Scientists at Washington University invented a battery-free cellphone that uses microvolts of energy from radio signals in the environment or light, hoping to put an end to the traditional way of charging mobile devices.

According to a report published in the Science Daily, the team of researchers has removed the energy front while inventing the battery-free cellphone.

The team also made Skype calls with the battery-free cellphone, showing that the prototype prepared with commercial and ready-to-use content could receive and transmit the speech and communicate with the central station.

In battery-free cellphone prototype that benefits from the small vibrations generated by speech, the user presses a button to switch between "transfer" and "listen" modes.

A special center was designed for the phone to receive and transmit radio signals, and the prototype reportedly requires three and a half microvolt of energy.

Other battery- free technologies based on ambient energy, such as temperature sensors, intermittently conserve power.

"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," the Science Daily reported.

The team also stated that they are also working on video transmission via a battery-free mobile phone.