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We demonstrate a reliable method to detect the concentration of Nitrate in water using an etched Fiber Bragg Grating (FBG) sensor. The sensor was etched using 48% Hydrofluoric (HF) acid solution to function as a chemical sensor and interact with Nitrates. The Bragg wavelength (λb) shifted due to the changes of Nitrate concentration. The sensitivity achieved by this sensor is 2.4 × 10-3 nm/ppm. The overall shift of the Bragg wavelength is 0.12 nm from 0-50 ppm.

Honey, a natural sweet substance and also a high-value foodstuff has been a target for adulteration. This paper reports the early stage development of optical fiber tip sensor using a standard single mode fiber for adulterated honey detection. The development of simple, sensitive and low-cost sensor for direct detection of adulterated honey is a considerable interest in this context. A pure stingless bee honey was mixed with glucose adulterant at different volume ratios for the adulteration process. By changing this chemical composition, the refractive index of the adulterated honey varied and Fresnel reflection occured at the interface between the fiber tip and the adulterated honey solution also changed. The average sensitivity achieved by this sensor is 0.29 dBm/% with linear regression value up 0.97. This shows that, the sensor has a potential in adulterated honey detection.

<p>Glucose must be carefully regulated to ensure its safety and quality. Nowadays, chemists often face difficulty to measure glucose concentrations as the current methods for the analysis are expensive and require complex procedures which have reduced the interest among chemists to use these techniques. This study evaluated the performance of a single mode optical fiber tip sensor for glucose detection. The sensing mechanism mainly depends on the Fresnel’s reflection that occurs at the flat fiber tip region while the sensor performance was evaluated based on its sensitivity and linearity. The sensor was tested in glucose solution at different concentration range; high range (0% - 14%), medium range (0% - 1.4%) and low range (0% - 0.14%). The sensor showed a good performance when sensing the glucose solution at high and medium concentration range with strong linearity of more than 90% and an average sensitivity of 0.0979 dBm/% and 0.1019 dBm/%, respectively. However, the low concentration range showed no significant changes during sensing. Based on the findings obtained in this study, the optical fiber tip sensor has the potential to be utilized for glucose detection and suitable for high and medium concentration range measurement.</p>