Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 36 for “"chemical detection"”.
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Chemical Detection and Sensing Using Optical Interferometry
Chemical detection, including analysis of gases and liquids, is a large field in environmental research and industry. It requires sensitive, rapid, and inexpensive chemical sensors. Many industrial materials such as coatings and adhesives readily absorb chemical analytes, which may result in …
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Optofluidic Bragg grating sensors for chemical detection
… UV written Bragg grating refractometers for detection of chemical analytes. The technique of direct UV writing uses the localised refractive index increase of a photosensitive planar glass layer upon exposure to a tightly focussed UV beam to fabricate a wide range of integrated optical …
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Organic/carbon nanotubes hybrid thin films for chemical detection.
… several advantages attributed to their unique chemical structure. Carbon nanotubes (CNT), on the other hand, are known to enhance the properties of nano-composites in the conjugated molecules, due to their one dimensional electronic skeleton, high surface area and high aspect ratio. In this …
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Organic lateral heterojunction devices for vapor-phase chemical detection
… demonstrated effective ultra-trace, vapor-phase detection of trinitrotoluene (TNT) at security checkpoints and during vehicular sweeps, achieving sensitivity levels comparable to the canine nose. In this sensor scheme, a large contribution to the noise signal is the inefficient transduction of …
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Phosphine-Mediated Ligations: A Powerful and Versatile Method for the Selective Chemical Detection of Nitroxyl
Nitrogen oxides are a class of small molecules with profound physiological and environmental consequences. Nitric oxide (NO), the most well-known of these, is a key endogenous signaling agent effecting platelet disaggregation and vasorelaxation. Nitroxyl (HNO), the product of NO reduction and …
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Compact Optical Sensing Systems for pH and Other Substances Detection - Theory and Implementation
Chemical detection is of importance in research and industry. Optical sensors based on contact imaging realize the chemical detection in compact, efficient and inexpensive ways. In the first project real-time optical pH sensor based on complementary metal–oxide–semiconductor (CMOS) contact imaging …
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Improving Detection and Identification Methods for Volatile Organic Explosives
Although numerous chemical detection methods have been posited and tested for portability and detection of explosives, to date no method has solved the simultaneous issue of speed, reliability, selectivity and sensitivity. In order to advance the chemical and biological detection of explosives as …
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Harnessing inorganic coordination chemistry for novel sensing applications
We explore strategies to exploit the rich chemical reactivity available to inorganic coordination complexes in order to realize chemiresistive detectors, electronic device elements that undergo a change in resistance in the presence of analyte, through either incorporation of a conductive material …
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MEMS-based resonant sensor arrays : selective detection of volatile and toxic chemicals
… there is a strong need today for robust chemical sensing systems that are portable in addition to being highly sensitive. While there are many options available for gaseous chemical detection and identification, not all are well-suited toward the creation of a portable device. Boston …
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Colloidal Electronics
… two concepts - Autoperforation and Asymmetric Chemical Doping - as means to fabricate and power electronic circuit elements on top of colloidal particles. These advances allow us to build the first colloidal electronic system that perform autonomous functions integrating energy harvesting, …
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DUAL-SIGNAL READOUT ANALYTICAL TOOLS: DESIGN, CHARACTERIZATION, AND APPLICATIONS IN SENSING
This thesis contributes to the field of chemical sensors by developing dual-signal detection devices that enhance both sensitivity and reliability. It introduces a new generation of bimodal and ratiometric sensors suitable for varied applications, especially in the crucial areas of health and …
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Colorimetric Sensor Array: Do I See What You Smell
We have developed and patented a unique chemical detection technology in which colorimetric changes in an array of dyes constitute a signal much like that generated by the mammalian olfaction system; each dye is a cross-responsive sensor. This technology uses a disposable printed array of …
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Molecules and materials for the optical detection of explosives and toxic chemicals
… the highly sensitive and selective vapor-phase detection of both explosives and highly toxic chemicals, including chemical warfare agents. There are varieties of analyte targets, however, that remain challenging for detection by these methods. Research towards improving this technology has …
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Suspended microchannel resonators for biomolecular detection
Microfabricated transducers enable the label-free detection of biological molecules in nanoliter sized samples. Integrating microfluidic detection and sample-preparation can greatly leverage experimental efforts in systems biology and pharmaceutical research by increasing analysis throughput while …
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A highly digital, reconfigurable and voltage scalable SAR ADC
… military surveillance, environmental monitoring, chemical detection and more recently, medical monitoring systems. Each node of the sensor network requires energy efficient circuits powered off small batteries or harvested energy. In such systems, a single reconfigurable analog-to-digital …
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Design of a silicon carbide micro-hotplate geometry for high temperature chemical sensing
Silicon carbide, high temperature, chemical sensors are the next step in chemical detection technology; allowing for the development of low cost, robust, lower power, and widely applicable chemical sensors. SiC offers the thermal conductivity, electrical properties, and operating temperatures not …
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Phase separation in thermally-drawn fibers: From porous domains to structured Si-Ge spheres
… functions ranging from optical transmission to chemical detection. However, while a wide range of materials have been successfully drawn in various phases - such as metals, semiconductors, and ferroelectric polymers - the overall structure of the fiber is typically axially-invariant and the …
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Electrochemical Impedance Spectroscopy using adjustable nanometer-gap electrodes
Electrochemical Impedance Spectroscopy (EIS) is a simple yet powerful chemical analysis technique for measuring the electrical permittivity and conductivity of liquids and gases. Presently, the limiting factor for using EIS as a portable chemical detection technology is the lack of absolute …
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High Resolution Distributed Sensing Using Exposed-Core Fibres
… to biomedical applications, with a focus on the detection of small particles. A high-resolution distributed sensing method has been proposed, in which an exposed-core fibre (ECF) is used to detect micro-scaled sized particles. While the ECF has been reported for chemical detection in the past …
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Layer-by-layer assembly in confined geometries
… was investigated for a number of different chemical systems. The first part of this thesis concerns the modification of microfluidic and nanofluidic devices which hold great potential as a platform for manipulation and analysis of small sample volumes. The high throughput and high surface …
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