Tesi sul tema "MIS devices"
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1
Torres, Almarza Ignacio. "Interfacial effects in polymer MIS devices". Thesis, Bangor University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409836.
Testo completo
2
Thomas, Nicholas John. "GaAs/Langmuir-Blodgett film MIS devices". Thesis, Durham University, 1986. http://etheses.dur.ac.uk/6829/.
Testo completoAbstract (sommario):
Langmuir-Blodgett (LB) films have previously been used as organic insulating layers in compound semiconductor metal-insulator- semiconductor devices, with promising preliminary results. This thesis describes the first investigation of the use of LB films In gallium arsenide metal-insulator-semiconductor devices. Diodes incorporating thin layers of w-tricosenoic acid or substituted copper phthalocyanine possessed 'leaky' electrical characteristics, i.e. there is some conduction through the LB film. This 'leaky' behaviour was exploited to produce the first metal- Insulator-semiconductor-switch (MISS) incorporating an LB film. MISS devices on n-p(^+) GaAs were produced with good switching characteristics and a high yield (~90%), using LB film thicknesses between 9 and 33 nm. It was shown that the 'punch through' mechanism was responsible for the switching behaviour. p-n(^+) GaAs/LB film MISS diodes behaved rather differently, with good switching characteristics only found at reduced temperature. Some degradation of the characteristics of LB film MISS devices was noted, although this was reduced by using the more robust phthalocyanlne LB films. Metal-tunnel-insulator-semiconductor diodes were produced on the ternary alloy Ga(_.47)In(_.53)As, using LB film monolayers. The barrier height was apparently larger than that of Schottky barriers on this material, with a very substantial reduction in current density due to tunnelling through the LB film. Using this technique it may be possible to produce very high performance GaInAs fleld-effect-transistors, which are analogous to GaAs metal-semiconductor field effect transistors.
3
Clifton, Paul Alan. "Characterisation of silicon MIS negative resistance devices". Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6434/.
Testo completoAbstract (sommario):
Metal-insulator-semiconductor switches (MISS), in which the T denotes some form of thin semi-insulating layer and the semiconductor part consists of a pn junction, are part of the general class of regenerative switching devices which includes the thyristor. The switching behaviour of the MISS derives from the ability of the MIS junction to exhibit current gain and to exist in two modes, deep depletion and inversion. In this thesis, a general model for the regenerative switching is proposed after investigating the properties of the MIS junction both theoretically and experimentally. Results from MIS diodes with tunnelling-thickness oxide Mayers indicate that interface states play a dominant role in their electrical behaviour and that the uniformity of the oxide is poor, giving rise to a large spread in the current-voltage characteristics. Subsequently, the epitaxial form of the MISS device is investigated and in particular the importance of isolation of the pn junction. It is concluded that spreading effects set a practical lower limit to the device dimensions, making the epitaxial form unsuitable for microelectronic applications. An alternative semi-insulator, 'silicon-rich oxide' (SRO) is introduced as an optional I-layer with possibly greater integrity than tunnel oxide. MIS diodes formed with SRO are shown to have very similar properties to tunnelling diodes. Large area devices fabricated using this material are surprisingly discovered to exhibit stable negative differential resistance (NDR). Although this discovery at first appears to be contrary to normal circuit stability criteria and to the regenerative feedback model itself, both of these points are resolved. It is shown that the frequency of oscillation of an unstable device is controlled by the external circuit. Then it is proposed that if this frequency is greater than the maximum frequency of operation of the regenerative mechanism, stable NDR is observed. In the final chapter, alternative lateral MISS structures which should overcome the geometrical limitations of epitaxial devices are discussed.
4
Holman, Brian. "The electrical characterization of tantalum capacitors as MIS devices". Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219849377/.
Testo completo
5
Lancaster, Janet. "Organic MIS Devices Based on a High-k Dielectric". Thesis, Bangor University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520852.
Testo completo
6
Evans, N. J. "Influence of gases on the electrical properties of MIS devices". Thesis, Durham University, 1986. http://etheses.dur.ac.uk/6866/.
Testo completoAbstract (sommario):
This thesis studies the effects of gas ambients on the electrical properties of the insulator-semiconductor interface of a MIS capacitor. A microcomputer-controlled instrumentation system has been developed to extract this information from measurement of the a.c. admittance of MOS or MIS devices. The system incorporates several novel developments in circuitry and software which enable these admittance data to be automatically collected and processed in the frequency domain by remote recalibration of the instrumentation. This advancement permits interface state density information to be calculated more quickly and accurately than has been previously possible using manually-operated equipment. The system has been used to investigate the influence of gases on the density of interface states in a MIS capacitor, in particular the palladium/silicon dioxide/silicon structure which is sensitive to hydrogen gas. A distinct change in the distribution of surface state density across the silicon bandgap has been observed upon exposure to a hydrogen ambient. An alternative insulating layer, an organic Langmuir-Blodgett film multilayer of ω-tricosenoic acid, has been characterised and examined, and increased sensitivity of this structure to hydrogen gas has been indicated.
7
Usman, Muhammad. "Impact of Ionizing Radiation on 4H-SiC Devices". Doctoral thesis, KTH, Integrerade komponenter och kretsar, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-60763.
Testo completoAbstract (sommario):
Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied. In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damag elevels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in deviceperformance produced by low dose ion implantations can be recovered at 420 oC, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain. Silicon dioxide (SiO2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al2O3 and Ta2O5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al2O3 is further investigated with respect to thermalstability and radiation hardness. It is observed that high temperature treatment of Al2O3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al2O3 is more resistant to ionizing radiation than currently used SiO2 and it is a suitable candidate for devices in radiation rich applications.QC 20120117
8
Noborio, Masato. "Fundamental Study on SiC Metal-Insulator-Semiconductor Devices for High-Voltage Power Integrated Circuits". 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/78006.
Testo completo
9
Fontaine, Lya. "Développement de briques technologiques pour la réalisation de composants de puissance MOS sur diamant". Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30060.
Testo completoAbstract (sommario):
Un des défis de notre époque est lié à la production et à la gestion de l'énergie électrique. Dans ce cadre, l'amélioration des composants à semi-conducteurs de puissance est une des clés pour répondre à ce défi. La grande majorité des composants de puissance actuels sont réalisés à base de silicium. Cependant, les exigences des applications de l'électronique de puissance en termes de tenue en tension, de densité de puissance, de température et de fréquence de commutation sont de plus en plus élevées. Les propriétés physiques intrinsèques des semiconducteurs à large bande interdite (SiC, GaN, Diamant) permettent d'envisager la conception et la fabrication de composants de puissance bien plus performants que les structures tout silicium. Dans ce contexte, nos travaux portent sur le développement et l'optimisation des étapes technologiques permettant la réalisation de composants de puissance MOS en diamant. Ils ont été réalisés dans le cadre du projet ANR MOVeToDIAM, coordonné par le LAAS-CNRS, dans la continuité des travaux sur diamant effectués au laboratoire depuis 2005. Le diamant est donc un semiconducteur à large bande interdite (Eg = 5,5 eV) particulièrement indiqué pour les applications fortes puissances et températures élevées. Il possède de fortes mobilités de porteurs (2200 cm2/V.s pour les électrons et 2050 cm2/V.s pour les trous), permettant le passage de fortes densités de courant, un champ de rupture élevé (Ec ~ 10 MV/cm) et une forte conductivité thermique (lambda ~ 20 W.cm-1.K-1) facilitant la dissipation thermique. Cependant, malgré ces propriétés prometteuses, de nombreux verrous technologiques sont encore à lever afin de conduire à la fabrication de composants de puissance sur diamant. Nous avons donc étudié et optimisé plusieurs étapes technologiques critiques afin de pallier les problèmes induits notamment par la petite taille des échantillons (2x2mm2 à 3x3mm2). Les étapes de photolithographie ont été développées et optimisées pour deux types de résine (AZ4999 positive et NLOF 2035 négative) à l'aide d'un Spray-Coater et d'une machine d'écriture directe par laser, améliorant ainsi fortement la résolution minimale, jusqu'à 1µm, des motifs définis sur les échantillons. Afin de caractériser les contacts ohmiques, nous avons développé deux structures de tests : le TLM droit (Transmission Line Method) et le TLM circulaire ou cTLM (Circular Transmission Line Method).[...]One of the challenges of our time is related to the production and management of electrical energy. In this context, the improvement of power semiconductor devices is one of the keys to meet this challenge. Most of current power devices are made of silicon. However, the demands of power electronics applications in terms of voltage withstand, power density, temperature and switching frequency are becoming higher. The intrinsic physical properties of wide-bandgap semiconductors (SiC, GaN, Diamond) make it possible to consider the design and fabrication of power devices that are much more efficient than all-silicon structures. In this context, our work focuses on the development and optimization of technological steps enabling the realization of diamond MOS power devices. They were carried out as part of the ANR project MOVeToDIAM, coordinated by LAAS-CNRS, in the continuity of the work on diamond made in the laboratory since 2005. Diamond is therefore a wide bandgap semiconductor (Eg = 5.5 eV) particularly suitable for high power and high temperature applications. It has high carrier mobilities (2200cm2/Vs for electrons and 2050cm2/Vs for holes), allowing the passage of high current densities, a high breaking field (Ec ~ 10 MV/cm) and a strong thermal conductivity (lambda ~ 20 W.cm-1.K-1) facilitating heat dissipation. However, despite these promising properties, many technological locks are still to be lifted in order to lead to the fabrication of power devices on diamond. We have therefore studied and optimized several critical technological steps to overcome the problems caused by the small sample size (2x2mm2 to 3x3mm2). The photolithography steps were developed and optimized for two types of resin (positive AZ4999 and negative NLOF 203) using a Spray-Coater and a direct laser writing machine, thus greatly improving the minimal resolution, up to 1 µm, of the patterns defined on the samples. In order to characterize ohmic contacts, we have developed two test structures: the Transmission Line Method (TLM) and the Circular TLM (Circular Transmission Line Method). If the realization of ohmic contacts on P-type diamond is mastered, the specific contact resistance must be further improved to limit its impact on the electrical performance of the devices. In addition, according to the literature, no ohmic contact has been made on N-type diamond, because of the difficulty of achieving high levels of doping, which remains a major obstacle to the development of the diamond industry. The fabrication of ohmic contacts on P-type and N-type diamond has been optimized on different samples.[...]
10
Pace, Bedetti Horacio Martin. "The effect of "Postural Freedom" in laparoscopic surgery". Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/122312.
Testo completoAbstract (sommario):
[ES] La cirugía laparoscopia está considerada uno de los principales avances quirúrgicos en las últimas décadas. Esta técnica ha demostrado numerosas ventajas comparadas con la cirugía convencional abierta y ha sido extensamente usada para procesos quirúrgicos en el área abdominal. Para el paciente, la cirugía laparoscópica supone diversas ventajas, como por ejemplo menor dolor post operativo, tiempos de recuperación menores, menor riesgo de infección, o reducción del trauma.
