No description available.

Thesis (doctoral)--Technische Universiteit Delft, 1997. / Vita. Includes bibliographical references.

Thesis (doctoral)--Technische Universiteit Delft, 1997. / Vita. Includes bibliographical references.

Thesis (M.S.)--Ohio State University, 2005. / Includes bibliographical references (leaves 191-194). Available online via OhioLINK's ETD Center

Thesis (doctoral)--Tampere University of Technology, 2005. / Includes bibliographical references (p. 142-146). Also available on the World Wide Web.

Mode of access: Internet via World Wide Web. Available at http://hdl.handle.net/1947/10020. / "October 2009" Includes bibliographic references.

Thesis (M.S.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Darrell Spells; submitted to the Dept. of Chemistry. Includes bibliographical references (p. 46-47).

Numerous reports have been published detailing a wide variety of strategies for the production of many different prototype screen-printed biosensors, hmvever, few of these devices have been developed to the commercialisation stage. There is an unquestionable need for disposable biosensors suitable for decentralised analysis that can be mass-produced at low cost by a simple process; screen-printed carbon electrodes (SPCEs) fulfil both of these criteria. Conventional methods for producing biosensors based on this technology usually involve the deposition of a biological recognition element (typically an enzyme) onto a SPCE which has been printed using an organic solvent-based ink. The removal of organic solvents from the manufacturing process is a highly desirable goal as it should result in improved health and safety and also the possibility of incorporation of enzymes directly into the ink. The latter is difficult to achieve with conventional screen-printing inks as enzymes are inactivated by both the organic solvents themselves and the elevated temperatures required in the curing step. The studies described in this thesis utilise a screen-printing ink which incorporates a water-based binder and the electro catalytic mediator cobalt phthalocyanine (CoPe.) It is demonstrated that the addition of different oxidase enzymes directly into this ink allows for the one-step manufacture of biosensors with desirable performance characteristics, notably high precision and outstanding stability. A water-based carbon ink incorporating CoPC was used to produce robust and precise SPCEs which were found to act as effective sensors for H20 2• The sensors were operated in stirred solutions at an applied potential of +0.5 V, which was shown to be a significant reduction in the potential required for H20 2 detection at an un-modified electrode. The ink was modified further by adding glucose oxidase (GOD) to its bulk prior to printing. This allowed for the one-step printing of glucose biosensors which dried at room temperature. These biosensors were investigated using amperometry in stirred solution which revealed long-term operational stability and a shelf-life of at least 18 months. The analytical signal was shown to arise from the electro catalytic oxidation of the H20 2 produced by the enzyme in the presence of glucose and O2. Using these biosensors with a background correction technique, it was possible to determine the concentration of glucose present in a bovine serum sample with a good degree of both accuracy and precision. This demonstrated that the newly-developed glucose biosensors were capable of operating reliably in a biological sample. In order to extend the linear range, the ink composition was re-formulated and chronoamperometry was used as the measurement technique. The sensitivity of these new glucose biosensors was found to be comparable to that of the earlier system, and the upper limit of the linear range was successfully extended. A simple method for interference removal was developed, which involved the use of 'dummy' sensors that did not contain any enzyme. Using this system, it was possible to quantify glucose in dilute human plasma samples which had been spiked with glucose in order to represent diabetic samples. The generic nature of the CoPC modified water-based ink was illustrated by adding a different enzyme, lactate oxidase (LOD,) which is known to be much more delicate than GOD, into the ink. Even under un-optimised conditions, the LOD-containing biosensors gave a measurable response to lactate over a clinically useful range. Owing to their unusual properties, the study of materials with dimensions smaller than 100 nm is playing an increasingly important role in the development of biosensors. In an attempt to extend the linear range of the GOD-containing biosensors to higher glucose concentrations, the possibility of using nanoscaled cobalt phthalocyanine (n-CoPC) as a mediator was investigated. It was shown that the response of the n-CoPC containing sensors towards H20 2 was superior to those incorporating the bulk mediator. GOD was added to the n-CoPC modified ink, and the resulting glucose biosensors displayed a superior sensitivity and linear range to the bulk-CoPC containing biosensors produced earlier. The increased sensitivity was attributed to the increased sensitivity of the base transducer, and further experiments were conducted to determine the reason for the extended linear range. Remarkably, it was discovered that the n-CoPC modified biosensors were capable of operating in the absence of O2, which implied that the n-CoPC must be interacting in some way with the redox centre of GOD. Such direct electron transfer has been reported for biosensors incorporating other types of nanomaterials but, as far as is known, never for CoPC. In order to investigate the possibility of determining another clinically important analyte, cholesterol oxidase was introduced into the n-CoPC modified water-based ink. Although the resulting cholesterol biosensors did not display the same Orindependent operation, a good sensitivity and a linear response up to at least 2 mM cholesterol was achieved. Free cholesterol was determined in 40 dilute human plasma samples which had been spiked with cholesterol to represent a clinically useful range of total cholesterol concentrations; the results agreed well with a standard reference method (R2 = 0.95.)

No description available.

Smart materials are very important because of their potential applications in the biomedical, petroleum and aerospace industries. They can be used to build systems and structures that self-monitor to function and adapt to new operating conditions. In this study, we are mainly interested in developing a computational framework for the analysis of plate structures comprised of composite or functionally graded materials (FGM) with embedded or surface mounted piezoelectric sensors/actuators. These systems are characterized by thermo-electro-mechanical coupling, and therefore their understanding through theoretical models, numerical simulations, and physical experiments is fundamental for the design of such systems. Thus, the objective of this study was to perform a numerical study of smart material plate structures using a refined plate theory that is both accurate and computationally economical. To achieve this objective, an improved version of the Reddy third-order shear deformation theory of plates was formulated and its finite element model was developed. The theory and finite element model was evaluated in the context of static and dynamic responses without and with actuators. In the static part, the performance of the developed finite element model is compared with that of the existing models in determining the displacement and stress fields for composite laminates and FGM plates under mechanical and/or thermal loads. In the dynamic case, coupled and uncoupled electro-thermo-mechanical analysis were performed to see the difference in the evolution of the mechanical, electrical and thermal fields with time. Finally, to test how well the developed theory and finite element model simulates the smart structural system, two different control strategies were employed: the negative velocity feedback control and the Least Quadratic Regulator (LQR) control. It is found that the refined plate theory provides results that are in good agreement with the those of the 3-D layerwise theory of Reddy. The present theory and finite element model enables one to obtain very accurate response of most composite and FGM plate structures with considerably less computational resources.