Using ambient backscatter, devices can interact with users and communicate with each other without the use of batteries. Information is exchanged by reflecting/absorbing pre-existing radio signals.
This is a new communication technique, which researchers call “ambient backscatter.” It takes advantage of TV and cellular transmissions that exist and surround us throughout our daily lives. Two devices communicate with one another by reflecting existing signals to exchange information. University of Washington engineers and researchers built small, battery-free devices with antennas that can detect, harness and reflect a TV signal, which then is picked up by another similar devices.
The technology could enable a network of devices and sensors to communicate with no power source or human attention needed.
“We can repurpose wireless signals that are already around us into both a source of power and a communication medium,” said lead researcher Shyam Gollakota, a UW assistant professor of computer science and engineering. “It’s hopefully going to have applications in a number of areas including wearable computing, smart homes and self-sustaining sensor networks.”
“Our devices form a network out of thin air,” said co-author Joshua Smith, a UW associate professor of computer science and engineering and of electrical engineering. “You can reflect these signals slightly to create a Morse code of communication between battery-free devices.”
Smart sensors could be built and placed permanently inside almost any structure and set to communicate with one another. For example, sensors placed in a bridge could monitor the health of the concrete and steel, then send an alert if one of the sensors picks up a hairline crack. The technology can also be used for communication – text messages and emails, for example – in wearable devices, without requiring battery consumption.
It’s also feasible to build this technology into devices that do rely on batteries, such as smartphones. It could be configured so that when the battery dies, the phone could still send text messages by leveraging power from an ambient TV signal.
Applications are endless, researchers say, and they plan to continue advancing the capacity and range of the ambient backscatter communication network.