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Sensors 2011, 11(12), 11871-11884; doi:10.3390/s111211871

Advances in SAW Gas Sensors Based on the Condensate-Adsorption Effect

Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China
* Author to whom correspondence should be addressed.
Received: 27 September 2011 / Revised: 24 November 2011 / Accepted: 19 December 2011 / Published: 20 December 2011
(This article belongs to the Section Physical Sensors)
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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.
Keywords: gas sensor; gas chromatography (GC); surface acoustic wave (SAW); threshold detection limit gas sensor; gas chromatography (GC); surface acoustic wave (SAW); threshold detection limit
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Liu, J.; Wang, W.; Li, S.; Liu, M.; He, S. Advances in SAW Gas Sensors Based on the Condensate-Adsorption Effect. Sensors 2011, 11, 11871-11884.

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