Gas concentration pattern analysis of the H<inf>2</inf>O-CO<inf>2</inf> vibration by high-speed ultrasound gas sensor for detecting human specific lung gas exchange

In this paper, we developed new real time human respiration analysis method with our proposed high time sampling gas concentration meter using ultrasound. Our proposed gas concentration sensor use 400 kHz ultrasound and realize 1 kHz gas concentration sampling speed for ppm level gas changes. This device reveals human specific about 50-200 millisecond H ₂ O-CO ₂ gas concentration exchange and this result could not analyze by previously proposed gas concentration measurement methods such as InfraRed, semiconductor gas sensor, GC-MS. We found the rapid gas exchange from H ₂ O to CO ₂ contained air was seen specific in human being and we revealed the reason from the anatomical analysis and the gas ventilation test. Firstly we described the proposed new ultrasound sound speed measurement method, the signal processing and the measurement circuit diagram. Next we analyzed human respiration gas variation patterns by developing gas mask type respiration sensor with 3 healthy subjects and medical symptoms such as asthma, hyperventilation, and bronchial asthma subjects. The millisecond level high-speed analysis of human respiration process will be useful for next generation healthcare, rehabilitation and sports science.