US Firm Shown Television Running on Wireless Power

July 26, 2009 - 12:49 pm | 40 views

Technology.am (July 26, 2009) — US firm Witricity developed a system that can deliver power to devices without the need for wires. He showed off a commercially available television using the system. This system could replace the miles of expensive power cables and billions of disposable batteries.

wireless-power Eric Giler, chief executive of US firm Witricity, showed mobile phones and televisions charging wirelessly at the TED Global conference in Oxford.

He said something like 40 billion disposable batteries built every year for power, and trillions of dollars had also been invested building an infrastructure of wires.

Mr Giler showed off a Google G1 phone and an Apple iPhone that could be charged using the system.

The system is based on work by physicist Marin Soljacic at the Massachusetts Institute of Technology (MIT). It exploits “resonance”, whereby energy transfer is markedly more efficient when a certain frequency is applied.

Witricity’s approach exploits the resonance of low frequency electromagnetic waves. The system uses two coils – one plugged into the mains and the other embedded or attached to the gadget.

Each coil is carefully engineered with the same resonant frequency. When the main coil is connected to an electricity supply, the magnetic field it produces is resonant with that of with the second coil, allowing “tails” of energy to flow between them. As each “cycle” of energy arrives at the second coil, a voltage begins to build up that can be used to charge the gadget.

Mr Giler said the main coil could be embedded in the “ceiling, in the floor, or underneath your desktop”.

Devices using the system would automatically begin to charge as soon as they were within range, he said.

The system is able to operate safely because the energy is largely transferred through magnetic fields. There’s nothing going on when he walked around a television running on wireless power.

It is able to do this by exploiting an effect that occurs in a region known as the “far field”, the region seen at a distance of more than one wavelength from the device.

In this field, a transmitter would emit mixture of magnetic and potentially dangerous electric fields. But, at a distance of less than one wavelength – the “near field” – it is almost entirely magnetic.

Hence, Witricity uses low frequency electromagnetic waves, whose waves are about 30m (100ft) long. Shorter wavelengths would not work.

Mr Giler said Witricity’s approach could be used for a range of applications from laptops and phones to implanted medical devices and electric cars.

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