New Directions in Screen Printing and Related Fabrication Processes

Choudrhy, Nadeem Azram (2013) New Directions in Screen Printing and Related Fabrication Processes. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

This thesis reports the development of screen printed electrodes and associated fabrication processes in order to develop and understand new electrochemical based sensors. There are three main sections to this thesis. In the first part, an overview of sensors, in particular electrochemical sensors, that are commercially available and their current problems and limitations with conventional electrodes and electrode materials is discussed. Second, an introduction into screen printing and their advantages are given. The full process by which these next generation electrodes are manufactured is thoroughly described followed by examples of screen printed-electrodes and their powerful application as well as their low detection limits which compare well to existing literature on the market. The first example of a copper (II) oxide screen-printed electrode is reported, which is characterised with microscopy and its efficiency for the electrochemical sensing of glucose, maltose, sucrose and fructose is explored. It is shown that the non-enzymatic electrochemical sensing of glucose with cyclic voltammetry and amperometry is possible with low micro-molar up to milli-molar glucose readily detectable, which compares competitively with nano-catalyst modified electrodes. An additional benefit of this approach is that metal oxides with known oxidation states can be incorporated into the screen-printed electrodes allowing one to identify exactly the origin of the observed electro-catalytic response which is difficult when utilising metal oxide modified electrodes formed via electro-deposition techniques which result in a mixture of metal oxides/oxidation states. These next generation screen printed electrochemical sensing platforms provide a simplification offering a novel fabrication route for the mass production of electro-catalytic sensors for Analytical and Forensic applications. Other examples such as, bespoke screen printed electrodes which can be used as a template to produce randomly dispersed electro-catalytic micro-domains for analytical sensing purposes, are also shown to further demonstrate the applications and utility of screen printed electrodes. The final section focuses on electrode design. It is demonstrated that the electron transfer properties of disposable screen-printed electrodes can be readily tailored via the introduction of a polymeric formulation into the ink used in their fabrication. This approach allows the role of the binder on the underpinning electrochemical properties to be explored and quantified for the first time, allowing the electrochemical reactivity of the screen-printed electrodes to be tailored from that of edge plane-like to basal plane-like reactivity of highly ordered pyrolytic graphite. Building on this fundamental study of the origin of electron transfer at these novel electrodes, the first example of “Cosmetic Electrochemistry” is demonstrated where a commercially available cosmetic product, a deodorant, can be used to confer microelectrode behaviour on a macroelectrode. Proof-of-concept is shown that a graphite screen-printed electrode can be sprayed with an off-the-shelf cosmetic product and within seconds is ready to use. The polymer contained within the cosmetic product partially blocks the graphite screen-printed electrode surface leaving the underlying graphite electrode exposed in the form of graphite micron-sized sites which are randomly distributed across the electrode surface. The creation of microdomain sites enhance mass transport of the target analyte and it is shown that the electroanalytical performance of the cosmetically modified electrode, via the cathodic stripping of lead, could achieve a similar performance to current state-of-the-art methodologies. Further examples are also reported with the introduction of plaster-trodes where a commercially available plaster is electrolytically modified with electrocatalytic material and is used to detect various alcohols