Over the last decade, immobilization of proteins onto inorganic materials is becoming more crucial to extend a deep understanding of interaction between proteins and nanoparticles. With understanding of the real interaction lying under the protein-nanoparticle relations, it is possible to organize the conformation and orientation of surface and framework species of nanoparticles to generate ideal surfaces for potential biotechnological applications. Due to their unique properties such as large clean surface, tunable surface properties, adjustable surface charge, and dispersibility in aqueous solutions, zeolite and zeo-type materials are one of the remarkable classes of inorganic materials that are widely studied in the literature. These properties make zeolites promising alternative candidates for the immobilization of enzymes and incorporation into biosensing devices. In the current study, a new approach was developed for direct determination of urea, glucose, and butyrylcholine where zeolites were incorporated to the electrode surfaces of a conductometric biosensor and Ion Sensitive Field Effect Transistors were used to immobilize the enzymes. Biosensor responses, operational stabilities, and storage stabilities of the new approach were compared with results obtained from the standard membrane methods for the same measurements. For this purpose, different surface modification technique, which are simply named as Zeolite Modified Transducers (ZMTs) were compared with Standard Membrane Transducers (SMTs). During the conductometric measurements ZMT electrodes were used, which allowed the direct evaluation of the effect of zeolite morphology on the biosensor responses for the first time. It was seen that silicalite added electrodes lead to increased performances with respect to SMTs. As a result, the zeolite modified urea and glucose biosensors were successfully applied for detecting urea and glucose, which can offer improved possibilities to design biosensors. The results obtained show that zeolites could be used as alternatives for enzyme immobilization in conductometric biosensors development. Furthermore, the sensitivities of urease and butyrylcholinesterase biosensors, prepared by the incorporation of zeolite Beta crystals with varying acidity on the surface of pH-sensitive

As working time increases for most people, dining out and staying up late is inevitable, resulting in bad health conditions. The concentrations of calcium and sodium ion in human blood not only respond directly to health conditions, but can also obtain symptoms of different diseases by observing it. This shows that the concentrations of calcium and sodium ion in human blood are an important index of health. In order to manufacture disposable ion sensor and make it easy to measure, this study uses extended gate field effect transistor (EGFET) with an ion selective membrane(ISM) on top of the gate sensitive layer to replace traditional ion sensitive field effect transistor (ISFET). The ISM adsorbs the appointed ion by means of ion selective medicament which is covered by a macromolecule. The main processing steps of the extended gate field effect transistor developed in this study involve at least four photolithographic and two thin-film deposition processes. The influence of the channel¡¦s width to length ratio, the design of channel, the area of the gate sensitive layer, the energy and dose of ion implantation used for the transistor and ion sensor were investigated. Based on the measurement results of the ion sensor, a sensitivity of 40mV/decade with linearity of 98.589 % is measured for calcium ion concentration in human blood ranging from 5 ¡Ñ 10-3 mol/L to 5 ¡Ñ 10-4 mol/L. On the other hand, a sensitivity of 56 mV/decade with linearity of 98.589 % is measured for sodium ion concentration in human blood ranging from 1 mol/L to 10-1 mol/L.

A theory of the carrier transport, optical emission, and photoconductivity from optoelectronic devices based on ambipolar long-channel carbon-nanotube (CNT) field-effect transistors (FETs) is presented in this dissertation. In optical emitters based on ambipolar long-channel CNT FETs, an analytic diffusive-transport model for various recombination mechanisms is provided for the first time. The relationship and the scaling of emitted light-spot size and emitted optical power are clearly depicted for the first time as well. We also implement a numerical diffusive-transport approach for the light emission, in which the focus is on the effects of radiative and nonradiative recombination in the channel, with the movement of the spatial recombination profile in response to the gate and drain voltages. For the first time, we find that the emitted light-spot size and the emitted optical power depend sensitively on the operative nonradiative recombination mechanisms. We implement a numerical diffusive-transport approach including exciton photogeneration as well for photoconductors based on ambipolar long-channel CNT FETs with uniform and near-field photoexcitation. We show that the photocurrents are typically much smaller than the dark currents, and explain some possible reasons. Moreover, the exciton densities in CNTs are calculated and the effect of exciton diffusion is presented.

Conjugated polymers represent the next generation of conducting materials that will enable technological devices incorporating thin film transistors, photovoltaic cells etc., in a cost-effective roll-to-roll manner. Given the importance of microstructure on charge transport, ordered self-assembly in polymeric semiconductors assumes paramount relevance. This thesis thus focuses on a fundamental investigation of the correlations between the morphology and microstructure of the first high mobility solution processable semiconducting polymer, poly(3-hexylthiophene)(P3HT), and its corresponding charge transport properties. The evolution of polymer chain conformations is first studied, leading up to the formation of the conducting channel. An intermediate lyotropic liquid crystalline phase is identified, characterized by anisotropic ordering of the polymer chains. Methods for tuning the microstructure of P3HT thin films are also discussed, with an emphasis on understanding the role of molecular parameters, such as regioregularity and process parameters such as the film formation method. An ultrasound based technique for inducing the formation of ordered π-stacked molecular aggregates is also introduced. The results presented here not only provide understanding of microstructure-charge transport correlations, but also the very process of film formation in solution processable organic semiconductors, which could in turn hold the key to approaching the mobility benchmark represented by single crystals.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 158-172). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 157 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 111-119). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Sanjay K. Banerjee. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Jack C. Lee. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 112-119). Available also in a digital version from Dissertation Abstracts.