Wednesday, 20 August 2014
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Researchers claim lens could aid wireless power transfer

The efficiency of wireless power transfer systems could be improved by incorporating a lens made from metamaterials, US researchers claim.

A team from Duke University in Durham, North Carolina, and the Mitsubishi Electric Research Laboratories in Cambridge, Massachusetts, carried out the latest feasibility research.

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 metres.

Finding a way to increase the inductive coupling in such systems could improve the power-transfer efficiency.

To this end, a ‘superlens’ has a property call negative permeability, meaning 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 numerical calculations, 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.

The team also considered materials with magnetic anisotropy, meaning the magnetic properties are directionally dependent. Its 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.

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