Now electricity itself goes wireless
An American firm has demonstrated a system which allows devices to recharge without being connected to the mains. The wireless technology can work on devices as large as a television set, but will have the most natural use for mobile devices such as laptops and smart phones.
The system was developed from work by Massachusetts Institute of Technology physicist Marin Soljacic. It involves transferring energy between two magnetic coils, one attached to the mains and the other embedded in the device.
The two coils are set to resonate at the same frequency, meaning electromagnetic waves can transfer from the first coil, with energy absorbed by the second coil. The BBC explains that a similar wireless transfer of energy can be pictured by imagining an opera singer’s voice causing a wine glass to shatter.
While such technology already existed in principle (it was explored in the 19th century by Nikola Tesla), the system developed by WiTriticity has two important features: it uses a magnetic field which does not cause any damage to humans, and it does not require a clear line of site between the coils, meaning a device can charge while in a pocket or bag.
At the moment, the system only works with smaller devices. WiTricity chief Eric Giler demonstrated the system at a conference in Oxford, England using both an Android G1 handset and an iPhone. While the coil could be built directly into the G1, there was not enough space in the iPhone so it had to be attached with a specially fitted sleeve.
The system can only work within a distance equal to one wave length at the relevant frequency; beyond this point it would generate electric rather than just magnetic fields. In this case, that wave length is 30 meters. However, in the current models, full power is only available over a two meter distance.
WiTricity hopes to have the system available commercially within 18 months. At first it would only be suitable for convenience at home, saving the need to plug in phones every time they needed charging. However, if it were to catch on and become widespread, it could theoretically remove the need to remember to pack a charger every time you went away.
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