enabled them to engineer the temperature dependence of emissivity to precisely cancel out the intrinsic blackbody profile for both heating and cooling. The design results in temperature-independent thermally emitted power within the long-wave atmospheric transparency […]
Colour-changing artificial ‘chameleon skin’ powered by nanomachines
Phys.org August 21, 2019 Researchers in the UK have demonstrated that gold nanoparticles coated with a poly(N‐isopropylacrylamide) (pNIPAM) shell undergo reversible dis/assembly below and above the critical temperature of 32 °C. Loading these particles into microdroplets at high density creates light‐driven artificial chromatophores. Triggering the nanoparticle assembly gives dramatic color changes from nanoparticle localization at the base of the droplets, resembling zebrafish melanophores. These reversible chromatophore states can be switched by both bulk and optical heating. The material could be used in applications such as active camouflage and large-scale dynamic displays…read more. TECHNICAL ARTICLE
Two teams build invisibility cloaks for water applications
Phys.org August 14, 2019 Two teams of researchers (China, USA – Duke University, South Korea) created passive cloaks using different techniques. Both of them have possible real-world applications. One team created cloak by enclosing an object within a ring of 523 specially designed small pillars—the arrangement of the pillars deflected incoming fluid flow, resulting in zero drag on the object that was hidden. This method could possibly be used to reduce drag on ships or other watercraft. The second approach, based on waveguide cloaks, consisted of installing long, thin iron platforms on the bottom of a tank in its corners. […]