Behold, the first battery-free mobile phone that uses almost no power

6 Jul 2017

The prototype battery-free mobile phone. Image: Mark Stone/University of Washington

Imagine a smartphone that doesn’t need a battery because it consumes almost no power? Well, it is now a reality.

Whether it be carrying around power banks or finding a wall socket to plug a charger into, many people live day-by-day worrying about their smartphone’s insatiable thirst for power.

But a new development at the University of Washington (UW) has achieved a major breakthrough that could one day see the removal of a phone’s battery altogether, not only creating more real estate to more advanced technology, but could greatly benefit the global environment.

Future Human

In a published paper, the UW researchers revealed their battery-free handset that is able to harvest the few microwatts of power it requires from either ambient radio signals or light.

Able to make Skype calls

During testing, the team was able to make a number of Skype calls on the handset made of commercial, off-the-shelf components that can receive and transmit speech and communicate with a base station.

“We’ve built what we believe is the first functioning cellphone that consumes almost zero power,” said co-author of the paper, Shyam Gollakota.

“To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed.”

To solve this 21st century problem, the UW team realised that the greatest consumer of power in a smartphone is when it converts analogue signals that convey sound into digital data that a phone can understand.

To get around this, the team connected an antenna to components of the phone linked to its microphone and speaker.

As a person speaks, the tiny vibrations in the microphone or speaker generates enough ambient energy to convert motion into changes in standard analogue radio signal emitted by a telecoms base station.

Battery-free phone

What the interface of the battery-free phone looks like. Image: Mark Stone/University of Washington

‘Battery-free cellphone coverage everywhere’

Another co-author of the paper, Vamsi Talla, envisaged what this technology could one day be used for.

“You could imagine in the future that all cell towers or Wi-Fi routers could come with our base station technology embedded in it,” he said.

“And if every house has a Wi-Fi router in it, you could get battery-free cellphone coverage everywhere.”

However, this is not the first time that ambient phone technology has been developed including attempts to harvest energy from temperature sensors and accelerators.

But unlike this latest phone, these devices required the phone to go into sleep mode between each task making it more trouble than it’s worth.

The next task will now be to focus on improving the battery-free phone’s operating range and encrypting conversations to make them secure while also working to make it an actual smartphone with streaming video and creating a low-power screen.

Colm Gorey was a senior journalist with Silicon Republic