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Metamaterials

The acoustic cloak was constructed from several sheets of plastic plates dotted with repea...

Metamaterials are already being used to create invisibility cloaks and "temporal cloaks," but now engineers from Duke University have turned metamaterials to the task of creating a 3D acoustic cloak. In the same way that invisibility cloaks use metamaterials to reroute light around an object, the acoustic cloaking device interacts with sound waves to make it appear as if the device and anything hidden beneath it isn't there.  Read More

A liquid crystal 'flower' under magnification (Photo: University of Pennsylvania)

Scientists at the University of Pennsylvania have grown liquid crystal flowers, making it possible to create lenses as complex as the compound eye of a dragonfly. When perfected, the technology could allow the growth of lenses on curved surfaces, and structures to be assembled out of liquid crystals to build new materials, smart surfaces, microlens arrays and advanced sensors.  Read More

Figure of a plasmonic metasurface hologram of the word 'PURDUE' that is about the width of...

Holography is one of the more dramatic forms of photography, in which a three-dimensional image is stored on a photographic plate in the form of interference fringes. Researchers at Purdue University in Indiana have developed a different approach, in which a 3D image is stored in a structure of thousands of V-shaped nanoantennas etched into an ultrathin gold foil. The new approach dramatically shrinks the size of a hologram, potentially enabling photonic and plasmonic devices and optical switches small enough to be integrated into computer chips.  Read More

The five-cell metamaterial array developed by Duke engineers that converts stray microwave...

Joining the ranks of devices designed to harvest energy from ambient electromagnetic radiation comes an electrical circuit from researchers at Duke University that can be tuned to capture microwave energy from various sources, including satellite, sound or Wi-Fi signals. The researchers say the device converts otherwise lost energy into direct current voltage with efficiencies similar to that of current solar cells.  Read More

A prototype window design that lets air pass through, but attenuates outside sounds by 30-...

There are few things better than lazing around the house on a warm summer day, whose fragrant zephyrs speak of spicy isles and heaven-breathing groves.* At least, until the neighbors start their leaf-blowers and the city needs to tear up the sidewalks. Noise pollution is one of the scourges of urban and suburban life, which can drown out nature's melodies to cause annoyance, stress, and hearing loss. Now, however, a team of South Korean engineers has invented a remarkable window that lets air in while keeping a great deal of noise out.  Read More

A Stanford breakthrough in optical metamaterials could enable fabrication of a wide-spectr...

To make a Harry Potter-style invisibility cloak requires that the materials from which it is made have a negative refractive index over all optical wavelengths, from red to violet. However, the artificially-structured optical materials from which cloaks are made thus far have been restricted to a very narrow range of optical wavelengths, limiting their ability to cloak over a range of colors. That obstacle to progress ends now, as a group of Stanford optical engineers at Stanford has succeeded in designing a broadband metamaterial that exhibits a negative refractive index over nearly the entire rainbow.  Read More

Yaroslav Urzhumov with the 3D-printed invisibility cloak developed at Duke University

Invisibility cloaks have been around in various forms since 2006, when the first cloak based on optical metamaterials was demonstrated. The design of cloaking devices has come a long way in the past seven years, as illustrated by a simple, yet highly effective, radar cloak developed by Duke University Professor Yaroslav Urzhumov, that can be made using a hobby-level 3D printer.  Read More

The MIT metamaterial lens

We expect the world to be predictable. Water flows downhill, fire burns and lenses bend light in a particular way. That worldview took a jolt as Isaac Ehrenberg, an MIT graduate student in mechanical engineering, developed a three-dimensional, lightweight metamaterial lens that focuses radio waves with extreme precision. That may not seem too disturbing, but the lens is concave and works in exactly the opposite manner of how such a lens should.  Read More

Mathematicians are proposing a cloaking system, which could allow buildings to be rendered...

While “cloaking” technology may have once been limited exclusively to the realm of science fiction, regular Gizmag readers will know that it is now finding its way into real life – just within the past few years, scientists have demonstrated various experimental cloaking systems that prevent small objects from being seen, and in one case, from being heard. Such invisibility systems involve the use of metamaterials, which are man-made materials that exhibit optical qualities not found in nature. These are able to effectively bend light around an object, instead of allowing it to strike the object directly. Now, mathematicians from the University of Manchester are proposing technology based on the same principles, that would allow buildings to become “invisible” to earthquakes.  Read More

The plasmonic metamaterial cloak (top) and some of components used to make it (Photo: Andr...

We’ve previously seen – or should that be “not seen” – invisibility cloaks in the laboratory that are able to render two-dimensional objects invisible to microwaves. Such feats relies on the use of metamaterials – man-made materials that exhibit optical properties not found in nature and have the ability to guide light around an object. Now researchers at the University of Texas at Austin (UT) claim to have brought invisibility cloaks that operate at visible light frequencies one step closer by cloaking a three-dimensional object standing in free space with the use of plasmonic metamaterials.  Read More

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