Advances in SAW gas sensors based on the condensate-adsorption effect

A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2011-12, Vol.11 (12), p.11871-11884
Main Authors: Liu, Jiuling, Wang, Wen, Li, Shunzhou, Liu, Minghua, He, Shitang
Format: Article
Language:English
Subjects:
Adsorption
Chromatography
Chromatography, Gas
Condensates
Control theory
Feedback
Frequency stability
gas chromatography (GC)
gas sensor
Gas sensors
Gases
Models, Theoretical
Oscillators
Resonators
Sensors
surface acoustic wave (SAW)
Surface acoustic waves
threshold detection limit
Velocity
VOCs
Volatile organic compounds
Volatile Organic Compounds - analysis
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Summary:A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg.
ISSN:1424-8220
1424-8220
DOI:10.3390/s111211871