Fabrication of an evanescent-field fibre optic biosensor in the development of an online bacteria detection system

Optical fibres are fast gaining popularity as biosensors in the field of pathogen detection. This is due to their low cost, high accuracy, high efficiency and rapid detection time. This study aims to optimise the benefits of optical fibres to explore the fabrication of an online bacteria detection system. Escherichia coli (E. coli) was the bacteria of interest as its presence in water supply networks is an indicator of faecal contamination. This study focused on the functionalisation of fibre optic cables. Fibres are functionalised using the 3-aminopropyl triethoxy silane (APTS) followed by glutaraldehyde (GA). The bacterial probes chosen for this study were FITC-conjugated E. coli antibodies. A total of six techniques of antibody immobilisation were experimented with. The 6 techniques were surface application with Petri dish, surface application with fibre tray, surface application with glass cover, immersion, immersion with rotation and immersion with agitation. An epi-fluorescence microscope was used to observe the bacteria capture on the surface of the glass cores. However despite systematic and comprehensive experiments, the 6 techniques failed to create reproducible results of bacteria capture. An X-ray photoelectron spectroscopy test was conducted to deduce the surface modification processes of each stage of the functionalisation process. The results concluded that there was an issue with the glutaraldehyde functionalisation step. Recommendations were made to fulfil the advancement of the development of the online bacteria detection system.Bachelor of Engineering (Environmental Engineering