Artificially structured metamaterials may boost wireless power transfer

Mar 13, 2012

Scientists calculate that a "perfect lens," a slab of artificial material engineered to focus electromagnetic fields in ways that natural materials can't, may increase the efficiency of some wireless power transfer systems.

More than one hundred years after the pioneering inventor Nikola Tesla first became fascinated with wireless energy transfer, the spread of mobile electronic devices has sparked renewed interest in the ability to power up without plugging in. Now researchers from Duke University in Durham, N.C., and the Research Laboratories in Cambridge, Mass., have proposed a way to enhance the efficiency of wireless power transfer systems by incorporating a lens made from a new class of .

When a changing electric current flows through a wire it generates a magnetic field, which in turn can induce a voltage across a physically separate second wire. Called inductive coupling, this electromagnetic phenomenon is already used commercially to recharge devices such as cordless electric toothbrushes and mobile phones, as well as in more recently developed experimental systems that can, for example, wirelessly power a light bulb across a distance of more than two meters. Finding a way to increase the inductive coupling in such systems could improve the power . The research team from Duke and Mitsubishi hypothesized that a superlens, which can only be made from artificially-structured metamaterials, might be able to do the trick.

A superlens has a property call negative permeability. This means it can refocus a magnetic field from a source on one side of the lens to a receiving device on the other side. By running , the team determined that the addition of a superlens should increase system performance, even when a fraction of the energy was lost by passing through the lens.

When the researchers first began studying how a superlens might affect wireless , they focused on lenses made from that exhibited uniform properties in all directions. In their new study, accepted for publication in the American Institute of Physics' Journal of Applied Physics, the team also considered materials with magnetic anisotropy, meaning the magnetic properties are directionally dependent. Their results suggest that strong magnetic anisotropy of the superlens can offer further improvements to the system, such as reduction of the lens thickness and width.

Explore further: Researchers find first direct evidence of 'spin symmetry' in atoms

More information: "Magnetic superlens-enchanced inductive coupling for wireless power transfer" is accepted for publication in the Journal of Applied Physics.

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Sonhouse
not rated yet Mar 13, 2012
Is there any danger of having such devices in the home? Could you sit down in a chair and watch tv for a couple hours if a wireless charger was nearby?
Modernmystic
not rated yet Mar 13, 2012
Is there any danger of having such devices in the home? Could you sit down in a chair and watch tv for a couple hours if a wireless charger was nearby?


If it's not ionizing radiation it's no different that sitting in your chair and watching TV for a couple of hours with the lights on...
Eikka
not rated yet Mar 13, 2012
If it's not ionizing radiation it's no different that sitting in your chair and watching TV for a couple of hours with the lights on...


Well, there could be problems in passing hundreds of watts of power through a person, if there's a possibility that something like a ring on your finger could pick the field up.

These things are based on oscillating magnetic fields, and they do have a tendency of inducing eddy currents in conductive materials where a current loop can form, which is why transformers use laminated steel instead of solid metal cores - to break the loops.

For a long time I've wanted to see what happens if you take one of those witricity devices, and put a sheet of aluminium foil in front of it. I predict that the foil will get pushed away, and the induced current may burn a hole in it.

Another interesting experiment would be to light a candle inside the field and watch where the ionized gas goes.
Callippo
not rated yet Mar 13, 2012
If it's not ionizing radiation it's no different that sitting in your chair and watching TV for a couple of hours with the lights on...
Never say never. Long molecules of DNA are sensitive even to microwave radiation. http://www.techno...v/24331/ After all, under certain circumstances even common watter can be splitted into hydrogen a peroxide with radiowave and quite quickly: http://www.youtub...lIm5a1Lc Do you want to generate peroxide radicals in your body? Me not. In addition, there are another problems, like the risk of spark formation between metallic parts of furniture and the risk of accidental fire.
Modernmystic
not rated yet Mar 13, 2012
So why is it that I've had several MRIs and am not riddled with cancer? We're just not that magnetic...at all.

In addition, there are another problems, like the risk of spark formation between metallic parts of furniture and the risk of accidental fire.


First sensible objection to this kind of thing I've heard...

nuge
not rated yet Mar 14, 2012
This is going to be the Age of Metameterials. This is just such an exciting area at the moment, we are just at the stage where we are discovering so many new applications that we had not even foreseen before.
Eikka
not rated yet Mar 14, 2012
So why is it that I've had several MRIs and am not riddled with cancer? We're just not that magnetic...at all.


And the MRI machine uses a static magnetic field.