We’ll believe it when we see it—or rather, don’t see it—but scientists from Tufts and Boston University claim to have invented the world’s first pliable invisibility cloak. Made from silk and coated in gold, the visibility-challenged outerwear still requires some tweaking before it’s ready to enable Hogwarts-style hijinks: the new metamaterial only works at terahertz frequencies between radio and infrared light on the electromagnetic spectrum, according to a paper published in the July issue of Advanced Materials.

silk, cocoons

Photo by phonks


Metamaterials, unlike their decidedly less “meta” brethren, derive their optical properties (for instance, color) from their physical rather than chemical makeup. A common metamaterial structure known as a split ring resonator (or SSR) can imbue ordinary materials with extraordinary properties, such as the ability to bend, absorb, or reflect light.

The “cloak”: a 1 centimeter-square swatch of silk stenciled with 10,000 gold resonators.

To create their invisible metamaterial, the Boston scientists stenciled 10,000 gold resonators on a 1 centimeter-square swatch of silk. When ordinary silk is exposed to terahertz waves, the waves pass straight through. The resonator-fortified metamaterial, however, created a resonance—one that could still be detected even when the silk was implanted into a muscle.



Although the researchers who developed the technology foresee the cloak working at shorter wavelengths, including those in the visible range, their current focus is on its biomedical applications, such as implantable glucose sensors for diabetics that alter with fluctuating levels of glucose in the body. The change in the metamaterial could even be relayed as a text message on a cellphone, making finger-pricking unnecessary.

Silk is biocompatible, which means it’s more readily accepted by a human body than most other implants.

Because silk is biocompatible, the human body won’t reject it the way it would most other implants. Mini-“cloaks” of silk could allow doctors and radiologists to cover certain organs and tissues and see through them, resulting in a better visual lock on organs and tissues that are usually blocked behind.

+ Metamaterial Silk Composites at Terahertz Frequencies

[Via Discovery News]