Abstract
The paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic-surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection. The Pt thin film was coated over an unclad core of an optical fiber (FO) using a DC magnetron sputtering technique, while the 4-NP responsive PANI layer was synthetized using a cost-effective electroless polymerization method. The presence of the electrolessly-grown PANI on the Pt-coated FO was observed by field-emission scanning electron microscopy and subsequently evidenced by energy dispersive X-ray analysis. These FO-SPR sensors with a demonstrated bulk sensitivity of 1515 nm/RIU were then employed for 4-NP sensing, exhibiting an excellent limit-of-detection (LOD) in the low picomolar range (0.34 pM). The proposed sensor’s configuration has many other advantages, such as low-cost production, small size, immunity to electromagnetic interferences, remote sensing capability, and moreover, can be operated as a “stand-alone device”, making it thus well-suited for applications such as “on-site” screening of extremely low-level trace pollutants.
Highlights
The paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic-surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection
FO-SPR sensors was evaluated by performing refractive index (RI) measurements in serial sucrose dilutions
Despite few theoretical attempts[20,21], this work reports for the first time on the fabrication of a reflectiontype FO-SPR sensor based on a Pt plasmonic layer and the determination of its performance indicators
Summary
The paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic-surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection. Different from the above-mentioned detection techniques, fiber optic – surface plasmon resonance (FO-SPR) sensing is a relatively novel biochemical method with the advantages of featuring a compact footprint, label-free detection and real-time monitoring capabilities, as well as offering the possibility to perform rapid and noninvasive measurements[10,11,12] Such a reflection-type FO-SPR sensor is commonly prepared by uncladding first a small portion at one end of the FO, and coating the exposed FO core by a plasmonic metal layer, typically. PANI is an organic polymer with excellent stability and physico-chemical properties in terms of high electrical conductivity, large electro-active surface, and unique combination of RedOx states and proton doping p rofiles[4,24] These particular features render PANI as an extremely responsive polymer to several molecular species, being so far successfully used in energy storage applications[25], pH monitoring[26], gas sensing[27] and pollutants detection including nitrophenol c ompounds[4]. This work represents a step forward in the fabrication of reliable FO-SPR sensors, with improved performance, and with extended functionality
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