They succeeded by creating a system that only needed 3.5 microwatt to call and receive calls. The downside is that users need to be close to phone stations within 50 feet to receive and amplify the call signal.
Researchers are planning to continue developing the surrounding energy extraction system to improve power supply and call support when users are far away from the phone base station.
When researchers have found new ways to gather energy from the surrounding environment, they also plan to add a display screen as E-ink displays that use less energy, and Add support for encrypted conversations, streamed videos.
Before implementing these ideas, researchers want to overcome the biggest drawback of the phone, which is the button that users press to switch between sending and receiving modes. Basically, this device is a walkie-talkie, because it requires users to press a button to switch between the two modes.
However, the research team says that this is not the biggest technical hurdle, because it is possible to create a system that automatically detects when a user is talking and performs a switch between the two modes. this. The team also said they created the phone with the available components and also tried to make calls from Skype to the phone in addition to regular calls.
The technology to collect energy from the surrounding environment and this energy-optimized calling mechanism has been detailed in a research paper called Battery-Free Cellphone.