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Cost-Effective Integrated Wireless Monitoring of Wafer Cleanliness Using SOI TechnologyJanuary 2010 (has links)
abstract: The thesis focuses on cost-efficient integration of the electro-chemical residue sensor (ECRS), a novel sensor developed for the in situ and real-time measurement of the residual impurities left on the wafer surface and in the fine structures of patterned wafers during typical rinse processes, and wireless transponder circuitry that is based on RFID technology. The proposed technology uses only the NMOS FD-SOI transistors with amorphous silicon as active material with silicon nitride as a gate dielectric. The proposed transistor was simulated under the SILVACO ATLAS Simulation Framework. A parametric study was performed to study the impact of different gate lengths (6 μm to 56 μm), electron motilities (0.1 cm2/Vs to 1 cm2/Vs), gate dielectric (SiO2 and SiNx) and active materials (a-Si and poly-Si) specifications. Level-1 models, that are accurate enough to acquire insight into the circuit behavior and perform preliminary design, were successfully constructed by analyzing drain current and gate to node capacitance characteristics against drain to source and gate to source voltages. Using the model corresponding to SiNx as gate dielectric, a-Si:H as active material with electron mobility equal to 0.4 cm2/V-sec, an operational amplifier was designed and was tested in unity gain configuration at modest load-frequency specifications. / Dissertation/Thesis / M.S. Electrical Engineering 2010
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CFD MODELING IN DESIGN AND EVALUATION OF AN ENDOVASCULAR CHEMOFILTER DEVICENazanin Maani (8066141) 02 December 2019 (has links)
<p>Intra-Arterial Chemotherapy (IAC) is a preferred treatment
for the primary liver cancer, despite its adverse side-effects. During IAC, a
mixture of chemotherapeutic drugs, e.g. Doxorubicin, is injected into an artery
supplying the tumor. A fraction of Doxorubicin is absorbed by the tumor, but
the remaining drug passes into systemic circulation, causing irreversible heart
failure. The efficiency and safety of the IAC can be improved by chemical
filtration of the excessive drugs with a catheter-based Chemofilter device, as
proposed by a team of neuroradilogists. </p>
<p>The objective of my work was to optimize the hemodynamic and
drug binding performance of the Chemofilter device, using Computational Fluid
Dynamics (CFD) modeling. For
this, I investigated the performance of two distinct Chemofilter
configurations: 1) a porous “Chemofilter basket” formed by a lattice of
micro-cells and 2) a non-porous “honeycomb Chemofilter” consisting of parallel
hexagonal channels. A multiscale modeling approach was developed to resolve the
flow through a representative section of the porous membrane and
subsequently characterize the overall performance of the device. A heat and
mass transfer analogy was utilized to facilitate the comparison of alternative
honeycomb configurations. </p>
A multiphysics approach was
developed for modeling the electrochemical binding of Doxorubicin to the
anionic surface of the Chemofilter. An effective diffusion coefficient was
derived based on dilute and concentrated solution theory, to account for the
induced migration of ions. Computational predictions were supported by results
of <i>in-vivo</i> studies performed by
collaborators. CFD models showed that the honeycomb Chemofilter is
the most advantageous configuration with 66.8% drug elimination and 2.9 mm-Hg
pressure drop across the device. Another facet of the Chemofilter project was
its surface design with shark-skin inspired texturing, which improves the
binding performance by up to 3.5%. Computational modeling enables optimization
of the chemofiltration device, thus allowing the increase of drug dose while
reducing systemic toxicity of IAC.
