Researchers have discovered a way to achieve energy transfer "through thin air" over large distances and without clunky devices.
A research team has finally figured out how to transmit energy using " low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver," a Duke University news release reported.
This "superlens" focuses magnetic fields and can translate these fields (emanating from twin power coils) from one coil to the other creating an electric current.
The team found they could transmit energy through the air with more efficiency than would be seen without the use of the lens.
"For the first time we have demonstrated that the efficiency of magneto-inductive wireless power transfer can be enhanced over distances many times larger than the size of the receiver and transmitter," Yarislay Urzhumov assistant research professor of electrical and computer engineering at Duke University, said. "This is important because if this technology is to become a part of everyday life, it must conform to the dimensions of today's pocket-sized mobile electronics."
To achieve this feat the team created a square superlens that looked like a "few dozen giant Rubik's cubes stacked together," according to the news release. The walls of the structure contains copper coils that react with each other to form a metamaterial with the ability to react with magnetic fields " in such a way that the fields are transmitted and confined into a narrow cone in which the power intensity is much higher," the news release reported.
The team placed an electric coil with a current running in a specific direction on one side of the superlens, this created a magnetic field around the coil. This field loses power as it moves farther away.
"If your electromagnet is one inch in diameter, you get almost no power just three inches away," Urzhumov said. "You only get about 0.1 percent of what's inside the coil."
When the superlens is in place the magnetic field can be focused at a distance of one foot and still emit a noticeable electric current. This had been accomplishment has been made before, but only when the distance met the size of the coils.
"It's actually easy to increase the power transfer distance by simply increasing the size of the coils," Urzhumov said. "That quickly becomes impractical, because of space limitations in any realistic scenario. We want to be able to use small-size sources and/or receivers, and that's what the superlens enables us to do."
Intuitively, cranking up the power can also increase the power of the device; although this can be dangerous at certain levels.
"Most materials don't absorb magnetic fields very much, making them much safer than electric fields," Urzhumov said. "In fact, the FCC approves the use of 3-Tesla magnetic fields for medical imaging, which are absolutely enormous relative to what we might need for powering consumer electronics. The technology is being designed with this increased safety in mind."
The researchers hope one day they can use the technique to perform functions such as charging cell phones.
"The true functionality that consumers want and expect from a useful wireless power system is the ability to charge a device wherever it is - not simply to charge it without a cable," Urzhumov said. "Previous commercial products like the PowerMatTM have not become a standard solution exactly for that reason; they lock the user to a certain area or region where transmission works, which, in effect, puts invisible strings on the device and hence on the user. It is those strings - not just the wires - that we want to get rid of."
