To see the other types of publications on this topic, follow the link: Optical sensors.
Dissertations / Theses on the topic 'Optical sensors'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Optical sensors.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Wavering, Thomas A. "Optical Path Length Multiplexing of Optical Fiber Sensors." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36037.
Full textAbstract:
Optical fiber sensor multiplexing reduces cost per sensor by designing a system that minimizes the expensive system components (sources, spectrometers, etc.) needed for a set number of sensors. The market for multiplexed optical sensors is growing as fiberoptic sensors are finding application in automated factories, mines, offshore platforms, air, sea, land, and space vehicles, energy distribution systems, medical patient surveillance systems, etc. Optical path length multiplexing (OPLM) is a modification to traditional white-light interferometry techniques to multiplex extrinsic Fabry-Perot interferometers and optical path length two-mode sensors. Additionally, OPLM techniques can be used to design an optical fiber sensor to detect pressure/force/acceleration and temperature simultaneously at a single point. While power losses and operating range restrictions limit the broadscale applicability of OPLM, it provides a way to easily double or quadruple the number of sensors by modifying the demodulation algorithm. The exciting aspect of OPLM is that no additional hardware is needed to multiplex a few sensors. In this way OPLM works with conventional technology and algorithms to drastically increase their efficiency. [1]Master of Science
2
Chen, George Y. "Optical microfiber sensors." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/386492/.
Full textAbstract:
The technology and applications of optical fibers have progressed very rapidly in recent years. Fiber-optic sensors have been commercially successful and well established in various industries from biomedical to defense. They exhibit many advantages over their electrical counterparts, including higher responsivity, higher detection bandwidth, higher temperature performance, better immunity to electromagnetic interference, all-dielectric composition, greater environmental ruggedness and distributed sensing capability. However, the physical dimensions and the minimum bend radius of the optical fiber sets a lower limit on the final package size. In applications where the working space is stringent or where physical intrusion must be minimized, it becomes highly desirable to develop ultra-compact sensors that can maintain the level of performance despite the miniaturization. The recent emergence of optical microfibers has opened up a new era of technological innovations. Microfibers have the potential to solve the problem with its range of enabling properties, including large evanescent field, strong optical confinement, bend insensitivity, low stiffness and high configurability. This thesis focuses on the innovative development of relatively unexplored areas of microfiber-based sensing as well as the envisioning of performance-enhancing techniques that can shape the on-going development of such sensors. In particular, extensive advancement was made in light of the simple demonstration of a novel current sensor with potentially gigahertz detection bandwidth. This includes the development of the resonator design to achieve higher compactness, and the first reported fabrication of the spun optical microfiber to counter the effects of linear birefringence. Well established and successfully proven sensing configurations such as the flexural disc and air-backed mandrel were adopted to create miniaturized microfiber-based accelerometers and microphones, with potential responsivity enhancements of at least one order of magnitude.
3
Feth, Shari. "Sapphire optical fiber sensors." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-12232009-020350/.
Full text
4
Bristow, Julian Paul Gregory. "Integrated optical components for optical fibre sensors." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329519.
Full text
5
Talebi, Fard Sahba. "Optical resonator sensors and systems." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52834.
Full textAbstract:
Silicon-on-insulator (SOI)-based sensors are attractive for sensing applications in environmental safety, oil and gas, medical research, and clinical applications. Since these devices are typically developed using Complementary metal-oxide-semiconductor (CMOS)-compatible multi-project-wafer (MPW) shuttles, they bring the potential for having sensing systems on chips (SSOCs), and for mass fabrication and low cost production. The objective of this thesis is to improve the sensitivity, accuracy, and repeatability of sensors fabricated on the SOI platform. Such sensors have the potential to be the key components of an SSOC.
One can increase the sensitivity of a resonator sensor by increasing the interaction between the evanescent field of the guided mode and the analyte. In this thesis, two methods for increasing this interaction in micro-ring resonator-based sensors are investigated: 1) using the transverse electric (TE) guided mode in ultra-thin strip waveguides and 2) using the quasi-transverse magnetic (TM) guided mode in thin strip waveguides. Using analyses and simulations, micro-ring sensors were designed to be fabricated within the constraints of a MPW CMOS-compatible process. Using the TE sensors, the temperature-induced errors were reduced by a factor of three; and the TM sensors exhibited twice the sensitivity of the best SOI micro-ring resonator-based sensors reported to date.
Moving towards the actual implementation of an SSOC, a system of sensors was design to correct for unwanted variations in the measurements. This system drew on multivariate techniques to achieve improvements that resulted in measurements that were more repeatable and more accurate in the presence of environmental variations. The capability of this system is investigated by designing a cascade of previously developed micro-ring sensors with various waveguide thicknesses. With this system of sensors, we achieved an R2 value of predictions over 0.996 in the presence of a 2 K temperature drift. This approach significantly improved the repeatability and reliability of the measurements in the presence of undesirable variations and drifts. In another move towards achieving an SSOC, integrating photodetectors in resonator sensors was investigated. To accomplish this, ion-implantation on micro-ring sensors was used. Such integrated photodetector-sensors were designed, fabricated, and tested. Their measured sensitivities were within 90% of the expected values.Applied Science, Faculty of
Graduate
6
Sukumaran, Muralidharan. "Optical sensors for immunoglobulin G." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620564.
Full text
7
Skinner, Graham A. "Development of novel optical sensors." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=16863.
Full text
8
Prabha, Rajeev Kiron. "Organic photodiodes as optical sensors." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808422/.
Full text
9
Shih, Jessica Chu-Huei. "Concentric-core optical fiber sensors." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91069.
Full textAbstract:
This thesis describes the implementation of a mechanical strain sensor which uses concentric core optical fiber waveguide as the sensing element. When this particular type of fiber is strained, a transfer of optical power occurs between propagating modes in the two concentric cylindrical cores of the fiber. This strain-induced redistribution of optical power may be detected at the output end of the fiber using either two separated optical detectors or a two dimensional detector array. The calibrated strain sensitivity of the sensor is reported and suggestions for continuing research are discussed.M.S.
10
Gautier, Nicolas. "Flow control using optical sensors." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066640/document.
