Internet-of-things! Researchers, led by an Indian-origin scientist, have
developed a new technology that lets wireless devices communicate with
each other without relying on batteries or wires for power.
communication technique, called "ambient backscatter," takes advantage
of the TV and cellular transmissions that already surround us around the
Two devices communicate with each other by reflecting the
existing signals to exchange information. The researchers built small,
battery-free devices with antennas that can detect, harness and reflect a
TV signal, which then is pickedup by other similar devices.
The technology could enable a network of devices and sensors to communicate with no power source or human attention needed.
can re-purpose wireless signals that are already around us into both a
source of power and a communication medium," said lead researcher Shyam
Gollakota, from the University of Washington.
going to have applications in a number of areas including wearable
computing, smart homes and self-sustaining sensor networks," said
"Our devices form a network out of thin air. You can
reflect these signals slightly to create a Morse code of communication
between battery-free devices," said co-author Joshua Smith.
technology can also be used for communication - text messages and
emails, for example - in wearable devices, without requiring battery
The researchers tested the ambient backscatter
technique with credit card-sized prototype devices placed within several
feet of each other.
For each device the researchers built
antennas into ordinary circuit boards that flash an LED light when
receiving a communication signal from another device.
the devices were tested in a variety of settings, including inside an
apartment building, on a street corner and on the top level of a parking
They found that the devices were able to communicate with
each other, even the ones farthest from a TV tower. The receiving
devices picked up a signal from their transmitting counterparts at a
rate of 1 kilobit per second when up to 2.5 feet apart outdoors and 1.5
feet apart indoors.
This is enough to send information such as a sensor reading, text messages and contact information.
is 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.