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This Cellphone Can Make Calls Even Without a Battery


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The works of the prototype cellphone.

Researchers at the University of Washington in Seattle have developed a prototype cellphone that functions without a battery.

Credit: Mark Harris

Researchers at the University of Washington in Seattle (UW) have developed a prototype cellphone that functions without a battery, drawing power from the surrounding environment.

The researchers created the handset by developing a new technique called backscatter, which enables a device to communicate by reflecting incoming radio waves.

The cellphone uses digital signals to dial numbers, while the backscatter process for voice calls is analog.

To develop the phone commercially, the new circuitry could be built into a home Wi-Fi router or a traditional cell tower.

"Real cell towers have a hundred times as much power, and would increase the range to perhaps a kilometer," says UW researcher Vamsi Talla.

However, the system can only run on very low power. For example, the large touchscreens that are common on modern smartphones require about 400 milliwatts of power, more than 100,000 times as much power as the new device needs.

From Wired
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