Full textAbstract:
Le contrôle d'écoulement en utilisant des capteurs optiques est étudié dans un contexte expérimental. Le calcul de champs de vitesses en temps réel en utilisant une caméra pour l'acquisition et une carte graphique pour le calcul est détaillé. La validité de l'approche en terme de rapidité et de précision est étudiée. Un guide complet pour l'optimisation logicielle et matérielle est donné. Nous démontrons que le calcul dynamique de champs de vitesse est non seulement possible mais plus facile à gérer que l'utilisation d'un appareillage (PIV) classique. Un canal hydrodynamique est utilisé pour toutes les expériences. Celui-ci comporte une marche descendante pour le contrôle d' écoulements décollés. Les actionneurs sont des jets. Dans le cas de la marche descendante une étude paramétrique approfondie est faite pour qualifier les effets d'une injection en amont des jets, celle-ci étant traditionnellement effectuée à l'arrête de la marche.Plusieurs méthodes de contrôle sont étudiées. Un algorithme de contrôle basique de type PID est mis en place pour démontrer la viabilité du contrôle d'écoulement en boucle fermée par capteurs optiques. La zone de recirculation située derrière la marche est calculée en temps réel dans un plan vertical et horizontal. La taille de cette région est manipulée avec succès. Une approche basée sur des observations de la dynamique de l'écoulement est présentée.Des résultats précédents dans la littérature montrent que la recirculation peut être réduite avec succès en agissant sur l'écoulement à la fréquence naturelle de lâchés tourbillonnaires liés à l'instabilité de Kelvin-Helmholtz de la couche cisaillée crée par la marche. Une éthode basée de détection de vortex est introduite pour calculer cette fréquence, qui est ensuite utilisée dans une boucle de contrôle qui assure que l'écoulement est toujours pulsé à la bonne fréquence. Ainsi en utilisant des capteurs optiques la recirculation est réduite de façon simple.Ensuite nous implémentons un contrôle de type feed-forward dont l'efficacité a préalablement été démontrée en simulation. Cette approche vise à prévenir l'amplification de perturbations amont par la couche cisaillée. Nous montrons comment une telle méthode peut être implémentée avec succès dans un contexte expérimental. Enfin, nous implémentons également une approche radicalement différente basée sur un algorithme génétique. Des lois de contrôle aléatoires sont testées et évaluées. Les meilleurs sont répliquées, mutées et croisées. Ce processus se poursuit itérativement jusqu'à ce que le coût soit minimisé. Bien que lente à converger cette approche donne des résultats encourageants à travers une loi de commande originaleFlow control using optical sensors is experimentally investigated. Real-time computation of flow velocity fields is implemented. This novel approach featuring a camera for acquisition and a graphic processor unit (GPU) for processing is presented and detailed. Its validity with regards to speed and precision is investigated. A comprehensive guide to software and hardware optimization is given. We demonstrate that online computation of velocity fields is not only achievable but offers advantages over traditional particle image velocimetry (PIV) setups. It shows great promise not only for flow control but for parametric studies and prototyping also.A hydrodynamic channel is used in all experiments, featuring a backward facing step for separated flow control. Jets are used to provide actuation. A comprehensive parametric study is effected to determine the effects of upstream jet injection. It is shown upstream injection can be very effective at reducing recirculation, corroborating results from the literature.Both open and closed loop control methods are investigated using this setup. Basic control is introduced to ascertain the effectiveness of this optical setup. The recirculation region created in the backward-facing step flow is computed in the vertical symmetry plane and the horizontal plane. We show that the size of this region can be successfully manipulated through set-point adaptive control and gradient based methods.A physically driven control approach is introduced. Previous works have shown successful reduction recirculation reduction can be achieved by periodic actuation at the natural Kelvin-Helmholtz frequency of the shear layer.A method based on vortex detection is introduced to determine this frequency, which is used in a closed loop to ensure the flow is always adequately actuated. Thus showing how recirculation reduction can be achieved through simple and elegant means using optical sensors. Next a feed-forward approach based on ARMAX models is implemented. It was successfully used in simulations to prevent amplification of upstream disturbances by the backward-facing step shear layer. We show how such an approach can be successful in an experimental setting.Higher Reynolds number flows exhibit non-linear behavior which can be difficult to model in a satisfactory manner thus a new approach was attempted dubbed machine learning control and based on genetic programming. A number of random control laws are implemented and rated according to a given cost function. The laws that perform best are bred, mutated or copied to yield a second generation. The process carries on iteratively until cost is minimized. This approach can give surprising insights into effective control laws
11
Barnes, Adam. "Sapphire fiber in optical sensors." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-09052009-041053/.
Full text
12
CASALICCHIO, MARIA LUISA. "Innovative Plastic Optical Fiber Sensors." Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2497120.
Full textAbstract:
This thesis describes the development of new types of fiber optic sensors for the measurement of
mechanical quantities such as displacement, vibration and acceleration.
Also, it describes the realization of specific acquisition systems designed to interrogate the developed
sensors.
Since optical fibers have been historically associated with high speed telecommunication links
because of their very large bandwidth and low attenuation, there is a great interest for their employment
in sensor applications.
Fiber sensors represent a promising solution in many fields since fibers can be used for the measurement
of several quantities, not only mechanical as those investigated in this work, but also
chemical with the possibility to detect specific chemical or bio-chemical molecules.
Among the physical quantities to be detected, the displacement measurement is required in some
applications, especially in structural civil and mechanical fields, where it is possible to evaluate
the cracks evolution, providing information about the safety of the structure under monitoring in
order to detect eventually risky situations.
All the developed sensors are able to measure the displacement along one or two axis, that can
be employed also during vibration tests especially at high frequencies, and also acceleration sensors
to monitor acceleration at low frequencies.
The developed sensors are based on plastic optical fibers instead of the traditional glass fibers,
which are traditionally employed in optical communications.
This change is related to the aim of realizing sensors maintaining the excellent typical characteristics
of the fibers, such as electromagnetic immunity, intrinsically fire safety and flexibility of
applications, but with costs comparable to those of commercial electromechanical sensors.
Indeed, nowadays, the commercial fiber optic sensors are based on glass fibers because they have
very good performance.
However, they find limited applications due to the high costs of their complex interrogation systems
and also for the procedure required to splice the fibers.
On the other hand, plastic optical fibers represent a promising alternative because of their geometrical
and optical properties that allow employing low-cost non coherent sources such as LED
and also simplifying the procedure for the sensor connection and installation.
Therefore, the design of the proposed plastic optical fiber displacement sensors is described
with the sensor practical arrangement and the realized prototypes. An acquisition system has
been designed and realized to characterize the sensors and the characterization results are also
provided. Moreover, the development and the characterization of a plastic optical fiber sensor able
to measure the displacement in two directions have been described.
