Ambient backscatter tech allows devices to communicate, sans batteries
By Ben Coxworth
August 14, 2013
In order for the Internet of Things to become a reality, devices will need to be able to communicate with the internet and with one another. If they have to be powered up in order to so, however, a lot of electricity is going to be wasted. That’s where a new technology known as “ambient backscatter” comes into the picture. Developed by engineers at the University of Washington, it uses ever-present existing TV and cellular signals to provide the power and medium for battery-less communications.
Each device utilizing the ambient backscatter system is equipped with an antenna that picks up TV or cellular signals and converts them into electricity, which it then uses to reflect a Morse code-like version of that signal. Similar antennas on other devices in turn detect that coded, reflected signal, and can respond accordingly. No human intervention is required.
Not only would the technology let devices communicate without being turned on, but it would also allow for things such as structural sensors to be embedded in concrete or other materials, where they would be impossible to access for battery-changes – as long as the signals could reach through the material to their antennas, they could communicate.
Led by Prof. Shyam Gollakota, U Washington researchers added the antennas to credit card-sized circuit boards. Each device had an integrated LED that illuminated when it received a signal, but no battery. It was found that pairs of the cards placed several feet apart could communicate with one another, even when up to 6.5 miles (10.5 km) away from the nearest TV transmission tower. The rate at which they could exchange information was reportedly sufficient to relay data such as sensor readings or text messages.
This, in turn, leads to another possible use for the technology. In the future, smartphones might be able to use ambient TV and cellular signals to transmit text messages, even once their battery has died. Additionally, ambient backscatter tags on those phones (or on anything else) could be used to transmit their location if they were misplaced.
More information is available in the video below.
Source: University of Washington