The end of the charger? Wi-Fi powered phones could one day make plug-in powering obsolete

Engineering students have created a device that captures wave signals

The energy from these waves are then converted to an electric current



Students claim the voltage produced is higher than in USB chargers

The invention could one day be used to charge phones using Wi-Fi signals

Forget wireless or portable phone chargers, a pair of engineering students have created a device that could charge a phone’s battery using Wi-Fi.

The device uses so-called metamaterials that can capture energy waves and convert them into an electric current.

The amount of voltage the device creates is also said to be more powerful than that produced through current USB chargers.



Students from Duke University have created a device, pictured, that converts microwaves into an electric current. Having successfully tested their energy harvester, the researchers claim it could be modified, and one day, fitted to phones to charge batteries using Wi-Fi signals

WHAT ARE METAMATERIALS?

Metamaterials are engineering structures capable of harvesting various forms of wave energy. By arranging certain materials, including copper and fibreglass but also gold, in a particular shape and pattern, the properties of those materials can combine to become an almost ‘super’ material. Duke University's David Smith explained: ‘Imagine a fabric woven of thread. In this fabric, light is only allowed to flow over the threads. ‘If you punch a hole in the fabric with a pin, light will go around the hole and resume its original course of travel, since light can only travel over the thread. ‘ He continued that because light waves can only travel in this way, the hole is practically ‘invisible’. Metamaterial arrays work in the same way to control how waves move around the structure, making it possible to capture and harvest them, and their energy.



It was created by Allen Hawkes and Alexander Katko from Duke University's Pratt School of Engineering with help from professor of electrical and computer engineering, Steven Cummer.

The team used five fibreglass and copper energy conductors wired together on a circuit board to create what's called a metamaterial array.



Metamaterials are engineering structures capable of harvesting various forms of wave energy.

By arranging certain materials, including copper and fibreglass but also gold, in a particular shape and pattern, the properties of those materials can combine to become an almost ‘super’ material.

Duke University's David Smith explained: ‘Imagine a fabric woven of thread. In this fabric, light is only allowed to flow over the threads.

‘If you punch a hole in the fabric with a pin, light will go around the hole and resume its original course of travel, since light can only travel over the thread. ‘

He continued that because light waves can only travel in this way, the hole is practically ‘invisible’.

Metamaterial arrays work in the same way to control how waves move around the structure, making it possible to capture and harvest them, and their energy.



The team used five fibreglass and copper energy conductors wired together on a circuit board, pictured, to create a metamaterial array. By arranging certain materials, including copper and fibreglass but also gold, in a particular shape and pattern, this array can control how waves behave

Hawkes and Katko’s device was designed to harvest the energy from microwaves.

They claim their five-cell metamaterial can convert these waves into 7.3 volts with an efficiency of 36.8 per cent.

By comparison, USB chargers for phones and other small devices provide around 5 volts.

The five-cell metamaterial converts waves into 7.3 volts of electricity. By comparison, USB chargers, pictured, provide around 5 volts

Having successfully tested their energy harvester with microwaves, the researchers claim it could be used to harvest the signal from other sources such as satellite signals, sound waves or Wi-Fi signals.

‘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.

‘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.’

Katko continued that a metamaterial coating could also be applied to the ceiling of a room and used to redirect lost or dropped Wi-Fi signals.

The researchers added that a similar device could one day be fitted to phones and other small electronic devices.

This could make it possible to charge phones by connecting it to a Wi-Fi network, without the need for a charger or power point.

‘Our work demonstrates a simple and inexpensive approach to electromagnetic power harvesting,’ said Cummer.