New invention 'harvests' electricity from background radiation and could be used to beam power to remote locations or recharge phones wirelessly

Device captures microwaves and converts them into electricity

Future versions could harvest satellite, sound or Wi-Fi signals



Technology could be used to recharge phones without cables or beam electricity to mountaintops

Engineers at Duke University have designed a breakthrough gadget that 'harvests' background microwave radiation and converts it into electricity, with the same efficiency as solar panels.

The development, unveiled on Thursday, raises exciting possibilities such as recharging a phone wirelessly and providing power to remote locations that can't access conventional electricity.

And the researchers say that their inexpensive invention is remarkably versatile. It could be used to capture 'lost' energy from a range of sources such as satellite transmissions, sound signals or Wi-Fi.

The future: The device that is capable of harvesting microwave signals from the air consists of five fiberglass and copper conductors wired together on a circuit board

The Duke engineers used metamaterials, which their press release describes as ' engineered structures that can capture various forms of wave energy and tune them for useful applications.'

They say the device harvested microwaves with an efficiency of 36.8 percent, similar to modern solar cells that capture light energy.

A report that will appear in the journal Applied Physics Letters in December states that this invention is capable of converting microwave signals to enough direct current voltage to recharge a cell phone battery.

The gadget, created by undergraduate engineering student Allen Hawkes, graduate student Alexander Katko and lead investigator Steven Cummer, consists of five fiberglass and copper conductors wired together on a circuit board.

It is capable of providing 7.3V of electricity. As the press release points out, current USB chargers provide around 5V.

Hawkes said: 'We were aiming for the highest energy efficiency we could achieve. We had been getting energy efficiency around 6 to 10 percent, but with this design we were able to dramatically improve energy conversion to 37 percent, which is comparable to what is achieved in solar cells.'

Proud: Alexander Katko (left) and Allen Hawkes (right) pioneered the breakthrough. 'It's possible to use this design for a lot of different frequencies and types of energy, including vibration and sound energy harvesting,' said Katko

His colleague, Katko, added: 'It's possible to use this design for a lot of different frequencies and types of energy, including vibration and sound energy harvesting.



'Until now, a lot of work with metamaterials has been theoretical. We are showing that with a little work, these materials can be useful for consumer applications.'

Possible uses for the new technology include building metamaterial into homes to ensure Wi-Fi signals are not just lost.

Electrical products could also have a device attached to increase efficiency by ensuring that excess power is not wasted.

In theory, the invention could also be used to beam signals from phone towers that could then be converted into electricity.



Electronic devices could be recharged wirelessly or electricity sent to remote areas without power cables.



Power: The device harvested microwaves with an efficiency of 36.8 percent, similar to the solar cells installed on this California home in a file photo

The researchers explained that a series of the power-harvesters could even capture signals from satellites passing overhead.

This could allow for electricity in hostile environments such as mountaintops or deserts. Cummer said: 'Our work demonstrates a simple and inexpensive approach to electromagnetic power harvesting.