Cardiorespiratory monitoring using a mechanical and an optical system

A continuous monitoring of cardiorespiratory activity can play an essential role in the health prevention since the cardiovascular and ventilatory systems regulate several vital functions of the human body and adapt themselves in response to various stressors. Typically, early detection of cardiorespiratory irregularities is performed by monitoring respiratory and heart rate (RR and HR) at rest. Among several technological solutions, the most promising are based on mechanical and optical systems such as gyroscopes (GYRs) and accelerometers in inertial measurement units, and fiber Bragg gratings (FBGs) embedded into wearable and non-wearable items.In this work, we investigated the capability of a mechanical system (i.e., a GYR) and an optical system (i.e., a flexible sensor based on FBG) to perform the simultaneous RR and HR monitoring. The system placement varied according to the sensor type to ensure the best unobtrusive cardiorespiratory monitoring: the GYR was worn on the chest, and the FBG-based flexible sensor was placed on a chair in contact with the chest back. Results showed similar performances between the mechanical and optical systems when compared to a reference instrument (mean absolute percentage error -MAPE < 7.7% and 6.1% for HR and MAPE ≤ 0.23% and 1.7% for RR for the FBG and the GYR, respectively).