A groundbreaking advance in health monitoring technology developed by researchers at the University of Glasgow could lead to a new generation of contactless medical devices.
The innovative system uses radar to accurately ‘listen’ to patients’ heart sounds, similar to how doctors use traditional stethoscopes. This new approach significantly improves upon previous methods that relied on measuring chest movements to determine heart rate.
The research team, led by Professor Qammer H. Abbasi and Dr Hasan Abbas from the James Watt School of Engineering, demonstrated their advanced signal processing techniques in a study published in the IEEE Journal of Biomedical and Health Informatics. By isolating and measuring the heart sounds of human volunteers, they achieved remarkable accuracy in contactless heart rate monitoring.
The system employs a 24GHz continuous-wave radar to transmit electromagnetic waves towards fully-clothed volunteers lying down. The reflected waves allow the researchers to measure chest movements and the sounds generated by the opening and closing of heart valves. This method closely resembles the way stethoscopes function in clinical settings.
The principles behind radar-based heart monitoring involve the Doppler effect and signal processing techniques. When electromagnetic waves encounter a moving object, such as a beating heart, the reflected waves experience a frequency shift proportional to the object’s velocity. This phenomenon is known as the Doppler effect.
In heart monitoring, the radar system transmits a continuous wave at a specific frequency (24GHz in this study). As the heart contracts and expands, it causes minute movements in the chest wall. These movements alter the frequency of the reflected radar waves, creating Doppler shifts that contain information about the heart’s motion and the sounds it produces.
Advanced signal processing algorithms are employed to extract the heart sound information from the reflected signals. These algorithms filter out noise, interference, and the larger-scale motion of the chest due to breathing. By isolating the Doppler shifts specific to the heart’s movement and sounds, the system can accurately determine the heart rate and potentially diagnose various cardiac conditions.
The key advantages of radar-based monitoring over traditional contact methods include:
- Non-invasiveness: No physical contact or wearable sensors are required to improve patient comfort and reduce skin irritation or infection risk.
- Continuous monitoring: Radar systems can provide round-the-clock monitoring without requiring frequent adjustments or replacements of sensors.
- Penetration through clothing: Unlike optical methods, radar waves can penetrate clothing, taking measurements without the need for direct skin contact.
As radar technology continues to advance, with increasing sensitivity and resolution, its applications in medical diagnostics are expected to expand significantly. The principles demonstrated in this study could be extended to monitor other vital signs, such as respiration rate and blood pressure, opening up new possibilities for comprehensive, non-invasive health monitoring.
To test their method’s effectiveness, the researchers collected heart sound and chest movement data from male and female volunteers over various time intervals and at different heart rate intensities. They simultaneously monitored the volunteers’ hearts using an electrocardiogram (ECG) machine, considered the gold standard for clinical heart rate measurements.
The results showed that the new system could measure heart sounds across all intensities with nearly 99% accuracy, with discrepancies from the ECG readings of less than one beat per minute. In comparison, the conventional chest movement measurements fell short of the ECG by 8 to 50 beats, depending on the heart rate intensity.
“Unlike camera-based patient monitoring technologies, radar preserves patient privacy by collecting only their vital signs and no information about their movements or activities,” explained Dr. Hasan Abbas. “The system we’ve developed could form the basis of a game-changing user-friendly healthcare technology in the future.”
Professor Muhammad Imran, head of the Communications, Sensing and Imaging Hub at the University of Glasgow, emphasized the potential impact of this research. “This paper shows that radar can be used to monitor heart sounds with remarkable precision, which could make it invaluable for use in clinical settings and at home in the future. We’re already looking at other ways to precisely read people’s other vital cardiovascular signs using this technique.”
The researchers believe the significant accuracy in contactless heart sound detection could unlock the technology’s full potential for continuous vital sign monitoring in critical situations. This refined technique for radar remote health monitoring could also facilitate the diagnosis of heart diseases in the future.
As sensing technologies advance, the prospect of non-invasive, round-the-clock patient monitoring becomes increasingly feasible. The development of this ‘radar stethoscope’ represents a significant step towards realizing the full potential of contactless health monitoring, offering a promising solution for improved patient care and disease diagnosis.
TLDR
Researchers from the University of Glasgow have developed a ‘radar stethoscope’ that accurately measures heart rate without physical contact – The system uses a 24GHz radar to detect heart sounds and chest movements – Advanced signal processing techniques isolate heart sounds and calculate heart rate with 99% accuracy compared to ECG – The contactless method improves upon conventional chest movement measurements and preserves patient privacy – The technology could enable continuous vital sign monitoring and facilitate heart disease diagnosis in the future
