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This research investigates the use of conducting polymer coatings on platinum (Pt) electrodes for use in neuroprostheses. Conducting polymers aim to provide an environment conducive to neurite outgrowth and attachment at the electrode sites, producing intimate contact between neural cells and stimulating electrodes. Conducting polymers were electropolymerised onto model Pt electrodes. Conventional polymers polypyrrole (PPy) and poly-3,4-ethylenedioxythiphene (PEDOT) doped with polystyrenesulfonate (PSS) and para-toluenesulfonate (pTS)were investigated. Improvement of material properties was assessed through the layering of polymers with multi-walled carbon nanotubes (MWNTs). The ability to incorporate cell attachment bioactivity into polymers was examined through the doping of PEDOT with anionic laminin peptides DCDPGYIGSR and DEDEDYFQRYLI. Finally, nerve growth factor (NGF), was entrapped in PEDOT during polymerisation and tested for neurite outgrowth bioactivity against the PC12 cell line. Each polymer modification was assessed for electrical performance over multiple reduction-oxidation cycles, conductivity and impedance spectroscopy, mechanical adherence and hardness, and biological response. Scanning electron microscopy was used to visualise film topography and x-ray photon spectroscopy was employed to examine chemical constitution of the polymers. For application of electrode coatings to neural prostheses, optimal bioactive conducting polymer PEDOT/pTS/NGF was deposited on electrode arrays intended for implantation. PC12s were used to assess the bioactivity of NGF functionalised PEDOT when electrode size was micronised. Flexibility of the design was tested by tailoring PEDOT bioactivity for the cloned retinal ganglion cell, RGC-5, differentiated via staurasporine. It was established that PEDOT films had superior electrical and cell growth characteristics, but only PPy was able to benefit from incorporation of MWNTs. Bioactive polymers were produced through inclusion of both laminin peptides and NGF, but the optimum film constitution was found to be PEDOT doped with pTS with NGF entrapped during electrodeposition. Application of this polymer to an implant device was confirmed through positive neurite outgrowth on vision prosthesis electrode arrays. The design was shown to be flexible when tailored for RGC-5s, with differentiation occurring on both PEDOT/pTS and PEDOT/DEDEDYFQRYLI. Conducting polymers demonstrate the potential to improve electrode-cell interactions. Future work will focus on the effect of electrical stimulation and design of bioactive polymers with improved cell attachment properties.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 87-90.

Pen-based computers bring the promise of tapping into people’s expressiveness with pen and paper and producing a platform that feels familiar while providing new functionalities only possible within an electronic medium. To this day, pen computers’ success is marginal because their interfaces mainly replicate keyboard and mouse ones. Maximizing the potential of pen computers requires redesigning their interfaces so that they are sensitive to the pen’s input modalities and expressiveness. In particular, pressure is an important and expressive, yet underutilized, pen input modality. This dissertation advances our knowledge about pressure-aware, pen-based interactions and how people use these techniques. We systematically explore their design by first investigating how pressure can affect pen interactions. We propose novel techniques that take advantage of the pressure modality of a pen to control, link, and annotate digital video. We then study people’s performance using pressure to navigate through a set of elements and find that they can discriminate a minimum of six different pressure regions. We introduce the concept of Pressure Widgets and suggest visual and interaction properties for their design. We later explore pressure’s use to enhance the adjustment of continuous parameters and propose Zliding, a technique in which users vary pressure to adjust the scale of the parameter space, while sliding their pen to perform parameter manipulations. We study Zliding and find it a viable technique, which is capable of enabling arbitrarily precise parameter adjustments. We finally present a novel interaction technique defined by the concurrent variation in pressure applied while dragging a pen. We study these pressure marks and find that they are a compact, orientation-independent, full interaction phrase that can be 30% faster than a stateof-the-art selection-action interaction phrase. This dissertation also makes a number of key contributions throughout the design and study of novel interaction techniques: -It identifies important design issues for the development of pressure-sensitive, pen operated widgets and interactions, -It provides design guidelines for interaction techniques and interface elements utilizing pressure-enabled input devices, -It presents empirical data on people’s ability to control pressure, and -It charts a visual design space of pressure-sensitive, pen-based interactions.

