Development and Testing of Piezoresistive and Inertial-Based Chest Bands for Breathing Monitoring

This work proposes the development of two BLE-connected chest bands for monitoring breathing activity. The first relies on a custom strain sensor based on a piezoresistive fabric and a low-power conditioning and acquisition section. A microcontroller unit jointly processes the collected strain data with inertial ones provided by an integrated IMU to extract the respiration rate (RR). Also, the second band uses an inertial-based detection method through a dual-accelerometer approach for deriving the respiratory signal. In detail, two IMUs are placed on the user's chest and back for extracting the differential inertial signal, containing information related to the breathing activity regardless of the body movements. Both chest bands integrate a BLE module to remotely transmit the acquired information to a host device. Several tests were carried out to determine the performances of the two respiratory monitoring systems. The performance comparison demonstrates the effectiveness of the dual-inertial solution, obtaining a −0.4 BrPM mean difference (MD) and +1.21 and −2.01 BrPM limits of agreement (LoA).