A new electromagnetic technology allows connected objects to communicate with each other battery-free by repurposing WiFi, TV and cellular signals that are already all around us.

Battery-free connected objects using ‘ambient backscatter’

The number of small connected devices and sensors is increasing and we are using them more and more in our daily lives. However, powering them remains a sizeable challenge. Installing wires is often just not feasible and batteries need to be replaced or recharged – an impractical exercise on a large scale such as in the smart meters used for smart power grids. Nevertheless, these small devices are essential for smart management of infrastructure, cities and healthcare. Now researchers at the University of Washington Seattle, USA have come up with an answer to the need for battery-free communication, using a novel approach that captures and ‘repurposes’ wireless signals that are already around us into both a source of power and a communication medium. This new technology allows us to envisage a completely connected wireless world and brings the Internet of Things a step closer to reality.

Battery-free wireless devices

The researchers presented their results at the ACM Special Interest Group on Data Communication  (SIGCOMM) 2013 conference in Hong-Kong in August. The highly sophisticated technology they have developed, which they are calling ambient backscatter’, can be used in small devices of all kinds, picking up signals from mobile telephones, TVs, and other Wi-Fi networks which are already in the air. Once captured, the signals can be ‘repurposed’ to serve both as a power source and a communication medium, enabling objects to communicate with each other and with other connected objects such as mobile phones. What happens is that the signals are reflected slightly so as to create a sort of Morse code based on pulsations, explained one of the researchers. At the moment, signals can be picked up by a receiving device at a rate of 1 kilobit per second at a distance of up to 2.5 feet outdoors, which is not very fast, but adequate for sending a text message.

Towards the Internet of Things

A whole range of applications for this research can be envisaged. Lead researcher Shyam Gollakota, an assistant professor of computer science and engineering, explains: “The technology is hopefully going to have applications in a number of areas including wearable computing, smart homes and self-sustaining sensor networks.” In short, this technical advance could bring us a giant step closer to the Internet of Things, i.e. a world where all objects and places are connected to each other, thus opening the way to smarter resource management. In the area of smart homes, for example, sensors could measure various indicators, such as temperature, oxygen level, etc, on a permanent basis and feed the information back in real time to the occupants. Medicine could also benefit from backscatter-assisted wireless management. The researchers atUniversity of Tokyowho recently developed smart patches that can be used inside the body announced that they still needed to solve the need for continuous wires-free power. Moreover it is also feasible to build ambient backscatter technology into devices we use on a daily basis that normally rely on batteries, such as smartphones, so that if the battery dies the phone can still be used.


By Thomas Meyer
Journalist, Business Analyst