Fluorescent Probe-Based Fiber Optic Sensor for Real-Time Monitoring of Chloride Ions in Coastal Concrete Structures

Area of Science:

• Materials Science
• Civil Engineering
• Chemical Sensing

Background:

• Coastal concrete structures face degradation from chloride ion penetration.
• Current chloride monitoring methods are inefficient and lack real-time capabilities.
• Corrosion accelerates due to chloride-induced passive film deterioration on rebar.

Purpose of the Study:

• To develop a novel fluorescent-probe-based fiber optic sensor for chloride ion monitoring in concrete.
• To enable real-time detection and early warning of chloride ingress.
• To overcome limitations of conventional chloride detection methods.

Main Methods:

• Utilized quinine sulfate as a sensitive fluorescent probe for chloride ions.
• Employed sol-gel and 3D-printing techniques for sensor fabrication.
• Conducted tests using concrete simulation fluid and cement mortar specimens.

Main Results:

• Achieved high sensitivity (>0.01 M) and accuracy (<3 mm penetration depth).
• Demonstrated real-time monitoring with 0.1% concentration sensitivity and 2.7 mm depth accuracy.
• Exhibited unique selectivity, unaffected by other ions at 10x concentrations.

Conclusions:

• The quinine sulfate-based fiber optic sensor provides effective real-time chloride monitoring.
• The sensor offers high sensitivity, selectivity, and a compact design for practical applications.
• This technology promises enhanced structural health monitoring for coastal concrete infrastructure.