New wireless technology can see people through walls

MIT researchers have developed WiFi technology that is capable of seeing a human through an obstacle ‒ like a wall ‒ and reconstructing the image by analyzing the reflections from the signals. The technology has a variety of practical applications.

The new device, called RF-Capture, is based on previous methods of capturing movements across a house. That technology is currently used by firefighters to determine if they need to save anyone in a burning building, as well as by mothers to see their baby's breathing, Popular Mechanics reported.

It was developed at MIT’s Wireless Center, which is hosted in the Computer Science and Artificial Intelligence Laboratory, or CSAIL. Previous research from the lab developed a wireless system to detect gestures as subtle as the rise and fall of a person’s chest, allowing them to determine a person’s heart rate with 99 percent accuracy.

RF-Capture doesn’t require the user to wear any sensor, yet it can differentiate between different unseen people by transmitting wireless signals that can pass through physical objects and reflect off whatever is on the other side. It then analyzes that data and pieces them together to “see” what is behind the object. The device can distinguish between 15 people with nearly 90 percent accuracy. It can also trace a person’s handwriting in the air and determine how a person is moving based on its analysis, the CSAIL team said on its website.

The researchers foresee a myriad of practical ways RF-Capture can be used in the real world.

“We’re working to turn this technology into an in-home device that can call 911 if it detects that a family member has fallen unconscious,” MIT professor Dina Katabi, director of the Wireless@MIT center, said in a statement. “You could also imagine it being used to operate your lights and TVs, or to adjust your heating by monitoring where you are in the house.”

And it can be used in the world of fantasy, too.

“Today actors have to wear markers on their bodies and move in a specific room full of cameras,” MIT PhD student Fadel Adib said. “RF-Capture would enable motion capture without body sensors and could track actors’ movements even if they are behind furniture or walls.”

It could also be incorporated in gaming interfaces, creating technology way beyond current motion-sensing systems like Nintendo Wii or console add-ons like Microsoft Kinect.

“The possibilities are vast,” Adib said. “We’re just at the beginning of thinking about the different ways to use these technologies.”

Adib is the lead author and Katabi a co-author of a new paper on the technology that has been accepted to the SIGGRAPH Asia conference taking place in Kobe, Japan in November.

RF-Capture uses a compact array of 20 antennas to transmit the wireless signals ‒ yet it emits just 1/10,000 the amount of radiation given off by a standard cell phone.

The team is also working on another wireless product called Emerald that would detect, predict and prevent falls among the elderly, which they presented to President Barack Obama during the White House’s first annual Demo Day in August. The device would also call 911 if it detects an unconscious family member.

“In the same way that cellphones and WiFi routers have become indispensable parts of today’s households,” Katabi said, “wireless technologies like this will help power the homes of the future.”