Para el cirujano en cambio, la situación es completamente diferente, esta práctica requiere mayor esfuerzo, concentración y estrés mental que la práctica convencional abierta. Además fuerza al cirujano a adoptar posiciones no-neutras en falanges, manos, muñecas, y brazos. Estas posturas no-neutras son la principal causa de fatiga muscular y aumentan el riesgo de problemas musculo-esqueléticos.
Estos problemas han sido ampliamente estudiados por diferentes equipos de investigación, los cuales están tratando de mejorar la experiencia del cirujano en el quirófano. El enfoque utilizado en este estudio es diferente del utilizado anteriormente por la mayoría de estos equipos, los cuales suelen propones soluciones basadas en cambios ergonómicos con la intención de mejorar la geometría del mango de pistola convencional, ya que se considera ergonómicamente deficiente. El problema con este enfoque, es que las deficiencias no se encuentran únicamente en el mango, sino en la utilización de un punto de entrada fijo que fuerza a los cirujanos a mantener posiciones desfavorables.
En este trabajo, se introduce el concepto "Libertad Postural" en el ámbito de la cirugía, este se basa en la hipótesis de que, si las herramientas no forzaran la posición de los cirujanos, estos mantendrían posiciones más favorables y cercanas al rango de posiciones neutras durante los procesos laparoscópicos.
Los beneficios de este concepto han sido demostrados por medio de análisis de movimiento y de electromiografía de superficie, los cuales indican que la "Libertad Postural" es causante de un claro aumento de las posiciones neutras y de la reducción de la fatiga muscular, y han sido testeados por cirujanos en entornos simulados, los cuales encuentran beneficioso utilizar la "Libertad Postural" como característica base de este nuevo diseño de herramienta laparoscópica.
En la sección final de este trabajo se propone un diseño que implementa el concepto de libertad postura con el cual se reduciría la fatiga muscular y los problemas musculo esqueléticos asociados a la práctica laparoscópica.
Este diseño tiene la característica de actuar como una nueva sección del brazo, siendo una articulación que soporta los giros y grandes desplazamientos que normalmente tienen que desarrollar los brazos del cirujano. Además, esta solución es económica y fácil de fabricar, lo cual permitiría su uso por cirujanos de todo el mundo.[CAT] La cirurgia laparoscòpia està considerada un dels principals avanços quirúrgics en les últimes dècades. Aquesta tècnica ha demostrat nombrosos avantatges comparats amb la cirurgia convencional oberta i ha sigut extensament usada per a processos quirúrgics en l'àrea abdominal. Per al pacient, la cirurgia laparoscòpica suposa diversos avantatges, com per exemple menor dolor post operatiu, temps de recuperació menors, menor risc d'infecció, o reducció del trauma. Per al cirurgià en canvi, la situació és completament diferent, aquesta pràctica requereix major esforç, concentració i estrés mental que la pràctica convencional oberta. A més força al cirurgià a adoptar posicions no-neutres en falanges, mans, nines, i braços. Aquestes postures no-neutres són la principal causa de fatiga muscular i augmenten el risc de problemes musculo-esquelètics. Aquests problemes han sigut àmpliament estudiats per diferents equips d'investigació, els quals estan tractant de millorar l'experiència del cirurgià en el quiròfan. L'enfocament utilitzat en aquest estudi és diferent de l'utilitzat anteriorment per la majoria d'aquests equips, els quals solen proposes solucions basades en canvis ergonòmics amb la intenció de millorar la geometria del mànec de pistola convencional, ja que es considera ergonòmicament deficient. El problema amb aquest enfocament, és que les deficiències no es troben únicament en el mànec, sinó en la utilització d'un punt d'entrada fix que força als cirurgians a mantindre posicions desfavorables. En aquest treball, s'introdueix el concepte "Llibertat Postural" en l'àmbit de la cirurgia, aquest es basa en la hipòtesi que, si les eines no forçaren la posició dels cirurgians, aquests mantindrien posicions més favorables i pròximes al rang de posicions neutres durant els processos laparoscòpics. Els beneficis d'aquest concepte han sigut demostrats per mitjà d'anàlisi de moviment i de electromiografía de superfície, els quals indiquen que la "Llibertat Postural" és causant d'un clar augment de les posicions neutres i de la reducció de la fatiga muscular, i han sigut testats per cirurgians en entorns simulats, els quals troben beneficiós utilitzar la "Llibertat Postural" com a característica base d'aquest nou disseny d'eina laparoscòpica. En la secció final d'aquest treball es proposa un disseny que implementa el concepte de llibertat postura amb el qual es reduiria la fatiga muscular i els problemes *musculo esquelètics associats a la pràctica laparoscòpica. Aquest disseny té la característica d'actuar com una nova secció del braç, sent una articulació que suporta els girs i grans desplaçaments que normalment han de desenvolupar els braços del cirurgià. A més, aquesta solució és econòmica i fàcil de fabricar, la qual cosa permetria el seu ús per cirurgians de tot el món.
[EN] Laparoscopic surgery is considered one of the main surgical advances in the last decades, this technique has demonstrated numerous advantages compared to open conventional surgery and it is widely used in abdominal procedures around the world. For the patient, laparoscopic surgery suppose less post-operative pain, shorter recovery time, lower risk of infection, and reduction of the trauma among other benefits. For the surgeon, the situation is completely different, this practice requires more effort, concentration and mental stress than conventional open procedures. It forces the surgeon to adopt non-neutral postures with phalanges, hands, wrists, and arms being this non-neutral postures the main cause of muscular fatigue and high risk of musculoskeletal disorders. The poor ergonomic postures accelerate muscle fatigue and pain because, outside the neutral range, muscles require more energy to generate the same contractile force than in neutral position. This increase of muscular fatigue is associated with the potential to commit errors that may harm the patient during the surgery. Because this problem is widely studied and different research centers are already trying to improve their surgeons experience in the operation room, the approach used during this work is different than most of the ones presented in previous works. Generally, the solutions proposed are based on ergonomic changes in the handle shape of the instrument, because the conventional pistol-grip handle is considered ergonomically poor. But the problem is not only in the shape of the handle but also in the fixed point of entrance that force the positions for the surgeon despite the handle¿s shape. In this work, the concept of postural freedom in laparoscopic surgery is introduced and evaluated. The postural freedom concept is based on the hypothesis that the surgeon involuntarily would maintain neutral postures if the instrument does not force him or her to reach extreme position with the upper limbs. The benefits of this concept has been demonstrated, by means of electromyography and motion capture. It reduces the localized muscular fatigue and increases the number of neutral postures during laparoscopic simulations. In the final section it is proposed a design that implements the postural freedom concept with, according on the results, the potential to reduce the localized muscular fatigue and the musculoskeletal problems associated to the practice. The design proposed here acts as a new section on the arm, being an articulation that support the turns and big displacements that currently suffer the surgeon¿s body. The solution is affordable and easy to manufacture and could be used by surgeons worldwide.
Pace Bedetti, HM. (2019). The effect of "Postural Freedom" in laparoscopic surgery [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/122312
TESIS
11
Tran, Ngoc Linh. "Mid-Infrared Intersubband Polaritonic Devices". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST001.
Testo completoAbstract (sommario):
Les polaritons intersousbandes (ISB) sont le résultat du régime de couplage fort lumière-matière entre les transitions intesousbandes de puits quantiques dopés et un mode photonique en microcavité. En raison de leur nature bosonique, les polaritons ISB peuvent être sujet à une diffusion stimulée par l'état final via différents mécanismes tels que la diffusion polariton-polariton ou la diffusion polariton-phonon. Les polaritons ISB sont très prometteurs dans la perspective du développement d'une nouvelle classe de laser, qui repose sur la diffusion stimulée par l'état final au lieu de l'inversion de population des lasers classiques. Cette thèse est consacrée au développement de dispositifs optoélectroniques (lasers et modulateurs) basés sur les polaritons ISB. À cet égard, nous avons développé une plateforme de cavité métal-métal (MIM) avec une ouverture périodique sur le miroir métallique supérieur, qui peut être utilisée pour réaliser des expériences d'injection électrique et optique dans les polaritons ISB. Nous avons démontré la formation des polaritons ISB et leur immunité à la présence d'un élargissement inhomogène. En outre, nous avons optimisé la largeur de ligne des transitions ISB par une technique de croissance d’épitaxie appelée interruption de croissance. En utilisant ces cavités MIM, nous avons réussi à démontrer la diffusion des polaritons vers un état final via leur interaction avec des phonons optiques longitudinaux (LO) sous injection résonante de lumière cohérente. Nous avons également développé des modulateurs d'amplitude en espace libre, qui reposent sur le changement de réflectance du régime de couplage fort auquel un biais de radiofréquence (RF) est appliqué. Enfin, nous avons montré l'existence d'une nouvelle forme d'état excitonique dans la bande de conduction des puits quantiques dopés. Pour cette démonstration, nous avons profité du fort confinement offert par le résonateur MIM pour lier ensemble les charges répulsives d'une transition ionisanteIntersubband (ISB) polaritons are the result of the strong light-matter coupling regime between intersubband transitions in doped quantum wells and a microcavity photonic mode. Owing to their bosonic nature, ISB polaritons can be subject to final state stimulated scattering via different mechanism such as polariton-polariton scattering or polariton-phonon scattering. ISB polaritons hold great promises in view of the development of a novel class of laser, which rely on final state stimulated scattering instead of the population inversion in conventional lasers. This thesis is devoted to the development of optoelectronic devices (lasers and modulators) based on ISB polaritons. In this respect, we have developed a metal-metal (MIM) cavity platform with a periodic opening on the top metallic mirror, which can be employed to perform both electrical and optical injection experiments within ISB polaritons.We have demonstrated the formation of ISB polaritons and their immunity to the presence of inhomogeneous broadening. In addition, we have optimized the linewidth of ISB transitions via an epitaxial growth technique known as growth interruption. Using these MIM cavities, we have successfully demonstrated the evidence of polaritons scattering towards a final state via their interaction with longitudinal optical (LO) phonons under resonant injection of coherent light. We have also developed free-space amplitude modulators, which rely on the change of reflectance of the strong coupling regime to which a radio frequency (RF) bias is applied. Finally, we have shown the existence of a new form of excitonic state within the conduction band of doped Quantum Wells. For this demonstration, we have taken advantage of the strong confinement offered by MIM resonator to bind together the repulsive charges of an ionizing transition.frequency range. In the presented work, we have developed a metal-metal cavity platform with a periodic opening on the top metallic mirror, which can be employed to perform both electrical and optical injection experiments. We have shown the formation of ISB polaritons and we have addressed an issue related to polaritons, i.e., the immunity of ISB polaritons to the presence of inhomogeneous broadening in active regions with high doping. In addition, we have optimized the linewidth of ISB transitions via epitaxial growth techniques such as modulation doping and the growth interruption. Using the metal-metal cavity platform, we have successfully demonstrated the optical pumping experiment into a bright polariton state to reveal the evidence of the polariton scattering towards a final state via interaction with the longitudinal optical (LO) phonon. We have also developed free-space amplitude modulators, which rely on the modulation of the strong coupling regime at a high speed via an applied electric field. Lastly, we have experimentally investigated a new type of the strong coupling regime for bound-to-continuum transitions in quantum well. This finding indicated that the strong light-matter coupling can non-perturbatively modify the excitation nature (ionizing), leading to the formation of polariton modes with the bound state nature
12
Lippitt, Alex. "Development of a bioimpedance-based swallowing biofeedback device with smart device integration". Thesis, University of Canterbury. Electrical and Computer Engineering, 2015. http://hdl.handle.net/10092/10975.
