The use of magnetic meta-materials significantly increases the efficiency of wireless energy transmission systems

EnergyJune 15, 2015

For the last decade, researches in the area of wireless transmission of energy led to the development of several practical technologies, such as wireless charging of mobile and household devices, electric cars, etc. However, all these technologies have the restrictions in ranges and rather small efficiency at energy transmission even at those small distances at which they are capable to function.

In the new researches conducted by the scientists from university of Tentszi, Shanghai, China the way of considerable efficiency improvement of wireless energy transmission technology was developed. The use of a special magnetic metamaterials, the artificial materials having difficult structure and structure of a surface, and the efficiency of transfer increased from several percent to 20 percent at distance of transfer to 4 centimeters.

The idea of wireless energy transmission arose in the 1890th when Nikola Tesla started making the first experiments in this direction. Now, more than a century later, this idea drew attention of scientists again. And in 2007 researchers from the Massachusetts Institute of Technology showed the first practical systems of wireless transfer which were issued by the Witricity company organized for this business.

On coincidence, with meta-materials there was a rather similar history. At the beginning of the 20th century scientists began study in the field of artificial materials which could interact with light in very unusual ways, but only at the beginning of the 2000th when appropriate technologies appeared, the first samples of true meta-materials were made.

The meta-material created by the Chinese scientists are a basis of a design of the coils ensuring functioning of not radiating wireless energy transmission, the technology used by the majority of the existing devices of energy transmission. One coil creates a magnetic field, and the second coil of inductance serves for creation of an electric component of electromagnetic oscillations.

As in the majority of meta-materials, the structures used in metamaterial of coils need to have the sizes, multiple lengths of waves where this device works. Such approach makes it possible to realize the management of electromagnetic waves radiation of such ways that cannot be received when using simple magnetic materials. In this case, the basis of metamaterial is made by structures, some kind of “metaatoms”, the sizes in 2.6 centimeters which are components of spiral copper coils. The special size of structures in 2.6 centimeters is very important, it provides strong communication between resonant properties of metaatoms and wavelength of electromagnetic radiation which is responsible for the increase in efficiency of energy transmission.

Despite the use of “wonderful” meta-materials, the 32% efficiency of energy transmission strongly depends on a distance of 3 centimeters, 15% of five centimeters and 20% of 4 centimeters. But the most interesting distance is 4 centimeters, ideally suitable for a set of certain scopes, such as gymnastics of cardiodrivers and other implanted medical devices.

In the near future, researchers are going to adopt the technology of wireless energy transmission developed by them for a set of areas of practical application. And first of all they should develop new manufacturing techniques of meta-materials which will make it possible to manufacture such materials in large lots and at a lower cost, than their present one.

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