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Material and device design for organic photovoltaicsHowells, Calvyn T. January 2015 (has links)
This thesis presents novel materials for photovoltaic conversion. The materials described are solution-processable organic semiconductors and have been used in the fabrication of organic photovoltaic cells (OPVs). The widely used PEDOT:PSS layer was investigated in P3HT and PTB7 photovoltaics. By doping, the efficiencies recorded were amongst the highest reported in the field using a conventional architecture. Two low band-gap BODIPY-based polymers were introduced and shown to have properties favourable for optoelectronics. Photovoltaics consisting solely of the polymers as the active component surpassed the performance expected without the use of an acceptor, indicating ambipolar behaviour, which was verified by charge carrier mobility measurements. When blended with an acceptor, the devices demonstrated a short-circuit current density similar to that of P3HT, a well-studied and successful OPV material. They also revealed a broad spectral response and were shown to operate as photodiodes. Two small molecules containing diketopyrrolopyrrole (DPP) and BODIPY were introduced and characterised. The addition of thiophenes red shifted the absorption but did not result in a sufficient bathochromic shift. Instead, a propensity to aggregate limited the performance. PLQY measurements showed the aggregation to quench luminescence. The study demonstrated the importance of controlling aggregation for efficient devices. Two solution-processable small molecules with a germanium-bridged spiro centre were investigated, and the molecular, electrochemical and optical properties discussed. The small molecule with shorter conjugation length exhibited an interesting packing motif shown to be favourable for charge transport. The mobility measurements were an order of magnitude higher than those reported for sexithiophene, a small molecule analogue, and the same order of magnitude as P3HT. The two-dimensional charge transporting nature of the material was verified with two independent techniques: time of flight (TOF) and organic field-effect transistor (OFET) measurements. The mobility of the material was found to vary with annealing, a result of morphological changes. These were studied with optical, electron and scanning probe microscopies. By controlling the morphology with the implementation of a well-defined annealing method, it was possible to improve the performance of OFETs and planar-heterojunction OPVs. Solution-processed bulk-heterojunction OPVs were fabricated, characterised and optimised with Ge spiro molecules. A PCE similar to that of P3HT, 2.66 %, was achieved for the one, whilst a PCE of 1.60 % was obtained for the other. The results are encouraging, and there is scope for improvement by increasing the overlap between the absorption and solar spectrum, for example.
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Générateurs thermoélectriques imprimés sur substrats souples à base de matériaux hybrides pour des applications autour de la température ambiante / Hybrid thermoelectric generators printed on flexible substrates for applications at near room temperatureFerhat, Salim 12 June 2018 (has links)
Les dispositifs thermoélectriques, légers et flexibles, peuvent être particulièrement intéressants aujourd’hui dans le contexte de l’émergence de l’informatique ubiquitaire, ainsi que de la crise environnementale liée à la consommation d’énergie électrique. Cependant, beaucoup de problèmes doivent encore être résolus pour rendre les dispositifs de récupération de chaleur commercialement viables. Dans cette thèse nous avons élaboré une méthode de conception et de fabrication par impression jet d’encre de générateurs flexibles à base de semi-conducteurs organiques et hybrides. En premier lieu, les travaux ont été consacrés au développement de matériaux thermoélectriques efficaces, stables et synthétisés par voie liquide. Les stratégies d’optimisation employées reposent sur la modulation de la concentration de porteurs de charge et le contrôle de la morphologie microscopique du matériau. En second lieu, nous avons effectué un travail de conception et de modélisation de dispositifs thermoélectriques ainsi que de leurs paramètres géométriques en utilisant des outils numériques. La modélisation numérique a été réalisée par la méthode des éléments finis 3D et par couplage d’effets physiques multidimensionnels. L’aboutissement de notre projet a été la formulation des matériaux en encres pour la fabrication de générateurs thermoélectriques par la technique de dépôt par impression jet d’encre. Différentes structures et architectures ont été expérimentalement caractérisées et systématiquement comparées aux évaluations numériques. Ainsi, nous présentons une approche intégrale de conception et de fabrication de dispositifs thermoélectriques opérant à des températures proches de l’ambiant. / Flexible lightweight printed thermoelectric devices can become particularly interesting with the advent of ubiquitous sensing and within the context of current energy and environmental issues. However, major drawbacks of state of the art thermoelectric materials must be addressed to make waste heat recovery devices commercially feasible. In this PhD thesis, we’ve elaborated and described a method to fabricate optimized, fully inkjetprinted flexible thermoelectric generators based on organic and hybrid semiconductors. This research project can be divided into three stages: First is the development of effective, stable and solution-processed p-type and n-type thermoelectric materials. Our effort in optimizing thermoelectric materials were based on modulation of charge carrier concentration and on control of morphology. Second, design and modeling of thermoelectric devices and their geometric parameters using numerical simulation methods. Numerical simulations were based on a 3D-finite element analysis and simulation software for coupled physical problems to model and design thermoelectric devices. Finally, formulation of materials into ink in order to produce thermoelectric generators by inkjet printing deposition. Various structures and architectures were experimentally characterized and systematically compared to numerical evaluations. Hence, we produced an extensive study on designing and producing thermoelectric devices operating at near ambient temperature and conditions.