The main drawback of the developed sensors are stability issues and for this reason laboratory
and in situ-tests have been carried out in order to verify the sensor performance over the time.
I
The results obtained with the stability tests have highlighted the necessity to develop displacement
sensors with increased stability. To this aim, a compensation technique based on two different
wavelengths has been developed.
The same working principle of the developed displacement sensor has been exploited to realize
a fiber vibrometer to be employed during the vibration monitoring for measuring without contact
the vibrations of the device under test.
The sensor development, a suitable calibration procedure developed to overcome the problem of
real targets with a non uniform reflectivity, and the experimental tests have been described.
Furthermore, the preliminary results concerning the feasibility study of a plastic optical fiber
accelerometer are reported.
13
Utou, Frumence E. "Fiber optic sensors ensuring structural integrity." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/1300.
Full textAbstract:
Thesis (DTech (Mechnical Engineering))--Cape Peninsula University of Technology, 2005Among the issues that are taken into consideration for many years by Engineers and Technologists is the integrity of the servicing elements in structures and mechanisms. It is a documented phenomenon that after a certain period of time, in service, engineering components tend to change their original state, and begin to develop faults and defects. This includes the original shape distortion due to effects such as bending, twisting, and cracks. The above-sited effects may be caused by the sudden or accumulative effect of overloading, thermal shocks, corrosion etc, which eventually lead to malfunction of these engineering components. The occurrence of the cracks may be as a result of stress variation in excess of different or similar materials; thermal shocks, vibration, etc. A system of structural health monitoring using optical fiber sensors to track down a crack occurrence and its propagation is considered to be a promising method in warning of catastrophic events. Taking advantage of optical fibers' properties and behavior, such as easy interaction with other materials, small size, low weight, corrosion resistance, geometrical flexibility and an inherent immunity to electromagnetic interference, there is potential in adopting the Fiber Optic Sensors (FOS) for structural health monitoring systems. Structural integrity does not confine itself to crack detection only. For example there are many instances where unwanted or excessive displacement may occur. Optical fibers play an important role in proximity sensing as evidenced in the literature [49] to [54] and available commercial systems. However it is felt that FOS displacement sensors may suffer in measurement accuracy due to in situ conditions.
14
Brady, Geoffrey Phillip. "Fibre Bragg grating sensors : interrogation and multiplexing techniques." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309781.
Full text
15
Eberlein, L. M. "Carbon dioxide and oxygen optical sensors." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636762.
Full textAbstract:
A review of sensors for carbon dioxide and oxygen, with special focus on optical sensors, is presented in Chapter 1. The major experimental procedures and materials used in the PhD research project are given in Chapter 2. The results of a study of the use of different plasticisers, including phosphate-, phthalate- and adipate-based types for the creation of a range of colourimetric plastic film sensors for carbon dioxide are reported in Chapter 3. The response characteristics, i.e., carbon dioxide sensitivity and the response/recovery times are studied when different types of plasticiser are used in the formulation of a sensor for carbon dioxide. Of the types of plasticisers used in this work, the most efficient appeared to be phosphate-based. Chapter 4 describes the results of an investigation of the response characteristics, i.e., carbon dioxide sensitivity, temperature and response/recovery characteristics, of a plastic film colourimetric sensor for carbon dioxide when a small amount of aromatic alcohol, such as m-cresol, is included in the film formulation. The effects on the carbon dioxide sensitivity containing different aromatic alcohols is also examined. Chapter 5 investigates the luminescent ruthenium ion-pair [Ru(dpp)32+(Ph4B-)2] incorporated into the hydrophobic medium of the polymer, poly(vinyl chloride), plasticised with tributyl phosphate. A detailed study on the response characteristics, i.e., film sensitivity towards oxygen and response and recovery times, were studied as a function of plasticiser content, temperature and stability in use, and with age. The major response characteristics depend very strongly upon the overall level of plasticiser present in the film. In Chapter 6, pyrene is incorporated into a number of polymer-plasticiser encapsulation media for the creation of a new range of luminescent plastic film sensors for optical sensing of oxygen. Furthermore, pyrene and Reichardt's dye are used as single polarity probes of the encapsulation medium in an attempt to correlate the oxygen-sensitivity of a pyrene-based oxygen sensor and the encapsulating medium polarity.
16
Inci, M. Naci. "Optical coatings for fibre optic sensors." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1455.
Full text
17
Smith, Richard. "Optical fibre sensors for radioactive environments." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318305.
Full text
18
Yupapin, P. V. P. "Optical pressure sensors using interferometric techniques." Thesis, City University London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357418.
Full text
19
Tubb, Andrew John Colwill. "Optical fibre surface plasma wave sensors." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624855.
Full text
20
Geiger, Harald. "Quasi-distributed optical fibre strain sensors." Thesis, University of Southampton, 1995. https://eprints.soton.ac.uk/399104/.
Full textAbstract:
This thesis presents for the first time two complementary techniques to monitor the optical path length in optical fibre over both long and short sensing lengths. Both techniques may be used to measure the physical environment of the optical fibre, in particular strain and temperature, and are suitable for multiplexed operation. Signal-to-noise analysis shows that current optical time domain reflectometry (OTDR) systems do not fully exploit the spatial resolution theoretically available. A new OTDR technique exploits the theoretical findings to monitor the range of reflective markers in an optical fibre. Measuring strain in fibre sections of several metres is demonstrated. 100?m spatial resolution has been achieved with a pulse duration equivalent to 1 m fibre length and within one second measurement time. The first fibre Bragg grating interrogation system using an acousto-optic tunable filter (AOTF) is described. The interrogation system locks the AOTF wavelength to the wavelength of a selected grating. Measuring the frequency of the AOTF control signal provides an accurate measurement of the grating wavelength. A detailed system analysis is presented to enable the optimisation of system parameters. A wavelength resolution corresponding to 0.4 microstrain is achieved within 0.1sec measurement time, close to the resolution predicted by the system model. This technique allows the use of fibre gratings as sensors for the measurement of both quasi-static and dynamic strains. The combination of the two systems facilitate the utilisation of optical fibre to monitor a structure both over a few metres and at critical points. Both sensor types offer new measurement possibilities as embedded structure monitors, for example for in-service health and usage monitoring or as nerves for active control of smart structures.
