While most smartphone makers at this point are concentrating on squeezing in a bigger battery in a slimmer phone, a researcher has been working for years to have now created a prototype cell phone that does not have a battery at all, and it still makes calls to nearby Android smartphones. So basically, it can make calls, and send text, but has no battery in it. Though, the device is still in the prototype stage.
Brainchild of Vamsi Talla, a research associate at the lab of Joshua Smith, researches computer science and electrical engineering at UW, Wired reports. Explaining the pertinence of his years of hard work in a gist, Smith says, “If you had to pick one device to make battery-free, what would you pick,” he asks. “A cell phone is one of the most useful objects there is. Now imagine if your battery ran out and you could still send texts and make calls.”
Realizing that vision required rethinking almost everything about how cell phones function today. In order to operate without a battery, the phone would have to rely only on energy that it could harvest from its surroundings. And so, Smith’s prototype cellphone draws its power from nothing but thin air!
But if you are expecting this to be a full fledges touch screen smartphone, hold your horses right there! The phone has a basic touch-sensitive number pad and its only display is a tiny red LED that glows briefly when a key is pressed. A large touchscreen would require around 400 milliwatts, over one hundred thousand times as much as power as Talla’s phone currently needs.
However, it is needless to say, that drawing power for a cellphone through thin air, and by means of a lithium ion (commonly used) battery, cannot be the same. A hybrid system like how this prototype device uses, is able to generate only a few tens of microwatts, whereas a traditional cell phone uses tens of thousands of times more power, around 800 milliwatts, when making a call.
And so, Smith’s team of researchers developed a technique called backscatter that allows a device to communicate by reflecting incoming radio waves, a bit like an injured hiker sending an SOS using the sun and a mirror. Smith has already spun out a start up called Jeeva Wireless to commercialize what he calls “passive Wi-Fi”, which is a digital backscatter technology for ultra-low power Wi-Fi gadgets. However, even passive Wi-Fi proved too power-hungry for the cell phone project.
“Converting analog human speech to digital signals consumes a lot of power,” says Talla. “If you can communicate using analog technology, you’re actually more power efficient.” So although the cell phone uses digital signals to dial numbers, the backscatter process for voice calls is purely analog.
Somewhat similar to the communication technology the spies used during the Cold War, some of the key components of Talla’s phone are housed remotely to save power. A nearby base station has circuitry for converting and connecting to the digital cellular network, currently via Skype. The prototype base station uses an unlicensed frequency, limited to low-power transmissions. Because the phone relies on those signals for its energy harvesting, it has a range of just 15 meters from the base station.
To develop the phone commercially, that circuitry could be built into a Wi-Fi router at home or, more likely, a traditional phone tower. “Real cell towers have a hundred times as much power, and would increase the range to perhaps a kilometer,” says Talla.
However despite all the flaws that the first prototype of Talla’s phone has, he promises better call quality and an E-Ink display for text messages on the next generation device, possibly along with a camera to snap selfies.
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