抄録
We applied a newly developed high-speed ultrasonic gas sensor to a respiratory monitoring system. This sensor was developed based on the principle of amplitude attenuation described by gas kinetic theory in a gas medium. Since the sensor measures mean molecular mass without using a chemical reaction (i.e., using ultrasonic amplitude, a physical property), high-speed data acquisition has been realized for monitoring the respiratory gas-change process. Although the measurement of CO2 in respiratory gases using an infrared absorption detector has already been established as a standard monitoring technique, the detectors are bulky and the fastest sampling rate is 100 kHz. at best. The newly developed respiratory gas-monitoring sensor is small and can obtain respiratory data at a sampling rate of over 1 kHz. We compared our proposed ultrasonic gas sensor with a commercial infrared respiratory sensor (Nihon Koden: TG-920P), and found that newly developed sensor can detect temporal changes in concentrations of CO2 and H2O with much better fidelity than the commercial respiratory sensor.
