Contactless Methods For Measuring Respiratory Rate: A Review

Recent advances in understanding the importance of respiratory frequency ( f
_R
) as a sensitive marker of a variety of physiopathological stressors are fostering growing interest in respiratory monitoring. This interest is further stimulated by the ever-increasing efforts that companies are devoting to the development of systems measuring f
_R
. There are a variety of techniques based on different sensors and technologies for f
_R
monitoring. These techniques are commonly classified as contact-based or contactless, depending on whether the system which embeds the sensor is in contact with the body or not. This review is focused on the contactless methods for f
_R
monitoring. We have introduced the main fields of use where contactless respiratory monitoring is important and provided a taxonomy to classify the most popular contactless techniques for f
_R
monitoring. Finally, we have described the performances of the most popular methods, the main open challenges, and the main perspectives.