Te2As3Se5 (TAS) fibers are often used in bio-sensing applications requiring direct contact between the fiber and live cells. However, the toxicity and stability of chalcogenide glasses typically used in such bio-sensing applications are not well known. The stability and toxicity of TAS glass fibers were therefore examined. The surface of TAS fibers stored for up to three years in air were analyzed using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), and atomic force microscopy (AFM). It is shown that an oxide layer develops on the surface of TAS fibers stored in air. This oxide layer is highly soluble in water and therefore easily removed. Additional studies using cyclic voltammetry show that the fresh TAS glass surface is insoluble in water for at least a few days, and attenuation measurements show that oxidation does not affect the transmission properties of the glass fibers. It was also determined that old, oxidized fibers pose a toxic threat to cells, while washed and new fibers show no toxic effect. Therefore, it is concluded that a soluble oxide layer forms on the surface of TAS fibers stored in air and that this layer has a toxic effect on cells in an aqueous environment. However, through etching, the oxide layer and the toxicity can be easily removed.In other applications of telluride glasses, such as the search for possible signs of life on exoplanets, a glass transmitting further into the IR is required in order to detect molecules, such as CO2. A new family of Tellurium based glasses from the Ge-Te-I ternary system has therefore been investigated for use in space and bio-sensing applications. A systematic series of compositions has been synthesized in order to explore the ternary phase diagram in an attempt to optimize the glass composition for the fiber drawing and molding process. The resulting glass transition temperature range lies between 139°C and 174°C, with deltaT values between 64°C and 124°C. The most stable glass composition was found to be Ge20Te73I7. The Ge-Te-I glasses were found to have an effective transmission window between 2-20 microns, encompassing the region of interest for the identification of biologically relevant species such as carbon dioxide. Furthermore, the successful fibering and molding of the composition Ge20Te73I7 are shown. Lastly, an investigation into glass conductivity was completed resulting in a maximum conductivity value on the order of 10^-4 Ohm-1 cm-1 for the composition Ge20Te73I7.In an attempt to take advantage of the high conductivity of telluride glasses, a new approach to virus detection in an aqueous environment has been developed using the electrophoretic deposition of protein and viruses on the charged glass surface for in situ infrared characterization and identification. A proof of concept experiment has been completed using a germanium ATR plate and an indium tin oxide (ITO) plate as the experimental electrodes. Charged proteins and viruses were driven to the surface of the oppositely charged germanium ATR crystal, once a potential was applied to the system. FTIR/ATR spectroscopy was used before and throughout electro-deposition to enable the in situ observation of the deposition with time. This technique resulted in the successful deposition and removal of the protein Bovine Serum Albumin (BSA), and deposition of the virus MS2, a bacteriophage that infects only bacteria, with an applied voltage of only 1.1V. Furthermore, based on analysis of the ATR spectra, distinct spectral features were identified for the protein and virus showing the potential for identification and characterization of biological molecules in an aqueous environment. A Ge20Te73I7 ATR plate was synthesized but unsuccessfully applied as an electrode in these experiments, likely due to an inconsistent conductivity along the plate. A glass from the Ge-As-Te system with a lower but more consistent conductivity was thereafter synthesized and successfully used as an electrode and sensing element in the electro-deposition experiment.

El progreso de la nanociencia y la nanotecnología está haciendo posible generar nuevos materiales basados en estructuras de carbono con propiedades únicas y con numerosas aplicaciones tecnológicas. Entre estas aplicaciones se encuentra la mejora de los biosensores, dispositivos capaces de realizar análisis químicos con gran rapidez.Las propiedades mecánicas y eléctricas extraordinarias de los nanotubos de carbono han estimulado extensamente su investigación a lo largo de todo el mundo desde su descubrimiento por Sumio Iijima en 1991. En esta tesis, el estudio del comportamiento electrocatalítico de nanotubos de carbono y al mismo tiempo el diseño de nuevos (bio)sensores electroquímicos han sido el principal objetivo, haciendo uso de diferentes alternativas de integración dentro de los sistemas de (bio)detección, basadas en modificaciones de las superficies del electrodo con nanotubos de carbono, o en el uso de nanotubos de carbono basados en (bio)compositos. / The extraordinary mechanical properties and unique electrical properties of carbon nanotubes (CNTs) have stimulated extensive research activities across the world since their discovery by Sumio Iijima in 1991. The range of applications for CNTs is indeed wide ranging from nanoelectronics, with quantum wire interconnects and field emission devices to composites, chemical sensors and biosensors. The application of CNTs to design novel and improved (bio)sensors is the principal objective of this thesis. Different alternatives for CNTs integration into (bio)sensing systems have been developed and the results obtained including some previous theoretical introduction, the state of the art in the field, conclusions and future prospects are presented through the 7 chapters of this PhD thesis.

