Researchers have developed a new system that uses radar and a metasurface in a seat belt to monitor a driver’s heart rate and respiration. A researcher says that this can contribute to improving road safety both by improving research and by implementing it in everyday use.
Radar is increasingly used to measure various physiological parameters such as heart rate and respiration more precisely than a heart-rate monitor.
Radar detects changes in how electromagnetic waves are reflected in the body and can translate this into heart rate, pulse waveform and respiration.
Radar is widely used in measuring human physiology in various settings, and researchers have developed radar technology to be used in motor vehicles.
The technology uses an electromagnetic metasurface, which is artificial sheet material with sub-wavelength features. This is positioned in the seat belt and amplifies the signal the radar device emits and detects to measure the heart rate and respiration of the driver of a motor vehicle in real time.
This enables research on how drivers react physiologically in various road situations and can improve road safety by continuously monitoring the vital signs of drivers and detecting abnormalities.
The research behind the technology has been published in Sensors.
“This technology can measure the heart rate and respiration of anyone driving a motor vehicle without them having to wear or do anything. All that is needed is our technology in the seat belt, the driver using the seat belt and a small radar device located out of sight,” explains a researcher behind the study, Rifa Atul Izza Asyari, a PhD Fellow at the Maersk Mc-Kinney Moller Institute, University of Southern Denmark, Odense.
Novel use of existing technology
The technology uses radar to emit and receive signals and a metasurface in the seat belt positioned close to the driver’s chest to amplify the radar signals.
A metasurface is a structured, planar material designed similarly to a printed circuit board, with electronic and conductive properties. Its elements are precisely arranged to manipulate and process electromagnetic waves, such as electrical signals, that interact with its surface.
In the technology developed by the researchers, the metasurface in the seat belt focuses radar waves from a device on the dashboard onto the driver’s chest. This enables the radar to measure heart rate, respiration or movement as the waves pass through the metasurface, focus on the chest and then return to the radar device.
The innovatory aspect of the technology involves using the metasurface to focus radar waves with the aim of increasing the sensitivity of the radar so that it can measure vital signs remotely without being in contact with the skin.
Since radar does not need to be able to see anything or be in contact with anything and can pass through many materials, the technology is especially suitable for measuring the heart rate of a person in normal everyday situations – for example, driving a motor vehicle.
“The idea of using radar combined with a metasurface is not new, but using it in this way for biomedical applications and in motor vehicles is new,” says Rifa Atul Izza Asyari.
Measuring the status of blood vessels
The researchers previously developed other ways to apply their technology, including for wristwatches or with metasurfaces that are placed on the chest, using radar to remotely monitor people’s health status in a hospital or other healthcare settings.
This technology measures heart rate, pulse waveform and respiration more precisely than existing options. The technology is so precise that it can also measure the status of the blood vessels, and the higher precision greatly improves the diagnostic value.
“The pulse strength and the shape of the pulse waveform contain diagnostic information on how elastic the blood vessels are. This indicates the person’s cardiovascular health, and we can measure this while people are driving without them even having to be aware that their health is being monitored,” explains Rifa Atul Izza Asyari.
For research and self-driving cars
There are several aims behind precisely measuring the vital signs of drivers. Researchers aim to determine how drivers’ cardiovascular system reacts in various road situations, including in passing situations, road crashes and congestion.
The system provides crucial information on what is happening to drivers internally.
The technology can then become useful in everyday situations. This could be valuable for older drivers, since it can report that their cardiovascular system is normal in most situations, but if it reports something abnormal they should stop and ask for assistance rather than continuing to drive.
Another possible application is in self-driving cars, which are increasingly being used and could monitor the vital signs of passengers who need to do no more than buckle their seat belts.
“All these features can improve road safety. We are considering creating a spin-out company based on the technology so that it does not just remain a potential technology but is realised,” concludes Rifa Atul Izza Asyari.
