The technology to transmit energy through thin air has so far resulted in bulky devices which only work over very small distances. Now researchers from Duke University have utilised low-frequency magnetic fields which allow wireless power transfer over much larger distances than the previously limited single-figure-millimetre-range transmitters.
The team from Pratt School of Engineering used metamaterials to create a square 'superlens' that focuses the magnetic fields. Each side of each component of the superlens is fixed with a copper coil which translates the magnetic field. The end of the coil is then connected to its twin nearly a foot away, inducing an electric current in the receiving coil.
The superlens has allowed, for the first time in such experiments, power to be successfully, efficiently and safely be sent through the air. The efficiency of the results is also many times greater than what could be achieved with the same setup without the superlens.
Yaroslav Urzhumov, Assistant Research Professor of Electrical and Computer Engineering at Duke University commented: "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."
Urzhumov hopes to drastically upgrade the system so it becomes more suitable for realistic power transfer scenarios such as charging mobile devices whist they move around within a room. The extra range means devices can be recharged without being within millimetres of the induction charging pad. "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," added Urzhumov. In the Duke University professor's view, the incredibly limited range is exactly the reason why "Previous commercial products like the PowerMat have not become a standard solution."
