Contactless vital sign monitoring systems: a comprehensive survey of remote health sensing for heart rate and respiration in internet of things and sleep applications

With the coronavirus pandemic, companies and governments around the world have been investing millions of dollars in the development of contactless sensor technologies that minimize the need for physical interactions between patients and healthcare providers. This has led to rapid progress in healthcare research on innovative contactless technologies, particularly for infants and elderly individuals with chronic diseases that require continuous, real-time monitoring and control. The combination of sensing technology and wireless communication has emerged as a promising research area, as patients often find it unpleasant or anxiety-provoking to wear sensor devices, and physical contact can exacerbate the spread of contagious diseases. To address these issues, research has focused on sensor-less or contactless technology to send and analyse wireless signals to remotely monitor and measure vital signs without requiring physical contact or sensor devices. Herein, we have provided a comprehensive survey and study of non-invasive/contactless vital sign monitoring systems, particularly the heart rate and the respiration rate monitoring systems to achieve accurate and reliable measurements. We have found that there is a lack of a comprehensive comparison and analysis over existing contactless vital sign monitoring systems. Therefore, we first present and classify the existing non-invasive monitoring designs based on their approaches and techniques, and then compare them based on the performance and accuracy.