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Enhancement of sensitivity and selectivity of chemical sensors through thin film coatings and surface modifications

by 1972- Headrick, Joseph Jeremy

Abstract (Summary)
Chemical sensors have become major analytical tools for how we monitor and obtain information about the chemical nature of ourselves and our surroundings. Two characteristics of chemical sensors that are under constant development and improvement are their selectivity and their sensitivity. Selectivity is a concern of any chemical sensor, without it the signal obtained by a chemical sensor cannot be related to the target species concentration with any confidence. With chemical sensors the selectivity is generally created by the used of a chemical recognition layer such as a permeable membrane, or a thin chemical film. The sensitivity of a chemical sensor is a concern, as with any quantitative analytical method, so that small differences in analyte concentration are distinguishable and trace analysis can be performed. In this work the selectivity and sensitivity of two distinctly different devices used as chemical sensors are investigated. The first device combines a scintillation fiber with a selective polymer coating to create a chemical sensor selective for 137Cs. Both the selectivity and sensitivity of the scintillation fiber are improved with the addition of the chemical recognition layer. The second device investigated is a microcantilever sensor. Microcantilevers have been used to monitor chemicals present in both air and liquid environments. However, in moving from measurements made in air to measurements made in liquids, a great deal of sensitivity is lost due to differences in the interfacial energies of the iv microcantilevers in these two different environments. To overcome this limitation surface modification of the microcantilevers was investigated to improve the sensitivity of these devices. Surfaces of the microcantilevers were modified by several different methods, the binding of gold nanobeads to the surface, creation of a roughened dealloyed surface, and the physical milling and chemical etching of grooves into the surface of the microcantilevers, each of these surface modifications was shown to enhance the sensitivity of microcantilever chemical senors over microcantilever chemical sensors with smooth surfaces. v
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School:The University of Tennessee at Chattanooga

School Location:USA - Tennessee

Source Type:Master's Thesis

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