Wearable systems for respiratory monitoring: solutions based on strain measurements

Respiratory variables potentially contain a wealth of fundamental information of the physiological status since they are sensitive to psychological, environmental and physical stressors. However, the knowledge of respiratory parameters can be considered an underutilized resource in the field of non-invasive physiological monitoring. Recent advances in wearable sensors are helping to overcome some of the historical barriers of continuous respiratory monitoring. Here we focus on two of the most popular and promising sensors used in this field: electrical resistance sensors (ERSs) and fiber Bragg grating sensors (FBGs). We report the working principle of these sensors and their potential value in the design of wearables for respiratory monitoring. We also report the experience of our research group on this topic by underlying the main components of systems based on the two mentioned sensors and underlying the ways to tackle some issues of these sensors by showing experimental experiences. We conclude with a discussion of challenges and opportunities for these sensors in the development of wearables for many fields of application.