Scientists use Wi-Fi to detect moving bodies behind walls

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By Phi Tran Comment

WiTrack heart rate

MIT scientists have found a new use for Wi-fi: motion detectors. WiS is a low-powered Wi-Fi based system that works similarly to sonar and radar imaging.

WiZ is being developed at MIT by Dina Katabi, a professor in MIT’s Department of Electrical Engineering and Computer Science, and her graduate student Fadel Adib.  “We wanted to create a device that is low-power, portable and simple enough for anyone to use, to give people the ability to see through walls and closed doors,” said Katabi.

By transmitting Wi-Fi signals through walls, scientists basically have X-Ray vision capable of detecting moving bodies and even heart rates at 99% accuracy levels. This works because as Wi-Fi moves through space, only a fraction of the waves make their way back from their original transmitter. According to Adib, “If the person moves behind the wall, all reflections from static objects are cancelled out, and the only thing registered by the device is the moving human.”

While monitoring moving bodies through walls might sound suspicious – even creepy, the scientists pointed out that WiZ can be used for good. For example, WiZ can be used by parents to monitor babies from another room without installing a crib device or baby camera. Another use could be for search and rescue teams who are searching for missing persons or bodies that are alive but not audibly responsive. Since WiZ is so accurate and inexpensive, it’s feasibly good enough to replace health-trackers, which are prone to skin irritations and are generally inconvenient.