Optofluidic Sensor for Iron Detection Based on Inline Fabry–Perot Interferometer Fabricated by Femtosecond Laser Pulses and Selective Etching

Abstract

In this work, an inline Fabry-Perot interferometer (FPI)-based optofluidic sensor is demonstrated for iron detection in aqueous solution. The fiber structure consists of two fluidic channels across the fiber core, manufactured by using laser ablation with a femtosecond laser followed by chemical etching with buffered oxide etch (BOE) etchant. Following that, the FPI structure is functionalized with deferoxamine (DFO) that has strong affinity with iron ions. In the investigation, the FPI structure shows a linear sensitivity of 10.176 nm/ppm to the test analytes with different iron ion concentrations (0.1–0.5 ppm) and a limit of detection (LOD) of 0.0485 ppm. The proposed sensor is a potential candidate for in situ water testing and real-time monitoring of water quality, particularly for ground water applications.