Design and evaluation of a ubiquitous chest-worn cardiopulmonary monitoring system for healthcare application: a pilot study

Ambulatory recording of physiological data will provide us deep insight into the physical condition of patients and athletes, and assessing treatment effects and training performances. This study presents a miniature wearable cardiopulmonary monitoring system called “Smart Chest Strap,” which consists of an elastic band worn around the user’s chest with integrated sensors, a physiological signals acquisition unit, and a mobile phone. The physiological signals including electrocardiogram, respiratory inductance plethysmograph, and accelerations (ACC) are sampled, digitalized, stored, and simultaneously transmitted to a mobile phone via Bluetooth. A medical validation test with participants performing discontinuous incremental treadmill (0–12 km/h) exercise was conducted. The results indicate nearly perfect correlations (0.999, 0.996, 0.994), small mean bias (0.60 BPM, 0.51 BPM, 0.05 g), and narrow limits of agreement (±2.90 BPM, ±1.81 BPM, ±0.09 g) for heart rate (HR), breathing rate (BR), and ACC represented as vector magnitude units (VMUs). There is a general trend of decrease in accuracy, precision, and correlation for HR, BR, and VMU as velocity increases, but these validity statistics are all within acceptable error limits and clinically accepted. The findings demonstrate that the Smart Chest Strap is valid and will have wider applications in healthcare, sports, and scientific research areas.