A non-invasive ultrasonic gas sensor for binary gas mixtures

A non-invasive gas sensor has been fabricated for quantitative measurement of a specific gas in a binary mixture such as H2, He, etc. mixed in air, based on time of flight (TOF) measurements of the ultrasonic signal. A test gas with different concentration was mixed in air and its concentration was determined using the observed TOF data and a theoretically derived relation. The results were compared with the actually used values of gas concentration in the mixture, and a good agreement was found between them. The method can find potential use for various applications in different fields, such as chemical industry and medical diagnosis.