Single Mid-Wave Infrared Thermal Camera Enables Noncontact Vital Signs Monitoring

Infrared thermal cameras are widely used to measure surface temperatures and have become common tools for fever screening during infectious disease outbreaks. However, body temperature alone often provides limited information when identifying individuals with infections. Many infected individuals may not exhibit a fever, making temperature-based screening less reliable as a standalone method. Researchers are now exploring ways to enhance infrared screening systems by enabling them to measure additional physiological signals.

Researchers at Osaka Metropolitan University (Osaka, Japan) have developed a method that allows a single mid-wave infrared (MWIR) camera to measure multiple vital signs simultaneously. The approach enables noncontact monitoring of body temperature, respiratory activity, and heart rate using thermal imaging. The technique analyzes thermal signals captured by the camera to extract physiological information without requiring wearable sensors or other monitoring equipment.

To estimate respiratory activity, the system visualizes exhaled airflow by detecting the absorption of mid-wave infrared radiation by carbon dioxide in breath. This allows researchers to track breathing patterns and calculate respiratory rate. Heart rate was estimated by analyzing extremely subtle temperature fluctuations on the skin surface detected by the high-resolution thermal camera. These variations correspond to changes in blood flow associated with cardiac activity.

The experimental results demonstrated strong agreement with standard reference measurements. Respiratory rate, heart rate, and body temperature measurements showed high correlation and acceptable limits of agreement in Bland–Altman analyses. The system also quantified exhalation volume based on airflow visualization, with results consistent with expected physiological ranges.

The findings, published in Sensors, suggest that multi-vital monitoring can be achieved using a single infrared camera without complex instrumentation or direct patient contact. Such systems could improve infection screening by combining temperature checks with additional physiological indicators. Researchers believe the technology could also support remote health monitoring, hospital triage, and home-based health assessments where noncontact physiological measurement is beneficial.

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Osaka Metropolitan University