Researchers from University of Washington was successful in building the first battery-free cellphone in the world, and set the record for the first Skype call to be made on a battery-free cellphone.

With battery life being a major challenge to modern day cell phone manufacturers, research efforts have turned to battery-free cell phones, a dream that saw a step forward this June.

On June 30th This year, Researchers from University of Washington, have published the results of their experiment, Battery-Free Cellphone, which counts as a major contribution towards achieving a real-world battery-free cell phone.

Researchers have built a prototype cellphone that operates without a battery. The cellphone uses only few micro-watts of power compared to the 100 micro-watts today’s cellphones use to make a voice call. Designing the system to use such low amount of power made it possible for researchers to make their system operate by harvesting power from ambient light, the system incorporates tiny photodiodes that extract energy from ambient light and convert it into electrical power to operate the cellphone. In addition, their system can operate on the power harvested from RF signals transmitted from a home-made computer system called the basestation. Researchers also indicated that their system can sense speech, actuate the earphones and switch between uplink and downlink communications, all in real time.

To successfully design a battery-free cellphone system, researchers had to overcome a major challenge faced by other battery-free electronics alike, which is to keep the system operating continuously. Manufacturers used a trick to enable devices to work without a battery, which is alternate periods of operation and power harvesting, which means that the device would shut off periodically. This trick can be practical with various type of electronics, but certainly won’t be on a cellphone.To solve this problem, researchers chose a counterintuitive path which is not usual in the cellphone industry, to go analog. This allowed the battery-free cellphone to incorporate a technology called “analog backscatter”, which is a way to get and reflect the signal rather than generating the signal itself, which in turn allows the system to consume much less power.

To demonstrate their system’s capability in real life, researchers have made the first Skype call on a battery-free cellphone over a cellular network.

Vamsi Talla, one of the phone's designers and a computer science and engineering research associate at the University of Washington, indicated that this prototype is still an early stage and there are still a lot of improvement to be done for this technology to become a reality. However, he said he hopes that the introduction of 5G networks would help make this dream a reality.

Read the full study here.