Invisibility Cloak of Silk and Gold

Scientists Finally Make 'Invisibility Cloak' With Silk

A scientist at Tufts University alongwith some colleagues from the Boston University has finally created an "Invisibilty Cloak" and that too from silk and coated in gold.

This new material only works on long terahertz waves but some scientists who took part in the development of the metamaterial think that the cloak will also work in much smaller wavelengths.

Discovery News 

Invisibility Cloak Made From Silk

Is a silk invisibility cloak in our future? For now a silk invisibility cloak works only on relatively long terahertz waves.

Invisibility cloaks, along with their optically exotic cousins, perfect absorbers and perfect reflectors and others, belong to a special class of materials known as metamaterials. Unlike most materials, which derive optical properties like color from their chemical make up, metamaterials derive their properties from the physical structure.

A curly cue, or short spiral, is a common  metamaterial structure. Scientists call them split ring resonators, or SSRs. Usually scrawled into metals, SSR can give ordinary materials extraordinary abilities, like absorbing or reflecting all the specific wavelengths of light, or bending a wavelength around an object.

To create their silk-based metamaterial, the Tufts and Boston University scientists, including Richard Averitt, started with a one-centimeter-square piece of silkworm silk. (In another recent paper, Omenetto's colleague and another co-author of the Advanced Material's paper, David Kaplan of Tufts, created silk-producing bacteria.) Onto that tiny piece of dielectric silk they stenciled 10,000 gold resonators.

The potential applications of silk-based invisibility are huge. Omenetto and his colleagues at Tufts aren't even focused on Harry Potter or Star Trek-style invisibility materials, although he says that is one potential application.

Their main focus is in biomedical applications. [...]

Silk-based invisibility would also allow doctors and radiologists to cloak various organs or tissues and see through them, said Omenetto, getting a better image of the organs or tissues usually hidden behind.


Implantable silk metamaterials could advance biomedicine, biosensing

In Situ Bio-Sensing

To demonstrate the concept, the researchers conducted a series of in vitro experiments that examined the electromagnetic response of the silk metamaterials when implanted under thin slices of muscle tissue. They found that the metamaterials retained their novel resonance properties while implanted. The same process could be readily adapted to fabricate silk metamaterials at other frequencies, according to Tao.

"Our approach offers great promise for applications such as in situ bio-sensing with implanted medical devices and the transmission of medical information from within the human body," says Omenetto. "Imagine the benefits of monitoring the rate of drug delivery from a drug-eluting cardiac stent, making a perfect absorber that can be implanted to attack diseased tissue by heat, or wrapping an 'invisibility cloak' around an organ to examine the tissue behind it."

Tufts University

Implantable Silk Metamaterials Could Advance Biomedicine, Biosensing

Below, silk-based metamaterial photographed on a background of silk fibers. The tiny, flexible devices can be rolled into capsule-like shapes (above). (Credit: Hu Tao, Tufts University)

Scientists Finally Make 'Invisibility Cloak' With Silk
Invisibility Cloak Made From Silk : Discovery News
Implantable silk metamaterials could advance biomedicine, biosensing
Implantable Silk Metamaterials Could - Tufts University

silk optics
Behind the Secrets of - Tufts University
Implantable Silk Metamaterials Could Advance Biomedicine, Biosensing | Before It's News
Richard Averitt (Boston University, Physics Department)