Noncontact Visualization of Respiration and Vital Sign Monitoring Using a Single Mid-Wave Infrared Thermal Camera: Preliminary Proof-of-Concept.

Infrared thermal cameras can noninvasively measure the surface temperatures of objects and are widely used as fever-screening systems for infectious diseases. However, body temperature measurements alone are often insufficient for identifying people with infections. To address the inherent limitations of fever-based screening, this study aimed to develop analytical methods that enable multi-vital sensing alongside body temperature measurement using a single mid-wave infrared (MWIR) camera. Respiratory parameters were assessed by visualizing exhaled airflow based on MWIR absorption by carbon dioxide, whereas the heart rate was estimated from subtle temperature fluctuations captured using high thermal resolution. The experimental results validated the proposed method, showing that the developed system achieved good agreement with reference measurements; the respiratory rate, heart rate, and body temperature showed strong correlations (r = 0.864-0.987) and acceptable limits of agreement in Bland-Altman analyses. The exhalation volume was quantified from the visualized airflow and was found to align with the expected physiological ranges. These results demonstrate that noncontact multi-vital sensing can be achieved using a single MWIR camera, without the need for complex instrumentation. The proposed method holds promise for high-precision infection screening, remote health monitoring, and in-home physiological assessment.