Localized surface plasmon resonance based U-shaped optical fiber probe for the detection of Pb2+ in aqueous medium

This work represents a detection technique of lead ion (Pb2+) in aqueous medium based on optical fiber sensor. U-shaped optical fiber is chosen for this work due to higher sensitivity and point of care capability. Oxalic acid functionalized AuNPs were coated in the sensing probe. Corresponding to variation in concentration of lead ion, output voltage, power and intensity are measured with respect to time using optical photo detector. From the linear fiting of curves, it is found that voltage, power and intensity response curve has limit of detection 1.87, 1.75 and 2.10 ppb, R-2 value of 0.98, 0.99 and 0.98 with the linear range is 1-20 ppb. Other heavy metal ions have negligible effect on this sensing element, thus affirming selectivity towards lead ion. Adoption of U-shaped probe with optical detector in lieu of spectrometer makes this sensor probe compact and cost effective.