Measuring heart and breath: BRAMS-Bio-Box (B3), a wearable open-source physiology recording platform

Psychology and social neuroscience study the biological basis of real-world interactive behaviors, such as dancing or playing music in groups. Autonomic nervous system reactivity, assessed through cardiac and respiratory signals, plays an important role in these behaviors. However, affordable, scientifically validated, research-grade devices for synchronous, real-time physiological monitoring of multiple individuals in natural settings remain scarce. We propose a wearable open-source physiological monitoring device, the BRAMS-Bio-Box (B3), that can record cardiac and respiratory signals simultaneously from multiple individuals. B3 can be built cost-effectively using open-source blueprints and software we provide to yield a transparent, flexible option for research-grade physiological data collection. We empirically validated B3 against a widely used reference device in nine participants performing various motor and guided-respiration tasks. Heart rate (HR) and heart rate variability (HRV) were derived from electrocardiographic (ECG) signals, while respiratory sensors were evaluated for respiration rate and the accuracy and consistency of exhalation event detection. B3 derived HR and HRV closely matched reference measures across tasks, with high quality ECG recordings and minimal data loss, except during vigorous arm swinging. Respiratory rate and pattern metrics, including exhalation peak timing, also showed strong agreement. The B3 thermistor accurately tracked respiration rate even at higher breathing frequencies, although minor timing offsets occurred during some guided respiration segments. Overall, B3 performed comparably to the reference system for cardiac and respiratory measures, offering an affordable, open-source solution for physiological monitoring in real-world interactive settings.