Metamaterials for Wireless Power Transfers of Small and Large Devices

According to an electrical engineer team at Duke University, metamaterials can theoretically make it possible to improve wireless power transfers to small devices, such as laptops or cell phones, and eventually to larger applications, such as cars or elevators. Metamaterials are fabricated exotic composite materials that are engineered to exhibit properties not readily found in nature. Theoretically, metamaterial can improve the efficiency of recharging devices without wires.

Metamaterial for Wireless Power Transmission Research Highlights

  • Metamaterial likely to be used in future wireless power transmission resembles a miniature set of tan Venetian blinds
  • Can improve the efficiency of recharging devices without wires
  • Metamaterial postulated would be situated between the energy source and the recipient device
  • Metamaterial would make it seem as if there was no space between the transmitter and the recipient
  • Loss of power should be minimal
  • Metamaterials can be fabricated and arranged to make the design of wireless power transmission systems more focused
  • Can help increase power levels without doing damage (normally, large amounts of energy would burn up anything in its path)
  • Would likely be made of hundreds to thousands of individual, thin, conducting loops arranged into an array
  • Each piece is made from copper-on-fiberglass substrate (used in printed circuit boards), with excess copper etched away
  • Pieces can be arranged in an almost infinite variety of configurations

Metamaterial-enhanced coupling between magnetic dipoles for efficient wireless power transfer
Physical Review B Journal
Yaroslav Urzhumov and David R. Smith

Non-radiative coupling between conductive coils is a candidate mechanism for wireless energy transfer applications. In this paper, we propose a power relay system based on a near-field metamaterial superlens, and present a thorough theoretical analysis of this system. We use time-harmonic circuit formalism to describe all interactions between two coils attached to external circuits and a slab of anisotropic medium with homogeneous permittivity and permeability. The fields of the coils are found in the point-dipole approximation using Sommerfeld integrals, which are reduced to standard special functions in the long-wavelength limit. We show that, even with a realistic magnetic loss tangent of order 0.1, the power transfer efficiency with the slab can be an order of magnitude greater than free-space efficiency when the load resistance exceeds a certain threshold value. We also find that the volume occupied by the metamaterial between the coils can be greatly compressed by employing magnetic permeability with a large anisotropy ratio.

More info: Pratt School of Engineering – Duke University