Microwave sensors can detect changes in heart rate without electrodes by monitoring reflected microwaves from the human body. The microwaves scatter off the body and the sensor detects phase changes caused by small movements from breathing and the beating heart. Researchers developed signal processing algorithms to filter out random motions and detect heart rate changes in real time. They plan to apply this non-contact monitoring technique for clinical overnight monitoring of vital signs and daily health monitoring such as detecting driver sleepiness.

1. Microwave sensor detects changes in heart rate | ISweek - Industry sourcing
Current medical techniques for monitoring heart rate and other vital signs use electrodes
attached to the body, but these are impractical to use on patients that move around.
Plasma physicist Atsushi Mase, a scientist at Kyushu University in Japan, and colleague
Daisuke Nagae have developed a new monitoring technique that uses microwaves to
resolve the problem.
The system uses very weak microwaves to irradiate – and scatter off – the human body.
A microwave sensor then monitors the reflected waves, which change in phase in
response to motions of the body, including the regular displacement of the chest during
breathing or, the slight movement of the chest caused by the beating heart.
’The skin surface moves slightly, synchronising to respiration and heartbeat,’ said Mase.
Using signal processing algorithms and techniques to filter out the effects of random
body motions, Mase and Nagae were able to detect changes in heart rate in near real
time.
’We plan to apply the system to various conditions, including for clinical use – such as for
the overnight monitoring of vital human signs – and as a daily health monitor, including
detecting signs of sleepiness in drivers and preventing stress-related illnesses,’ added
Mase.
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