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Title: Development of manufacturing techniques for graphene-based transducers with potential application in biosensor technology
Authors: Faqihi, Abdullah Abdu
Issue Date: 2022
Publisher: Newcastle University
Abstract: Biosensors play a significant role in the healthcare sectors and in scientific and technological progress in general. Good diagnostic and biosensing interactions are mainly advantaged by the manufacture of electrodes that can efficiently deliver better electrochemical performance. Biosensors have been extensively implemented for various analytical tasks in areas such as medical diagnostics, food safety, and environmental monitoring, and an effective biosensor properly detects the biological and chemical reactions generated by the bio-interaction in the sample measured. The focus in the current study is the development of a laser scribing technique for graphene oxide (GO) in a vacuum chamber. The reduction of GO was investigated under four conditions involving the atmospheric environment, vacuum, and Nitrogen and Argon gases. A laser scribing technique which reduces GO to generate rGO was characterised using scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to visualise the morphological structures of rGO. The SEM results demonstrated a spongier appearance for GO2 (laboratory prepared graphene oxide) compared to GO1 (commercial graphene oxide) material. Raman spectroscopic characterisation highlighted that, for both GO materials, the LSGN2 electrode showed improved response characteristics and a tendency to exhibit better closeness to single- layer graphene. Moreover, the XPS results showed that the percentage of oxygen decreased after the reduction process. The results of the electrochemical analysis suggested that GO2 has superior electrochemical activity compared to GO1. The LSGN2 electrode has been tested using solutions of potassium ferricyanide and 1,1′-ferrocene dimethanol, and the electrochemical behaviour of the electrode was acceptable for both according to cyclic voltammetry results, which indicates the reproducibility of the electrode. Likewise, the peak current ratio of LSGN2 for both solutions was better compared with the same electrode material prepared under the other conditions. The ∆Ep for each redox species indicates higher values than the ideal Nernstian value of 59 mV. The Ψ values of all of the scan rates for the potassium ferricyanide and 1,1′-ferrocene dimethanol fall within the acceptable range of Ψ, indicating a quasi-reversible system which has been also confirmed by K0 and Mtrans values.
Description: PhD Thesis
Appears in Collections:School of Engineering

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