The optical performance of a U-shaped optical fiber sensor for glucose sensing applications

This project demonstrated the development of a de-cladded U-shaped optical fibre used to measure optical performance and sensitivity in response to varying concentrations of glucose solutions. The optical fibre was fabricated by bending it into a U-shaped pattern with a curvature diameter of 1 cm and 2 cm. Subsequently, the cladding layer in the curved region was de-clad using a flame heating method for durations of 40 and 50 minutes. Optical characterization was conducted by transmitting a 1550 nm laser through the modified fibre that had dropped glucose solutions ranging from 1 mM to 8 mM. Changes in output power, due to refractive index variations in the glucose solutions, were detected using a photodiode. Scanning electron microscope (SEM) results revealed that the highest reduction in cladding thickness occurred at 2 cm curvature diameter with reductions of 4.58% and 5.34% for 40 minutes and 50 minutes heating, respectively. The optical response showed a linear decrease in output power with increasing glucose concentration. The highest sensitivity achieved was 2.5 μW/mM with R2=0.90 for the 1 cm curvature diameter with 50 minutes of burning. In contrast, the 1 cm curvature at 40 minutes of burning time produced a sensitivity of 1.05 μW/mM (R² = 0.99). De-cladded of the cladding layer enhanced sensitivity in curvature region with precisely to detect small changes in output power for different concentrations of glucose solutions. Overall, the integration of the de-cladded cladding layer and U-shaped patterns of optical fibre sensors apparently offers more sensitive sensing detection capabilities.