Double-knotted U-shaped spiral optical fiber probe for measuring glucose solutions

The study focuses on the glucose concentrations by an U-shaped spiral fiber optical probes device. In this article, we used zero-knotted and double-knotted U-shaped spiral fiber optical probes with 0.6 mm bending radius for measuring glucose solutions was investigated. The fiber optical probe is worked on the different concentrations of the glucose solution and obtain the effective refractive index changes. The principle theory underlying the probe is the whispering gallery mode (WGM). The experimental results show that the double-knotted transmission loss sensitivity can achieve 0.061 dB/% and the highest linearly was 0.99 at the same time. The indicated that the double-knotted U-shaped spiral optical fiber probe with small radius has good the resolution of glucose concentration measurements.