Communications of the ACM
Wireless Network Can Watch Your Breathing
University of Utah researchers have found that wireless signals can indicate if people in the area are breathing. The researchers surrounded a volunteer with 20 inexpensive, off-the-shelf wireless units, which sent 2.4 gigahertz radio waves around them. The units measured the signal strength four times a second, fast enough to measure changes caused by individual breaths.
Using 30 seconds of data, the system was able to accurately estimate the participant's breathing rate to within 0.4 breaths per minute. The researchers, led by Neal Patwari, concluded that the wireless signals bent around the participant's chest as it rose with each inhalation, causing them to travel a longer distance and decrease slightly in power.
The technology could allow participants to rest more easily during sleep studies, as they would not have to be connected to machines by wires and tubes. In addition, a previous study by Patwari found that a wireless network could be set up outside a home to track people as they move from room to room, which could be beneficial for law enforcement surveillance.
From New Scientist
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