Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Beyond good vibrations: New insights into metamaterial magic

07.11.2017

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.


The shape and positioning of the rods in this metamaterial cause light--the arrow--to bend at a negative angle, a process called negative refraction. Better understanding of this dynamic will speed the development of new metamaterials such as perfect lenses and invisibility cloaks, says Michigan Tech's Elena Semouchkina.

Credit: Navid Ganji, Michigan Tech

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.

Simple!

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.

Media Contact

Allison Mills
awmills@mtu.edu
906-487-2343

 @michigantech

http://www.mtu.edu 

Allison Mills | EurekAlert!

More articles from Physics and Astronomy:

nachricht Writing and deleting magnets with lasers
19.04.2018 | Helmholtz-Zentrum Dresden-Rossendorf

nachricht Ultrafast electron oscillation and dephasing monitored by attosecond light source
19.04.2018 | Yokohama National University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Scientists re-create brain neurons to study obesity and personalize treatment

20.04.2018 | Health and Medicine

Spider silk key to new bone-fixing composite

20.04.2018 | Materials Sciences

Clear as mud: Desiccation cracks help reveal the shape of water on Mars

20.04.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>