21
Volanthen, Mark. "Multiplexed and distributed optical fibre sensors." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/394567/.
Full textAbstract:
This thesis presents three novel optical fibre sensor systems which monitor optical path lengths. The systems have been used to measure strain in an optical fibre. All three systems make several measurements at different locations along a fibre, allowing the spatial distribution of a measurand to be obtained. For the first time, incoherent optical frequency domain reflectometry is used together with time division multiplexing to measure the optical path length of an array of fibre sections. Sensing sections are 5m long and are defined by broadband optical reflectors. A closed loop interrogation system is demonstrated to monitor the sensors in real time with an accuracy of 2.1µ(epsilon)/(root)Hz, in good agreement with the theoretically predicted value. Simultaneous monitoring of multiple fibre Bragg grating sensors, several millimetres in length, is also demonstrated by simultaneously generating multiple passbands in a single acousto-optic tunable filter. This is the only technique demonstrated to simultaneously monitor multiple gratings using a single wavelength-tunable device. The first distributed Bragg grating sensor to measure arbitrary strain profiles is also demonstrated. Low-coherence interferometry selects the interrogation position and a tunable filter measures the local wavelength. Two configurations of the technique are presented, which have achieved spatial resolutions of 300µm and real-time strain measurements with 5.4µ(epsilon)/(root)Hz accuracy, showing good agreement with theoretically predicted values. The only grating sensor network to be both distributed and multiplexed is presented together with the first results.
22
Murphy, Kent A. "Novel phase-modulated optical fiber sensors." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39712.
Full text
23
Simpson, Alexander George. "Optical fibre sensors and their interrogation." Thesis, Aston University, 2005. http://publications.aston.ac.uk/8006/.
Full textAbstract:
This thesis describes novel developments in the fabrication and understanding of type IA fibre Bragg gratings, the uses of said gratings as optical sensors and the interrogation of optical sensors using tilted fibre Bragg gratings. This thesis presents the most detailed study of type IA gratings performed to date and provides the basis of a dual grating optical sensor capable of independently measuring strain and temperature. Until this work it was not known how to reliably fabricate type IA gratings or how they would react to high ambient temperatures, nor was it known what effect external parameters such as fibre type, dopant levels, inscription laser intensity, or hydrogenation levels would have on the physical properties of the grating. This comprehensive study has yielded answers to all of these unknowns and produced several unexpected uses for type IA gratings, such as the use of the previously unreported strong loss band at 1400nm to locally heat fibres by optical absorption and thereby fabricate optically tuneable gratings which do not affect directly adjacent standard gratings. Blazed fibre Bragg gratings have been studied in detail and used to produce several high quality prototype sensor interrogation systems yielding stability an accuracy values unsurpassed by similar devices reported in literature. An accurate distribution map of light radiated by blazed gratings is shown for the first time and has been studied in respect of polarisation state showing that for certain easily achievable conditions a blazed grating spectrometer may be deemed to be polarisation insensitive. In a novel implementation of the system, it is shown that the dynamic wavelength range of a blazed grating spectrometer may be at least doubled by superimposing blazed gratings.
24
Lubian, Elisa. "Porphyrin Derivatives as Optical Molecular Sensors." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427495.
Full textAbstract:
In this Doctorate Thesis project, a small library of four structurally related melamine-bridge bis(porphyrin-ZnII) receptors, was synthesized The coordination properties of these porphyrin derivatives has been investigated by UV-vis spectroscopy for a series of aliphatic diamines of general formula H2N (CH2)n NH2 (n = 4-8). A marked colour variation occours due to a favourable host-guest ditopic interaction. The binding constants, higher than 10e7 M-1, make these receptors excellent candidates for the development of sensor devices for continuous flow analyses, in which the porphyrin derivatives are covalently supported onto appropriate solid materials.
These dimeric metalloporphyrin hosts (molecular tweezers), have also been successfully exploited as chirality probes for determination of the absolute configuration (AC) for a wide variety of chiral molecules (diamines, amino esters, amino amides, amino alcohols and secondary monoalcohols) by using circular dichroism spectroscopy, in collaboration with Prof. Nina Berova of Columbia University.
The deposition of porphyrin derivatives on different matrices was also investigated. Characterizations of substrates were carried out by scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning tunneling microscopy. These results show promising potential in the synthesis of highly ordered networks of surface-supported functional materials for sensing and solar energy applications.Il progetto di ricerca di questa Tesi di Dottorato ha riguardato la sintesi, la caratterizzazione e lo studio delle proprietà di ricognizione molecolare di nuovi derivati bis-porfirinici contenenti un ponte triazinico. Studi di spettroscopia UV-vis hanno permesso di determinare l’affinità di tali recettori nei confronti delle diammine lineari di formula generale H2N(CH2)nNH2, con n = 4-8. Le costanti di formazione dei complessi host-guest sono molto grandi, fino a 10e7 M-1, grazie all’effetto ditopico realizzato dai due centri porfirinici. La coordinazione delle diammine al dimero porfirinico è associata ad una variazione marcata del colore e questo fatto ha favorito l’impiego di tali derivati in ambito sensoristico. A tal proposito, è stata messa a punto una procedura per supportare i dimeri porfirinici su materiali polimerici per la costruzione di sensori da utilizzare per l’analisi in flusso continuo. Questi derivati sono stati anche utilizzati come pinze molecolari (tweezers) per la determinazione della configurazione assoluta di molecole chirali (diammine, ammino esteri, ammino ammidi e ammino alcoli, monoalcoli secondari) mediante l’impiego della spettroscopia di dicroismo circolare (CD), in collaborazione con la Prof. Berova della Columbia University. Parallelamente, sono stati realizzati studi di deposizione di derivati porfirinici su superfici in vista di applicazioni di tipo sensoristico e in campo energetico (fotovoltaico). La caratterizzazione dei substrati è stata condotta mediante misure di microscopia elettronica a scansione (SEM), microscopia a forza atomica (AFM) e microscopia a scansione ad effetto tunnel (STM). Questi studi di deposizione hanno dimostrato come, scegliendo le opportune condizioni di deposizione, sia possibile costruire dei sistemi ordinati a lungo raggio, su superfici di diversa natura, rendendo questi sistemi candidati ideali per lo sviluppo di nuovi materiali ad alto contenuto tecnologico.
25
Burford, Mary Kathleen. "Material process monitoring with optical fiber sensors." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/45077.
