Improving Touchless Respiratory Monitoring via LiDAR Orientation and Thermal Imaging

The importance of direct, touchless respiratory measurements in many areas—including microgravity environments, healthcare, sleep studies, and sports—is growing as more health discoveries are being made. Respiratory measurements can work as primary indicators of severe health issues. The most accepted methods for respiratory monitoring are capnography and pulse oximetry, which are used to measure respiratory rate and blood oxygenation levels, respectively. To a lesser degree, spirometry is used to roughly determine the volume of each breath exchange, and respiratory inductance plethysmography (RIP) is used to determine the movement of a subject's chest and abdomen during respiration. All of these sensors include some level of invasiveness, provide indirect measurements, require technical knowledge, and limit mobility, preventing them from being applied outside of a closely monitored setting. Our proposed solution circumvents these issues by providing non-invasive and robust respiratory monitoring by measuring tidal volume and respiratory rate remotely using LiDAR and thermal sensing. A system consisting of LiDAR and thermal sensors is used to determine both respiratory rate and tidal volume, giving the system the potential to replace conventional methods of respiratory monitoring. In this work, we enhance the LiDAR measurement by rotating the circular scanning device to better understand the posture of the body. In addition, prior respiratory monitoring systems used a single-pixel thermal camera, requiring the camera to be manually aligned and the human subject to wear a mask. In this work, we present a multi-pixel thermal camera to more fully automate the process and increase patient comfort. The multi-pixel thermal sensor may have additional medical benefits because respiration through the nose and mouth can be separately evaluated. In summary, the system presented in this work preserves the reliability of existing methods while providing more flexibility and comfort to the subject, requiring only basic technical knowledge, and directly measuring respiratory rate and tidal volume. This work contributes to a long-term goal of allowing constant remote sensing of respiratory rate, which will be beneficial in many applications, including manned space missions.