Cords tangled and left spewed in a jumble on the floor. Power outlets installed every few feet in the house. The little phone battery symbol ominously running down to red; the screen dimming in a desperate attempt to conserve what little power remains. This is just an inescapable part of everyday life, right? Maybe not for much longer.
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Although wireless power has existed for some time, the greatest hurdles in mass commercialization of wireless power have been efficiency and cost. Researchers at Duke University’s Pratt School of Engineering are rapidly making these hurdles irrelevant. Undergraduate engineering student Allen Hawkes, graduate student Alexander Katko, and lead investigator Steven Cummer have developed a way to convert microwaves already buzzing around our heads into pure energy. The most exciting aspect of this development is the potential to convert Wi-Fi into energy and charge our phone battery passively with Wi-Fi in the area.
The device the researchers created consists of five fiberglass and copper energy conductors wired together on a circuit board. The device converts microwaves into 7.3V of electricity, a 32% increase in charge compared to USB which provides only 5V. This amount of energy could give your phone battery a little boost.
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The efficiency and design is very similar to modern solar panels. While solar panels convert light energy from the sun into electrical current, the new energy harvester can be tuned to harvest the signal from such sources as satellites, sound, or even Wi-Fi. With this new technology a phone battery could be charged with anything, anywhere.
According to the team,
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.
The device takes advantage of a relatively new breakthrough in science called metamaterials; artificial materials not found in nature that are specifically engineered to capture various forms of wave energy. Metamaterials have been traditionally thought of as materials reserved for the distant future, but the researchers have proved this notion utterly wrong.
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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.
Using metamaterials, the researchers have outlined a whole string of applications for their breakthrough device, not just the charging of a phone battery. According to the researchers,
a metamaterial coating could be applied to the ceiling of a room to redirect and recover a Wi-Fi signal that would otherwise be lost. Another application could be to improve the energy efficiency of appliances by wirelessly recovering power that is now lost during use…With additional modifications the power-harvesting metamaterial could potentially be built into a cell phone, allowing the phone [battery] to recharge wirelessly while not in use. This feature could, in principle, allow people living in locations without ready access to a conventional power outlet to harvest energy from a nearby cell phone tower instead.
Whoa! Why not just paint the whole house with a paint/metamaterial mixture. Sprinkle metamaterials on the lawn. Think of a world where the phone battery is always full. Spread Wi-Fi harvesting capability by mixing some metamaterials into water balloons and letting the kids go at it. Metamaterials for everyone!
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After just completing a 9 month backpacking trip through several different countries, finding a power outlet to charge my phone battery, camera, and kindle was a daily struggle. Wi-Fi on the other hand was everywhere, even at the top of many mountains in Asia. If a device like this could drastically alter the life of a simple backpacker, imagine what it could do for society at large! The excuse “My phone battery died” will become completely obsolete.