Duke University researchers have demonstrated the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver. The team used metamaterials to create a “superlens” that focuses magnetic fields. The superlens translates the magnetic field emanating from one power coil onto its twin nearly a foot away, inducing an electric current in the receiving coil.
The experiment was the first time such a scheme has successfully sent power safely and efficiently through the air with an efficiency many times greater than what could be achieved with the same setup minus the superlens.
In the experiment, the team created a square superlens, which looks like a few dozen giant Rubik’s cubes stacked together. Both the exterior and interior walls of the hollow blocks are intricately etched with a spiraling copper wire reminiscent of a microchip. The geometry of the coils and their repetitive nature form a metamaterial that interacts with magnetic fields in such a way that the fields are transmitted and confined into a narrow cone in which the power intensity is much higher.
Going forward, the team wants to drastically upgrade the system to make it more suitable for realistic power transfer scenarios, such as charging mobile devices as they move around in a room. They plan to build a dynamically tunable superlens, which can control the direction of its focused power cone.
If successful, the usable volume of “power hot spots” should be substantially expanded. It may not be easy, however, to maintain the efficiency of the power beam as it gets steered to a high degree.