First Battery-Free Cellphone Harvests Ambient Power #Science #Technology

UW engineers have designed the first battery-free cellphone that can send and receive calls using only a few microwatts of power. 

Credit: Mark Stone/University of Washington


University of Washington researchers have invented a cellphone that requires no batteries—a major leap forward in moving beyond chargers, cords and dying phones. Instead, the phone harvests the few microwatts of power it requires from either ambient radio signals or light.

The team also made Skype calls using its battery-free phone, demonstrating that the prototype made of commercial, off-the-shelf components can receive and transmit speech and communicate with a base station.

The new technology is detailed in a paper published July 1 in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.

Phys.org:  First battery-free cellphone makes calls by harvesting ambient power

First off, they didn't invent it since this was based on research by Soviets but they didn't apparently do anything much to exploit it and the technology resumes now.  Washington is only dimly aware of it but there's been no Soviets about for over thirty years.


The researchers plan on continuing with this to further play out the idea.

Many other battery-free technologies that rely on ambient energy sources, such as temperature sensors or an accelerometer, conserve power with intermittent operations. They take a reading and then "sleep" for a minute or two while they harvest enough energy to perform the next task. By contrast, a phone call requires the device to operate continuously for as long as the conversation lasts.

"You can't say hello and wait for a minute for the phone to go to sleep and harvest enough power to keep transmitting," said co-author Bryce Kellogg, a UW electrical engineering doctoral student. "That's been the biggest challenge—the amount of power you can actually gather from ambient radio or light is on the order of 1 or 10 microwatts. So real-time phone operations have been really hard to achieve without developing an entirely new approach to transmitting and receiving speech."

Next, the research team plans to focus on improving the battery-free phone's operating range and encrypting conversations to make them secure. The team is also working to stream video over a battery-free cellphone and add a visual display feature to the phone using low-power E-ink screens.

- PO

The interested whizkid engineer is invited to pursue the original article since this crew looks like it's onto some novel technology.


Individual cellphones don't have much Lithium but the pool must be enormous when that small amount is aggregated across, say, a billion cellphones around the world.  Reducing or eliminating that won't likely change things for EVs which require individually much more Lithium than a cellphone but it does avoid needless consumption of a finite resource.