Liu, KunDong, LeiTittel, Frank K.2017-05-152017-05-152015Liu, Kun, Dong, Lei and Tittel, Frank K.. "Compact sound-speed sensor for quartz enhanced photoacoustic spectroscopy based applications." <i>Review of Scientific Instruments,</i> 86, no. 4 (2015) AIP Publishing LLC: http://dx.doi.org/10.1063/1.4918796.https://hdl.handle.net/1911/94255A compact sound-speed sensor based on a phase difference method was developed. The sensor employs a U-shaped stainless steel tube with two holes located on its front and back ends, which serves as a sound wave guide. The phase difference between the two holes was measured using two mini-microphones by means of a phase-sensitive detection technique. This method offers the advantage of eliminating the influence of signal fluctuations. The frequency of a sound source offered by a loudspeaker can be scanned between 1 kHz and 50 kHz. The slope of the phase difference as a function of frequency was obtained by scanning the frequency of the sound source. The speed of sound was retrieved from the rate of change of the phase difference. The performance of the sensor was evaluated over a wide range of speeds of sound from 260 m/s to 1010 m/s in different gas mixtures. The measured speed of sound was found to be in good agreement with the theoretical value for the sound-speed sensor.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1063/1.4918796