(Press-News.org) Contact information: Ken Kingery
ken.kingery@duke.edu
919-660-8414
Duke University
'Superlens' extends range of wireless power transfer
Engineers accomplish the first relatively long-range wireless power transfer by 'beaming' electromagnetic fields
DURHAM, N.C. -- Inventor Nikola Tesla imagined the technology to transmit energy through thin air almost a century ago, but experimental attempts at the feat have so far resulted in cumbersome devices that only work over very small distances. But now, Duke University researchers have demonstrated the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver.
The advance comes from a team of researchers in Duke's Pratt School of Engineering, who used metamaterials to create a "superlens" that focuses magnetic fields. The superlens translates the magnetic field emanating from one power coil onto its twin nearly a foot away, inducing an electric current in the receiving coil.
The experiment was the first time such a scheme has successfully sent power through the air with an efficiency many times greater than what could be achieved with the same setup minus the superlens.
The results, an outcome of a partnership with the Toyota Research Institute of North America, appear online in Scientific Reports on Jan. 10.
"For the first time we have demonstrated that the efficiency of magneto-inductive wireless power transfer can be enhanced over distances many times larger than the size of the receiver and transmitter," said Yaroslav Urzhumov, assistant research professor of electrical and computer engineering at Duke University. "This is important because if this technology is to become a part of everyday life, it must conform to the dimensions of today's pocket-sized mobile electronics."
In the experiment, Yaroslav and the joint Duke-Toyota team created a square superlens, which looks like a few dozen giant Rubik's cubes stacked together. Both the exterior and interior walls of the hollow blocks are intricately etched with a spiraling copper wire reminiscent of a microchip. The geometry of the coils and their repetitive nature form a metamaterial that interacts with magnetic fields in such a way that the fields are transmitted and confined into a narrow cone in which the power intensity is much higher.
On one side of the superlens, the researchers placed a small copper coil with an alternating electric current running through it, which creates a magnetic field around the coil. That field, however, drops in intensity and power transfer efficiency extremely quickly, the further away it gets.
"If your electromagnet is one inch in diameter, you get almost no power just three inches away," said Urzhumov. "You only get about 0.1 percent of what's inside the coil." But with the superlens in place, he explained, the magnetic field is focused nearly a foot away with enough strength to induce noticeable electric current in an identically sized receiver coil.
Urzhumov noted that metamaterial-enhanced wireless power demonstrations have been made before at a research laboratory of Mitsubishi Electric, but with one important caveat: the distance the power was transmitted was roughly the same as the diameter of the power coils. In such a setup, the coils would have to be quite large to work over any appreciable distance.
"It's actually easy to increase the power transfer distance by simply increasing the size of the coils," explained Urzhumov. "That quickly becomes impractical, because of space limitations in any realistic scenario. We want to be able to use small-size sources and/or receivers, and that's what the superlens enables us to do."
Urzhumov said magnetic fields have distinct advantages over the use of electric fields for wireless power transfer.
"Most materials don't absorb magnetic fields very much, making them much safer than electric fields," he said. "In fact, the FCC approves the use of 3-Tesla magnetic fields for medical imaging, which are absolutely enormous relative to what we might need for powering consumer electronics. The technology is being designed with this increased safety in mind."
Going forward, Urzhumov wants to drastically upgrade the system to make it more suitable for realistic power transfer scenarios, such as charging mobile devices as they move around in a room. He plans to build a dynamically tunable superlens, which can control the direction of its focused power cone.
"The true functionality that consumers want and expect from a useful wireless power system is the ability to charge a device wherever it is – not simply to charge it without a cable," said Urzhumov. "Previous commercial products like the PowerMat™ have not become a standard solution exactly for that reason; they lock the user to a certain area or region where transmission works, which, in effect, puts invisible strings on the device and hence on the user. It is those strings -- not just the wires -- that we want to get rid of."
INFORMATION:
CITATION: "Magnetic Metamaterial Superlens for Increased-Range Wireless Power Transfer," Lipworth, L., Ensworth, J., Seetharam, K., Huang, D., Lee, J.S., Schmalenberg, P., Nomura, T., Reynolds, M.S., Smith, D.R., and Urzhumov, Y. Scientific Reports, Jan. 10, 2014. DOI: 10.1038/srep03642
'Superlens' extends range of wireless power transfer
Engineers accomplish the first relatively long-range wireless power transfer by 'beaming' electromagnetic fields
2014-01-11
ELSE PRESS RELEASES FROM THIS DATE:
Social media helps users embrace differences and provide support to one another, MU study finds
2014-01-11
Social media helps users embrace differences and provide support to one another, MU study finds
Lady Gaga enables followers to embrace their awkwardness while deepening the perceived relationship they feel they have with the celebrity
COLUMBIA, Mo. ...
