Nav: Home

Beyond good vibrations: New insights into metamaterial magic

November 06, 2017

Metamaterials offer the very real possibility that our most far-fetched fancies could one day become real as rocks. From invisibility cloaks and perfect lenses to immensely powerful batteries, their super-power applications tantalize the imagination. That said, so far "tantalize" has been the operative word, even though scientists have been studying metamaterials for more than 15 years.

"Not many real metamaterial devices have been developed," says Elena Semouchkina, an associate professor of electrical engineering at Michigan Technological University. Soldiers can't throw invisibility cloaks over their shoulders to elude sniper fire, and no perfect lens app lets you see viruses with your smartphone. In part, that's because traditionally, researchers overly simplify how metamaterials actually work. Semouchkina says their complications often have been ignored.

So she and her team set about investigating those complications and discovered that the magic of metamaterials is driven by more than just one mechanism of physics. A paper describing their research was recently published online by the Journal of Physics D: Applied Physics.


Metamaterials may seem complex and futuristic, but the opposite is closer to the truth, says Semouchkina. Metamaterials ("meta" is the Greek word for "beyond") are engineered materials that have properties not found in nature. They are typically built of multiple identical elements fashioned from conventional materials, such as metals or nonconductive materials. Think of a Rubik's cube made of millions of units smaller than the thickness of a human hair.

These designer materials work by bending the paths of electromagnetic radiation--from radio waves to visible light to high-energy gamma rays--in new and different ways. How metamaterials bend those paths--a process called refraction--drives their peculiar applications. For example, a metamaterial invisibility cloak would bend the paths of light waves around a cloaked object, accelerating them on their way, and reunite them on the other side. Thus, an onlooker could see what was behind the object, while the object itself would be invisible.

The conventional approach among metamaterials researchers has been to relate a metamaterial's refractive properties to resonance. Each tiny building block of the metamaterial vibrates like a tuning fork as the electromagnetic radiation passes through, causing the desired type of refraction.

But not that simple . . .

Semouchkina wondered if there might be additional factors involved in bending the paths of the waves.

"Metamaterials seem simple, but their physics is more complicated," she says, explaining that she and her team focused on dielectric metamaterials, which are built of elements that don't conduct electricity.

The team ran numerous computer simulations and made a surprising discovery: it was the shape and repetitive organization of the building blocks within the metamaterial--their periodicity--that affected the refraction. Resonance seemed to have little or nothing to do with it.

The metamaterials they studied had characteristics of another type of artificial material, photonic crystals. Like metamaterials, photonic crystals are made of many identical cells. In addition, they behave like the semiconductors used in electronics, except they transmit photons instead of electrons.

"We found that the properties that go along with being a photonic crystal can mask the resonance of metamaterials, to the point they can cause unusual refraction-- including negative refraction, which is necessary for the development of a perfect lens," Semouchkina says.

Back to Basics

So what does this mean for the scientists and engineers designing tomorrow's super materials?

"Basically, we need to recognize that some of these structures can exhibit properties of photonic crystals, and we need to take their physics into account," Semouchkina says. "It's an evolving field, and it's a lot more complicated than we've given it credit for."

Semouchkina's team is working on developing invisibility cloaks using photonic crystals, but she stresses that metamaterials research can have other real-world applications. One of her projects focuses on using metamaterial concepts to improve the sensitivity of magnetic resonance imaging (MRI), which could lead to better medical diagnostics and advances in biological research.

"This is a very practical outcome, compared to the Harry Potter stuff," she says.

Understanding the underlying physics of metamaterials will speed up the development of such devices.

Michigan Technological University

Related Metamaterials Articles:

Researchers use metamaterials to create two-part optical security features
Researchers have developed advanced optical security features that use a two-piece metamaterial system to create a difficult-to-replicate optical phenomenon.
Artificial intelligence (AI) designs metamaterials used in the invisibility cloak
The research group of Prof. Junsuk Rho, Sunae So and Jungho Mun of Department of Mechanical Engineering and Department of Chemical Engineering at POSTECH developed a design with a higher degree of freedom which allows to choose materials and to design photonic structures arbitrarily by using Deep Learning.
Scientists take a 'metamaterials' approach to earthquake damage
At the SSA 2019 Annual Meeting, seismologists from around the world will discuss how metamaterial theory might be applied to everything from developing deflective barriers to manipulating the layout of buildings within a city as a way to minimize the impact of damaging surface seismic waves.
Fast and selective optical heating for functional nanomagnetic metamaterials
In a recent article published in Nanoscale, researchers from the Nanomagnetism group at nanoGUNE demonstrate the use of hybrid magnetic-plasmonic elements to facilitate contactless and selective temperature control in magnetic functional metamaterials.
Researchers 3D print metamaterials with novel optical properties
A team of engineers has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is possible using conventional optical or electronic materials.
Intelligent metamaterials behave like electrostatic chameleons
Chinese physicists have developed so-called metashells made of smart, adaptable metamaterials.
Hyperbolic metamaterials enable nanoscale 'fingerprinting'
Hyperbolic metamaterials are artificially made structures that can be formed by depositing alternating thin layers of a conductor such as silver or graphene onto a substrate.
New concept for tractor beam from Star Wars developed
Physicists from ITMO University developed a model of an optical tractor beam to capture particles based on new artificial materials.
Physicists name and codify new field in nanotechnology: 'electron quantum metamaterials'
New materials are being synthesized by twisting and stacking atomically thin layers.
Where deep learning meets metamaterials
A new Tel Aviv University study uses 'deep-learning' computer networks inspired by the layered and hierarchical architecture of the human brain to design basic nanophotonic, metamaterial elements for energy harvesting and medical diagnostics.
More Metamaterials News and Metamaterials Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.