Future ‘smart homes’ will passively monitor your breathing and heart rate

Researchers at MIT have developed a wireless sensing technology that passively monitors your breathing and heart rate — without touching your body. The system, called “Vital-Radio,” transmits a wireless signal and tracks how the signal is altered by motion in the environment, like the rising and falling of your chest, or skin vibrations caused by your heartbeat. In a recent paper, the scientists boasted that they can measure breathing and heart rate with a median accuracy of 99%, with machines that can ‘see’ through walls from eight meters away; these systems for tracking your vital signs may be commonplace in the ‘smart homes’ of the future.

Most vital sensors are cumbersome and intrusive, like nasal probes, chest bands, or special mattresses; oftentimes, the more comfortable the technology is, the less accurate its measurements. Vital-Radio does not require any ‘wearable’ technology — it transmits a low-power wireless signal, and measures the time it takes for the signal to reflect back to the device. The ‘reflection time’ depends on the distance of the object to the device, and changes as the object moves. In the image above, we see that when a person inhales, their chest expands and moves ‘outward,’ reducing the reflection time; when they exhale, their chest contracts ‘inward,’ increasing the reflection time.

In the past, wireless monitors of this kind have had difficulty distinguishing between moving objects, and became confused when there were multiple people in the environment. Systems for sensing movement have been in widespread use by rescue teams and the military — for example, a soldier can “see through a wall” to detect an ambush, or a first responder can sense the movements of a trapped victim through rubble. But these systems detect human beings by sensing motion caused by vital processes, rather than tracking and measuring the vital signs themselves. Vital-Radio’s innovation is the ability to ‘localize’ a signal and ‘isolate’ an individual in the environment, eliminating sources of interference (like noise or extraneous movements that mask the minute variations representing breathing and heart rate).

When someone is roaming around their house, the movement of their chest is impacted primarily by their walking — it no longer accurately represents their breathing and heart rate. The Vital-Radio looks for moments when its targets are “quasi-static,” the brief periods where they stop moving, to generate a graph of how the target’s vital signs fluctuate throughout the day. Vital signs are periodic — they appear at more or less regular intervals — whereas body and limb movements are irregular and unpredictable. Vital-Radio makes measurements in discrete time windows (in this study, windows of 30 seconds), in which it measures the periodicity of the reflected signal. If the periodicity is above a certain threshold, the computer concludes that the dominant motion is breathing and heart rate; otherwise, it discards the window.

The researchers considered a variety of potential uses for the technology. There are some obvious applications, like the ability to automate home systems, adapting lighting or temperature based on inferences about a person’s mood, or monitoring patients in an elderly care home. But difficult questions face any attempt to incorporate these systems into more ‘public’ places — for example, the scientists suggested that “a user walking up to a Vital-Radio enabled kiosk in an unfamiliar location (such as an airport) might receive customized assistance based on his stress level.” It’s nice to think of convenient, personalized kiosks… but it’s also easy to imagine, for example, the enthusiasm that counter-terrorism agencies might have for new ways of profiling ‘threats’ based on indicators of stress. These days, it’s hard not to be stressed out at the airport; then again, national security agencies don’t seem too concerned about the poor accuracy of their profiling techniques. So, how will these sorts of ambient monitoring technologies be regulated in the future? Stay tuned.

Originally published at www.sherbit.io.

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