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Damage And Fracture In Skin: Applications In Needle InsertionVivek Dharmangadan Sree (5930606) 08 February 2023 (has links)
<p>Subcutaneous injection through devices such as autoinjectors is a preferred delivery method for wide array of pharmaceuticals such as monoclonal antibodies. Needle insertion during drug delivery involves large deformation, damage, and fracture of the skin tissue and affects drug transport and uptake. Yet, our understanding of needle insertion biomechanics is limited, but is crucially important to create autoinjectors that lead to the least amount of pain, penetrate the skin to a desired depth, produce small lesions that minimize back flow of drug, and operate robustly even given the variability in the skin mechanics among individuals. Computational models of needle insertion lends itself as an excellent avenue for studying the biomechanics of injector- skin interactions and for proposing better device designs. This work is focused on introducing a comprehensive computational modeling framework for optimizing needle insertion by autoinjector devices, while addressing limitations in experimental data and constitutive modeling of damage and fracture mechanisms in skin</p>
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On the stabilization of ferroelectric negative capacitance in nanoscale devicesHoffmann, Michael, Pešić, Milan, Slesazeck, Stefan, Schroeder, Uwe, Mikolajick, Thomas 12 October 2022 (has links)
Recently, the proposal to use voltage amplification from ferroelectric negative capacitance (NC) to reduce the power dissipation in nanoelectronic devices has attracted significant attention. Homogeneous Landau theory predicts, that by connecting a ferroelectric in series with a dielectric capacitor, a hysteresis-free NC state can be stabilized in the ferroelectric below a critical film thickness. However, there is a strong discrepancy between experimental results and the current theory. Here, we present a comprehensive revision of the theory of NC stabilization with respect to scaling of material and device dimensions based on multi-domain Ginzburg–Landau theory. It is shown that the use of a metal layer in between the ferroelectric and the dielectric will inherently destabilize NC due to domain formation. However, even without this metal layer, domain formation can reduce the critical ferroelectric thickness considerably, limiting not only the range of NC stabilization, but also the maximum amplification attainable. To overcome these obstacles, the downscaling of lateral device dimensions is proposed as a way to prevent domain formation and to enhance the voltage amplification due to NC. These insights will be crucial for future NC device design and scaling towards nanoscale dimensions.
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Investigation into reliability and performance of an implantable closed-loop insulin delivery deviceJacob, Dolly January 2014 (has links)
An implantable closed-loop insulin delivery device (INsmart device) containing a glucose responsive gel has been developed within the INsmart research group, over a period of 10 years, to mimic pancreas. In this thesis, the reliability and performance capability of the INsmart device was studied for future clinical use. Investigations into the device material compatibility with insulin solution, assessed by monitoring insulin loss and degradant formation over a period of 31 days using RP-HPLC have shown that stainless steel and titanium are the most compatible materials. Polycarbonate contributes to insulin loss after 11 days, resin might not be the best material and polyurethane is the least compatible for future device designs. To study insulin delivery mechanism and kinetics from the device, fluorescently labelled human insulin (FITC-insulin) was synthesised and characterised using RP-HPLC and MS, to produce a product with predominantly di-labelled conjugate (>75%) with no unreacted FITC or native insulin. Clinically used insulin analogues were also fluorescently labelled to produce predominantly di-labelled FITC-insulin conjugate with potential future biological and in vitro applications. The drug release mechanism from the glucose sensitive gel held in the INsmart device, studied using fluorescein sodium was determined as a Fickian diffusion controlled release mechanism. The diffusion coefficient (D) for FITC-insulin in the non-polymerised dex2M-conA gel (NP gel) determined using mathematical models, QSS and TL slope methods was 1.05 ± 0.02 x 10-11 m2/s and in the cross-linked dex500MA-conAMA gel (CL gel) was 0.75 ± 0.06 x 10-11 m2/s. In response to physiologically relevant glucose triggers in the NP gel, the diffusivity of FITC-insulin increases with increasing glucose concentrations, showing a second order polynomial fit, device thus showing glucose sensitivity and graded response, mimicking pancreas. Rheological measurements further confirmed the gel glucose responsiveness demonstrated by a third order polynomial fit between FITC-insulin D and the NP complex viscosity in response to increasing glucose concentration. The knowledge of FITC-insulin diffusion kinetics in the gel has aided in making some theoretical predictions for the capability and performance of the INsmart device. Alternate device geometry and design optimisation is also explored.
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