With so many of the devices we use every day being powered by batteries, it is very important to keep them all charged. Typically this involves finding a cable and then keeping the device tethered to it and the wall, which is one of the reasons wireless charging has become popular, but the technology used has limited range. Researchers at Duke University, the University of Washing, and Intellectual Ventures' Invention Science Fund have come up with a new solution though that could charge devices up to 10 meters away.
Currently wireless charging technology uses magnetic fields to induce a current, but this can require large coils and the range of the magnetic field is limited. The new solution is to use focused microwave beams to transmit the energy across a room. This would normally involve using an antenna dish and aiming it at the target devices, but that is hardly ideal, so instead the researchers propose using a phased array, which is collection of small antennas that can all be adjusted and tuned independently, allowing the signal produced by the array to be directed. That converts the dish into a flat antenna, but this is still not an ideal solution because of their cost and amount of energy used, so the researchers have turned to metamaterials. These synthetic materials allow the microwave wave front to be controlled, aiming the beams exactly where you want them, and the best part is this technology already exists.
Actually, all of this technology already exists and is already being used in other applications, and the antennas could be produced at the same plants LCD televisions are manufactured. According to the calculations involved, one of these antennas about the size of a typical flat-screen TV could focus microwaves down to about the size of a cellphone within a 10 m distance. However, while this technology exists today there is still more work to be done before a consumer device could be made. For one thing, the charging system needs to be able to identify when a person or pet crosses the microwave beam, shutting it off. This and the other challenges that remain can be overcome though, so it is more a question of when then if.
Source: Duke University
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