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A wireless sensor node (WSN) system, capable of sensing animal motion and transmitting motion data wirelessly, is an effective and efficient way to monitor pigs' activity. However, the raw sensor data sampling and transmission consumes lots of power such that WSNs' battery have to be frequently charged or replaced. The proposed work solves this issue through WSN edge computing solution, in which a Random Forest Classifier (RFC) is trained and implemented into WSNs. The implementation of RFC on WSNs does not save power, but the RFC predicts animal behavior such that WSNs can adaptively adjust the data sampling frequency to reduce power consumption. In addition, WSNs can transmit less data by sending RFC predictions instead of raw sensor data to save power. The proposed RFC classifies common animal activities: eating, drinking, laying, standing, and walking with a F-1 score of 93%. The WSN power consumption is reduced by 25% with edge computing intelligence, compare to WSN power that samples and transmits raw sensor data periodically at 10 Hz. / Master of Science / A wireless sensor node (WSN) system that detects animal movement and wirelessly transmits this data is a valuable tool for monitoring pigs' activity. However, the process of sampling and transmitting raw sensor data consumes a significant amount of power, leading to frequent recharging or replacement of WSN batteries. To address this issue, our proposed solution integrates edge computing into WSNs, utilizing a Random Forest Classifier (RFC). The RFC is trained and deployed within the WSNs to predict animal behavior, allowing for adaptive adjustment of data sampling frequency to reduce power consumption. Additionally, by transmitting RFC predictions instead of raw sensor data, WSNs can conserve power by transmitting less data. Our RFC can accurately classify common animal activities, such as eating, drinking, laying, standing, and walking, achieving an F-1 score of 93%. With the integration of edge computing intelligence, WSN power consumption is reduced by 25% compared to traditional WSNs that periodically sample and transmit raw sensor data at 10 Hz.

Manipulation of light at the nanoscale has the promise to enable numerous technological advances in biomedical sensing, optical communications, nano-mechanics and quantum optics. As photons have vanishingly small interaction cross sections, their interactions have to be mitigated by matters (i.e. quantum emitters, molecules, electrons etc.). Waveguides and cavities are the fundamental building blocks of the optical circuits, which control or confine light to specific matters of interest. The first half of the thesis (Chapters 2 & 3) focuses on how to design various photonic nanostructures to manipulate light on nano- to micro- scale, especially to modify the light-matter interaction properties. Chapter 2 discusses how nano-slot waveguides and photonic crystal nanobeam waveguides are able to modify the emission of quantum emitters, in a different way that normal ridge waveguides are not able to. Chapter 3 focuses on a more complicated and powerful structure: the photonic crystal nanobeam cavity. The design, fabrication and characterization of the photonic crystal nanobeam cavities are described and demonstrated in detail, which lays out the foundation of the biomedical sensing applications in the second half of the thesis. The second half of the thesis (Chapters 4 & 5) focuses on the application of photonic crystal nanobeam cavities in the label-free sensing of biomedical substances. Chapter 4 demonstrates detection of solutions with different refractive index (aceton, methanol, IPA etc.), glucose concentration, single polystyrene nanoparticles and single streptavidin bio-molecules. Chapter 4 proposes a novel nonlinear optical method to further enhance the sensitivity. Chapter 4 also demonstrates high quality nanobeam cavities fabricated in polymers, that open up a new route to decrease the cost, as well as to achieve novel applications with functional polymers. The broader impact of this technology lies in its potential of commercialization of a new generation of biosensors with high sensitivity and high integration. Chapter 5 discusses progresses towards instrumentation of the nanobeam cavity sensing technology for research & development apparatus, as well as point-of-care diagnostic tools. / Engineering and Applied Sciences

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