The idea of using microwaves for human body sensors may be just a bit unsettling – think of the microwave oven. However, the device created by Atsushi Mase and Daisuke Nagae of Kyushu University (Japan) uses very low radiation microwaves. It’s a form of RADAR, RF (radio frequency), or Doppler sensor…common enough technology. What’s unusual is the work the researchers have done with the software that analyzes the reflected microwaves. By using sophisticated signal processing algorithms (programming that picks apart the microwave signals and removes all the ‘clutter’), the random movements of the body are filtered out, leaving only the minute movement of the chest caused by a beating heart and breathing lungs. This new sensor can monitor the heart rate without wires and while the person is moving.
Presented in the journal Review of Scientific Instruments [Measurement of heart rate variability and stress evaluation by using microwave reflectometric vital signal sensing] the researchers show that they are able to detect changes in the heart beat in (almost) real time. This is a first step in using a combination of radio waves and signal processing to develop information about human vital signs. It means, when the techniques are eventually commercialized, that patients undergoing treatment will not need to be tethered to electrodes.
As the authors say, this has many applications:
“We plan to apply the system to various conditions, including for clinical use — such as for the overnight monitoring of human vital signs — and as a daily health monitor, including detecting signs of sleepiness in drivers and preventing stress-related illnesses,” he says. In the future, the system could even be used as a security monitor to distinguish the subtle signs of stress in potential terrorists.
When a new piece of sensor technology includes “monitor potential terrorists,” it seems natural to also think about “monitor political dissidents” and “monitor business competitors.” This isn’t science fiction anymore.