US EPA

6872403 

Journal Article 

Optical Fiber Refractive Index Sensor for Chloride Ion Monitoring 

Lam, CCC; Mandamparambil, R; Sun, T; Grattan, KTV; Nanukuttan, SV; Taylor, SuE; Basheer, PAM; , 

2009 

1 

IEEE Sensors Journal
ISSN: 1530-437X
EISSN: 1558-1748 

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 

PISCATAWAY 

525-532 

10.1109/JSEN.2009.2016597 

WOS:000266878400005 

The development of a reflective, gold-coated long-period grating-based sensor for the measurement of chloride ions in solution is discussed. The sensor scheme is based around a long-period fiber grating (LPG)-based Michelson interferometer where the sensor was calibrated and evaluated in the laboratory using sodium chloride solutions, over a wide range of concentrations, front 0.01 to 4.00 M. The grating response creates shifts in the spectral characteristic of the interferometer, formed using the LPG and a reflective surface on the distal end of the fiber, due to the change of refracting index of the solution surrounding it. It was found that the sensitivity of the device could be enhanced over that obtained from a bare fiber by coating the LPG-based interferometer with gold nanoparticles and the results of a cross-comparison of performance were obtained and details discussed. The approach will be explored as a basis to create a portable, low-power device, developed with the potential for installation in concrete structures to determine the ingress of chloride ions, operating through monitoring the refractive index change.