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Proceedings Paper

Studies on measurement of chloride ion concentration in concrete structures with long-period grating sensors
Author(s): Jaw-Luen Tang; Tsung-Yu Chiang; Hsiang-Ping Chang; Jian-Neng Wang
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Paper Abstract

We report the development and demonstration of a simple and low-cost long-period grating (LPG) sensor for chloride ion concentration measurement in concrete structures. The LPG sensor is extremely sensitive to the refractive index of the medium surrounding the cladding surface of the sensing grating, thus allowing it to be used as an ambient index sensor or chemical concentration indicator with high stability and reliability. We have measured chloride ion levels in a concrete sample immersed in salt water solution with different weight concentration ranging from 0 % to 20 %, and results showed that the LPG sensor exhibited a linear decrease in the transmission loss and resonance wavelength shift when the concentration increased. The measurement accuracy for concentration of salt in water solution is estimated to be 0.6 % and the limit of detection for chloride ion is about 0.04 %. To further enhance its sensitivity for chloride concentrations, we have coated gold nanoparticles on the grating surface of the LPG sensor. The sensing mechanism is based on the sensitivity of localized surface plasmon resonance of self-assembled Au colloids on the grating portion of the LPG. With this method, a factor of two increases in sensitivity of detecting chemical solution concentrations was obtained. The advantage of this type of the sensor is relatively simple of construction and ease of use. Moreover, the sensor has the potential capability for on-site, in vivo, and remote sensing, and has the potential use for disposable sensors.

Paper Details

Date Published: 11 April 2006
PDF: 11 pages
Proc. SPIE 6174, Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, 61743R (11 April 2006); doi: 10.1117/12.658900
Show Author Affiliations
Jaw-Luen Tang, National Chung Cheng Univ. (Taiwan)
Tsung-Yu Chiang, National Chung Cheng Univ. (Taiwan)
Hsiang-Ping Chang, National Yunlin Univ. of Science and Technology (Taiwan)
Jian-Neng Wang, National Yunlin Univ. of Science and Technology (Taiwan)

Published in SPIE Proceedings Vol. 6174:
Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems
Masayoshi Tomizuka; Chung-Bang Yun; Victor Giurgiutiu, Editor(s)

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