Electrochemical sensors for integration on silicon

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Barry, Fiona
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University College Cork
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Water quality monitoring is crucial to ensure the safe consumption of drinking water by humans. It is of such importance that the UN has included a specific goal for the improvement of water and sanitation in their Sustainable Development Goals (SDG). According to the UN, a staggering 3 in 10 people are without access to safely managed drinking water. At present the standard method for water quality monitoring is by laboratory testing. These typically require transportation of the sample from source to the laboratory, additional reagents, and specialised personnel and equipment to carry out the analysis. In this thesis, electrochemical methods at micro-electrodes are explored and developed for reagent-free, point-of-care analysis that does not require the need for specialised training. The main goal of the thesis is to develop low-power micro-sensors for point-of-care analysis. To achieve this, interdigitated micro-electrodes were investigated wherein each comb of electrodes could be biased separately allowing for unique analysis opportunities. Discussed herein simulations of electrode geometries are used to establish the optimum design for the interdigitated electrode arrays. The fabricated interdigitated arrays are subsequently modified with nanoporous gold resulting in an increase in current for the detection of lead by 1.5-fold. These modified interdigitated electrodes successfully detected lead in 0.1 M acetate buffer pH 4.6 with a limit of detection of 0.43 ppb. However, issues arise when applying these electrodes to reagent-free tap water, where there is no discernible peak for lead seen below 50 ppb. To overcome this obstacle the interdigitated arrangement of the electrodes can be used to electrochemically control the pH of tap water without the need for additional reagents. This leads to the successful detection of lead in tap water to as low as 10 ppb.
Electrochemistry , Interdigitated arrays , Generator-Collector , Microelectrodes , Water quality
Barry, F. 2022. Electrochemical sensors for integration on silicon. PhD Thesis, University College Cork.