Full textAbstract:
Our motivation for this work is based on the need to rnom tor the cure and inservice
health of composite materials. We describe the continuation of an effort to design a multi-functional fiber optic sensor which can be embedded in polymeric composite laminates for monitoring the degree of cure during its fabrication, as well as internal composite strains occurring post-cure.3 In short, this dual-purpose sensor combines the characteristics of a Fresnel reflectometer with those of the extrinsic Fabry-Perot interferometer. For monitoring cure, a broadband source is used so the output intensity of the sensor is amplitude-modulated as the refractive index of the conlposite is increased during the polymerization process. Post-cure, a coherent light source is implernented so a. sinusoidal variation of the output signal occurs when strains within the
composite cause the sensor output to be phase-modulated. We demonstrate the
measurement of refractive index with the Fresnel reflectometer/EFPL and test it as an embedded refractive index monitor. Our experimental results demonstrate that the refractive index of 5-nlinute epoxy increases by approximately 2 % during the cure process. In addition, the sensor can be used as an interferometer to measure intenlal composite strains, where the phase difference between consecutive fringe peaks is one-half the wavelength of the source.Master of Science
26
Yu, Aihua. "Application of optical fibre Sagnac interferometers in optical modulators and sensors." Thesis, University of Essex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332807.
Full text
27
Noren, Jonathan Robert. "Electric Field Sensing in a Railgun Using Slab Coupled Optical Fiber Sensors." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3482.
Full textAbstract:
This thesis discusses the application of Slab Coupled Optical Fiber Sensors (SCOS) in a railgun. The specific goal of these sensors is to create an electric field profile at a specific point in the gun as the armature passes. The thesis explores the theory that powers the railgun as well as the principles of the SCOS sensors. It also elaborates on the various noise sources found throughout the detection system and concludes with a summary of the various field tests that were performed throughout this project. There are many benefits to using a railgun over traditional weapons in the field. These benefits not only include both safety and cost, but also greater overall defense capabilities. Unfortunately, the velocity skin effect (VSE) causes the current railgun designs to have limited life span through wear on the rails. In order to develop superior railguns and railgun armatures, the accurate detection of the VSE through measuring the electric field is of great interest. We used a SCOS, a small directionally precise dielectric sensor, as a small sensing area is required to be able to measure the electric fields inside of the rail gun. The actual usage of the SCOS within the railgun produced an additional set of problems that are not commonly encountered in the lab. The chief amongst these was noise from strain, RF pickup, and phase noise. This thesis also reports various methods used to reduce each of these noise sources.
28
Jarzebinska, Renata. "Tapered optical fibre sensors employing nanostructured coatings." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5585.
Full textAbstract:
Tapered optical fibres have been manufactured, characterised and studied. These are
compact devices made from single-mode optical fibre. A system for producing tapers has
been developed, employing flame heating of the optical fibre and computer controlled
rotation stages to stretch the fibre in a controlled and repeatable fashion.
Subsequently tapered fibres were coated with nanostructured films of materials that change
their optical properties in response to an external stimulus. An investigation of the effect of
depositing chemically sensitive nano-scale films onto tapered optical fibres has been
undertaken. Three different methods of deposition were applied: Langmuir-Blodgett
technique, electrostatic-self-assembly and – for the first time - chemical grafting. Six
different films of materials were deposited onto tapered fibres: 4-[2-(4-dimethylamino-
naphtalen-1-yl)-vinyl]-1-octadecyl-quinolinium iodide (merocyanine dye),
calix[4]resorcinarene, bilayers of poly(allyamine hydrochloride) (PAH) and anionic
tetrakis(4-sulfophenyl)porphine (TSPP), PAH and cyclodextrine, TiO2 nanoparticles
imprinted with ((1-(4-Nitrophenylazo)-2-naphthol (NPAN) compound), polyaniline
(PANI). During the deposition process the light was launched into each fibre and the
evolution of the transmission spectrum observed.
The coated tapers were subsequently investigated for their potential application as
chemical sensors: pH, red-ox, ammonia sensors. The response to a stimulus was
investigated by immersing the coated tapered fibre in an environment containing the
measurand.
The properties of these devices were also used in combination other photonics concepts,
such as fibre Bragg gratings written in the tapered region of a fiber, under investigation
within the Engineering Photonics Group to develop new sensor elements.
29
Badcock, Rodney Alan. "Optical fibre sensors for structural stain monitoring." Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389265.
Full text
30
Lin, John Chin-Hsiang. "Integrated optical sensors using waveguide grating reflectors." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239280.
Full text
31
Wild, L. B. "Thin-film optical sensors for carbon dioxide." Thesis, Swansea University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636598.
Full textAbstract:
In Chapter 3 a homologous family of dialkyl phthalates is used to investigate the effect of plasticiser/polymer compatibility on the response characteristics of transparent, thin-film optical gas sensors for carbon dioxide. A strong correlation is found between plasticiser/polymer compatibility and sensitivity in phenol red/ethyl cellulose CO2-sensitive films. This relationship applies to CO2-sensitive films based on other polymers such as polystyrene and poly(methyl methacrylate). This relationship also extends to optical O2-sensitive films, implying that the relationship is general for thin film optical sensors. In Chapter 4 an optical sensor is developed for breath-by-breath gaseous carbon dioxide analysis. The detector is based on a general formulation described in previous work where a phase transfer agent, tetraoctylammonium hydroxide (TOAOH), is used to incorporate a hydrophilic pH-sensitive dye into a hydrophobic plastic film to create an effectively solid-state colourimetric sensor. In this work the formulation has been modified to yield a sensor which is capable of responding to clinically important levels of carbon dioxide (0.1-5%) in less than 200ms. This is comparable with the response of commercially available capnometers based on infrared sensing of carbon dioxide, which are currently widely used for clinical analysis. In Chapter 5 the hydrophobic bases, tetraoctylammonium hydroxide (TOAOH), tetrakisdecylammonium hydroxide (TKAOH) and tetradodecylammonium hydroxide (TDAOH), are used to solubilise the anionic form of m-cresol purple in ethyl cellulose to create colourimetric thin-film sensors for monitoring carbon dioxide in the gas phase and dissolved in solution. When used for making dissolved carbon dioxide measurements both TKAOH and TDAOH appear significantly more resistant toward interference by protons or other ions at high concentration when compared to TOAOH, the hydrophobic base which has been used for such work in previous studies. In Chapter 6 the preparation and characterisation of three different plastic thin-film colourimetric sensors for gaseous ammonia are described. Each of these film optrodes gives a reproducible and reversible response towards gaseous ammonia. The sensitivity of the film sensors was found to be dependent upon the pKa of the encapsulated dye. The sensitivity of the plastic film sensor decreases markedly with increasing operation temperature and the 90% response and recovery times are slow and activation-controlled.
