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Warren-Smith, Stephen Li, Jiawen Peng, Lu School of Physics, Chemistry and Earth Sciences 2021 https://hdl.handle.net/2440/138202 Distributed fibre sensors were proposed more than 40 years ago, with their primary applications in physical sensing for civil infrastructure monitoring. Based on optical frequency domain reflectometry (OFDR), this thesis extends distributed sensing to biomedical applications, with a focus on the detection of small particles. A high-resolution distributed sensing method has been proposed, in which an exposed-core fibre (ECF) is used to detect micro-scaled sized particles. While the ECF has been reported for chemical detection in the past with high sensitivity due to the axial evanescent field along the entire fibre length, this thesis further reveals spatial distributed information of the micro-scaled particles by using the OFDR technique. The proposed scheme offers a compact and all-in-fibre approach, which avoids bulky instruments and external collection optics. Based on both theoretical analysis and experimental results, spatial distributions of micro-scaled particles in one dimension to two dimensions are detected using the few-mode property of the ECF. The size characterisation of micro-scaled particles has also been demonstrated using machine learning algorithms based on the multimode property of the ECF. The ECF OFDR platform is also demonstrated as a useful tool for whispering gallery mode (WGM) excitation of spherical particles, where both Fano resonance and multi-particle (integrated in a single ECF) WGM excitation are demonstrated. The multi-particle WGM excitation opens opportunity to build multi-point sensors or lasers, and to study coupling effects resulting from multiple closely spaced resonators. Overall, this thesis reports the novel applications of using ECFs for distributed detection of small particles with a detectable size down to 10 μm and two-dimensional spatial resolution of several microns. The particle detection with both spatial distributions and size characterisation using fibre optics bridges the gap between fibre sensing and imaging, which brings insights towards in vivo cellular studies in the future. Thesis (Ph.D.) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences, 2022 en high spatial resolution distributed sensing micro-scaled particles optical fibre optical fibre sensing microstructured optical fibres label free High Resolution Distributed Sensing Using Exposed-Core Fibres Thesis This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsopen.access