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Future trends in acoustic gas monitoring and sensing

A. G. PETCULESCU1,*

Affiliation

  1. Dept. of Mechanical Engineering, Northwestern University 2145 Sheridan Rd, Evanston, IL 60208, USA

Abstract

Traditionally, acoustic devices for monitoring gaseous environments have involved measuring the sound speed in the medium. However, measurements of sound speed alone do not always allow a quantitative analysis of the gas species present in the sensed volume. What has been habitualy omitted is the acoustic attenuation. The non-classical or relaxational attenuation of sound in fluids arises from the inability of internal molecular degrees of freedom (vibration, rotation, isomerism etc.) to fo low the acoustic fluctuations. This feature relates it directly to relaxation times, which are characteristic of the molecular species. Together with sound speed, attenuation can be used to obtain the effective specific heat of the fluid, which is the fundamental macroscopic footprint of all internal relaxation processes. It is the purpose of this paper to describe trends and chalenges in the development of the next-generation “smart” acoustic gas sensors. We outline, from physical principles, the operational “line of thought” that might be adopted in the processing units of future intelligent sensors to quantitatively detect and identify contaminant gases leaking into a host gaseous environment..

Keywords

Gas sensors, Acoustic devices, Sound attenuation, Inteligent sensor.

Submitted at: Oct. 14, 2005
Accepted at: Jan. 26, 2006

Citation

A. G. PETCULESCU, Future trends in acoustic gas monitoring and sensing, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 1, pp. 217-221 (2006)