32
Cameron, Charles B., and Steven Lurie Garrett. "Recovering signals from optical fiber interferometric sensors." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28494.
Full text
33
Yong, Yang. "Surface bonded optical fibres as ultrasonic sensors." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248759.
Full text
34
Elliott, Nicholas James. "Development of distributed optical fibre chemical sensors." Thesis, Glasgow Caledonian University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270520.
Full text
35
SIMOES, TIAGO BALTAR. "MONITORING FLEXIBLE RISERS WITH OPTICAL FIBER SENSORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18538@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROO interesse no monitoramento da integridade estrutural de risers flexíveis tem crescido significativamente nos últimos anos. Para dutos que já estão atingindo sua vida de projeto, sistemas de monitoramento podem fornecer alertas antecipados de possíveis falhas e também auxiliar o operador na programação de paradas para manutenção. Diferentes técnicas estão sendo testadas pelos operadores de dutos flexíveis tais como inspeção visual automatizada, monitoramento de vibrações e emissão acústica, além de técnicas baseadas em métodos eletromagnéticos. Algumas destas técnicas já estão sendo implementadas em unidades de exploração e produção marítimas no Brasil e em outros países. A presente contribuição aborda o monitoramento contínuo e em tempo real utilizando sensores a fibra óptica (Redes de Bragg) para detectar a ruptura dos arames nas armaduras de tração de risers flexíveis. Duas linhas são seguidas, monitoramento direto e monitoramento indireto. O monitoramento indireto consiste na instrumentação da capa polimérica do riser, de forma não intrusiva, e avalia possíveis alterações na mesma, causadas pelo rompimento dos arames. Para isso foi desenvolvido um transdutor, denominado Colar 3D, capaz de detectar variações no diâmetro externo, elongação e torção no duto. A técnica de monitoramento direto é denominada MODA (Monitoramento Óptico Direto nos Arames). Nesta técnica os arames são instrumentados individualmente com os sensores ópticos, que monitoram as tensões/deformações dos mesmos, assim, rompimentos de arames e comportamentos inesperados podem ser facilmente detectados. Resultados de ensaios em escala real mostraram que a probabilidade de detecção do monitoramento indireto aumenta significativamente quando o sistema é empregado em conjunto com outros tipos de monitoramento indireto. Os resultados de laboratório para o monitoramento direto apontaram alta sensibilidade e confiabilidade do sistema, que já foi instalado em três plataformas operadas pela Petrobra na Bacia de Campos.
The interest in structural health monitoring of flexible risers has grown significantly in recent years. For ducts that are already reaching their design life, monitoring systems can provide early warnings of potential failures and also assist the operator in scheduling downtime. Different techniques are being tested by operators of flexible pipes such as automated visual inspection, vibration monitoring and acoustic emission, in addition to techniques based on electromagnetic methods. Some of these techniques are already being implemented in units of maritime exploration and production in Brazil and other countries. This contribution discusses the continuous monitoring and real-time using optical fiber sensors (FBGs) to detect the breaking of wires in the tensile armor of flexible risers. Two lines are followed, direct monitoring and indirect monitoring. The proposed indirect monitoring technique consists in the nonintrusive instrumentation of the riser’s polymeric outer sheath, which will provide strain signals that change due to the breaking of wires in the armor layer. For that, a transducer capable of detecting variations in the outer diameter, as well as stretching and twisting in the duct was developed. In the direct monitoring technique, all the wires in the external armor layer are individually instrumented with optical sensors that continuously monitor their strains, so that any disruptions of wires and unexpected behavior can be easily detected. Results of full scale laboratory tests showed that the probability of detection of indirect monitoring increases significantly when the system is used in conjunction with other types of indirect monitoring. The laboratory results for the direct monitoring showed high sensitivity and reliability of the system, which has already been installed in three oil rigs operated by Petrobras in the Campos Basin.
36
Wang, Huan. "Crop assessment and monitoring using optical sensors." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38224.
Full textAbstract:
Doctor of PhilosophyDepartment of Agronomy
V. P. Vara Prasad
Crop assessment and monitoring is important to crop management both at crop production level and research plot level, such as high-throughput phenotyping in breeding programs. Optical sensors based agricultural applications have been around for decades and have soared over the past ten years because of the potential of some new technologies to be low-cost, accessible, and high resolution for crop remote sensing which can help to improve crop management to maintain producers’ income and diminish environmental degradation. The overall objective of this study was to develop methods and compare the different optical sensors in crop assessment and monitoring at different scales and perspectives. At crop production level, we reviewed the current status of different optical sensors used in precision crop production including satellite-based, manned aerial vehicle (MAV)-based, unmanned aircraft system (UAS)-based, and vehicle-based active or passive optical sensors. These types of sensors were compared thoroughly on their specification, data collection efficiency, data availability, applications and limitation, economics, and adoption. At research plot level, four winter wheat experiments were conducted to compare three optical sensors (a Canon T4i® modified color infrared (CIR) camera, a MicaSense RedEdge® multispectral imager and a Holland Scientific® RapidScan CS-45® hand-held active optical sensor (AOS)) based high-throughput phenotyping for in-season biomass estimation, canopy estimation, and grain yield prediction in winter wheat across eleven Feekes stages from 3 through 11.3. The results showed that the vegetation indices (VIs) derived from the Canon T4i CIR camera and the RedEdge multispectral camera were highly correlated and can equally estimate winter wheat in-season biomass between Feekes 3 and 11.1 with the optimum point at booting stage and can predict grain yield as early as Feekes 7. Compared to passive sensors, the RapidScan AOS was less powerful and less temporally stable for biomass estimation and yield prediction. Precise canopy height maps were generated from a CMOS sensor camera and a multispectral imager although the accuracy could still be improved. Besides, an image processing workflow and a radiometric calibration method were developed for UAS based imagery data as bi-products in this project. At temporal dimension, a wheat phenology model based on weather data and field contextual information was developed to predict the starting date of three key growth stages (Feekes 4, 7, and 9), which are critical for N management. The model could be applied to new data within the state of Kansas to optimize the date for optical sensor (such as UAS) data collection and save random or unnecessary field trips. Sensor data collected at these stages could then be plugged into pre-built biomass estimation models (mentioned in the last paragraph) to estimate the productivity variability within 20% relative error.
