Mechanism and sensitivity of Fe-C coated long period fiber grating sensors for steel corrosion monitoring of RC structures

The mechanism and sensitivity of long period fiber gratings (LPFG) corrosion sensor, which is made by coating LPFG with an inner layer of silver and an outer layer of Fe-C, are investigated in this study. Two silver and three Fe-C thicknesses were considered. Results indicate that a linear relationship is present between the change in the resonant wavelength and the mass loss of the outer Fe-C layer within certain ranges. The corrosion sensitivity and service life of LPFG corrosion sensor depend on the thickness of both silver and Fe-C layers.