We have prepared a novel fiber-optic evanescent wave sensor (FEWS) for dissolved oxygen
(DO) detection. The sensor fabrication was based on coating a decladded portion of
an optical fiber with a microporous coating, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane
and n-propyltrimethoxysilane. The fluorophores were immobilized in the porous coating
and excited by the evanescent wave field produced on the core surface of the optical
fiber. The sensitivity of the sensor was quantified by the ratio of the fluorescence
intensities in pure deoxygenated (I (0)) and in pure oxygenated environments (I).
Results show that the quenching response of DO is increased with the enhancement of
the coating surface hydrophobicity using the presented hybrid fluorinated ORMOSILs.
The calibration curve of I (0)/I to [O(2)] is linear from 0 to 40 ppm and the detection
limit is 0.05 ppm (3sigma) with a short response time of 15 s for DO detection.