Functionalized Fiber End Superstructure Fiber Bragg Grating Refractive Index Sensor for Heavy Metal Ion Detection

Area of Science:

• Fiber optic sensing
• Chemical sensing
• Environmental monitoring

Background:

• Refractive index (RI) sensing is crucial for chemical analysis.
• Existing sensors may lack robustness or simultaneous multi-parameter measurement capabilities.
• Heavy metal ion detection in water requires sensitive and reliable methods.

Purpose of the Study:

• To present a novel superstructure fiber Bragg grating (FBG) fiber end sensor.
• To demonstrate its capability for refractive index (RI) and heavy metal ion detection.
• To evaluate the sensor's performance, including sensitivity, temperature cross-sensitivity, and robustness.

Main Methods:

• Fabrication of a superstructure FBG fiber end sensor.
• Characterization of RI sensing performance across a range of 1.333 to 1.470.
• Application of a chelating agent coating for heavy metal ion detection.
• Simultaneous measurement of RI and ambient temperature.

Main Results:

• The sensor demonstrated high sensitivity up to 230 dB/RIU in the RI range of 1.370 to 1.390.
• It successfully detected heavy metal ions at concentrations above 100 ppm.
• RI sensing was unaffected by temperature or strain, indicating robustness.
• The sensor is reproducible and capable of simultaneous RI and temperature measurements.

Conclusions:

• The developed FBG fiber end sensor is a promising tool for RI and heavy metal ion detection in aqueous solutions.
• Its robustness, reproducibility, and ability to measure RI independently of temperature make it suitable for environmental monitoring.
• The sensor's design offers a versatile platform for various chemical sensing applications.