Fiber-optic fluorescence sensor for dissolved oxygen detection based on fluorinated xerogel immobilized with ruthenium (II) complex

摘要

A fiber-optic sensor based on fluorescence quenching was designed for dissolved oxygen (DO) detection. The fluorinated xerogel-based sensing film of the present sensor was prepared from 3, 3, 3-tri-fluoropropyltrimethoxysilane (TFP-TriMOS). Oxygen-sensitive fluorophores of tris (2, 2'- bipyridine) ruthenium (II) (Ru(bpy)3~(2+)) were immobilized in the sensing film and the emission fluorescence was quenched by dissolved oxygen. In the sensor fabrication, a two-fiber probe was employed to obtain the best fluorescence collection efficiency and the sensing film was attached to the probe end. Scanning electron microscope (SEM), UV-Vis absorption spectroscopy (UV-Vis) and fourier transform infrared spectroscopy (FTIR) measurements have been used to characterize the sensing film. The sensor sensitivity is quantified by I_(deoxy)/I_(oxy), where I_(deoxy) and I_(oxy) represented the detected fluorescence intensities in fully deoxygenated and fully oxygenated environments, respectively. Compared with tetramethoxysilane (TMOS) and methyltriethoxysilane (MTMS)-derived sensing films, TFP-TriMOS-based sensor exhibited excellent performances in dissolved oxygen detection with short response time of 4 s, low limit of detection (LOD) of 0.04 ppm (R.S.D. = 2.5%), linear Stern-Volmer calibration plot from 0 to 40 ppm and long-term stability during the past 10 months. The reasons for the preferable performances of TFP-TriMOS-based sensing film were discussed.