Motion Artifact Reduction for Respiratory Monitoring: A Multichannel Ultrasound Sensor for Diaphragm Tracking

The ability to assess the respiratory rate reliably is vital in the application of remote health monitoring. A newly developed pulmonary monitoring system based on diaphragm wall motion tracking is evaluated under human physical activity. Diaphragm excursions are tracked by a designed ultrasound sensory system utilizing three ultrasound PZT5 piezo transducers. We assess the accuracy and reliability of this system in monitoring the diaphragmatic function and its contribution to the respiratory workload. We also examine inertial and pulse-oximetry sensors as two alternative methods. Measurements are compared to a spirometer as the gold standard. The tests are designed in this study to investigate the performance of employed sensors in both the stationary and non-stationary human body situations. We conclude that by the direct tracking of the diaphragm motion, the proposed ultrasound system is fundamentally robust to motion artifacts. Outstanding results were obtained for the proposed system from six subjects in six different test models with an average sensitivity, specificity and false alarm of 89.7%, 93.1%, and 6.3%, respectively.