Answer: battery-free phones
As part of a Google Faculty Research Program, Jeeva Wireless CTO Vamsi Talla and a team of researchers at the University of Washington in Seattle created a cellphone that is battery-free.
The phone’s creators told the institute that it works by receiving “power from sunlight or RF waves sent from a nearby base station, a fixed point of communication for customer cellular phones on a carrier network. With a technique called backscattering, the phone can make a voice call by modifying and reflecting the same waves back to the base station.”
Currently this phone is only capable of voice calls, but the team behind it hopes to improve its range and audio quality, and even add a camera and a low-power E Ink display. These improvements could give the tech smartphone capabilities. If mass-produced, the phone also has the potential to be incredibly affordable — the team estimates that it could cost less than $1 to manufacture under the right conditions.