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Can we use ambient Wi-Fi signals to trickle charge cell phones?

By Joe Levi November 15, 2013, 10:56 am
Wireless Energy

We all have a smartphone or tablet, and we’re all acutely aware of how much battery life we can eek out of them. Most can get through their day, but many still have to recharge at some point before they call it a night. That’s when our devices typically get the life-giving electricity they need to make it through another day: tethered to an electrical outlet.

But you can get electricity from more sources that just the socket in your wall.

Many of you already know that I’m a proponent of wireless charging. I own four Qi wireless chargers, and four devices which can be charged without plugging them in. However, I’m continually reminded by readers that even Qi isn’t truly “wireless” charging — you still have to plug the charger into the wall, using a wire.


What if we could go really wireless?

Are you ready to get really geeky? There’s energy flowing all around you. Right now. Regardless of where you are on this huge planet of ours, you’re usually being bombarded by electromagnetic waves. Lots of them.

Some are naturally occurring phenomenon, such as the Aurora Borealis and the Aurora Australis. These beautiful displays are the visible manifestations of the collision of charged particles in the thermosphere. Imagine all the energy flowing around you that you cannot see.

Aurora Borealis
The Aurora Borealis, or Northern Lights, show us how beautiful charged particles can be.

We’ve been able to harness the electromagnetic spectrum to do all kinds of neat stuff. We can communicate with spacecraft half-way across our galaxy, HAM operators can talk around the world, radio and television stations can transmit entertainment across the countryside, cell towers can blanket huge swatches of cities,  and Wi-Fi bubbles are popping up everywhere.

All of these man-made signals begin when an electrical current is pushed out of an antenna as a radio wave. Think about that for a moment. Since these signals started out as electrical current, shouldn’t there be some way to convert them back into an electrical current?

That’s already happening today. Even in the most simple radio, the sound you hear coming out of the speaker is essentially the electrical energy being harvested from the radio waves — sort of. Your radio also has an amplifier and other electronics inside that help to clean up the signal and make it tolerable to listen to.

But what if you could create an antenna with the singular purpose of harvesting all the energy in a wide-range of frequencies, and put that back into a battery? With traditional radio waves that’s not very practical, but when we start talking about microwaves, cell towers, and Wi-Fi, the concept suddenly becomes possible. That’s what researchers at Duke University’s Pratt School of Engineering have been working on.

Wi-Fi phone charger

Pratt researchers were able to assemble an array of specialized cells that were able to output 7.3-volts of electricity. How many amps? Probably not many.

Squeezing that into your cellphone might be a little tricky.
Squeezing that into your cellphone might be a little tricky.

This proof-of-concept isn’t going to be the final product, of course. That “final product” is probably still years away. I don’t suspect we’ll see these arrays tucked inside our smartphones and tablets like some other media sources do, but I do think we may see them in standalone chargers that ever need to be plugged in. They’ll harvest energy all the time, storing it inside a battery, which will then charge your devices when you plug them in at night.

Regardless, it’s a very innovative way to collect energy that would otherwise be lost.

Your turn

What do you think about being able to collect “free energy from the sky”? Once it’s available in a retail package, is this something that you’d consider purchasing? Why or why not? Would you prefer to purchase a product like this, or a simple solar charger? Let us know your thoughts in the comments below!

Source: Pratt School of Engineering
Via: Gizmodo

Want to learn more about Qi wireless charging? Ever considered adding a solar panel to your smartphone? Or is packing around a spare battery more your style? As always, Pocketnow has got you covered!


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