Testo completoAbstract (sommario):
Low resolution pharyngeal manometry is an invasive diagnostic method that has recently been used as a biofeedback device for swallowing rehabilitation. The University of Canterbury Rose Centre uses pharyngeal manometry to diagnose and rehabilitate subjects who suffer from pharyngeal mis-sequencing. Pharyngeal mis-sequencing occurs when pressure is applied simultaneously throughout the pharynx rather than sequentially. Rehabilitation can only be performed in clinic due to the need for specialized equipment and trained staff, and the invasiveness of the test limits the time that can be spent training.
As an alternative method to measure the pharyngeal pressure sequence, bioimpedance has been investigated by a previous University of Canterbury Master’s student. A prototype was developed that measured bioimpedance in two locations as a proxy for pharyngeal pressure sequence. The prototype device named GULPS (Guided Utility for Latency in Pharyngeal Swallowing), measured a change in impedance during swallowing. However, the features of this waveform were inconsistent and were not present during every swallow.
The frequency of the current that passes through tissue affects its path through the tissue, therefore impacting the measured impedance. To improve the consistency of the impedance measurement, the effect of current injection frequency was investigated. A modular-hardware system was created from the original design to allow testing of different injection frequencies. The hardware was further developed by replacing the method of generating the constant amplitude current injection signal.
The improvement to the design resulted in a differently-shaped waveform to that of the previous prototype, including a new feature. This feature is a single peak that occurred in both channels and was reproduced in every swallow. Experimentation showed that the features were not obviously frequency dependent. The separation between the peaks of the two impedance channels was compared with the separation between the two pressure peaks recorded during simultaneous pharyngeal manometry but there was no significant correlation between the two measures of peak-peak separations.
Two alternative hardware/signal conditioning changes were trialled: electrical isolation of each channel and a subtraction method, which aims to remove the effect of the changing impedance between the two electrode channels. Electrical isolation of the two channels had no effect on the impedance waveforms. However, the subtraction method produced a different output and requires further investigation as the output was inconsistent.
Bluetooth communication was integrated into the GULPS hardware, and a corresponding Android Application (App) was written. The developed App was successful in displaying the impedance measurement output and adds greater user flexibility, allowing the user to interface with the bioimpedance measurement hardware from their tablet or phone.
With no measured significant correlation between GULPS and pharyngeal manometry, further research needs to be performed to better relate the features measured by GULPS to those seen during pharyngeal manometry. Until this can be achieved, the GULPS device cannot replace pharyngeal manometry for biofeedback-based rehabilitation of pharyngeal mis-sequencing.
13
Cheetham, Kieran James. "GaInAsSbP alloys for mid-infrared optoelectronic devices". Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618809.
Testo completoAbstract (sommario):
The GaInAsSbP pentanary system has been utilised to grow epilayers on InAs substrates using Liquid Phase Epitaxy, and used to form the basis of. optoelectronic devices in the technologically important Mm spectral range (3-5 μm). The photoluminescence spectra of a single epilayer confirmed that the dominant radiative recombination mechanism was band-to-band in the pentanary layer. XRD analysis indicated the epilayers did not suffer from spinodal decomposition, and SEM and SIMS confirmed the layers were flat and abrupt. Raman spectroscopy was carried out over a wide range of lattice-matched InAsSbP compositions for the first time, before a further study on GaInAsSbP. Binary-like optical phonon signals were identified, and their position was found to directly relate to the composition of the alloy. Phonon signals resulting from alloy disorder were identified in the Raman spectra, which provides a valuable tool for future work on determining crystal quality. Prototype mesa diode devices were fabricated using wet etching with the addition of an InAsSbP window layer. Uncooled photodetectors were found to operate at room temperature, limited by diffusion current. Thermophotovoltaic cells using the same structure, designed for use with comparatively low temperature heat sources, were found to have a 33% fill factor. This is the first report of a pentanary alloy used for such an application. The corresponding photoresponse spectra exhibited two peaks, attributed to recombination in both the window layer and active region. Room temperature LEDs were demonstrated, operating with a 50% duty cycle, with their emission peaking at ~3.75 μm. The analysis of the excitation dependent electroluminescence allowed the electron effective mass of 0.018 mo to be calculated for the GaInAsSbP alloy. The devices were found to be limited by CHCC Auger recombination, even though the CHSH mechanism was suppressed by increasing the spin-orbit split-off band, as confirmed by high pressure measurements. The bandgap dependence of GalnAsSbP on pressure was found to be 10.7 meV/khar, which is believed to be the first such investigation for a III-v pentanary alloy. Multi-ring structures v/ere fabricated and current crowding effects were investigated. It was found that by employing multiple rings, rather than spot contacts, there was an improvement in the current spreading. and hence the output of the device. When only the outer-most contact was energised the current crowding under the contact was sufficient to facilitate whispering gallery modes. Lasing was achieved at 4K with drive currents of >300 mA, peaking at 3.3 μm.
14
Soler, Penadés Jordi. "Group IV mid-infrared devices for sensing". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/413485/.
Testo completoAbstract (sommario):
Group IV photonics is a topical research field, with potential applications in diverse areas such as bio-chemical and environmental sensing, security, communications, healthcare and astronomy. Many of these applications require accessing longer wavelengths in what is called the mid-infrared (MIR) region and specifically in the "fingerprint" region, as it contains strong fundamental vibrational transitions of most molecules. The transparency range of the traditional material platform used for years in near-infrared (NIR) silicon photonics (silicon-on-insulator) is not suitable due to its limited wavelength transparency range, therefore new materials need to be explored. In this project SOI has been used to produce a slot waveguide at 3.8m, a wavelength range in which SiO2 absorption begins to be significant, but with a careful design and a proper selection of a suitable platform (i.e. thicker Si and SiO2 layers), low loss devices can still be produced, as it has been demonstrated extensively. A slot was chosen since it is a waveguide design highly suitable for sensing. The slot waveguide had a propagation loss of 1.4dB/cm and high field confinement in the slot gap. A new platform of suspended silicon with sub-wavelength lateral cladding has also been demonstrated, allowing the use of SOI for the full transparency range of Si. This platform has significant advantages compared to other, suspended solutions, in that a single etch step is required to fabricate the suspended waveguides and the resulting devices are more robust since the suspended region for a comparable device is much thinner, allowing the design of wider devices. This has been demonstrated with the design, fabrication and characterization of waveguides, bends, multimode interferomenters (MMI) and a Mach-Zehnder interferometer (MZI). The waveguides fabricated with this technique achieved a loss as low as 0.82dB/cm. The Ge-on-Si platform has also been developed with the demonstration of waveguides and MMIs with propagation loss as low as 0.58dB/cm at 3.8m for the former and 0.21dB insertion loss for the latter. Waveguides and MMIs have also been fabricated and characterized in the wavelength range between 7.5m and 9.5m with a minimum loss of 2.5dB/cm, extending the range at which this material has been characterized. Unforeseen losses in Ge have been discovered in this wavelength range, a discussion of the possible sources is included in this thesis. Evanescent field sensing of Thiodiglycol has also been demonstrated, showing a good agreement with a commercial FTIR in the aforementioned range.
15
Mittal, Vinita. "Mid-infrared integrated photonic devices for biosensing". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/416430/.
Testo completoAbstract (sommario):
This thesis describes the realisation of devices and techniques based on evanescent field sensing using planar optical waveguides for mid-infrared (MIR) absorption spectroscopy, to provide bio-chemical sensing capabilities for medical diagnostics. The fundamental vibrations of bio-chemical molecules occur in the MIR region, where their absorption is orders of magnitude stronger than their overtone bands in the near-infrared making it suitable for highly sensitive and specific absorption spectroscopy. Realisation of waveguides is an essential step towards mass-producible and low-cost integrated lab-on-chip devices. Two chalcogenide compositions were used to make waveguides, germanium telluride (GeTe4) as waveguide core and zinc selenide (ZnSe) as waveguide lower cladding. Two approaches were followed for waveguide fabrication: GeTe4 waveguides on bulk ZnSe and GeTe4 waveguides on thin films ZnSe deposited on Si. High contrast (Δn ~ 0.9) GeTe4 channel waveguides on ZnSe were fabricated using photolithography and lift-off. Waveguiding was demonstrated for the wavelength range between 2.5 and 9.5 μm for GeTe4 channel waveguides on bulk ZnSe substrates. GeTe4 waveguides fabricated on Si with ZnSe isolation layers were characterised for waveguiding and propagation losses in the wavelength range between 2.5 and 3.7 μm. ZnSe rib waveguides were also fabricated on oxidised Si by photolithography and dry etching and were characterised for propagation losses in the wavelength region of 2.5-3.7 μm. Absorption spectroscopy of liquid mixtures absorbing in the MIR was performed on the surface of the waveguide and the results were compared with a theoretical model.
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McDaniel, Sean A. "Mid-IR Ultrafast Laser Inscribed Waveguides and Devices". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1512639558935449.
Testo completo
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Green, Alexander Michael. "Resonant-cavity-enhanced optoelectronic devices in the mid-infrared". Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411496.
Testo completo
18
Sun, Zhongyuan. "Near- and mid-IR fibre grating devices and applications". Thesis, Aston University, 2016. http://publications.aston.ac.uk/30078/.
