For most of us, a battery-free phone would be a dream come true. Imagine having the ability to use your iPhone or Samsung Galaxy all day, everyday without concerning about charging it. Well, researchers from the University of Washington have created the first step, albeit a very small one, towards making that a reality. They’ve managed to make a prototype cell phone that operates while not using a battery.
The tiny device - that resembles little more than a circuit board - runs on simply 3.5 microwatts of juice, and uses a solar cell that’s “roughly the size of a grain of rice” to draw close power from surrounding light and radio signals. These signals are made by a special base station that sits about fifty feet away.
The researchers say the conversion of analog audio into digital data is the most energy-consuming part of a normal cell phone, and to get around this, their prototype’s microphone and speaker use small vibrations to encrypt the incoming and outgoing signals. There’s no fancy screen, however the phone uses capacitive touch buttons to dial and place a call, with their demo showing a call being received via Skype.
The trade-off is that it can’t send and receive audio at the same time, thus it functions a little sort of a walkie-talkie wherever the user must press and hold a particular button to either talk or listen to the other caller.
Of course, the researchers plan to continue developing their prototype and hope to add options like an e-ink screen and encryption for secure calls. They imagine battery-free phones turning into ubiquitous in the future by putting the base station technology in things like cell towers and WiFi routers, in turn permitting coverage to be out there nearly everywhere.
SOURCE University of Washington