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Contactless Measurement of Vital Signs with Radar Sensors

Figure 2: Operating principle of radar technology for vital sensing

and receives the reflected signal via the of the housings to meet the design require- Anonymous
Rx antenna (Figure 2). Generally, moving ments of consumers. The radar device analyzes only the modified
targets result in a Doppler shift, which can be echo of the signal it emits itself and is there-
measured by comparing the transmitted and Robust fore not dependent on any external signals. As
the received signals. This allows detection In addition, radar sensor functionality is a result, radar does not collect any personal
of the tiny movements of the chest caused barely impacted by surrounding conditions. data, such as images, sounds or videos. Thus,
by breathing and the heartbeat with highly For example, it continues to function reliably radar-based health-monitoring devices can
sensitive sensors like the Infineon XENSIV™ regardless of whether it is completely dark or be continuously used at home and in private
60-GHz radar sensors. Thanks to advanced very bright in the room or whether it is dusty, spaces without users having to fear violations
algorithms, the heartbeat and respiration rate foggy or humid. Hence, a radar sensor does of their privacy.
can be extracted accurately from the signal. not interfere with people’s daily lives. Thanks
This can also satisfy the requirements for to advanced signal processing, the sensor Energy-efficient
medical certification. can also differentiate between human and The low power consumption of only a few mil-
In the context of vital sensing, radar non-human targets, so small pets and other liwatts makes it possible to use the radar 24/7.
technology has five major advantages over sources of signal clutter can be ignored. Additionally, the typically radiated power is
previous technologies: It is unobtrusive,
robust, anonymous, energy-efficient and
small.
Unobtrusive
For vital sensing, radar technology has the
advantage that it hardly affects the patient.
The only requirement is that the user remains
within a certain distance of the device, typi-
cally within 1.5 meters. Preferably, the user’s
chest needs to be oriented toward the sensor,
but this is not mandatory. Because radar can
detect through non-conductive materials,
people can wear any kind of clothing or cover
themselves with a thin blanket. The same
feature gives engineers of radar-based devices Figure 3: At 4 × 4 mm, the Infineon BGT60UTR11AIP is the smallest 60-GHz radar
almost free choice in the material and shape sensor on the market.

www.eetimes.eu | MARCH 2023