Contactless respiration measurement system using 25-kHz spatial ultrasound Doppler sensor

Respiration is an important vital sign to detect abnormalities in the respiratory organ. However, conventional respiration sensors require contact with the human body, which poses challenges in terms of ease of use and infection control. In this study, we proposed a noncontact method for measuring respiration using ultrasound. We applied the proposed method to a seated subject wearing clothes and evaluated the accuracy of the respiration measurement. The results showed that the RMSEs of the respiration interval under the conditions of 20 cm, 30 cm, and 50 cm were 61.08 ms, 84.89 ms, and 110.98 ms, respectively.