Study: Autophagy predicts which cancer cells live and die when faced with anti-cancer drugs
2014-01-11
Study: Autophagy predicts which cancer cells live and die when faced with anti-cancer drugs
When a tumor is treated with an anti-cancer drug, some cells die and, unfortunately, some cells tend to live. A University of Colorado Cancer Center study published in the ...
Text messaging boosts flu vaccine rates in pregnant women
2014-01-11
Text messaging boosts flu vaccine rates in pregnant women
January 10, 2014 --A study by researchers at the Mailman School of Public Health evaluated the impact of text messaging reminders for influenza vaccine in a low-income obstetric ...
Complementary medicine in wide use to treat children with autism, developmental delay
2014-01-11
Complementary medicine in wide use to treat children with autism, developmental delay
Study shows large carnivore numbers and range declining worldwide
2014-01-10
Study shows large carnivore numbers and range declining worldwide
MISSOULA – New research co-written by University of Montana scientists finds steep declines in the worldwide populations and habitat range of 31 large carnivore species. The analysis, ...
Harvard scientists control cells following transplantation, from the inside out
2014-01-10
Harvard scientists control cells following transplantation, from the inside out
New work by Jeffrey Karp, Ph.D., has potential to make cell therapies more functional and efficient
Harvard stem cells scientists at Brigham and Women's Hospital and MIT can now engineer ...
Indigenous groups more vulnerable in the fight against flu
2014-01-10
Indigenous groups more vulnerable in the fight against flu
Research indicated that some Indigenous people such as in Alaska and Australia displayed limited immunity response to the effects of influenza.
Published in the Journal Proceedings of the National ...
Living on islands makes animals tamer
2014-01-10
Living on islands makes animals tamer
Study confirms Darwin's observations and numerous anecdotal reports of island tameness, says UC Riverside's Theodore Garland
RIVERSIDE, Calif. — Most of us have seen pictures and probably YouTube videos of "tame" animals ...
Evidence of harmful effect of bisphenol A-based plastics
2014-01-10
Evidence of harmful effect of bisphenol A-based plastics
Function and regeneration of switch proteins impaired
Bisphenol A impairs the function of proteins that are vital for growth processes in cells. This finding has been reported by researchers from the ...
Regorafenib: hint of minor added benefit
2014-01-10
Regorafenib: hint of minor added benefit
Advantage in overall survival, but disadvantage in severe side effects
Regorafenib (trade name: Stivarga) has been approved in Germany since August 2013 for adults with metastatic colorectal ...
LAST 30 PRESS RELEASES:
Signs identified that precede sudden arrhythmic death syndrome in young people
Discovery of bacteria's defence against viruses becomes a piece of the puzzle against resistance
Pre-eclampsia is associated with earlier onset and higher incidence of cardiovascular risk factors
Warwick astronomers discover doomed pair of spiralling stars on our cosmic doorstep
Soil conditions significantly increase rainfall in world’s megastorm hotspots
NK cells complexed with bispecific antibody yield high response rates in patients with lymphoma
Planetary health diet and mediterranean diet associated with similar survival and sustainability benefits
Singapore launches national standard to validate antimicrobial disinfectant products
Molecular stool test could improve detection of tuberculosis in adults with HIV
Suspected fibrocartilaginous embolus in Asian small-clawed otter (Aonyx cinereus)
Enhancing heat transfer using the turbulent flow of viscoelastic fluids
Exercise as an anti-ageing intervention to avoid detrimental impact of mental fatigue
UMass Amherst Nursing Professor Emerita honored as ‘Living Legend’
New guidelines aim to improve cystic fibrosis screening
Picky eaters by day, buffet by night: Butterfly, moth diets sync to plant aromas
Pennington Biomedical’s Dr. Leanne Redman honored with the E. V. McCollum Award from the American Society for Nutrition
CCNY physicists uncover electronic interactions mediated via spin waves
Researchers’ 3D-printing formula may transform future of foam
Nurture more important than nature for robotic hand
Drug-delivering aptamers target leukemia stem cells for one-two knockout punch
New study finds that over 95% of sponsored influencer posts on Twitter were not disclosed
New sea grant report helps great lakes fish farmers navigate aquaculture regulations
Strain “trick” improves perovskite solar cells’ efficiency
How GPS helps older drivers stay on the roads
Estrogen and progesterone stimulate the body to make opioids
Dancing with the cells – how acoustically levitating a diamond led to a breakthrough in biotech automation
Machine learning helps construct an evolutionary timeline of bacteria
Cellular regulator of mRNA vaccine revealed... offering new therapeutic options
Animal behavioral diversity at risk in the face of declining biodiversity
Finding their way: GPS ignites independence in older adult drivers
[Press-News.org] 'Superlens' extends range of wireless power transferEngineers accomplish the first relatively long-range wireless power transfer by 'beaming' electromagnetic fields