Researchers have developed a new technology that can remotely measure many physiological signals such as heart rate and breathing. The technology can even measure people’s heart rate as they move around in a dark room and assess vascular health.
Medical researchers and clinical practitioners want to be able to measure numerous physiological signals remotely, including measuring the heart rate and breathing of a person moving around a room.
Another great desire is being able to assess vascular health. Researchers have developed a technology that can do these things.
Comprising radar and a metasurface, the technology enables the physiological signals from the body to be measured very precisely.
The technology can be used remotely, even when there are obstacles in the way, or incorporated into a wristwatch or in clothing to enable much more precise measurement.
“There is considerable interest in continuously measuring a person’s heart rate and breathing without requiring a device to be attached, and we have now developed this,” explains Rifa Atul Izza Asyari, a researcher behind the study and PhD fellow, Maersk McKinney Moller Institute, University of Southern Denmark.
The research has been published in IEEE Sensors Letters.
Discovery patented
A metasurface is a surface that is usually constructed like a printed circuit board so that it has some electronic properties and some conductive elements.
The elements in the printed circuit board are positioned such that the metasurface can react when electrical waves hit the surface – in this case radar waves.
In the technology developed by the researchers, the metasurface can reflect these radar waves or focus them on a person’s skin and can then measure heart rate, breathing or movement when the waves are reflected back from the surface.
The innovation is to use a metasurface to focus a radar signal with the aim of increasing the its sensitivity so that it can measure heart rate and breathing remotely without being in contact with the skin.
“There are various signal sources. The signal for measuring heart rate is stronger on the chest than on the shoulder. Therefore it makes sense to focus the radar beam at the chest to very precisely measure a person’s heart rate. That is the main idea and also what we have patented,” says Daniel Teichmann, another researcher involved in the study and Professor, Maersk Mc-Kinney Moller Institute.
Since radar waves do not see or physically contact anything but can pass through obstacles, the technology is particularly suitable for measuring the heart rate of a person who is moving around a room or wearing clothes.
“Although combining radar and metasurfaces is not new, using it in this way for biomedical applications is new,” adds Daniel Teichmann.
Assessing vascular health
The researchers have developed several prototypes of their new device, including one for measuring heart rate remotely by focusing a radar beam onto a person’s chest. Another prototype measures heart rate on the wrist.
Devices already exist that can measure heart rate on the wrist, but the researchers’ prototypes can do this much more precisely and can also assess vascular health through the heart rhythm.
“Since we can focus our measurements of the heart rate and rhythm, we can increase the precision for higher diagnostic value. The strength of the heart rhythm but also the shape of the heart waves can contain more diagnostic information. This shows how elastic the vascular system is and can give an indication of a person’s cardiovascular health,” explains Rifa Atul Izza Asyari.
Can be wearable
A brilliant feature of the researchers’ metasurfaces is their extreme thinness and flexibility. This allows them to be incorporated into clothing, enabling to measure heart rate and assess vascular health. Additionally, these metasurfaces can be integrated into radar smartwatches, offering another convenient method for continuous monitoring of physiological signals.
This could be useful in monitoring personal health or for people who are hospitalised and people who are doing sport activities. However, the researchers need to take additional steps before their invention is ready to take off.
Among other improvements, they would like to make the metasurfaces smaller and want to carry out more experiments with them.
“We want to measure what happens when we manipulate a person's haemodynamics. This will validate that the technology can be used to precisely distinguish between normal states and unhealthy states,” concludes Daniel Teichmann.
“60 GHz FMCW millimeter wave radar assisted with dual-layer wideband flexible metasurface for accurate wrist pulse monitoring” has been published in IEEE Sensors Letters. The Novo Nordisk Foundation supported the research.