Testo completoAbstract (sommario):
This thesis presents a detailed research work on the fabrication, characterisation and applications of optical fibre grating devices with operation wavelengths cover from near- to mid- infrared (IR) range. One of the major contributions described in this thesis is the systematic investigation on the structures, fabrication methods and spectral, thermal, strain and surrounding refractive index (SRI) characteristics of near-IR fibre gratings including fibre Bragg gratings (FBGs), chirped fibre Bragg grating (CFBGs) and long period grating (LPGs). For some applications, such as special engineering sensors and high power fibre laser, the fibre gratings have been fabricated on different novel fibres (metal coated fibre and large mode field fibre), respectively. Another important contribution from the studies is experimental investigation on 45º tilted fibre gratings (45°-TFGs) and excessively tilted fibre gratings (ex-TFGs), and their applications. 45º-TFGs with high polarisation dependent loss (PDL) in single mode and polarisation maintaining (PM) fibres have been fabricated. The 45°-TFG has been employed as in fibre polariser to obtain the single polarised laser, which has been further developed as transverse loading sensor achieving high sensitivities. Furthermore, all fibre Lyot filter with narrow bandwidth (26 pm), constructed by two 45º-TFGs with 100m long cavity in PM fibre has been demonstrated. For ex-TFGs, SRI sensor based on a surface modified 81°-TFG, showing capability to detect glucose concentration with relatively high RI sensitivity (~168nm/RIU). Finally, an all-fibre loading sensor based on a hybrid 45° and 81° TFG structure has been demonstrated. Finally, I have fabricated fibre gratings into mid-IR 2μm range. The mid-IR FBGs have been evaluated for thermal and strain response, revealing higher temperature sensitivities than that in near-IR range. The mid-IR LPGs have been investigated for the thermal and refractive index sensitivities, also showing significant enhancement. The 45°-TFGs in mid-IR have been investigated for their PDL characteristics. The mid-IR FBGs and 45°-TFGs have been employed in Tm-doped fibre laser cavity to realize multi-wavelength continued wave (CW) and single polarisation operation.
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Asghari, Zahra Sadat. "Highf requency optoelectronic devices in the mid infrared wavelength region". Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC111.
Testo completoAbstract (sommario):
La région moyen-infrarouge se situe entre les domaines de l’optique et du THz du spectre électromagnétique. Cette région a un intérêt particulier dans les applications spectroscopiques et la communication dans l’espace libre.Grâce à des avancées technologiques sur la fabrication de dispositifs unipolaires basés sur des transitions inter-sous-bandes, la région du moyen-infrarouge est devenue accessible par une nouvelle famille de lasers et détecteurs à base de semi-conducteurs. Ces dispositifs optoélectroniques sont basés sur des transitions optiques entre les états électroniques de la bande de conduction d’une structure composée d’une succession de puits quantiques. Leur temps de vie caractéristique est de l’ordre du picosecondes et ainsi, les dispositifs inter-sous-bandes disposent de propriétés de dynamique ultra rapides intéressantes dans le développement des applications à hautes fréquences.L’objectif de cette thèse est le dessin d’un système prêt à l’emploi pour la communication dans l’espace libre à fort taux de transfert de bit dans le moyen-infrarouge, avec tous les composants qui fonctionnent à température ambiante. Dans ce but, nous avons étudié les performances hautes fréquences d’un système composé de détecteurs et de lasers à cascade quantiques.Dans un premier temps, nous avons caractérisé les propriétés électriques et optiques d’un détecteur à cascade quantique à 4.9 μm à température ambiante. La structure de bande ainsi que la distribution des charges a été étudié en détails dans différentes conditions de température et de tensions appliquées aux bornes du détecteur. Nous avons montré une température limite de détection de 135 K avec une detectivité à cette température de 2 × 1011 Jones, nous situant dans l’état de l’art. Par la suite, nous nous sommes concentrés sur la réponse en modulation à haute fréquence du détecteur à cascade quantique. Nous avons, en premier lieu, optimisé le système électronique afin qu’il soit compatible avec des mesures hautes fréquences. Avec ce système, nous avons mesuré une détection optique jusqu’à 5.4GHz en utilisant un détecteur à cascade quantique de taille 50 × 50 (μm)2 avec son pont suspendu en or adapté en impédance avec tout le reste du montage expérimental. Grâce à des mesures de rectification, nous avons montré que la fréquence de coupure est limitée par la structure de bande du détecteur en soit. Nous avons ensuite développé un système prêt à l’emploi pour les modulations hautes fréquences du laser à cascade quantique, ce dernier étant optimisé grâce une étude sur son contact d’injection. Nous montrons ainsi une fréquence de coupure optique de 10 GHz, limitée par le photo-détecteur. Enfin, comme preuve de concept, nous avons réalisé une communication dans l’espace libre de 4 Gb/s à l’échelle du laboratoire en utilisant un laser à cascade quantique et un photo-détecteur infrarouge à puits quantiques. Pour cela, nous avons utilisé une modulation par changement de phase binaire et nous avons obtenu un taux d’erreur de 10(−5)Mid infrared (MIR) covers the region of the electromagnetic spectrum between optics and THz ranges. This frequency range is of great interest for applications in spectroscopy and free space optical communications. The progress on unipolar devices based on intersubband transitions, has introduced in the MIR a new family of semiconductor lasers and detectors. These optoelectronic devices are indeed based on optical transitions between electronic states in the conduction band of a complex sequence of quantum wells. Their characteristic lifetime is of the order of picoseconds and therefore intersubband devices have a great potential for wideband ultrafast applications.The aim of this work is the design of a system for high data bit rate free space optical communication in the mid infrared spectral region, with all the components operating at room temperature. To this end, we investigate the high frequency performances of quantum cascade detectors (QCD) and lasers (QCL).Firstly, we carefully explore the electrical and optical characteristics of QCD at 4.9 μm operating at room temperature. A detailed study of the band structure and charge distribution at different operating temperature and under different applied bias is reported. We demonstrate a background limited infrared photodetector (BLIP) temperature of 135 K and a detectivity at this temperature of 2 × 1011 Jones, which is at the state of the art. We then focus on QCD response to high frequency modulation. We engineered and realized an electronic system compatible with high frequency operation. We report an optical response up to 5.4 GHz with a 50 × 50 (μm)2 square mesa using a gold air-bridge technology. Thanks to rectification measurements, we show that the band-pass is limited by the specific detector bandstructure. For the high frequency modulation of QCLs, we develop a plug and play system with an optimization on the injection contact that allows the demonstration of a cut off frequency of 10 GHz, limited by the photodetector. Finally, we present a proof of principle demonstration of a free space optical communication experiment using a QCL and a quantum well infrared photodetector (QWIP) at 4 Gb/s. We use a Binary Phase-Shift Keying (BPSK) modulation technique and we obtain a bit error rate of 10(−5)
20
Rose, Eric Q. "Generation of mid-wave infrared signature using microradiating devices for vehicle mounted identification friend or foe applications". Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Jun/09Jun%5FRose.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Physics)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Haegel, Nancy. "June 2009." Description based on title screen as viewed on 13 July 2009. Author(s) subject terms: Anti-fratricide, thermal emitter, vehicle mounted identification friend or foe, night vision device (nvd), thermal imaging. Includes bibliographical references (p. 95). Also available in print.
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Fox, Natasha. "Optical characterisation of novel mid-infrared device structures". Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/843108/.
Testo completoAbstract (sommario):
Optical techniques are used to characterise materials designed to emit and/or detect in the infrared. Two tri-metal InGaAlAs quantum well (QW) laser structure samples giown on InP are compared at room temperature to a conventional benchmark InGaAsP QW structure also grown on InP. The spectroscopic methods used to characterise the samples include photo-modulated reflectance (PR), electro-modulated reflectance (ER) and surface photo voltage spectroscopy (SPS). The positions of the QW transitions are compared with a theoretical model of a QW to find the conduction band offset. The InGaAlAs material system is shown to have a much higher conduction band offset of ~66% compared to that of ~40% in the InGaAsP sample. Having measured the QW bandgap and several higher order transitions successfully using conventional spectroscopic methods, a comparison with a novel spectroscopy technique, Fourier transform infrared surface photovoltage spectroscopy (FTIR-SPS) is performed. The technique is designed to make use of the simplicity of SPS whilst avoiding the physical limitations of grating spectroscopy which occur towards the infrared. The technique is shown to be in good agreement with conventional, grating-based spectroscopic measurements on the same sample. Four GalnSb/AIGalnSb type I QW laser structure samples grown on GaAs, aimed at emitting in the mid-infrared at ~4 mum with increasingly strained QWs are analysed at room temperature using FTIR-SPS. FTIR-SPS detects both the barrier bandgap, the QW ground state and up to 5 excited state QW transitions. These results are compared to temperature dependent photoluminescence (PL) of the QWs, where possible, and to temperature dependent PR of the barrier. The behaviour of the laser structure samples is compared to similar measurements made on four analogous multi-QW samples designed to give clear PL. The FTIR-SPS results are compared to a theoretical prediction of the samples' transition energies made using k.p theory. The theory and the experiment are shown to agree reasonably well if the theoretical QW energies are blue shifted by between 15 and 37 meV. The room temperature SPS measurements are also in good agreement with the temperature dependent PR of the barrier and PL of the QW. A novel vertical cavity surface emitting laser (VCSEL) aimed at emitting at 2.3 mum at room temperature and a corollary sample with the top mirrors removed were studied using PR and reflectivity (R) measurements. Using PR it was possible to measure the position of the cavity mode (CM), QW and one higher order transition. These measurements were compared to device measurements made of the QW and CM temperature dependence. The behaviour of the QW was in good agreement with the device measurements; however, there was some discrepancy in the energetic position of the CM in the two measurements. This is believed to be due mainly to effects of annealing the sample on the QW and CM. The measurements show that the device is strongly detuned at room temperature which is thought to account for its relatively poor behaviour. Finally, an InAs QD LED and a dilute InAsN QD test structure were studied as a function of temperature using PL. The dilute nitride QD was found to give luminescence at up to 3.6 mum at room temperature. It is believed that this is the longest interband wavelength PL ever observed from QDs of this material system grown on InP. There is also a considerably reduced temperature dependence in the dilute nitride QD structure as compared to that of nitrogen-free InAs Qds.
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Khan, Saeed. "Silicon photonic devices for optical delay lines and mid infrared applications". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5961.
Testo completoAbstract (sommario):
Silicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon.
Optical delay lines are among important silicon photonic devices, which are essential for a variety of photonic system applications including optical beam-forming for controlling phased-array antennas, optical communication and networking systems and optical coherence tomography. In this thesis, several types of delay lines based on apodized grating waveguides are proposed and demonstrated. Simulation and experimental results suggest that these novel devices can provide high optical delay and tunability at very high bit rate.
