Construction and evaluation of the fiber-optic sensor system for chemical vapor detection
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Publication Details
Author list: Kittidechachan M., Sripichai I., Supakum W., Thuamthai S., Angkaew S., Limsuwan P.
Publisher: Trans Tech Publications
Publication year: 2008
Volume number: 55-57
Start page: 509
End page: 512
Number of pages: 4
ISBN: 9780878493562
ISSN: 1022-6680
Languages: English-Great Britain (EN-GB)
Abstract
The fiber optic sensor system for chemical vapor detection was desiged and constructed. The system consisted of three parts; the optic unit, the fiber-optic sensing head and the flow controlling unit. The optic unit included a He-Ne laser source which lazes a red laser into an aligned optical fiber, a photo detector, and a signal processing with computer interface controlled by the Labviewฎ program version 7.1. The sensing head was made of a polyaniline thin film coated onto the de-cladded section of an optical fiber covered by a gas mixing cell. The concentration of measured gas was controlled by varying nitrogen gas flow rate. The nitrogen flow controller was set-up to obtain vapor concentration in the range of 0.04 to 0.40 % v/v. Vapors of hydrochloric acid (HC1) and n-butyl amine (a weak base) were used to test the performance of the sensor system. It was found that output intensity increases with an increasing HC1 concentration and decreases with increasing n-butyl amine concentration. The response toward the amine vapor was faster than that of the HC1 vapor (23 seconds for n-butyl amine and 72 seconds for HC1). Experiments performed at various concentrations of amine vapor (between 0.04 to 0.21 %v/v) found that a higher concentration yields faster response time. ฉ 2008 Trans Tech Publications, Switzerland.
Keywords
Amine, Chemical vapor detection, Fiber-optic sensor, Polyaniline
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