Use of polyethylene glycol coatings for optical fibre humidity sensing

Açıkgöz, Sabriye and Bilen, Bukem and Demir, Mustafa Muammer and Menceloğlu, Yusuf Z. and Skarlatos, Yani and Aktaş, Gülen and İnci, Mehmet Naci (2008) Use of polyethylene glycol coatings for optical fibre humidity sensing. Optical Review, 15 (2). pp. 84-90. ISSN 1340-6000 (Print) 1349-9432 (Online)

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Abstract

Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystal line structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed. (C) 2008 The Optical Society of Japan.
Item Type: Article
Uncontrolled Keywords: humidity; sensors; plastic fibre; optics; polyethylene glycol
Subjects: T Technology > TP Chemical technology > TP1080 Polymers and polymer manufacture
Divisions: Faculty of Engineering and Natural Sciences > Academic programs > Materials Science & Eng.
Depositing User: Yusuf Z. Menceloğlu
Date Deposited: 26 Oct 2008 19:35
Last Modified: 19 Jul 2019 12:54
URI: https://research.sabanciuniv.edu/id/eprint/9632

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