Millimeter-Wave Radar Measures Heartbeats Remotely

A novel sensing system based on spread-spectrum radar technology can measure heartbeats remotely, in real time, and with as much accuracy as an electrocardiograph.

Developed by researchers at Kyoto University (Japan), and Panasonic (Osaka, Japan), the remote sensing system combines radar technology with a heartbeat interval estimation algorithm that identifies diverse signals emanating from the body, isolate heartbeats from the composite radar signal, and calculate their intervals. According to the researchers, the technology could allow for the development of “casual sensing,” for instance by taking measurements as people go about their daily activities, such as going to bed or getting ready to start the day.

Although most conventional systems use either continuous waves or impulse-radio systems for remote vital monitoring, continuous waves suffer from non-stationary clutters, while impulse-radio systems cannot detect heartbeats. The researchers therefore used an ultra-wideband radar system with a moderate fractional bandwidth, resulting in both the suppression of clutters and high sensitivity in measuring accurate heart rates even in a dynamic environment. A study describing the concept was published in early 2015 in IEICE Electronics Express.

“The body sends out all sorts of signals at once, including breathing and body movement; it's a chaotic soup of information. Our algorithm differentiates all of that," said lead author Prof. Toru Sato, PhD, of the communications and computer engineering departments at Kyoto University. “Now that we know that remote sensing is possible, we'll need to make the measurement ability more robust so that the system can monitor subjects in various age ranges and in many different contexts.”

“Taking measurements with sensors on the body can be stressful and troublesome, because you have to stop what you’re doing. What we tried to make was something that would offer people a way to monitor their body in a casual and relaxed environment,” added Hiroyuki Sakai, a researcher at the Advanced Technology Research Laboratories at Panasonic. “The added convenience of remote sensing will be an incentive for people to monitor their health status for their own benefit.”

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Kyoto University
Panasonic