| Summary: | Over the past decade, analytical chemists have been faced with a significant task to develop techniques and methodologies that are fully applicable to real-time sample analysis while significantly lowering per-sample and per-measurement costs. Such advancements are expected to make a great impact in many different fields ranging from environmental analysis to the health, security, and manufacturing industries. Ion selective electrodes (ISEs) are a class of chemical sensors that in recent years went through a renaissance and showed excellent potential as tools for routine environmental monitoring and clinical analysis. They are cheap to manufacture, show excellent selectivity and sensitivity, are easily miniaturised and can be connected to simple communication devices. However, due to several limitations such as presence of transmembrane ion fluxes or plasticiser exudation, their full potential has not yet been utilised. This calls for improvements in materials and methodologies used for the preparation of ISEs. Herein, significant improvements in lower detection limits of carbonate ISEs were achieved by conditioning the electrodes in the ionophore solution thus minimising/eliminating membrane ion fluxes. In addition, it was demonstrated that selectivity of ISEs can be enhanced by replacing traditional plasticisers with alternative materials such as ionic liquids (ILs). To further utilise the potential of ILs in ion sensing, 1,2,3-triazole based IL was covalently attached to the polymer backbone yielding a one component ISE. The inherent presence of iodide in the polymeric membrane reduced the need for conditioning thus allowing for direct determination of iodide in human urine samples. Similar approaches were undertaken to develop self-plasticised aluminium optical sensors in which an initially water-soluble fluorophore was copolymerised with methacrylate-based monomer. This prevented its diffusion from the membrane into the aqueous phase. Low detection limit, high selectivity and the possibility of miniaturisation makes them potential candidates for developing aluminium sensors for clinical analysis. This research demonstrates that by improving sensing methodologies as well as using novel materials for the preparation of ISEs and optical sensors, functional devices with excellent robustness, durability and reproducibility can be produced thus indicating yet unexplored avenues for further developments in sensing.
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