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Abstract

This dissertation presents the design, fabrication, and evaluation of a portable electrochemical sensing platform for the detection of benzenediol isomers: catechol, hydroquinone and resorcinol, in acidic aqueous media. Using screen-printed carbon electrodes modified with carbon-supported platinum (Pt/C), the sensor demonstrated sensitive, selective, and reproducible electrochemical responses across a range of electrochemical techniques. The system was further validated on commercial products containing target analytes, confirming its applicability in complex, real-world matrices.
To ensure long-term reliability, the sensor was periodically characterised using electrochemical impedance spectroscopy and voltammetry-derived metrics such as polarisation resistance and effective double-layer capacitance. This enabled non-destructive monitoring of electrode degradation and fouling.
The study also examined the influence of potentiostat architecture on electrochemical processes, comparing analogue and digital scan modes and highlighting their impact on peak currents and capacitive artefacts.
A key innovation in this work was the application of frequency-domain analysis to electrochemical waveforms. Classical techniques such as cyclic voltammetry, linear sweep voltammetry, and differential pulse voltammetry were transformed into spectral representations using Fourier transforms. This provided new insight into the harmonic structure of applied electrochemical signals and the optimisation of waveform parameters. In addition, alternating current voltammetry was used to study the frequency response of the sensor, offering a deeper understanding of kinetic and capacitive processes.
All investigations contributed toward the development of a compact, Internet of Things-enabled electrochemical sensor platform. Both the hardware and software were designed from the ground up to meet specific user requirements, ensuring portability, real-time data acquisition, and wireless communication. This interdisciplinary effort merges concepts from analytical chemistry, materials science, electrical engineering, and embedded systems to advance the field of on-site electrochemical sensing.