While most of silicon photonics research has focused in the near-infrared wavelengths, extending the operating wavelength range of the technology into in the 3–5 &"181;m, or the mid-wave infrared regime, is a more recent field of research. A key challenge has been that the standard silicon-on-insulator waveguides are not suitable for the mid-infrared, since the material loss of the buried oxide layer becomes substantially high. Here, the silicon-on-sapphire waveguide technology, which can extend silicon's operating wavelength range up to 4.4 &"181;m, is investigated. Furthermore, silicon-on-nitride waveguides, boasting a wide transparent range of 1.2–6.7 ?m, are demonstrated and characterized for the first time at both mid-infrared (3.39 ?m) and near-infrared (1.55 ?m) wavelengths.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Macdonald, John Robert. "Active and passive mid-infrared photonic devices in ZnSe based materials". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2713.
Testo completoAbstract (sommario):
The work described in this thesis details the development of mid-infrared waveguide laser sources created through the fabrication of waveguide structures in Cr2+: ZnSe using ultrafast laser inscription (ULI). Current quantum cascade laser (QCL) technology in the 2 – 5 μm region offer compact and robust sources suited to use outside the laboratory but the technology does not offer the high average powers, >100 mW, and wide tuneability, 2 – 3.3 μm of Cr2+: ZnSe laser sources. The development of a Cr2+: ZnSe waveguide laser source provides an environmentally robust product with access to powers and tuneable ranges greater than that provided by QCL systems. The first phase of the investigation produced the first successful refractive index modification of ZnSe using ULI. Both positive and negative refractive index changes were achieved and utilised to fabricate a range of waveguides in ZnSe and Cr2+: ZnSe. Low loss near-infrared waveguides were demonstrated through exploitation of the positive refractive index change. Low loss mid-infrared depressed cladding waveguides were subsequently demonstrated utilising the negative refractive index change. These waveguides were characterised at wavelengths of 1928, 2300 and 3390 nm as representative of pump and signal wavelengths in Cr2+: ZnSe laser systems. Finally, the newly fabricated Cr2+: ZnSe waveguides were constructed into waveguide laser cavities and pumped with a thulium fibre laser source operating at 1928 nm. Laser operation is demonstrated in both waveguides devices at wavelengths of 2573 and 2486 nm with a maximum achieved output power of 285 mW and a slope efficiency of 45%. Furthermore, a tuneable laser source is constructed in the Littman-Metcalf configuration exhibiting a maximum tuning range of 510 nm, 2330-2840 nm, with output powers exceeding 25 mW across the full range. These waveguide laser devices offer an environmentally robust and compact source in the 2 – 3 μm region with improvements upon maximum power and tuneability ranges in current quantum cascade laser sources. The waveguide laser sources reported open the door to products offering the robust nature of QCL sources with the higher powers and 2 – 3 μm tuneability associated with current bulk Cr2+: ZnSe laser systems.
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Lauters, Michael E. "Organic Opto-Electronic Devices for Data Storage and Solid-State Lighting". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/193770.
Testo completoAbstract (sommario):
Metal/organic/indium tin oxide (ITO) structures, including OLEDs, are demonstrated to contain multiple nonvolatile conductance states that can be programmed by the application of an external bias above a certain threshold voltage (Vth). These conductance states are stable and in turn can be probed by the use of a bias lower in value than Vth. The unbiased retention time of states is greater than several weeks, and more than 48,000 write-read-rewrite-read cycles have been performed with minimal degradation. It is found that the programming of a continuum of conductance states is possible, and techniques to do so are outlined. The electrical conductivity of the highest and lowest states can differ by six orders of magnitude. Switching speeds below 50 ns are shown, resulting in an energy requirement of about 100 pJ to switch from one conductance state to another. The memory phenomenon is shown to be influenced by the active layer thickness and anode/surface roughness while temperature dependence is limited. The electrical characteristics of these devices are consistent with metal diffusion or filament phenomena found in metal-insulator-metal structures, suggesting a possible mechanism by which the states are stored.Electroluminescent devices employing several new organic-inorganic lumophore-functionalized macromolecules are presented. In this study, macromolecules incorporating several lumophores covalently bonded to the vertices of a cubical core structure based on Polyhedral Oligomeric Silsesquioxane (POSS) in multiple configurations are implemented as light-emitting centers. The hole-transporting polymer poly(N-vinylcarbazole) (PVK) and electron-transporting additive 2-(4-biphenylyl)-5-(4-tert-butylphenyl)1,3,4-oxadiazole (PBD) are used as a two-part host to enhance the carrier transport in these simple solution-processed single-layer devices. A study of energy transfer in several systems is carried out to understand the requirements needed to create white-light emission from a single macromolecule. A single macromolecule incorporating twenty-one blue and one yellow lumophore is shown to exhibit field-independent stable white-light electroluminescence with Commission Internationale de l'Eclairage (CIE) coordinates of (0.31, 0.37). An external quantum efficiency of 0.55 percent and a maximum brightness of 1600 cd/m2 are attained with simple solution-processed single-layer devices. High solubility and ease of purification give these macromolecule white-light emitters advantages over their small molecule and polymeric type counterparts.
25
Shah, Devanshi. "St. Jude Medical: Enhanced MICS (eMICS)". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/377.
Testo completoAbstract (sommario):
Heart disease is one of the most prevalent diseases in the world. The survival chances for patients with ventricular fibrillation/ventricular tachycardia reduces significantly as time passes without treatment and even after getting timely treatment recurring episode are common. These patients can benefit from an Implantable Cardioverter Defibrillator (ICD) which can monitor heart rhythm and provide immediate treatment. Due to the ever changing physical conditions and disease progression, the ICD needs to collect diagnostic data as well as support programming by the physician. The ICD uses inductive telemetry and radio-frequency telemetry for the communication with the external devices such as a programmer or a monitor. Inductive telemetry uses less energy than RF telemetry but has a very short range of communication. In addition to inductive telemetry, the St. Jude Medical ICD supports 2.45 GHz band based asynchronized wakeup and 400 MHz MICS band based synchronized wakeup. The 2.45 GHz band based wakeup has limited wakeup range and the 400 MHz MICS based synchronized wakeup has limited availability for connection because it requires synchronization with the base station. The enhanced Medical Implant Communications Service (eMICS) algorithm is a firmware based algorithm which addresses the issues with other two wakeup schemes and provides fast, robust, and seamless wakeup. This thesis describes the design, implementation, and initial testing of eMICS algorithm on the Unity device platform in Technology Project Management (TPM) phase. The eMICS automated test tool developed at St. Jude Medical was used to test the eMICS algorithm under a controlled lab environment, typical home environment, typical hospital/clinic environment, and in the field. The project was successfully completed and transferred to Product Project Management (PPM) phase. However, the suggested duration of 60-90 seconds for sniff interval which will cause the least effect on the battery life was found unacceptable, and there is also a strong need for energy efficient hardware which draws minimal amount of current during each sniff. Therefore, St. Jude Medical is collaborating with the hardware vender to implement eMICS algorithm in the next version of hardware.
26
de, la Mare Martin Ian. "Investigation of narrow gap dilute nitride materials for mid-infrared optoelectronic devices". Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.587052.
Testo completoAbstract (sommario):
This project investigates dilute nitrides such as InAsN and InGaAsN with a view to the fabrication of optoelectronic sources and detectors operating in the mid-infrared (2-5 um) spectral range which has many practical applications. Samples of both bulk epitaxial layers and state-of-the-art nanostructures have been grown by liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE). The effect of N incorporation on the material quantum efficiency has been studied using temperature dependent photo- and electroluminescence spectroscopy, high resolution x-ray diffraction and other techniques. InAsN and InGaAsN bulk epilayers were grown by liquid phase epitaxy under standard and neutral solvent growth techniques to investigate the feasibility of high quality material production. Photoluminescence (PL) showed that the dominant peak in the majority of the material was from a defect related transition which quickly quenched leaving just band - band recombination. Raman spectroscopy was employed to identify the types of defect levels present within the material, the strange behaviour of the PL from InGaAsN material was determined to be from a doubly-ionised defect involving a combination of In vacancies and higher order nitrogen complexes. High quality InAsN layers were grown from neutral solvent growth with an XRD full-width-half-maximum (FWHM) of 17.5 arc-seconds obtained from 0.3% N incorporation; this however was only observed in thin layers of the dilute nitride believed to be due to the rapid depletion of N within the growth melt. High quality InAsN was grown onto GaAs substrates using molecular beam epitaxy; PL from this material persisted up to room temperature with a final emission wavelength of 4 urn and nitrogen incorporation of 1%. The temperature dependence of the material was found to be superior to that of similar material grown onto InAs substrates and shown to have an 'S' shaped behaviour at low temperatures originating from tail states caused by inhomogeneous nitrogen incorporation typical of all nitrogen inclusive materials. A comparison with LPE material was then carried out. PL measurements showed that the LPE material had comparable emission intensities with narrower FWHM for low N content samples but MBE proved more favourable for higher N content material with the maximum N inclusion from LPE being 0.5%. The addition of Sb to InAsN multi quantum wells was then studied with the view to device fabrication. The addition of Sb was found to improve both lattice quality and PL intensities while reducing the overall strain of the material. Interpretation of the 4 K PL was shown to be intense with the observation of recombination originating from both the first heavy hole and light hole consistent with a type I band alignment. A model to determine the band alignment of the InAsSbN multiple quantum wells (MQWs) was derived from a single-band Schrodinger solver and found to be in good agreement with the experimental results. Finally InAsSbN light emitting diodes (LEDs) were fabricated and shown to exhibit strong electroluminescence reaching room temperature with final wavelengths of 3.7 urn and the presence of hydrocarbon absorption in the spectrum reveals that this material has potential for gas detection. Output powers of over 3 μW under 100 mA drive current at 50% quasi- continuous operation were obtained leading to an internal efficiency of 0.63%, an improvement over InAsSb and InSb quantum dot LEDs. These prototype devices show promise for type I dilute nitride materials operating in the mid infrared region.
27
Aldukhayel, Abdullah Mohammed. "Physical process in inter-band and inter-subband mid-infrared photonic devices". Thesis, University of Surrey, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658624.
Testo completoAbstract (sommario):
Mid-infrared light emitting diodes and quantum cascade lasers are of increasing interest due to their promising applications. They can be used in detecting and monitoring pollutant gases such as methane (CH4) and carbon dioxide (C02), Such devices are preferred for these purposes due to their potential for high sensitivity for detecting gases, long device lifetime, and potential low-cost. Mid-infrared light emitting diodes emitting at a wavelength of 3.7 !-lm based on the pentanary alloy GaInAsSbP engineered to provide a favourable band structure for the suppression of non-radiative Auger recombination were investigated. Temperature dependence measurements were made to investigate the performance of these LEDs. Hydrostatic pressure measurements at room temperature and at 100 K were used to tune the band gap towards resonance with the spin-orbit splitting to inv,estigate the influence of the hot-hole (CHSH) Auger process on LED performance. Analysis of the resulting electroluminescence showed that while Auger recombination related to hot electrons occurs, it confirms that the nonradiative Auger recombination process involving the spin-orbit split-off band (CHSH) is suppressed under ambient conditions. In order to identify the performance limitations of InGaAsI AIAs(Sb) quantum cascade lasers, experimental investigations of the temperature and pressure dependenGies of the threshold current (Ith) were undertaken. Using the theoretically estimated optical phonon current (Iph) and calculated carrier leakage (I leak) as a function of pressure the measured pressure dependence of the threshold current showed that electron scattering from the upper laser level into the L valley minima gives rise to the increase in Ith with pressure and temperature. It was found that this carrier leakage path accounts for approximately 3 % of Ith at R T and is negligible at 100 K. However, it is shown that even this small leakage current causes strong temperature sensitivity of the devices and limits their maximum operating temperature.
