Tapered optical fibre coated with chitosan for lead (II) ion sensing

Abstract

This Letter reports a lead (II) ion sensor composed of a tapered multimode fibre (MMF) coated with chitosan. The diameter and length of the tapered fibre region is 20 µm and 1 cm, respectively. Tapered MMF is used because it is more flexible and compact compared with plastic clad silica. Chitosan is chosen as the sensing layer because it can absorb heavy metal ions due to its unique properties as polyelectrolyte and chelating agent. The refractive index of the chitosan layer changes as it absorbs lead (II) ion and this leads to an increase in the absorbance measured by the spectrophotometer. This is tested by immersing the sensor in a solution that contains lead (II) ion with different concentrations, from 0.2 to 1 ppm. The results show that the absorbance measured by the spectrophotometer increased as the concentration of the lead (II) ion increased. The sensor's average sensitivity is measured as 40.554 abs/ppm. This sensor is simpler compared with surface plasmon resonance-based lead (II) ion sensor because it does not require metal coating prior to the sensing layer coating.

Polysaccharides as the Sensing Material for Metal Ion Detection-Based Optical Sensor Applications

“…Figures 13 and 14 show the microfiber experimental setup in reflectance and absorbance mode, respectively. The first report on the application of CS with a tapered optical fiber for Pb 2+ ion sensing was published by Ibrahim and co-workers in 2016 [11]. The diameter of the core-cladding was reduced from 125 μm/62.5 μm to 20 μm and the length of the tapered region was 1 cm.…”

“…Chitosan possesses O-H, N-H and C-O functional groups, whereas carrageenan possesses O=S=O, O-H and C-O functional groups. These two materials have good potential in optical sensor applications with their own unique sensing performance [ 11 ]. An extensive review on the usage of chitosan for photonics and nanomaterials research, which highlighted optical material properties and mechanisms, is well documented in [ 12 ].…”

Optical fiber tip sensor for glucose-adulterated honey detection

“…Fiber optic sensor has attracted considerable attention in the new sensor systems as it offers numerous advantages due to its small and thin size, biological inertness in nature and the safeness due to absence of electric current at the sensing point [4][5][6]. Fiber optic sensors are being widely used as chemical sensor in measuring the concentration of ethanol [7][8][9][10], sucrose and sodium chloride solution [11], glucose [12][13][14][15], preservative in milk [16], adulterated edible oil [17] and determination of nitrate [18], cadmium [19], fluoride [20], copper [21], magnesium [22] and lead ions [23] based on their concentrations in water.…”

An Advanced Hand-Held Microfiber-Based Sensor for Ultrasensitive Lead Ion Detection

“…Many research studies have focused on achieving selective detection and a low detection limit (LOD). For instance, Ibrahim et al fabricated a tapered multimode fiber by replacing the removed cladding layer with chitosan to detect Pb 2+ solutions of different concentrations, ranging from 0.2 to 1 ppm (parts per million) . The approach was found to be much simpler compared to the surface plasmon resonance-chitosan coated-based Pb 2+ sensor since it does not require additional metal coating .…”

“…For instance, Ibrahim et al fabricated a tapered multimode fiber by replacing the removed cladding layer with chitosan to detect Pb 2+ solutions of different concentrations, ranging from 0.2 to 1 ppm (parts per million). 14 The approach was found to be much simpler compared to the surface plasmon resonance-chitosan coated-based Pb 2+ sensor since it does not require additional metal coating. 15 Another selective detection of Hg 2+ using tapered fiber was described by Feng et al, based on a structure-switching DNA sensing mechanism which exhibited several significant advantages such as low cross-interference in a complex environment, rapid sensing, reversibility, free of reagents, and a LOD of 1.2 nM.…”