37
Wales, Dominic. "Planar integrated optical Bragg grating gas sensors." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/366987/.
Full textAbstract:
This thesis reports the development and modification of direct ultraviolet (UV) written planar integrated optical Bragg grating refractometers for detection of gases and vapours. The technique of direct UV writing utilises the localised refractive index increase within a UV-photosensitive silica layer, when the layer is exposed to a tightly focussed UV beam, to fabricate a wide range of optical waveguides and optical components. One such component, the Bragg grating, is used as an optical sensor for changes in refractive index. This thesis reports on the development of practical planar integrated optical Bragg grating gas sensors. This has been achieved through the use of two approaches. The first approach was to increase the number of gas molecules that can interact with the evanescent wave through the use of films of material that extended normally to the surface of the sensor device. Upon functionalisation of a planar Bragg grating sensor device with sol-gel thin films, a response between relative humidity and Bragg wavelength shift was revealed. Functionalisation of the Bragg grating sensor device with a polysiloxane polymer imparted sensitivity to solvent vapours. A quantitative structure-activity relationship (QSAR) approach was used to develop a linear regression model, between Bragg wavelength shift and solvent properties, which had good predicting power. The second approach was to utilise the associated change in refractive index of a material, when the material changed colour upon exposure to a gas, to create a measurable Bragg wavelength shift. This method was successfully achieved upon interrogation of a Bragg grating sensor device, which had been modified with an encapsulated pH sensitive organic dye upon exposure to hydrogen chloride fumes.
38
De, Vries Marten J. "Optical fiber sensors for advanced civil structures." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/38569.
Full text
39
Xue, Ruipeng. "Nanofiber Based Optical Sensors for Oxygen Determination." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405508835.
Full text
40
BANO, ANDON. "Optical Fiber Sensors for Water Quality Monitoring." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2903506.
Full text
41
O'Neill, Sean Francis. "Optical methods of acoustic detection." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270811.
Full text
42
Miller, Mark S. "Advances in elliptical-core two-mode optical fiber sensors." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41617.
Full textAbstract:
Methods designed to improve the practicality of the elliptical-core two-mode optical fiber sensors for use in real-life applications are presented. The improvements include the development of insensitive lead fibers and an optical device which allows fringe counting at the output of the sensor. The insensitive leads eliminate extraneous perturbations and effectively isolate the sensing region. The fringe counting optics are designed to generate quadrature-phase shifted signals, thereby allowing the determination of whether the strain is increasing or decreasing.
Work performed to advance the understanding of the effect of sensor placement within a composite specimen is also presented. Optical fiber sensors are embedded between different laminae of a graphite-epoxy composite panel, and the outputs of the sensors are shown to be proportional to the distance of the sensor from the neutral axis.Master of Science
43
Fogg, Brian Russell. "Weighted sensitivity optical fiber sensors : theory and applications /." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10102009-020314/.
Full text
44
Silva, Muñoz Rodrigo. "Structural Health Monitoring Using Embedded Fiber Optic Strain Sensors." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/SilvaMunozR2008.pdf.
Full text
45
Berwick, M. "Investigations toward Faraday effect optical current sensors and optical fibre frequency shifters." Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290423.
Full text
46
Chamorro, García Alejandro. "Electrochemical and optical nanomaterial-based biosensors for diagnostic applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/319692.
Full textAbstract:
La presente tesis describe el desarrollo de nuevos métodos de sensado basados en nuevas propiedades de nanomateriales aplicados en la detección de proteínas y ADN. El trabajo ha sido basado en dos plataformas de sensado: primero, electrodos serigrafiados de carbono (SPCEs). Estos electrodos fueron aplicados en un ensayo de detección por impedancia eléctrica de nanopartículas de oro (AuNPs). Del mismo modo, SPCE fueron adaptados mediante films de polythionina y nanopartículas de Iridio (IrOxNPs) para la detección de secuencias de ADN. La segunda plataforma utilizada fue basada en papel y tiene el formato de un inmunoensayo de flujo lateral (LFIA, del inglés lateral flow immunoassays). Esta plataforma se adaptó para la detección de una proteína específica Parathyroid like hormone (PTHLH) utilizando AuNPs como marcas, con el fin de obtener una nueva estrategia más simple, sin marcaje de isótopos radioactivos, menos costosa y más rápida. En el Capítulo 1 se da una visión general de las aplicaciones llevabas a cabo y mejoras aportadas por parte de nanomateriales en el campo de los biosensores, y las posibles aplicaciones en la detección de biomarcadores. En el Capítulo 2 se presentan los objetivos de la tesis. El uso de SPCE como plataforma para la detección de AuNPs mediante medidas de impedancia se presenta en el Capítulo 3 consiguiendo una mejor detección en comparación con métodos similares publicados para la detección de AuNPs. La técnica desarrollada es aplicada satisfactoriamente en la detección de AuNPs de diferente tamaño, y en un magnetoinmunoensayo utilizando AuNPs como marca para la detección de una proteína modelo. En el Capítulo 4, se presenta el trabajo relacionado con el desarrollo de nuevos sensores para la detección de DNA. El sistema está basado en la modificación de SPCEs mediante películas de un polímero y nanopartículas de óxido de iridio (IrOxNPs) sobre las cuales se inmovilizan secuencias de captura de DNA. La detección del ADN objetivo se consigue mediante medidas de impedancia eléctrica, basadas en el efecto de bloqueo del ADN hibridado para la difusión de un indicador redox a la superficie del electrodo. El biosensor resultante, que opera en modo libre de marcas, fue utilizado para la detección de secuencias de ADN específicas para el parásito de Leishmania. En el Capítulo 5 se presentan conclusiones generales y perspectivas futuras. En el Anexo A, se presenta el trabajo relacionado con las plataformas de papel para la detección de una proteína específica, PTHLH. El sistema de detección presentado es del tipo LFIA. La técnica desarrollada supone una alternativa menos costosa, más rápida y menos peligrosa a las técnicas disponibles actualmente. El límite de detección (LOD) conseguido está en el rango de ng mL-1 en muestras reales (medio de cultivo celular y lisado celulares). Además, se comprobó la compatibilidad del método desarrollado con suero humano utilizando suero humano con PTHLH añadido. En el Anexo B, se presenta el trabajo llevado a cabo en una estancia de investigación. En esta sección se presenta la fabricación de sensores electroquímicos de ADN (E-DNA) y basados en aptameros (E-Ab), y la aplicación