Vital-sign monitoring and spatial tracking of multiple people using a contactless radar-based sensor

Radar technologies represent an emerging key in healthcare. A radar-based sensor, in fact, can monitor the individual vital signs (heartbeat and respiration) of multiple people in a real enviroment, keeping track of individual people during daily activities (walking, standing up, sitting down, cooking, ...).

Jun 17, 2019
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The population aged 60 years and older has been steadily increasing worldwide. By 2050, the number of people aged over 60 years is expected to exceed 2 billions, about five times that in 1950. Moreover, the number of people aged over 80 will triple globally. More than 70% of people over 65 have two or more chronic health conditions (e.g. heart disease, lung disorders, sleep-apnea and somnambulism). The existing health care structures are nearing the point where they become an unsustainable burden to society. To provide good health care for all, technological and societal innovation seem the way to go. 

Although many medical devices exist for monitoring people in daily life, many create discomfort and are unpleasant for long-term use. People tend to dislike (or discontinue) wearing (and/or charging) them. Contactless vital signs monitoring without wearing a device is desirable but in practice this offers technological challenges: weak signals need accurate detection within practical distance ranges whilst reliably being distinguished from unwanted disturbance. This gets even more complicated in presence of clutter and when monitoring multiple randomly moving people.

Here, we demonstrate the feasibility of fully contactless radar-sensing (no body worn parts needed at all) of heartbeat and respiration on multiple people in a real world room setting, robust against moderate random body movements (moderate limb movements, desk work), whilst keeping track (one-dimensional localization/speed versus time) of individual persons during vigorous movement (walking, standing up, etc.). Our methodology combines magnitude and phase (Doppler) information to tackle issues that real environments impose. The same approach could be also used for other applications, including people counting, fall detection, activity level and human gait recognition.

Figure 1 | Vital signs monitoring experimental results. a, Vital signs (Doppler) signal extracted using classic phase extraction. b, Vital signs (Doppler) signal extracted using our approach. c, Comparison of the estimated respiration rate (RR) and heart rate (HR) with medical reference devices. d, Comparison of the estimated respiration rate (RR) and heart rate (HR) with medical reference devices in case of moderate random body movements.

Figure 2 | People tracking experimental results. a-b, Range and Range/Speed profiles, extracted with standard radar techniques (i.e., resolve the range/speed information), of a subject walking in the line of sight (LoS) of the radar. c, Extracted Range/Speed profile with our approach. d, Instant speeds measured using our algorithm and comparison of the calculated mean speeds and the expected (from reference) mean speeds. 

Read full article here: https://www.nature.com/articles/s41928-019-0258-6

In 2019, we presented at the International Solid-State Circuits Conference (ISSCC2019) a novel and compact radar transceiver, operating in the UWB radio band at 8 GHz, capable to track and detect the vital signs (heartbeat and respiration) of multiple subjects up to a distance of 15 meters. Its power consumption is below 1 mW, at least 100 times lower than the previous state-of-the-art. The transceiver complies with all the worldwide spectral regulations. Moreover, the transmitted power is well below the one of commercial systems (e.g., at least 100 times lower than Wi-Fi) making this radar safe for monitoring people 24/7. This radar, together with our innovative algorithms, represents a low-cost battery-powered solution for home and clinical environments.

https://ieeexplore.ieee.org/document/8662536

Imec has a proven track record in developing a broad range of top-notch radar sensors for different application fields, including the here discussed 8 GHz UWB radar for smart building applications, 79 GHz radar modules for automotive collision avoidance, and a single-chip 140 GHz radar for high quality vital signs detection and intuitive interactions, for example hand/finger gestures detection. Contact us if you are interested in one of these solutions.


Marco Mercuri

Researcher, Imec - Netherlands

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