28
Khoury, Mario. "Silicon-based light emitters towards quantum devices at telecom frequency". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0364.
Testo completoAbstract (sommario):
L'objectif de cette thèse est d'explorer le potentiel des impuretés complexes de carbone dans le silicium (G-centers) pour des applications dans les technologies quantiques. Ce défaut ponctuel a été initialement mis en évidence dans des échantillons de Si riches en carbone soumis à une irradiation électronique à haute énergie suivie d'un recuit à haute température. Une caractéristique clé des centers-G est leur émission infrarouge, correspondant à l'importante longueur d'onde de la bande O des télécommunications optiques qui s'étend entre 1260-1360 nm. Nous avons démontré que nous sommes capables de créer des centres G individuels par implantation ionique dans du SOI, du 28Si isotopiquement purifié sur isolant, et des nanostructures photoniques telles que des résonateurs diélectriques de Mie vers des sources intégrées de photons uniques dans le silicium émettant dans la gamme de longueur d'onde des télécommunications. Par lithographie optique et de gravure au plasma, associée à un démouillage à l'état solide de silicium cristallin ultra-mince sur isolant, afin de former des résonateurs de Mie monocristallins. En intégrant des centres G émetteurs de lumière dans les antennes en Si, j'ai conçu l'émission de lumière en réglant la dose de carbone, l'énergie du faisceau et la taille des îlots afin d'optimiser le couplage entre les émetteurs et les résonances de Mie. L'émission de lumière directionnelle à 120 K a été démontrée expérimentalement et confirmée par des simulations FDT. Nous estimons qu'avec un couplage optimal de l'émission des centres G avec les antennes résonantes, une efficacité de collecte d'environ 90 % peut être atteinte en utilisant un objectif conventionnelThe aim of this thesis it to explore the potential of complex carbon impurities in silicon (G-centers) for applications in quantum technologies. This point defect was originally highlighted in carbon-rich Si samples undergoing high-energy electron irradiation followed by high temperature annealing. A key feature of G-centers is their infrared emission, matching the important optical telecommunications wavelength O-band spreading between 1260-1360 nm. Through my PhD work we have demonstrated that we are able to create individual G-centers by ion implantation in conventional silicon on insulator, isotopically purified 28Si on insulator, and embed these emitters in photonic nanostructures such as dielectric Mie resonators. We developed a low-resolution optical lithography and plasma etching method joined with solid state dewetting of monocrystalline, ultra-thin, silicon on insulator to form monocrystalline, atomically-smooth, Mie resonators in well-controlled and large, periodic arrays.By integrating light emitting G-centers within the Si-based antennas we engineered the light emission by tuning carbon dose, beam energy and islands size in order to optimize the coupling between the emitters and the Mie resonances in space and frequency. directional (Huygens-like) light emission at 120 K was demonstrated experimentally and confirmed by finite difference time domain simulations. We estimate that, with an optimal coupling of the G-centers emission with the resonant antennas, a collection efficiency of about 90% can be reached using a conventional objective lens
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Austin, David. "Studies of plasmonics and metamaterials for mid-infrared device applications". Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522577.
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Fohrmann, Lena Simone [Verfasser]. "Near- and mid-infrared integrated silicon devices for sensing applications / Lena Simone Fohrmann". Berlin : epubli, 2019. http://d-nb.info/119256409X/34.
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Grave, Ilan Yariv Amnon Yariv Amnon. "GaAs quantum well devices for detection and nonlinear optics in the mid-infrared /". Diss., Pasadena, Calif. : California Institute of Technology, 1993. http://resolver.caltech.edu/CaltechETD:etd-08272007-111424.
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John, Jimmy. "VO2 nanostructures for dynamically tunable nanophotonic devices". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI044.
Testo completoAbstract (sommario):
L'information est devenue le bien le plus précieux au monde. Ce mouvement vers la nouvelle ère de l'information a été propulsé par la capacité à transmettre l'information plus rapidement, à la vitesse de la lumière. Il est donc apparu nécessaire de mener des recherches plus poussées pour contrôler plus efficacement les supports d'information. Avec les progrès réalisés dans ce secteur, la plupart des technologies actuelles de contrôle de la lumière se heurtent à certains obstacles tels que la taille et la consommation d'énergie et sont conçues pour être passives ou sont limitées technologiquement pour être moins actives (technologie Si-back). Même si rien ne voyage plus vite que la lumière, la vitesse réelle à laquelle les informations peuvent être transportées par la lumière est la vitesse à laquelle nous pouvons la moduler ou la contrôler. Ma tâche dans cette thèse visait à étudier le potentiel du VO2, un matériau à changement de phase, pour la nano-photonique, avec un accent particulier sur la façon de contourner les inconvénients du matériau et de concevoir et démontrer des dispositifs intégrés efficaces pour une manipulation efficace de la lumière à la fois dans les télécommunications et le spectre visible. En outre, nous démontrons expérimentalement que les résonances multipolaires supportées par les nanocristaux de VO2 (NC) peuvent être réglées et commutées dynamiquement en exploitant la propriété de changement de phase du VO2. Et ainsi atteindre l'objectif d'adaptation de la propriété intrinsèque basée sur le formalisme de Mie en réduisant les dimensions des structures de VO2 comparables à la longueur d'onde de fonctionnement, créant un champ d'application pour un métamatériau accordable défini par l'utilisateurInformation has become the most valuable commodity in the world. This drive to the new information age has been propelled by the ability to transmit information faster, at the speed of light. This erupted the need for finer researches on controlling the information carriers more efficiently. With the advancement in this sector, majority of the current technology for controlling the light, face certain roadblocks like size, power consumption and are built to be passive or are restrained technologically to be less active (Si- backed technology). Even though nothing travels faster than light, the real speed at which information can be carried by light is the speed at which we can modulate or control it. My task in this thesis aimed at investigating the potential of VO2, a phase change material, for nano-photonics, with a specific emphasis on how to circumvent the drawbacks of the material and to design and demonstrate efficient integrated devices for efficient manipulation of light both in telecommunication and visible spectrum. In addition to that we experimentally demonstrate the multipolar resonances supported by VO2 nanocrystals (NCs) can be dynamically tuned and switched leveraging phase change property of VO2. And thus achieving the target tailoring of intrinsic property based on Mie formalism by reducing the dimensions of VO2 structures comparable to the wavelength of operation, creating a scope for user defined tunable metamaterial
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Mendes, Letícia Francine. "Desenvolvimento de sensor eletroquímico modificado com polímeros molecularmente impressos (MIP) visando à quantificação de cortisol". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-19072018-141609/.
Testo completoAbstract (sommario):
O cortisol é um hormônio associado a vários processos fisiológicos importantes. Esta dissertação apresenta estudos sobre o desenvolvimento de um sensor eletroquímico simples e de baixo custo visando à quantificação do cortisol sem a necessidade de modificação da superfície do sensor com biomoléculas. Inicialmente, o foco do trabalho foi o desenvolvimento de um método analítico visando à detecção direta de cortisol utilizando eletrodos não modificados de carbono vítreo. Estes estudos mostraram problemas de reprodutibilidade devido à grande adsorção da molécula de cortisol ou seus produtos de redução na superfície do eletrodo. Assim, avaliou-se o uso de eletrodos de grafite como dispositivos descartáveis em plataformas de papel. Uma boa linearidade foi observada em um intervalo de concentração semelhante ao apresentado nos estudos envolvendo o eletrodo de carbono vítreo (10 a 100 181.mol L-1). Diante desse resultado, os dispositivos portáteis de baixo custo apresentaram ótimas características analíticas em comparação ao método anterior mostrando à potencialidade para aplicação em amostras reais. Concomitantemente, polímeros impressos molecularmente (MIPs) fabricados por processos químicos e eletroquímicos foram estudados com o intuito de aumentar a seletividade para a análise de cortisol. Os MIPs quimicamente fabricados foram sintetizados usando acrilamida como monômero e N, N\'-metilenobisacrilamida como agente de reticulante. Este material recombina-se com sucesso com o analito segundo os estudos de UV-Vis, no entanto a imobilização na superfície do eletrodo não foi possível. Assim, a polimerização eletroquímica do pirrol foi avaliada como uma maneira simples de produzir o MIP diretamente na superfície do eletrodo. A recombinação da molécula molde com os eletrodos modificados foi verificada por voltametria cíclica e técnica de microbalança eletroquímica de cristal de quartzo. A segunda abordagem apontou resultados promissores para o desenvolvimento de sensor piezelétrico modificado para detecção de cortisol.Cortisol is a hormone associated with several important physiological processes. This masters dissertation reports studies about the development of a simple and low cost electrochemical sensor aiming at the quantification of cortisol without the need of biomolecules immobilized at sensor surface. Initially, the focus was the development of an analytical method for the direct detection of cortisol using bare glassy carbon electrodes. These studies have shown problems of reproducibility due to large adsorption of the cortisol molecule or its reduction products on the electrode surface. Thus, it was evaluated the use of graphite electrodes as disposable devices in paperbased platform. A good linearity was observed in a concentration range similar to that obtained in studies involving the glassy carbon electrode (from 10 to 100 µmol L-1). In light of this result, the proposed low-cost portable devices presented great analytical features and low-cost in comparison with the previous method with potentiality for application in real samples. Concomitantly, molecularly imprinted polymers (MIPs) fabricated by chemical and electrochemical processes were studied to enhance the selectivity for cortisol analysis. The chemically manufactured MIPs were synthesized using acrylamide as monomer and N, N\'-methylenebisacrylamide as crosslinking agent. This material recombine successfully with the analyte according the UV-Vis study, but it was difficult to immobilize this material at the electrode surface. The electrochemical polymerization of pyrrole was evaluated as a simple way to produce the MIP directly on the electrode surface. The recombination of the template molecule with the modified electrodes was verified by cyclic voltammetry and electrochemical quartz crystal microbalance technique. The second approach pointed out promisor results to the development of modified piezoelectric sensor for cortisol detection.
