The application of a U-shaped whispering-gallery mode-based optical fiber sensor for glucose measurement

This paper presents a small U-shaped whispering gallery mode-based (WGM) optical fiber sensor used to sense differing glucose concentrations. This tubular U-shaped WGM sensor was fabricated by bending the radius of a single mode fiber to 0.75mm through a heating process, after which the fiber was packaged in a glass tube. The experimental results showed that the transmission dip loss variation of the sensor had a linear relationship with different glucose concentrations. The sensitivity of the U-shaped WGM glucose sensor was found to be 0.085 for glucose concentrations ranging from 6 %~38 %, while its linearity (R²) was 0.925. The results demonstrated that the proposed U-shaped WGM sensor has good potential for use in high-sensitivity glucose concentration sensing applications.