New ‘ambient backscatter’ technology draws power from the air

Invention could help power the Internet of Things and allow for smart cities with always-on sensors

Engineers from the University of Washington have created a new system of wireless communication devices that interact with one another without batteries or wired power.

The new technology is called ‘ambient backscatter’ and works by absorbing the many types of transmissions – from radio waves, Wi-Fi, mobile networks and the like – that are all around us in the air. Prototype devices talk to each other by using antenna to intercept and reflect these signals back and forth.

“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, an 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.”

Everyday objects could be enabled with battery-free tags to communicate with each other. A couch could use ambient backscatter to let the user know where his keys were left. Source: University of Washington

The new technology could greatly speed the development of the Internet of Things – the concept of imbuing our built environment with internet connectivity – as current technology is hamstrung by the need to supply each device with its own power source.

The researchers give the example of building such communicating sensors into a bridge, monitoring the integrity of the concrete and steel. If an irregularity is detected, a signal is sent. This technology could be cheaply integrated into a range of structures, without the worry that the power supply would run out.

Other applications could be more prosaic but equally useful – tags for your keys and wallet to help you find them if they’re lost; or sensors built-in to credit cards to enable easy wireless payments.

Researchers demonstrate how one payment card can transfer funds to another card by leveraging the existing wireless signals around them. Ambient RF signals are both the power source and the communication medium. Source: University of Washington

The prototypes tested by the team were able to send data at a rate of 1 kilobit per second when up to 2.5 feet apart outdoors, and 1.5 feet apart indoors. This was enough to send contact information,  and text messages, and was fully functioning even though the nearest source of ambient signals (a TV tower) was 6.5 miles away.

For a full demonstration of the technology, see the video below: