Hydrogen peroxide sensing with microstructured optical fibres : fuel, wine & babies.

Abstract

The capacity to measure the concentration of hydrogen peroxide in solution is critical for many disparate application areas, including wine quality sensing, aviation fuel monitoring and embryology. This thesis covers work related to the development of a low-volume hydrogen peroxide sensor, utilising microstructured optical fibres to perform measurements on small (<20 μL) sample volumes. This work has used the interaction between the guided light and fluorescent molecules within the holes of microstructured optical fibres to perform detection. This interaction has been used firstly to optimise the sensing architecture, using photostable Quantum dots as a characterisation tool. This work also has potential biosensing applications, using the Quantum dots was fluorescent labels for antibody reactions. This thesis covers work related to lowering the effective detection limit using microstructured optical fibres to detect fluorescent molecules, utilising novel glasses and implementing a theoretical model to reduce the amount of background signal that is generated within the fibre. New candidates for fluorescent molecules in fibre are also examined, resulting in a further reduction of the minimum detectable concentration. The second use of this interaction with the guided light involved the use of fluorophores that react with hydrogen peroxide to produce an increase in fluorescence. This increase in fluorescence can then be observed by monitoring the signal from either end of the fibre. By establishing a calibration curve that gives an expected fluorescence signal for a given hydrogen peroxide concentration it is then possible to correlate the observed fluorescence with the concentration of hydrogen peroxide present within the sample. Additionally this thesis presents practical improvements to microstructured fibre dip sensors, including splicing the sensing fibres to commercial optical fibres as well as methods for mixing low volumes of liquids to enable rapid detection of target molecules.