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Electrochemical materials and microfabrication for sensor devices
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Date
2025
Authors
Dixon, Ehren
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Publisher
University College Cork
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Abstract
An electrochemical sensor is an analytical chemistry device that can quantitatively detect the concentration of a target analyte by oxidising or reducing the analyte and measuring the resulting current. These versatile sensors can offer rapid, real-time, sensitive, selective and cost-effective detection of various chemicals, including metals, organic molecules, gases and biomolecules. Their design is also highly adaptable: electrode materials, size, surface modifications, and enzyme integration can be tailored to optimise detection for specific applications. This thesis presents the fabrication and optimisation of nanoporous copper (NPC) electrodes across macro- and micro-scale substrates, integrating this material into the microdisk array (MDA) platform to evaluate its potential as an electrochemical sensor and detecting analytes with catalytic affinities to copper. Fabrication involved preparing NPC electrodes using a sacrificial CuZn alloy technique, with the electrode’s structural and electrochemical properties characterised. Macro- and micro-scale substrates required distinct optimisations in the CuZn alloy’s fabrication, compositions, and etching times, resulting in unique NPC structures with varying attributes and improved surface areas.
NPC MDA sensors were then tested for the non-enzymatic detection of glucose, nitrate, lactate, and hexanal. Glucose was detected across relevant concentration ranges for bovine saliva catalytic oxidation in NaOH and pH-altered saliva, demonstrating high sensitivities, low detection limits, strong selectivity, and long sensor lifespans. Nitrate detection covered ranges found in Irish waters, employing nitrate reduction to nitrite in a pH-optimised acidic media, with minimal interference from most other species found in drinking water and a defined sensor lifespan when stored oxygen-free. Lactate detection relied on the alteration of NPC to an oxidised form to enable a more stable and linear response, while hexanal detection necessitated a new, unique sample holder and electrochemical set-up due to the analyte's volatility. Electrochemical techniques, including cyclic voltammetry (CV), chronoamperometry (CA), and material characterisation methods, confirmed the sensor platforms’ effectiveness and sensitivity, underscoring the potential of NPC MDA-based sensors for real-world applications.
This work establishes NPC microelectrodes as reliable, high-sensitivity platforms for non-enzymatic analyte detection, highlighting copper’s cost-effectiveness, ease of fabrication, and catalytic properties. The findings provide a foundation for future developments in NPC-based sensor technology, particularly for health diagnostics and environmental monitoring applications.
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Keywords
Electrochemistry , Electroanalytical chemistry , Research and development (R&D) , MEMS fabrication , Biosensors , Electrical Engineering , Bovine Health , Volatile organic compounds (VOC) , Glucose , Nanoporous materials , Materials science , Lactate , Nitrate , Hexanal
Citation
Dixon, E. 2025. Electrochemical materials and microfabrication for sensor devices. PhD Thesis, University College Cork.