Pen-based computers bring the promise of tapping into people’s expressiveness with pen and paper and producing a platform that feels familiar while providing new functionalities only possible within an electronic medium. To this day, pen computers’ success is marginal because their interfaces mainly replicate keyboard and mouse ones. Maximizing the potential of pen computers requires redesigning their interfaces so that they are sensitive to the pen’s input modalities and expressiveness. In particular, pressure is an important and expressive, yet underutilized, pen input modality. This dissertation advances our knowledge about pressure-aware, pen-based interactions and how people use these techniques. We systematically explore their design by first investigating how pressure can affect pen interactions. We propose novel techniques that take advantage of the pressure modality of a pen to control, link, and annotate digital video. We then study people’s performance using pressure to navigate through a set of elements and find that they can discriminate a minimum of six different pressure regions. We introduce the concept of Pressure Widgets and suggest visual and interaction properties for their design. We later explore pressure’s use to enhance the adjustment of continuous parameters and propose Zliding, a technique in which users vary pressure to adjust the scale of the parameter space, while sliding their pen to perform parameter manipulations. We study Zliding and find it a viable technique, which is capable of enabling arbitrarily precise parameter adjustments. We finally present a novel interaction technique defined by the concurrent variation in pressure applied while dragging a pen. We study these pressure marks and find that they are a compact, orientation-independent, full interaction phrase that can be 30% faster than a stateof-the-art selection-action interaction phrase. This dissertation also makes a number of key contributions throughout the design and study of novel interaction techniques: -It identifies important design issues for the development of pressure-sensitive, pen operated widgets and interactions, -It provides design guidelines for interaction techniques and interface elements utilizing pressure-enabled input devices, -It presents empirical data on people’s ability to control pressure, and -It charts a visual design space of pressure-sensitive, pen-based interactions.

Polymer coated sheet metal components find diverse applications in many industries. The manufacturing of the components generally involves forming of sheet metal into the desired shape and coating of the formed part with organic coating. An alternative manufacturing route is to coat the sheet metal first before forming. The change in the manufacturing sequence can potentially improve cost and reduce environmental impact. This approach, however, requires the coating to survive the deformation process. Thus, the effect of plastic deformation on coating adhesion is of primary interest to many engineers and researchers. This research aims at developing a methodology to predict the adhesion of coating after metal forming processes. A pull-off apparatus that measures the coating pull-off stress was used to indicate the coating adhesion strength. Several types of specimen were designed to obtain uniaxial tension, biaxial tension, and tension-compression deformation modes on pre-coated sheet by using a uniaxial tensile tester. Experimental results from two selected polymer coated sheet metals show that coating adhesion was affected by plastic deformation. An analytical model based on a virtual interface crack concept was developed to indicate the adhesion potential of the coating-substrate interface. From interfacial fracture mechanics, the initial adhesion potential is defined as the energy release rate characterized by the virtual interface crack and the initial pull-off stress. The analytical model was used to predict coating adhesion loss after deformation in uniaxial tension mode. The analytical model predictions agreed well with experimental results. Finite element analysis tool was applied to simulate more complex deformation modes in stamping of coated sheet meals. The stress field near the interface crack tip was used to calculate the energy release rate and predict the adhesion loss under different deformation modes. The predictions obtained from numerical method are also in good agreements with the experimental results in biaxial tension and tension-compression modes. The research has led to a better understanding of the effects of plastic deformation on coating adhesion. The developed adhesion test methods can be used to generate useful information on coating durability for diverse practical use. It is also expected that the results of the research will facilitate the development of better polymer coated sheet metal to be used in sheet metal forming processes.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed January 5, 2010). PDF text: vii, 129 p. : ill. (some col.) ; 3 Mb. UMI publication number: AAT 3360091. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes bibliographical references and vita.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, June 2003. / Thesis advisor(s): Geoffrey Xie, Rudolph P. Darken. Includes bibliographical references (p. 129). Also available online.

We observed the evolution of unstable fluid interfaces in experiments on viscous fingering, pinch-off, and bouncing jets. If we can first identify classes of universal behavior, then we can begin building a unified framework to understand nonlinear processes. We performed the first experimental test of the harmonic moments of viscous fingering patterns, grown by injecting air into a thin layer of silicone oil, which was confined between two closely spaced plates, called a Hele-Shaw cell. We observed that the predicted decay of the moments was accurate within our measurement uncertainty, which confirmed the predicted conservation of the moments for zero surface tension. With greater forcing, the air bubble will undergo a secondary tip-splitting instability, where the fingers of air fork into two or more fingers. We discovered two selection rules for the changing base width and the nearly invariant opening angle of fjords, which are the regions of oil between the fingers of air. We then compared our experiments on viscous fingering with diffusion-limited aggregation (DLA), a model of un-stable growth. We calculated that DLA and viscous fingering have the same spectrum of singularities [called f([alpha])] within measurement uncertainty. Since the spectrum is a global encapsulation of the growth dynamics and scaling properties, we say that the two processes are in the same scaling universality class. All of these results for viscous fingering are expected to apply to other physical systems which approximate Laplacian growth, a model of an interface where its growth rate is determined by the local gradient of a field [phi] obeying Laplace's equation [gradient² phi] = 0. Next we present preliminary work on the experimental test of two predictions for flows in Hele-Shaw cells: 1) soliton-like behavior of two viscous domains and 2) self-similar, universal pinch-off of an inviscid bubble in a viscous liquid. Finally, we report our observations and analysis of a liquid stream with constant viscosity (i.e. Newtonian) which rebounds from the free surface of a moving bath. The stream bounces on a thin layer of lubricating air which is replenished by the relative motion of the jet and the bath.