One of the unresolved problems of our portable devices is the battery life: it would be great if you do not have to worry anymore! The engineers at the University of Washington, who created the first mobile phone that also works without a battery, must have thought of it. The device draws the little energy it needs from its environment, using radio frequencies, Wi-Fi signals or light signals.
REVOLUTION
It can do so because it is almost zero-consumption: its way of operating, in fact, has been extremely simplified. In normal cell phone conversations, the analog signals picked up by the microphone of the device are converted into digital signals that propagate through the cellular network. This conversion is particularly expensive, in terms of energy: about 800 milliwatt per call go, thousands of times more than the 3.5 microwatts that the new device needs to work.
HOW DOES IT WORK
The battery-free cell phone is maintained on the analogue signal: it records the vibrations picked up by the microphone during the call and using a technology called backscatter(based on the reflection of radio signals in physical space and already used by Soviet spies at the time of the Cold War) transmits the signal at a nearby station, operating at most 15 meters away.
The phone sends digital signals to the station only when dialing the number - by connecting via Skype - while during the conversation it switches completely to analogue transmission, as if it were a walkie-talkie. For now, researchers have managed to make a voice call from the experimental phone to a normal Android device.
PERSPECTIVES
Now the team is working on improving voice reception but also on an electronic ink screen for text messages and a small camera. In the future, cell phones or even wi-fi routers could incorporate this technology: this would broaden the reception area and signal strength.
Summary in Video From Washington
