Readers of the Harry Potter series will recall a shimmering cloak that granted its wearer the power of invisibility. Outside the world of wand-toting wizards and witches, that fantastical notion has become closer to reality.
Scientists at Tufts and Boston University have created a small "invisibility cloak" made of a gold-etched silk.
The 1-cm square "cloak," made of a unique new metamaterial, works only on terahertz waves (T-rays) for now, but researchers hope in the near future to apply the same principles to make the material work at other wavelengths, and, with time, visible light spectrum.
"Unlike most materials, which derive optical properties like color from their chemical make up, metamaterials derive their properties from the physical structure," Discovery News writes.
In this case, Boston scientists created the metamaterial by "stenciling" 10,000 gold resonators onto a 1 cm square of silk. Popular Science describes the rest of the experiment:
They then blasted it with terahertz waves, which usually would pass right through. Instead, the researchers detected a resonance. Taking it a step further, the team implanted the silk into a muscle and found that they could still detect a resonance when they bathed the muscle in T-waves.
Scientists hope to use metamaterials for biomedical purposes, although they could also potentially use them for defense purposes.
Ecouterre explains why silk was chosen above other materials: "Silk is biocompatible, which means it's more readily accepted by a human body than most other implants." Gold-inscribed silk is also more flexible than other types of metamaterials, according to Popular Science.
Fiorenzo Omenetto, one of the researchers who developed the new metamaterial, published a paper in Advanced Materials describing his team's research and predicting the future application of metamaterials. According to Discovery News, Omenetto wrote that the so-called invisibility silk could "allow doctors and radiologists to cloak various organs or tissues and see through them [...] getting a better image of the organs or tissues usually hidden behind."
Omenetto also suggested using his metamaterial as a "glucose sensor" that could be implanted in the body of a diabetic person. "As the level of glucose changes inside the body, it changes the silk. Then as the silk changes, do does the metamaterial printed on the silk. That change would then be relayed to the person's cell phone; no needle prick necessary."