Our future mobile devices may never need to be charged.

Researchers from University of Washington have created a mobile phone prototype that doesn’t require any kind of battery to operate.

The efficient prototype made by the researchers requires just 3.5 microwatts to operate, and it takes an innovative approach to avoid the need for a battery. The device, instead, uses the power from radio signals and light and its solar cell is roughly the size of a grain of rice.

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The prototype is made of simple components: capacitive touch buttons and a circuit board. The team of scientists were also able to create a base station to transmit the signal with such a small amount of power.

Vamsi Tall, who is the joint author of the paper, says the base station technology they developed could make it possible for battery-free mobile phones to become a regular thing.

“You could imagine in the future that all cell towers or Wi-Fi routers could come with our base station technology embedded in it,” Tall said. “And if every house has a Wi-Fi router in it, you could get battery-free cellphone coverage everywhere.”