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Kaiser, Ingo [Verfasser]. "Systematik zur Entwicklung mechatronischer Systeme in der Technologie MID (Molded Interconnect Devices) / Ingo Kaiser". Paderborn : Universitätsbibliothek, 2009. http://d-nb.info/1033310107/34.
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Bradford, Christine Bradford. "MBE growth and characterisation of Zincblende MgS-based II-VI semiconductor material and devices". Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/407.
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Cripps, Stuart Anthony. "Photomodulation spectroscopy and characterisation of both near and mid-infrared semiconductor materials and devices". Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/726/.
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Vigneron, Pierre-Baptiste. "Mid-Infrared Detectors and THz Devices Operating in the Strong Light-Matter Coupling Regime". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS082/document.
Testo completoAbstract (sommario):
Les polaritons inter-sous-bandes, observés pour la première fois il y a une quinzaine d’années, sont des quasi-particules dont de nombreuses propriétés restent encore à découvrir. La recherche dans ce domaine se focalise actuellement sur la réalisation de condensats de Bose-Einstein. Une telle découverte pourrait révolutionner l’optoélectronique du moyen infra-rouge jusqu’au THz ouvrant la voie à l’instauration de nouveaux concepts de sources lumineuses,de détecteurs ou de systèmes logiques en couplage fort. Dans cette quête, le choix de la cavité résonnante est critique. Dans ce manuscrit nous proposons d’utiliser des cavités métal-isolant-métal (M-I-M) avec un réseau dispersif sur le métal supérieur. Ce type de cavité,conservant un confinement élevé entre les deux plans métalliques, offre de nombreuses possibilités d’ajustement de la résonance de cavité : via la géométrie de la cavité ( épaisseur de la cavité, période et recouvrement du réseau) ainsi que par le couplage de la lumière avec la cavité (vecteur d’onde incident). Les cavités M-I-M dispersives ouvrent donc un nouveau champ d’exploration des polaritons inter-sous-bande. Dans un premier temps nous avons introduit ces cavités dans le domaine du THz afin d’étudier les phénomènes de relaxation polariton-polariton. Un système expérimental dédié à cette exploration a été conçu pour mesurer la réflectivité des polaritons THz avec une fine résolution en angle. Dans une second temps, des capteurs moyen infrarouge en couplage fort avec une cavité M-I-M dispersive ont été conçus, fabriqués et mesurés dans le but d’explorer la génération de photo-courant à partir de polaritons et d’utiliser le couplage fort pour dissocier l’ énergie de détection de l’énergie d’activation. Cette seconde étude s’inscrit dans l’objectif de pompage électrique des polaritons ISB. Parallèlement à l’étude des polaritons, nous avons également participé au développement de techniques(interféromètre Gires-Tournois et revêtement anti-réflection) pour compresser les impulsions optiques de lasers à cascade quantique THzAfter fifteen years of intersubband polaritons development some of the peculiar properties of these quasi-particles are still unexplored. A deeper comprehension of the polaritons is needed to access their fundamental properties and assess their applicative potential as efficient emitters or detectors in the mid-infrared and THz.In this manuscript we used Metal-Insulator-Metal (MI-M) cavities with a top metal periodic grating as a platform to deepen the understanding of ISB polaritons.The advantages of M-I-M are twofold : first they confine the TM00 mode, second the dispersion of the cavity -over a large set of in-plane wave-vectors- offers various experimental configurations to observe the polaritons in both reflection and photo-current. We reexamined the properties of ISB polaritons in the mid-infrared and in the THz using these resonators. In the first part, we explore the implementation of dispersive M-I-M cavities with THz intersubband transitions. In the THz domain, the scattering mechanisms of the THz ISB polaritons need to be understood. The dispersive cavity is a major asset to study these mechanisms because it provides more degrees of freedom to the system. For this purpose, we fabricated a new experimental set-up to measure the polariton dispersion at liquid Helium temperature. After the characterization of the polaritons in reflectivity, a pump-probe experiment was performed on the polaritonic devices. The second part of this manuscript presents the implementation of M-I-M dispersive cavities with abound-to-quasi-bound quantum well infrared photo detector designed to detect in strong coupling. Beyond electrical probing of the polaritons, the strong coupling can disentangle the frequency of detection from the thermal activation energy and reduce the dark current at a given frequency. In parallel to the exploration of THz polaritons, we developed two techniques (Gires-Tournois Interferometer and Anti-reflection coating) in order to shorten the pulses of THz quantum cascade lasers with metal-metal waveguides
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Sweeney, Robin E., Elizabeth Budiman e Jeong-Yeol Yoon. "Instant scanner device for identifying wound infection utilizing Mie scatter spectra". SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/626485.
Testo completoAbstract (sommario):
Tissue biopsy and swab culture are the gold standards for diagnosing tissue infection; these tests require significant time, diagnostic costs, and resources. Towards earlier and specific diagnosis of infection, a non-destructive, rapid, and mobile detection device is described to distinguish bacterial species via light scatter spectra from the surface of an infected tissue, reagent-free. Porcine skin and human cadaveric skin models of wound infection were used with a 650 nm LED and an angular photodiode array to detect bacterial infections on the tissue surface, which can easily be translated to a typical CMOS array or smartphone. Tissue samples were inoculated with Escherichia coli, Salmonella Typhimurium, or Staphylococcus aureus and backscatter was collected from 100 degrees to 170 degrees in 10 degrees increments; each bacterial species resulted in unique Mie scatter spectra. Distinct Mie scatter spectra were obtained from epidermis (intact skin model) and dermis (wound model) samples, as well as from porcine and human cadaveric skin samples. Interactions between bacterial colonies and lipid particles within dermis samples generated a characteristic Mie scatter spectrum, while the lipid itself did not contribute to such characteristic spectrum as corroborated with body lotion experiments. The designed angular photodiode array is able to immediately and non-destructively detect tissue bacterial infection and identify the species of infection within three seconds, which could greatly improve point of care diagnostics and antibiotic treatments.
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Tiihonen, Mikael. "Spectral Management in Quasi-Phase-Matched Parametric Devices". Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4021.
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Merrick, Martin. "Optical studies of bandstructure and spin-dependent processes in mid-infrared semiconductor materials and devices". Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/804356/.
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Marks, Lori J. "Mid-tech Support Strategies for Students with Autism: Pairing Boardmaker with Simple Voice Output Devices". Digital Commons @ East Tennessee State University, 2004. https://dc.etsu.edu/etsu-works/3690.
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Zhang, Yang. "Control Implementation and Co-simulation of A 6-DOF TAU Haptic Device". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293508.
Testo completoAbstract (sommario):
In the research area of virtual reality, the term haptic rendering is defined as the process of computing and generating the interaction force between the virtual object and the operator. One of the major challenges of haptic rendering is the stably rendering contact with a stiff object. Traditional haptic rendering algorithms performs well when rendering contact with soft objects. But when it is used to simulate contact with objects with high stiffness, the algorithm may cause unstable response of haptic devices. Such unstable behavior (e.g., oscillation of the device) can destroy the fidelity of the virtual environment and even hurt the user. To address the above stability issues, a new design approach has been proposed in this paper. The proposed approach consists of three main process steps: modeling and linearization in ADAMS, LQR position controller design, verification with co-simulation. In the first step, a simulation model of the system is firstly created in ADAMS/View. Then this nonlinear ADAMS multi-body dynamics model is linearized and exported as a set of linear state space matrices with the help of ADAMS/Linear. In the second step, different from the traditional force-control algorithms, LQR position controller is developed in Matlab Simulink based on the exported matrices to emulate interactions with stiff objects. At last, the verification of control performance is carried out by setting up co-simulation between ADAMS and Simulink. A case study implementation of this proposed method was performed on the TAU device which was previously developed by Machine Design department at KTH. TAU is an asymmetrical parallel robot with six degrees of freedom for the simulation of surgical procedures like drilling and milling of hard tissues of bones and teeth. The results show that the linear model exported from ADAMS is sufficiently accurate and the proposed controller can render a virtual wall with stiffness at the level of 105 N/m.Inom forskningsområdet virtuell verklighet definieras termen hatisk återgivning (haptic rendering) som processen för beräkning och generering av interaktiva krafter mellan det virtuella objektet och användaren. En av de största utmaningarna med haptisk återgivning är att stabilt simulera känslan av beröring av styv material för användare. Traditionella algoritmer fungerar när det gäller att simulera känslan av beröring av mjuk material, men när algoritmerna används för att simulera kontakt med materialer med stor styvhet kan det orsaka instabilitet hos haptiska enheter. Sådana instabilitet, bland annat svängning hos enheten, kan förstöra den virtuella miljöns exakthet och till och med skada användare. Denna uppsats försöker ta itu med det ovanstående problemet genom att föreslå en ny designmetod. Metoden består av tre huvudsteg: modellering och linearisering med hjälp av ADAMS, design av LQR-positionskontroll, och verifiering med samsimulering (co-simulation). I det första steget skapas systemets simuleringsmodell med hjälp av ADAMS/View. Sedan linjäriseras denna icke-linjära ADAMS-multikroppsdynamikmodell. Modellen exporteras som linjära tillståndsmatriser med hjälp av ADAMS/Linear. I det andra steget designas en LQR-positionskontroll med hjälp av Matlab Simulink baserat på de exporterade matriserna tidigare för att simulera interaktioner med styv material, vilket skiljer sig från de traditionella kraftkontrollalgoritmer (force-control algorithms). I det sista steget utförs verifieringen av positionskontrollens prestanda genom att ställa in samsimulering (co-simulation) mellan ADAMS och Simulink. En testkörning av denna föreslagna metod har utförs på TAU-enheten som tidigare utvecklades av KTH institutionen för maskinkonstruktion. TAU är en asymmetrisk parallellsrobot med sex frihetsgrader för att simulera kirurgiska ingrepp som borrning av hårda vävnader i ben och tänder. Resultaten visar att den linjära modellen som exporteras från ADAMS är tillräckligt korrekt, för den föreslagna positionskontrollen kan framställa en virtuell vägg med styvhet vid 105 N/m.
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Diener, Romina [Verfasser], Thomas [Gutachter] Pertsch, Morten [Gutachter] Bache e Alex [Gutachter] Fuerbach. "Mid-infrared photonic devices for stellar interferometry / Romina Diener ; Gutachter: Thomas Pertsch, Morten Bache, Alex Fuerbach". Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1172206821/34.
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Jürgenhake, Christoph [Verfasser]. "Systematik für eine prototypenbasierte Entwicklung mechatronischer Systeme in der Technologie MID (Molded Interconnect Devices) / Christoph Jürgenhake". Paderborn : Universitätsbibliothek, 2017. http://d-nb.info/1144342945/34.
