Wearable sensors to evaluate stress and enhanced assisted rescue response

Firefighting is a physically and psychologically demanding profession that exposes individuals to extreme operational stress. To support decision-making in real time, the Safefire project developed and validated a chest-worn wearable electrocardiogram (ECG) system designed to continuously monitor physiological responses and assess stress in firefighters under realistic conditions.In this context, this dissertation evaluates the device performance across non-operational, simulated, and real operational scenarios, with a focus on robust signal acquisition, algorithmic processing, and accurate stress assessment.

Using vests with MOVESENSE sensors and two electrodes placed bilaterally on the lower chest, ECG signals were acquired from 46 firefighters and IST students, during physical exertion and stress-inducing activities. To mitigate noise and motion artifacts, the data-processing pipeline integrated automated R-peak detection with real-time signal-quality validation. User evaluations indicated overall satisfactory comfort and usability, with minor issues related to body awareness and device stability.

Two textile materials (MDPF and MPPAF) were tested for the electrode areas. Both displayed significant reductions in signal quality under repeated wash and operational use. Physiological analysis confirmed that heart rate variability (HRV) indices reliably reflected changes in activity intensity, and enabled differentiation between physical effort and psychological stress through a corrected RMSSD parameter.

Overall, the findings confirm the feasibility of integrating real-time signal-quality monitoring and stress assessment in wearable ECG systems for high-risk environments, while highlighting ongoing challenges related to comfort, durability, and consistent signal acquisition.