Optical fiber pH sensor based on lossy-mode resonances by means of thin polymeric coatings

This work describes the fabrication of an optical fiber sensor with spectral response to pH based on the deposition of a thin polymeric coating on an optical fiber core. If the thin polymeric coating has a high refractive index real part and a non-null imaginary part, this permits a coupling of ligh...

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Published inSensors and actuators. B, Chemical Vol. 155; no. 1; pp. 290 - 297
Main Authors Zamarreño, C.R., Hernáez, M., Del Villar, I., Matías, I.R., Arregui, F.J.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 05.07.2011
Subjects
acrylic acid
Actuators
Coatings
Layer by layer
Lossy mode resonances
Optical fiber
Optical fibers
pH sensor
polycyclic aromatic hydrocarbons
Polymeric coatings
Refractive index
Refractivity
Sensors
Swelling
wavelengths
Polymeric coatings
Lossy mode resonances
Layer by layer
pH sensor
Optical fiber
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Summary:This work describes the fabrication of an optical fiber sensor with spectral response to pH based on the deposition of a thin polymeric coating on an optical fiber core. If the thin polymeric coating has a high refractive index real part and a non-null imaginary part, this permits a coupling of light to the modes guided in the polymeric coating originating optical resonances. These resonances are named by some authors as lossy-mode resonances (LMR) or guided-mode resonances. Moreover, the location of the resonances in the optical spectrum varies as a function of the coating thickness and refractive index. Hence, the utilization of the well-known poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) pH sensitive polymeric coating that presents a variation of the thickness with the pH of the solution (known as swelling/deswelling behaviour) permits the fabrication of optical fiber pH sensors based on wavelength detection. The fabrication of ready-to-use devices requires considering several aspects such as the adequate polymeric coating thickness or the selection of the resonance to be monitored. As a result, LMR-based optical fiber pH sensors with accuracy of ±0.001 pH units and an average sensitivity of 0.027 pH units/nm within the range between pH 3 and pH 6 have been obtained after an adequate design.
Bibliography:http://dx.doi.org/10.1016/j.snb.2010.12.037
ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2010.12.037