WiTricity- Wireless Technology

Imagine a world free of plugs and leads, where you no longer risk tripping over the tangle of spaghetti flex coiling beneath the hi-fi centre or TV.


Kitchen work surfaces would be clear of obstructive cables, and the vacuum cleaner would not jar to a halt when you roam too far from a wall socket.


It could become a reality sooner than you think.

Scientists have carried out the first practical demonstration of "WiTricity" - the efficient transmission of electric power without wires.

In a lab at the Massachusetts Institute of Technology in Cambridge, US, researchers managed to beam electricity between two coils to illuminate a 60-watt light bulb from a distance of seven feet.


The experiment heralds a truly wireless future, in which electrical appliances are no longer tethered to the wall.

Portable devices may also be unburdened of bulky batteries in the home.

The concept is not, in itself, new.

Power transformers contain coils that transmit energy to each other over very short distances. And at the start of the 20th century, the American inventor Nikola Tesla dreamed of wireless power spanning the globe.

He conducted experiments showing how it could be done, but the huge coils he used to generate electromagnetic fields only managed a very low level of power transfer.

The key to the new approach is resonance, the effect that allows an opera singer to crack a wine glass by striking the right note.

If the glass is filled with just enough wine, it will vibrate at the same frequency as the singer’s voice.

Other glasses placed around it containing different amounts of wine will be unaffected, even if the soprano’s piercing crescendo is loud enough to shatter the resonating glass.

The coils used in the WiTricity experiment were coupled together the same way.


One coil, attached to a power source, acted as the "sender" unit. It generated an electromagnetic field, but crucially, it was a non-radiating magnetic field of limited range that did not simply dissipate into space.


The "receiver" coil was designed to resonate at the same frequency as long as it was within range of the magnetic field. This in turn induced an electric current to flow within the coiled wire.


When the power to the sending coil was switched on, the light bulb connected to the receiving coil lit up, even when objects were placed between them.


The prototype energy transfer system was more than powerful enough to run a laptop over room-size distances. WiTricity is rooted in such well-known laws of physics it may seem surprising that it was not developed before.


The MIT researchers point out that the past there was no great demand for such a system.

Now, with the growing popularity of battery-driven portable electronic devices, the technology’s time may have come.


Team leader Professor Solijacic told how his three-year-old son questioned why his grandfather’s 20-year-old telephone handset was attached by a cord.


"That is the mindset of a child growing up in a wireless world," said Prof Solijacic.

"My best response was ‘it is strange and awkward, isn’t it? Hopefully we will be getting rid of some more wires, and also batteries, soon."