Ultra-low voltage electrowetting

Electrowetting, the manipulation of surface wettability with an electric field, is an emerging technology used in next generation displays and cameras. This has been made possible by the development of ‘electrowetting -on- die lectric’ by Berge in 1993. Howev er, such a system operates on large voltages poorly suited to portable devices. In recent years, theoretical and experimental results have suggested that electrowetting using the interface between two immiscible electrolyte solutions (ITIES) may provide a solution to this problem. By applying less than 1 V to such a system, it is possible to induce substantial changes in the wettability — and hence the shape — of liquid droplets. However, there is a large degree of hysteresis in such a system meaning that there is a poor correlation between droplet shape and applied potential. Furthermore, the stability of the ITIES over long periods is of concern. This thesis attempts to address the current problems with ITIES electrowetting highlighted above. By moving to smoother and more lubricated surfaces, a substantial reduction in hysteresis was seen. These surfaces were produced by template stripping. In addition, several other surfaces were prepared as potential electrowetting substrates. These involved surface functionalisation by plasma treatment or the reduction of diazonium compounds; preparation of ultra smooth glassy carbon and preparation of a hydrophobic conducting polymer. The potential range over which an ITIES is stable was also improved with the use of a novel mixed organic solvent phase. By optimising the electrode and electrolyte compositions, an electrowetting system operating on less than 1 V with a contact angle range of 53 o and a gap of only 100 mV between forward and reverse scans was possible. Other electrowetting systems with no hysteresis were also developed, although these did not operate within the potential limits defined by the onset of Faradaic processes.Open Acces

Preparation and characterisation of high-density ionic liquids incorporating halobismuthate anions

A range of ionic liquids containing dialkylimidazolium cations and halobismuthate anions ([BiBrxClyIz]− and [Bi2BrxClyIz]−) were synthesised by combining dialkylimidazolium halide ionic liquids with bismuth(III) halide salts. The majority were room temperature liquids, all with very high densities. The neat ionic liquids and their mixtures with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide were characterised using Densitometry, Viscometry, NMR Spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI), Liquid Secondary Ion Mass Spectrometry (LSIMS), Matrix-assisted Laser Desorption/Ionization Mass Spectrometry (MALDI), X-Ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA), to establish their speciation and suitability for high-temperature applications

A Graphene Surface Force Balance

We report a method for transferring graphene, grown by chemical vapor deposition, which produces ultraflat graphene surfaces (root-mean-square roughness of 0.19 nm) free from polymer residues over macroscopic areas (>1 cm2). The critical step in preparing such surfaces involves the use of an intermediate mica template, which itself is atomically smooth. We demonstrate the compatibility of these model surfaces with the surface force balance, opening up the possibility of measuring normal and lateral forces, including friction and adhesion, between two graphene sheets either in contact or across a liquid medium. The conductivity of the graphene surfaces allows forces to be measured while controlling the surface potential. This new apparatus, the graphene surface force balance, is expected to be of importance to the future understanding of graphene in applications from lubrication to electrochemical energy storage systems

Kupffer Cells Hasten Resolution of Liver Immunopathology in Mouse Models of Viral Hepatitis

Kupffer cells (KCs) are widely considered important contributors to liver injury during viral hepatitis due to their pro-inflammatory activity. Herein we utilized hepatitis B virus (HBV)-replication competent transgenic mice and wild-type mice infected with a hepatotropic adenovirus to demonstrate that KCs do not directly induce hepatocellular injury nor do they affect the pathogenic potential of virus-specific CD8 T cells. Instead, KCs limit the severity of liver immunopathology. Mechanistically, our results are most compatible with the hypothesis that KCs contain liver immunopathology by removing apoptotic hepatocytes in a manner largely dependent on scavenger receptors. Apoptotic hepatocytes not readily removed by KCs become secondarily necrotic and release high-mobility group box 1 (HMGB-1) protein, promoting organ infiltration by inflammatory cells, particularly neutrophils. Overall, these results indicate that KCs resolve rather than worsen liver immunopathology

A graphene surface force balance.

We report a method for transferring graphene, grown by chemical vapor deposition, which produces ultraflat graphene surfaces (root-mean-square roughness of 0.19 nm) free from polymer residues over macroscopic areas (>1 cm(2)). The critical step in preparing such surfaces involves the use of an intermediate mica template, which itself is atomically smooth. We demonstrate the compatibility of these model surfaces with the surface force balance, opening up the possibility of measuring normal and lateral forces, including friction and adhesion, between two graphene sheets either in contact or across a liquid medium. The conductivity of the graphene surfaces allows forces to be measured while controlling the surface potential. This new apparatus, the graphene surface force balance, is expected to be of importance to the future understanding of graphene in applications from lubrication to electrochemical energy storage systems