A Silver Nanoparticle Modified Etched Fiber Bragg Grating Sensor for Arsenic Detection

The global data on arsenic (As) contamination in drinking water and the severity of As exposure emphasize the utmost need for early and efficient detection of As in water. In this work, we report a quantitative optical detection of As in drinking water using silver nanoparticle (AgNP) functionalized etched-fiber Bragg grating (e-FBG) sensor. The selective attachment of As (III) to AgNP is applied here for the sensitive detection of As, which is exemplified as a Bragg wavelength shift ( $\Delta \lambda _{B}{)}$ in the functionalized e-FBG sensor. The detection limit is found to be 10 femtomolar (fM) with dynamic range up to 100 nanomolar (nm), which is less than the World Health Organization (WHO) standards for drinking water (not over 50.5 nm). The e-FBG sensor shows a good reproducibility (standard error < 10 pm), specificity, and sensitivity (86.13 pm/ $10^{-{1}}\cdot \text{M}$ ) to As in real time at ambient conditions. The quantitative As value, with a 94% recovery in tap water sample, makes the e-FBG sensor better than the other methods.