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World’s first battery-free cellphone makes calls via light and radio signals

We may be a step closer to a world in which phone charging is no longer needed, thanks to research from University of Washington. The engineers there managed to create a phone capable of calling people with energy from light and radio signals from the ambient. It might be the “first functioning cellphone that consumes almost zero power,” according to associate professor Shyam Gollakota.

As the Inhabitat reports, the battery-free cellphone can function on a few microwatts of power harvested from RF signals coming from a base station 31 feet away or from light from a solar cell the size of a grain of rice. The team of engineers already made Skype calls using the phone.

According to a university press release, “An antenna connected to those components converts that motion into changes in standard analog radio signal emitted by a cellular base station. This process essentially encodes speech patterns in reflected radio signals in a way that uses almost no power.”


The cellphone can run on such low power because the scientists got rid of the battery-draining process of converting analog signals into digital data. Their phone can use the small vibrations from the speaker or microphone that come whenever someone is talking or listening while making a call.

The research was published in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable, and Ubiquitous Technologies.

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Daisy Wilder