de dicha tecnología en sensores serigrafiados de oro y en SPCE modificados con AuNPs. El Anexo C representa la investigación llevada a cabo como continuación de otra hecha anteriormente en nuestro grupo. Las condiciones y materiales encontrados previamente se aplicaron en la fabricación de una plataforma de nanocanales para la detección de una proteína secretada por células cultivadas directamente sobre la plataforma de sensado.This thesis describes the study and development of new biosensing approaches based on novel properties of nanomaterials for the detection of proteins and DNA. The work has been performed in basis of two sensing platforms: first platform, the carbon screen-printed electrodes (SPCEs), were used in a more sensitive detection of gold nanoparticles (AuNPs) through electric impedance measurements. Furthemore, the same platform (SPCE) was adapted through polythinione films and iridium oxide nanoparticles (IrOxNPs) for the detection of specific DNA sequences in a label free assay. The second platform, paper-based platforms in format of Flow Immunoassay (LFIA), using gold nanoparticles as labels is adapted for the detection of a specific protein, Parathyroid like Hormone (PTHLH), with the aim to find a new strategy for simpler, non-hazardous, cheaper and faster detection of the protein. In Chapter 1 a general overview of the application of nanomaterials for the improvement of biosensors and its application in the field of diagnostics and biomarkers detection is presented. In Chapter 2 the objectives of the thesis are presented. Use of SPCE as platform for detection of gold nanoparticles (AuNPs) through electric impedance measurements is presented in Chapter 3. The developed technique is successfully applied in the detection of AuNPs of different sizes, and in a magnetoimmnuoassay for the detection of a model protein using AuNPs as electrochemical labels. In Chapter 4, a novel biosensor for the detection of DNA is presented. The system is based in SPCE modified with polymer films and Iridium Oxide nanoparticles, where capturing DNA sequences have been immobilized. Detection of target DNA sequences is performed through electric impedance measurements, based in the blocking effect of the DNA against the diffusion of a redox indicator to the surface of the electrode. A label free immunoassay for detection of specific sequences of Leishmania parasite’s DNA is shown. In Chapter 5 general conclusions and future perspectives of the presented work are discussed. In Annex A the work related to the paper-based platform for protein detection is presented. In this annex, detection of a specific protein (parathyroid like hormone, PTHLH) through LFIA strips is described. The developed LFIA strips represent a cheaper, faster and non-hazardous alternative to current available systems for PTHLH detection. Limits of detection (LOD) in the range of ng mL-1 for PTHLH in real samples (cell culture media, cell lysates) are reported. Furthermore, the developed system is challenged using human serum spiked with PTHLH, proving the potential of the system to detect PTHLH In human serum. In Annex B the work carried out in a research stay is presented. In this section fabrication of electrochemical DNA (E-DNA), and electrochemical aptamer (E-Ab) biosensors is described. The aim of the work was focused on adapting the E-DNA and E-Ab technology to SPCE, using AuNPs as connecting platform between the thiol modified DNA and the SPCE. Annex C represents a research done as a continuation of a previous one done in the group related mostly to the study of compatible materials with interest to be used as cells growth platforms with interest in sensing. As continuation of this work, in Annex C the conditions and materials previously selected to grow cells are applied in a nanochannel platform for the detection of a protein secreted by the cells grown directly on the sensing platform.
47
Gibson, Richard S. "Slab-Coupled Optical Fiber Sensors for Electric Field Sensing Applications." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3248.pdf.
Full text
48
Shreeve, Bryson J. "Magnetic Field Sensing with Slab Coupled Optical Fiber Sensors." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2774.
Full textAbstract:
This thesis reports an in-fiber magnetic field sensor that is able to detect magnetic fields as low as 2 A/m at a spatial resolution of 1 mm. The small sensor consists of a magneto-optic slab waveguide, bismuth-doped rare earth iron garnet (Bi-RIG) that is coupled to an optical fiber. By coupling light from the fiber to the slab waveguide, it becomes an in-fiber magnetic field sensor. This is due to the Magneto-Optic Kerr effect; a change in refractive index is proportional to the applied magnetic field. When an AC field is applied, an AC component in the output power can be detected by a spectrum analyzer. The novelties of Magneto-Optic Slab Coupled Optical Sensor (MO-SCOS) devices include their small compact nature and a dielectric structure allowing low electromagnetic interference. Due to their compact size they are capable of placement within devices to measure interior electromagnetic fields immeasurable by other sensors that are either too large for internal placement or disruptive of the internal fields due to metallic structure. This work also reports progress on EO SCOS development. The EO sensor has found application in new environments including the electromagnetic rail gun, and a dual-axis sensor.
49
Chadderdon, Spencer L. "Application Improvements of Slab-Coupled Optical Fiber Sensors." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3976.
Full textAbstract:
This dissertation explores techniques for improving slab-coupled optical fiber sensor (SCOS) technology for use in specific applications and sensing configurations. SCOS are advantageous for their small size and all-dielectric composition which permit non-intrusive measurement of electric fields within compact environments; however, their small size also limits their sensitivity. This work performs a thorough analysis of the factors contributing to the performance of SCOS and demonstrates methods which improve SCOS, while maintaining its small dimensions and high level of directional sensitivity. These improvements include increasing the sensitivity by 9x, improving the frequency response to include sub 300 kHz frequencies, and developing a method to tune the resonances. The analysis shows that the best material for the slab waveguide is an electro-optic polymer because of its low RF permittivity combined with high electro-optic coefficient. Additional improvements are based on changing the crystal orientation to a transverse configuration, which enhances the sensitivity due to a combined increase in the effective electro-optic coefficient and electric field penetration into the slab. The transverse SCOS configuration not only improves the overall sensitivity but increases the directional sensitivity of the SCOS. Lithium niobate and electro-optic polymer are both experimentally shown to exhibit minimal frequency dependent sensitivity making them suitable for broad frequency applications. Simultaneous interrogation of multiple SCOS with a single tunable laser is achieved by tuning the resonant wavelengths of KTP SCOS so their resonances overlap.
50
Vukusic, Peter. "Sensing thin layers using surface plasmon resonance." Thesis, University of Exeter, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358142.
Full text