Chitosan/PAA based fiber-optic interferometric sensor for heavy metal ions detection

An interferometric sensor with a no-core fiber (NCF) spliced between single mode fibers (SMF) and functionalized with chitosan (CS)/poly acrylic acid (PAA) self-assembled polyelectrolyte layers for the detection of heavy metal ion Nickel (II) (Ni2+), is proposed and experimentally demonstrated. The sensing scheme is based on interference of core and cladding modes to detect changes in refractive index induced by Ni2+ adsorption on the functionalized sensor. Wavelength shifts were measured real-time for the continuous monitoring of adsorption of Ni2+ at different concentrations. The proposed sensor exhibits a linear response in the concentration range upto 500 μM, with a Ni2+ detection sensitivity of 0.05537 nm/μM and concentration detection limit of 0.1671 μM.