Investigation of micro-devices for neurobiological applications

The aim of this project is to integrate neuronal cell culture with commercial or in-house built micro-electrode arrays and MEMS devices. The resulting device is intended to support neuronal cell culture on its surface, expose specific portions of a neuronal population to different environments using microfluidic gradients and stimulate/record neuronal electrical activity using micro-electrode arrays. Additionally, through integration of chemical surface patterning, such device can be used to build neuronal cell networks of specific size, conformation and composition. The design of this device takes inspiration from the nervous system because its development and regeneration are heavily influenced by surface chemistry and fluidic gradients. Hence, this device is intended to be a step forward in neuroscience research because it utilizes similar concepts to those found in nature. The large part of this research revolved around solving technical issues associated with integration of biology, surface chemistry, electrophysiology and microfluidics. Commercially available microelectrode arrays (MEAs) are mechanically and chemically brittle making them unsuitable for certain surface modification and micro-fluidic integration techniques described in the literature. In order to successfully integrate all the aspects into one device, some techniques were heavily modified to ensure that their effects on MEA were minimal. In terms of experimental work, this thesis consists of 3 parts. The first part dealt with characterization and optimization of surface patterning and micro-fluidic perfusion. Through extensive image analysis, the optimal conditions required for micro-contact printing and micro-fluidic perfusion were determined. The second part used a number of optimized techniques and successfully applied these to culturing patterned neural cells on a range of substrates including: Pyrex, cyclo-olefin and SiN coated Pyrex. The second part also described culturing neurons on MEAs and recording electrophysiological activity. The third part of the thesis described integration of MEAs with patterned neuronal culture and microfluidic devices. Although integration of all methodologies proved difficult, a large amount of data relating to biocompatibility, neuronal patterning, electrophysiology and integration was collected. Original solutions were successfully applied to solve a number of issues relating to consistency of micro printing and microfluidic integration leading to successful integration of techniques and device components.

Design, fabrication and characterisation of components for microfluidic enzymatic biofuel cells

The concept of a biofuel cell takes inspiration from the natural capability of biological systems to catalyse the conversion of organic matter with a subsequent release of electrical energy. Enzymatic biofuel cells are intended to mimic the processes occurring in nature in a more controlled and efficient manner. Traditional fuel cells rely on the use of toxic catalysts and are often not easily miniaturizable making them unsuitable as implantable power sources. Biofuel cells however use highly selective protein catalysts and renewable fuels. As energy consumption becomes a global issue, they emerge as important tools for energy generation. The microfluidic platforms developed are intended to maximize the amount of electrical energy extracted from renewable fuels which are naturally abundant in the environment and in biological fluids. Combining microfabrication processes, chemical modification and biological surface patterning these devices are promising candidates for micro-power sources for future life science and electronic applications. This thesis considered four main aspects of a biofuel cell research. Firstly, concept of a miniature compartmentalized enzymatic biofuel cell utilizing simple fuels and operating in static conditions is verified and proves the feasibility of enzyme catalysis in energy conversion processes. Secondly, electrode and microfluidic channel study was performed through theoretical investigations of the flow and catalytic reactions which also improved understanding of the enzyme kinetics in the cell. Next, microfluidic devices were fabricated from cost-effective and disposable polymer materials, using the state-of-the-art micro-processing technologies. Integration of the individual components is difficult and multiple techniques to overcome these problems have been investigated. Electrochemical characterization of gold electrodes modified with Nanoporous Gold Structures is also performed. Finally, two strategies for enzyme patterning and encapsulation are discussed. Several protein catalysts have been effectively immobilized on the surface of commercial and microfabricated electrodes by electrochemically assisted deposition in sol-gel and poly-(o-phenylenediamine) polymer matrices and characterised with confirmed catalytic activity.

Nietzsche and Montaigne: cheerful naturalism

The influence of the Essays of Michel de Montaigne on the thought of Friedrich Nietzsche has, hitherto, received scant scholarly attention. The aim of this thesis is to address this lacuna in the literature by making evident the importance of the Essays to the development of Nietzsche’s philosophy. I argue that, in order to fully appreciate Nietzsche’s thought, it must be recognized that, from the beginning to the end of his philosophical life, Montaigne was for him a thinker of the deepest personal and philosophical significance. Against the received scholarly opinion, which would see Montaigne as influential only for Nietzsche’s middle works, I contend that the Essays continue to be a key inspiration for Nietzsche even into his late and final works. Montaigne, with his cheerful affirmation of life, his experimental mode of philosophizing, and his resolutely naturalized perspective, was an exemplar for Nietzsche as a philosopher, psychologist, sceptic and naturalist. The Essays not only stimulated Nietzsche’s thinking on questions to do with morality, epistemology and the nature of the soul but also informed his conception of the ideal philosophical life. Moreover, to explore the Essays from a Nietzschean viewpoint, allows the drawing out of the more radical aspects of Montaigne’s thought, while to probe Montaigne’s impact on Nietzsche, provides insight into the trajectory of Nietzsche’s philosophy as he broke free from romantic pessimism and embraced the naturalism that would guide his works from Human, All Too Human onward.

Bullion rings in Viking Age Britain and Ireland

This paper examines a simple type of silver ring, here termed the ‘bullion-ring’, that occurs in several Viking Age contexts in Britain and Ireland. It is proposed that the type may be dated to the later ninth and early to mid-tenth century, and that it developed in Ireland as a convenient way of storing silver as a result of inspiration from southern Scandinavia. Its distribution patterns suggest that it may have developed in one of Munster’s Scandinavian settlements rather than in Dublin, the core of the Hiberno-Scandinavian silver-working tradition.