Acoustic wave devices to measure gas flow: Comparison between surface acoustic wave (SAW) and shear horizontal acoustic plate mode (SH-APM) oscillators
✍ Scribed by Dominique Rebière; Corinne Déjous; Jacques Pistré; Jean-Louis Aucouturier; Colette Tiret; Roger Planade
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 432 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0924-4247
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✦ Synopsis
In recent years there has been growmg Interest m usmg acoustic waves for a broad spectrum of physical and chenucal sensor applications In this paper we describe two types of acoustic flow sensors For both devices, mterdlgltal transducers (IDTs) on a plezoelectrlc substrate have been used to realize delay lines The substrate IS quartz with a SAW (SH-AFM) propagation direction along (normal to) the mstallograpluc X axts The delay hne, mounted m an oscdlator configurabon and heated at a constant power with a screen-pnnted resIstor, 1s placed m the path of the flowmg fluid Cooling caused by fluid motion induces a change m the oscdlator frequency The sensltmty of the two configuratIons (SAW and SH-APM) to flow rate at various heatmg power levels IS presented and discussed Takmg into account smphfied assumptions, we obtain an evaluation of the dtierent heat-loss sources (thermal conductIon, natural and forced convections) The Interest of the SH-APM oscdlator m terms of sensltmty and response time IS demonstrated Tlus IS all the more mterestmg as SH-APM devices are able to work m a liquid envtronment