Design of pH Sensors in Long-Period Fiber Gratings Using Polymeric Nanocoatings

Author

Corres, Jesus M. ; Matias, Ignacio R. ; Del Villar, Ignacio ; Arregui, Francisco J.

Author_Institution

Electr. & Electron. Eng. Dept., Univ. Publica de Navarra, Pamplona

Volume

7

Issue

3

fYear

2007

fDate

3/1/2007 12:00:00 AM

Firstpage

455

Lastpage

463

Abstract

In this paper, two different pH sensors based on the deposition of nanometric scale polymeric films onto the surface of a long-period fiber grating (LPFG) have been studied and compared. An electrostatic self-assembled (ESA) method has been used to create sensitive films with an optimal overlay thickness. Two types of sensors have been designed: The first one is based on polyallylamine hydrochloride (PAH), polyacrylic acid (PAA), and the second one was done incorporating the pigment Prussian blue (PB) in the PAH/PAA matrix. A theoretical model of multilayer cylindrical waveguides based on coupled-mode theory has been used to predict the position of the attenuation bands as a function of the overlay thickness. Both sensors were tested and compared in terms of sensitivity and response time. A faster response was obtained with the introduction of PB particles in the polymeric matrix. Linear sensors in the pH range 4-7 were obtained, showing good repeatability and high sensitivity

Keywords

Bragg gratings; chemical sensors; fibre optic sensors; nanostructured materials; pH measurement; PAH/PAA matrix; coupled-mode analysis; coupled-mode theory; electrostatic self-assembled method; long-period fiber grating; multilayer cylindrical waveguides; nanometric scale polymeric films; nanophotonics; nanostructured materials; optical fiber sensors; pH sensors; pigment Prussian blue; polyacrylic acid; polyallylamine hydrochloride; polymeric matrix; polymeric nanocoatings; sensitive films; Electrostatics; Fiber gratings; Nonhomogeneous media; Optical fiber sensors; Pigmentation; Polymer films; Predictive models; Self-assembly; Transmission line matrix methods; Waveguide theory; Coupled-mode analysis; electrostatic self-assembly (ESA); long-period fiber gratings; nanophotonics; nanostructured materials; optical fiber sensors; pH sensor;

fLanguage

English

Journal_Title

Sensors Journal, IEEE

Publisher

ieee

ISSN

1530-437X

Type

jour

DOI

10.1109/JSEN.2007.891933

Filename

4100636