Are Battery-Free Cellphones Becoming a Reality?

This might be a must-have soon: a battery-free cellphone. Do not give up your iPhone 7 or your Samsung S8 just yet, but this prototype created by the University of Washington has a bright future. We will bet on it!

How amazing would it be to update your Facebook status, check your Instagram stories and listen to your favorite playlist without having to worry about charging your battery? Students Vamsi Talla, Bryce Kellogg, Sam Crow, and Wu Meiling wanted to make our lives easier and built a battery-free cellphone. For now, all you can do is call – so Facebook and Instagram will have to wait – but isn’t it what a phone is initially supposed to do?

The small device was introduced to the world in a paper (download here) with: “We present the first battery-free cellphone design that consumes only a few micro-watts of power.” This green engineering ingenuity is a PCB. “The battery-free device prototype is built using commercial-off-the-shelf components on a printed circuit board,” the paper says.

The battery-free cellphone is a printed circuit board. – Photo Credit: University of Washington

The battery-free cellphone runs on wireless power and tiny solar chargers. In order to operate only using wireless, you need to be no more than 31 feet away from a basestation to harvest power. If power harvested from the photodiodes is used, the distance extends to 50 feet away from the basestation. The modified radio waves then gives the phone enough power to take calls consuming between two and three micro-watts.

Now you can plug in your headphones and receive or send voice signals. The phone has no screen, only buttons. To place a call, you simply dial a number, which the basestation relays to the cellular network. In this case, Skype. You are then connected to the dialed number and the phone you want to reach will ring. Easy, right?

The demo shows a call being received using Skype. – Photo credit: University of Washington

The prototype functions in the same way talkie-walkies do. You must hold a certain button – the “A” button – while you are speaking, and release it to wait for your interlocutor to speak.

The conversion of analog audio– audio recorded using methods that replicate the original sound waves – into digital data consumes the most energy in our phones. In an effort to save energy, the researchers use small vibrations through the microphone and speaker to encode the incoming and outgoing signals.

Of course, nobody is willing to trade their smartphone for a printed circuit board that can only make calls and cannot even send text messages. The researchers are well aware of this reality. They plan to spend many more hours working on their device to turn it into a competitive cellphone just like the iPhones and Galaxys people want. It will take some time before they can get there, but if there is one thing we know for sure, it is that technology moves quickly.

Source: University of Washington

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