Fluorescence fiber optic temperature sensor based on fused upconversion luminescent nanoparticles

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Fiber optic sensors offer remote and precise measurement capabilities.
• Upconversion luminescence (UCL) exhibits temperature-dependent characteristics suitable for sensing applications.
• Developing novel sensing materials and techniques is crucial for advancing temperature measurement technologies.

Purpose of the Study:

• To propose and validate a new fluorescence fiber optic temperature sensor.
• To leverage the temperature-dependent fluorescence intensity ratio (FIR) of upconversion luminescence (UCL).
• To embed upconversion nanoparticles (UCNPs) within a fiber optic platform for sensing.

Main Methods:

• Fabrication of a sensing unit by embedding NaYF4:Er3+,Yb3+ upconversion nanoparticles (UCNPs) into a multi-mode quartz fiber using fiber fusion.
• Stimulation of UCL using a 980 nm laser.
• Measurement of FIR across a temperature range of 40 °C to 100 °C.
• Experimental validation and spectral analysis.

Main Results:

• The proposed sensor successfully utilizes the temperature-dependent UCL.
• The fluorescence intensity ratio (FIR) demonstrated a clear correlation with temperature, following Boltzmann distribution law.
• The temperature sensor achieved a sensitivity ranging from 0.0087 to 0.0144 K⁻¹.
• Experimental validation confirmed the sensor's design rationality.

Conclusions:

• A novel fluorescence fiber optic temperature sensor based on FIR and UCL has been successfully developed.
• The sensor shows potential for accurate temperature monitoring in the 40 °C to 100 °C range.
• The use of UCNPs embedded in quartz fiber offers a robust platform for advanced optical temperature sensing.