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Schierbaum, Thomas [Verfasser]. "Systematik zur Kostenbewertung im Systementwurf mechatronischer Systeme in der Technologie Molded Interconnect Devices (MID) / Thomas Schierbaum". Paderborn : Universitätsbibliothek, 2017. http://d-nb.info/1127628151/34.
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Jürgenhake, Christoph [Verfasser]. "Systematik für eine prototypenbasierte Entwicklung mechatronischer Systeme in der Technologie MID (Molded Interconnect Devices) / Christoph Jürgenhake". Paderborn : Universitätsbibliothek, 2018. http://d-nb.info/1153057166/34.
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Lundh, Oskar. "Communication protocols for mid-range mobile IoT devices : And their applicability to a publicly shared bikes platform". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-222378.
Testo completoAbstract (sommario):
Internet of Things, or the infrastructure of the information age society, is an expanding area of research. It is the idea that physical things that we have today, can be turned into devices by being connected to a network. The purpose of these devices is through more sensors and actuators, allow smarter and more robust infrastructure to be built, as well as improving consumer devices interoperability. This thesis will investigate the current state of the art application layer communication protocols that have been developed with resource constrained mobile devices in mind. It will look specifically at high latency mid-range wireless cellular communication by investigating how the protocols affect energy consumption for an embedded Internet of Things device. This is done with the constraint that these findings needs to be applicable to the fifth generation of cellular networks, as well as extensions to current generation standards. The application layer communication protocols Constrained Applications Protocol(CoAP), Message Queue Telemetry Transport(MQTT) and Hypertext Transfer Protocol(HTTP) used on multiple modem modules, are investigated in a quantitative approach in deductive survey experiments, testing a variety of what is concluded to be typical sensor and actuator scenarios. The goal with the survey, is to ultimately select the protocol that shows to be the most suitable for a project to build a prototype platform for embedded mobile devices in the shape of publicly shared bikes in a city. This prototype is described and its architecture and design decisions are presented and argued for. The survey discovers that CoAP is the most suitable protocol for the purpose of the thesis, and proceeds to show how it is applied to the described platform.
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Sangtarash, Sara. "Theory of mid-gap quantum transport through single molecule : new approach to transport modeling of nanoelectronic devices". Thesis, Lancaster University, 2017. http://eprints.lancs.ac.uk/88312/.
Testo completoAbstract (sommario):
Molecules due to their very small sizes, possess discrete energy levels and electrons can transmit from one side of the molecule to the other with high probability if their energy coincides with molecular energy levels. In the weak coupling limit such on-resonance electron transport is described by the simple Lorentzian-shaped Breit-Wigner formula. On the other hand, electrons with energy different than the molecular energy levels have to tunnel through the energy gap between two molecular energy levels (off resonance transmission). Consequently the electron transmission probability is much smaller than on resonance regime. Interesting phenomena including quantum interference could be observed in this regime at room temperature. In this thesis, I discuss both regimes though, my main aim is to introduce a new theory called ”mid- gap theory” to predict the conductance ratio between different connectivities driven by quantum interference (QI) in the tunneling regime. Both theory and experiment have focused primarily on elucidating the conditions for the appearance of constructive or destructive interference. In the simplest case, where electrons are injected at the Fermi energy EF of the electrodes, constructive QI arises when EF coincides with a delocalized energy level En of the molecule. Similarly a simple form of destructive QI occurs when EF coincides with the energy Eb of a bound state located on a pendant moiety. Unless energy levels are tuned by electrostatic, electrochemical or mechanical gating, molecules located within a junction rarely exhibit these types of QI, because EF is usually located in the HOMO-LUMO (H-L) gap. Furthermore few analytic formulas are available, which means that pre-screening of molecules often requires expensive numerical simulations. For this reason, discussions have often focused on conditions for destructive or constructive QI when EF is located at the centre of the H-L gap. In this thesis, based on a simple description of connectivity, I demonstrate that the conductance ratio between two different connectivities of a core molecule could be predicted simply by using the ratio between two magic numbers of the core molecule. This will be discussed in the chapters 4-6. This simple theory not only predicts conductance ratios, but it could be used also to propose new strategies for molecular electronic design and applications such as single molecule switches and thermoelectricity. In this thesis after an introduction to nano and molecular electronics, I discuss general ideas about nanoscale transport and the methods which could be applied to model nano and molecular scale devices. In chapter 3, on resonance transport is discussed. For a wide variety of molecules, the conductance G decays with length L as Aexp(−βL) and it is widely accepted that the attenuation coefficient β is determined by position of the Fermi energy of the electrodes relative to the energy gap of the molecular bridge, whereas the terminal anchor groups which bind the molecule to the electrodes contribute to A. In contrast with this expectation, in chapter 3, I demonstrate that gateway orbitals located on the anchor groups can significantly decrease the value of β, thereby creating a new design strategy for realizing low-conductance molecular wires. In chapters 4-6, I introduce mid-gap theory and drive a mid-gap ratio rule (MRR) which is an exact formula for conductance ratios of tight-binding representations of molecules in the weak coupling limit, when the Fermi energy is located at the centre of the HOMO-LUMO (H-L) gap. It does not depend on the size of the H-L gap and is independent of asymmetries in the contacts. I also show how conductance ratios change, when one of the carbon atoms within the parent polycyclic aromatic hydrocarbons (PAH) core is replaced by a heteroatom to yield a daughter molecule. I show that this heteroatom substitution could be used to enhance the conductance in a PAH molecule by several orders of magnitude. A good agreement between this new simple theory and experiment shows that, the MRR provides a useful tool to predict the conductances of PAH molecules prior to synthesis. Therefore it could be used to design molecules with desirable properties or to propose new molecular devices.
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Didier, Pierre. "Novel mid-infrared quantum cascade devices for applications in free-space optics, data security and microwave photonics". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAT029.
Testo completoAbstract (sommario):
Cette thèse de doctorat porte sur la transmission optique en espace libre (FSO) dans la région de l’infrarouge moyen couvrant trois aspects principaux : la transmission FSO à grande vitesse, la communication privée par synchronisation chaotique, et l’intégration de systèmes de communication FSO-RF. Dans le domaine de la transmission FSO à grande vitesse, cette recherche s’intéresse à différents schémas de modulation, de filtrage et d’équalization. Des dispositifs en cascade tels que les lasers en cascade interbande (ICL) et les lasers en cascade quantique (QCL) sont utilisés. Des débits de données allant jusqu’ ´ a 14 Gbps sont obtenus en utilisant des ICL et des photodétecteurs interbandes en cascade (ICIP) dans la fenêtre 3-5 µm. Des QCL et des modulateurs externes bases sur l’effet stark sont également mis en œuvre, permettant d’atteindre des débits de données allant jusqu’ à 68 Gbps. Ces dispositifs offrent une puissance modulée élevée, ce qui les rend adaptes aux transmissions sur de longues distances. La thèse explore également l’application des techniques de synchronisation chaotique pour la communication privée sur les liaisons FSO. Les propriétés chaotiques des sources lumineuses dans l’infrarouge moyen sont exploitées, ce qui permet de dissimuler des messages dans des signaux chaotiques. La complexité du chaos généré permet une transmission privée; les utilisateurs légitimes obtenant de faibles taux d’erreur alors que ceux des utilisateurs non légitimes sont important. En outre, la thèse étudie l’intégration des systèmes de communication FSO et RF. L’objectif est de créer une conversion entre les liaisons FSO à grande vitesse et les liaisons RF. Des techniques de battement hétérodyne sont utilisées, combinant des lasers à cascade quantique pour générer des signaux de battement. Cette approche permet la transmission de signaux FSO sur la bande Ka par l’intermédiaire d’un détecteur QWIP. La recherche démontre la faisabilité de l’intégration FSO-RF, ouvrant des possibilités de combiner les avantages des deux systèmes de communication. Dans l’ensemble, cette thèse présente des avancées en matière de transmission FSO à grande vitesse, de communication sécurisée utilisant la synchronisation chaotique, et d’intégration des systèmes FSO et RFThis doctoral thesis focuses on free-space optical (FSO) transmission in the mid-infrared region covering three main aspects: high-speed FSO transmission, private communication through chaotic synchronization, and integration of FSO-to-RF communication systems. In the field of high-speed FSO transmission, the research optimizes modulation schemes, equlaization for high speed data transmission in the mid-infrared spectrum. Cascade devices such as interband cascade lasers (ICLs) and quantum cascade lasers (QCLs) are utilized. Data rates of up to 14 Gbps are achieved using ICL and interband cascade interband photodetectors (ICIPs). QCLs and external modulators based on electrically modulated absorption are also implemented, achieving data rates up to 68 Gbps. These devices high modulated power, making them suitable for long-distance transmissions. The thesis also explores the application of chaos synchronization techniques for private communication over FSO links. Chaotic properties of light sources in the mid-infrared are leveraged, enabling the concealment of messages within chaotic signals. The complexity of the generated chaos allows for private transmission, with legitimate users achieving low error rates while non-legitimate users experience a higher error rate. Furthermore, the thesis investigates the integration of FSO and RF communication systems. The aim is to create a conversion between high-speed FSO links and RF links. Heterodyne beating techniques are utilized, combining quantum cascade lasers to generate beat signals. This approach enables the transmission of FSO signals over the Ka band through a QWIP detector. The research demonstrates the feasibility of FSO-to-RF integration, opening possibilities for combining the advantages of both communication systems. Overall, this thesis presents advancements in high-speed FSO transmission, secure communication using chaotic synchronization, and integration of FSO and RF systems. The research findings have implications for various fields, including telecommunications, satellite communication, and secure data transmission
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Wu, Chin-Lung, e 巫金龍. "DLC Film Growth and MIS Devices Characterization". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/12016459966205978684.
Testo completoAbstract (sommario):
碩士國立中山大學
電機工程學系研究所
94
Diamond-Like carbon (DLC) films has a lot of advantages, such as high hardness, high thermal conductivity, low expansion coefficient, low friction coefficient, high chemical stability, high impedance. These properties make the DLC films suitable for becoming an insulator in metal insulator semiconductor structure. In this study, DLC films were deposited by electro-deposition technique onto silicon (Si) substrates, in which a mixture of acetic acid and water is used as the electrolyte. The structure of the DLC films is characterized by Raman Spectroscopy. The thermal evaporation technique was used to deposit an aluminum films on the DLC/Si-substrates, to make it as the structure of metal-insulator semiconductor (MIS), and the electrical properties of the MIS were measured by semiconductor parameter analyzer. DLC films were deposited by varying the parameters of electro-deposition process included mainly as the concentration of solution, the spacing between electrode and silicon substrate, deposition temperature, and the applied voltages. The properties and film growth of DLC attributed to the effect of parameters were described in detail. Finally, an electro-deposition model is obtained to describe the growth mechanism of electro-deposition of DLC film.