Absorbance response of a graphene oxide coated U-bent optical fiber sensor for aqueous ethanol detection

Abstract

In this work, the dynamic change of the absorbance for aqueous ethanol detection based on a graphene oxide (GO) coated U-bent optical fiber sensor (UOFS) was investigated. The U-bent probe was fabricated by bending an unclad multimode plastic cladding silica fiber (nominally at 62.5/125 μm) into a U-shaped structure. GO film was coated on the surface of the U-bent probe using a dip-coating technique. Transmission electron microscopy (TEM), Raman spectroscopy and scanning electron microscopy (SEM) were performed to characterize the GO film. A comparison of absorbance spectra and the dynamic absorbance response of the UOFS with and without GO film towards aqueous ethanol with a concentration from 5% to 100% was carried out in a wavelength range from 500 to 800 nm. The UOFS coating with GO film exhibits higher resolution and sensitivity compared with that of the UOFS without GO film. In addition, the UOFS with GO film shows excellent repeatability and reversibility, and the response and recovery times are as short as 1–2 s.