Researchers from the University of Washington have demonstrated that we can get rid of batteries altogether. The Cell phone uses a technique called backscatter. It basically uses the radio waves that already move around us to communicate. This device is still in its infant stages. But the team was able to successfully demonstrate a voice call from a battery-less phone to an Android smartphone.
The phone has basic touch-sensitive number pad and its only display is a tiny red LED that glows briefly when a key is pressed. A large touchscreen would require around 400 milliwatts.
The first thing the team tackled was communication. Smith’s lab developed a technique called backscatter. Allows a device to communicate by reflecting incoming radio waves, a bit like an injured hiker sending an SOS using the sun and a mirror.
Re-inventing a spy technology used during the Cold War
While developing analog backscatter essentially re-inventing a spy technology used during the Cold War. In 1945, the Soviets presented the American Ambassador in Moscow with a carving of the Great Seal of United States. Inside hidden audio bug that only activated when illuminated by the correct frequency of radio waves. Using the energy of the waves themselves to operate. To develop the phone commercially, that circuitry could be built into a Wi-Fi router at home or, more likely, a traditional phone tower.
The signal moves over an unlicensed frequency to a base station that connects to the digital cellular network via Skype. The base station doesn’t just connect the cell phone to the network, it also delivers the necessary power to make it work. The current base station allows the phone to be at most 49 feet from it not really portable, but things might change in the future by integrating base stations with phone towers.
The team is now working to improve the call quality and how the call happens. Currently, it works like a walky-talky, so you press a button to switch from speaking to listening. The team is also considering an e-ink display to send texts and possibly even a camera.