Real time detection of milk’s spoilage using Au/GO bend SMF sensor based on localized surface plasmon resonance effect

Abstract

Potential of hybrid gold nanoparticles/Graphene Oxide (Au/GO) coated single mode fiber (SMF) sensor by exploiting localized surface plasmon resonance (LSPR) effect for detection of spoiled milk is studied. Various diameters of SMF’s cladding are prepared ranging from its original size, d=0.1250mm to d=0.1215mm. A mechanical polishing technique using sandpaper is applied to etch the cladding area in which results the SMF with diameter less than 0.1250mm. Hybrid layers of Au/GO are deposited onto the SMF via drop-casting technique by varies the number of layers of GO between one to five layers, meanwhile Au nanoparticles are kept constant at one layer. To generate LSPR, light with excitation wavelength of 1310nm and 1550nm are transmitted at the first end of Au/GO coated SMF resulting in strong scattering and extinction spectra. The fiber is bend about 8cm in diameter to produce evanescent waves around it. To investigate the sensitivity of sensor in detecting milk’s spoilage condition, the Au/GO bend SMF sensor is immersed into the milk’s solution which has been exposed to the environment for 24 hours, 48 hours and 72 hours. The maximum optical power response, ΔP%=6.85% is obtained when the one layer of Au/GO coated bend SMF had been immersed into the milk solution with exposure time of 24 hours. The values of ΔP% decrease about 3.50% and 2.00% respectively with the increment of exposure time at 48 hours and 72 hours. These results indicate the sensing ability of our proposed sensor to detect different levels of spoiled milk as the exposure time increased. The output of this study validates the main role of LSPR effect in enhancing the sensitivity of Au/GO bend SMF sensor for real time detection of milk’s spoilage.