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Proceedings Paper

Hydrazine concentration fiber optic reversible sensor
Author(s): Alfred Andrawis; Yuelin Peng; XingZhong Yan; Barun Ranjitkar
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Paper Abstract

This paper reports the development of a reversible fiber optic leak sensor capable of detecting the presence and the concentration of traces of hydrazine. The sensor operates in the lowest attenuation wavelength range of commercial silica fibers. The sensing material utilized in this sensor is a mix of organic compounds that contains pentacenediquinone (PDQ) as an active sensing element. The index of refraction of this mix is adjusted to closely match that of fiber's silica core. In the absence of hydrazine this mix exhibits a weak absorption in the near-infrared. When the PDQ reacts with hydrazine, oxygen atoms from the PDQ are replaced by a molecule of hydrazine resulting in water as a by-product. This replacement significantly increases the absorption of the mix specifically at wavelength between 1310 and 1430 nm. This absorption was found to be proportional to hydrazine gas concentration. The reaction however is a self-reversible i.e. in the presence of water; the by-products of the reverse reaction would be PDQ and hydrazine. A modified cladding fiber sensor was fabricated by replacing part of cladding with the PDQ sensing mix. Due to evanescence-wave absorption by the modified sensing cladding, the optical signal passing through this sensor exhibited a reversible intensity change in the presence hydrazine at different concentrations. Sensor's percentage response magnitude and response time were found to be proportional to HZ gas concentration. Hence, in addition to low loss operating wavelength advantage, this sensor is capable not only to detect HZ presence of but also its concentration.

Paper Details

Date Published: 17 May 2011
PDF: 4 pages
Proc. SPIE 7753, 21st International Conference on Optical Fiber Sensors, 77535A (17 May 2011); doi: 10.1117/12.886074
Show Author Affiliations
Alfred Andrawis, South Dakota State Univ. (United States)
Yuelin Peng, South Dakota State Univ. (United States)
XingZhong Yan, South Dakota State Univ. (United States)
Barun Ranjitkar, South Dakota State Univ. (United States)

Published in SPIE Proceedings Vol. 7753:
21st International Conference on Optical Fiber Sensors
Jacques Albert; Wojtek J. Bock, Editor(s)

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