Le développement considérable des détecteurs bolométriques au cours de la dernière décennie témoigne de la puissance et de la sensibilité de la mesure thermique d'un dépôt d'énergie. Notre étude se situe dans le cadre de la recherche d'une résolution ultime en énergie et en position. Nous avons mis au point un dispositif ultravide qui a rendu possible l'optimisation des conditions de dépôt, d'adhésion et de traitement thermique des détecteurs, grâce à la capacité de transférer l'échantillon entre les différentes enceintes, sans remise à l'air. Cet appareillage nous a permis de développer un bolomètre entièrement constitué de films minces, centré sur un matériau thermométrique de 10 nm d'épaisseur, ayant une très faible capacité calorifique et une très bonne sensibilité, grâce aux propriétés de la transition métal-isolant. Le volume et la forme de chacun des éléments du bolomètre composite sont définis par un masquage mécanique et une gravure ionique, ce qui nous permet de concevoir un détecteur pour lequel la capacité calorifique, le temps de réponse thermique et l'impédance électrique de chaque élément peuvent être définis en jouant sur l'épaisseur des films et leur facteur de forme. Deux bolomètres prototypes ont été fabriqués par cette méthode. L'un est destiné à l'astrophysique spatiale, l'autre est destiné à des mesures calorimétriques de monocouches atomiques. Nous montrons qu'une limite à la réduction de la taille du volume actif du matériau apparaît à basse température, et que cette limite est liée à la décroissance très rapide du couplage électron-phonon avec la température. Elle est évaluée, sur le plan théorique, pour un microbolomètre de 10 µm par 11 µm. Ceci nous conduit à montrer que la réduction de la température de fonctionnement aux plus basses températures ne représente pas un optimum pour un microbolomètre.

Microfluidics is gaining in importance due to its wide ranging benefits and applicability in chemical and biological analysis. Although traditional microfluidic devices are created with glass or silicon based fabrication technologies, polymer based devices are gaining in popularity. Soft lithography and replica molding are techniques for the rapid prototyping of such devices, utilizing Polydimethylsiloxane (PDMS) as the dominant material. Other benefits include its low costs and ease of fabrication. Even though soft lithography is a well researched and developed fabrication process, new applications have been discovered in which the technology can be applied. Often, changes in the fabrication process are necessary for their application in other areas of research. This thesis will address several microfluidic applications using soft lithography. These areas of research include microfluidic thermometry, isoelectric focusing (IEF), and micromixers. In microfluidic thermometry, a novel thin film PDMS/Rhodamine B has been developed allowing whole-chip temperature measurements. In addition, compatibility problems between Rhodamine B and PDMS microfluidic devices were resolved. The thin film fabrication process, experimental results, and issues with its use are discussed. Future work and attempts at improving the thin film performance are also provided. IEF involves applications in which samples are separated according to its electrostatic charge. Two types of IEF applications are shown in which soft lithography has been shown to be beneficial to its development and performance. In isoelectric focusing with the use of thermally generated pH gradients, soft lithography allows for the rapid design, production and testing of different channel layouts. In general, due to PDMS insulation and overall low heat transfer rates, the temperatures detected are more gradual than those previously reported in literature. IEF using carrier ampholytes are also discussed, with preliminary results in which devices fabricated using soft lithography are compared to commercially available IEF cartridges. Its fabrication issues are discussed in detail. In micromixers, soft lithography fabrication issues and overall integration with flow mechanisms is discussed. In general it is difficult to perform mixing in the microscale due to the predominantly laminar flow and flow rate restrictions. Channel geometry is insignificant, as can be seen through numerical simulations.

Microfluidics is gaining in importance due to its wide ranging benefits and applicability in chemical and biological analysis. Although traditional microfluidic devices are created with glass or silicon based fabrication technologies, polymer based devices are gaining in popularity. Soft lithography and replica molding are techniques for the rapid prototyping of such devices, utilizing Polydimethylsiloxane (PDMS) as the dominant material. Other benefits include its low costs and ease of fabrication. Even though soft lithography is a well researched and developed fabrication process, new applications have been discovered in which the technology can be applied. Often, changes in the fabrication process are necessary for their application in other areas of research. This thesis will address several microfluidic applications using soft lithography. These areas of research include microfluidic thermometry, isoelectric focusing (IEF), and micromixers. In microfluidic thermometry, a novel thin film PDMS/Rhodamine B has been developed allowing whole-chip temperature measurements. In addition, compatibility problems between Rhodamine B and PDMS microfluidic devices were resolved. The thin film fabrication process, experimental results, and issues with its use are discussed. Future work and attempts at improving the thin film performance are also provided. IEF involves applications in which samples are separated according to its electrostatic charge. Two types of IEF applications are shown in which soft lithography has been shown to be beneficial to its development and performance. In isoelectric focusing with the use of thermally generated pH gradients, soft lithography allows for the rapid design, production and testing of different channel layouts. In general, due to PDMS insulation and overall low heat transfer rates, the temperatures detected are more gradual than those previously reported in literature. IEF using carrier ampholytes are also discussed, with preliminary results in which devices fabricated using soft lithography are compared to commercially available IEF cartridges. Its fabrication issues are discussed in detail. In micromixers, soft lithography fabrication issues and overall integration with flow mechanisms is discussed. In general it is difficult to perform mixing in the microscale due to the predominantly laminar flow and flow rate restrictions. Channel geometry is insignificant, as can be seen through numerical simulations.

The development of microscale and nanoscale devices has outpaced the development of metrology tools necessary for their complete characterization. In the area of thermal MEMS technology, accurate measurements across a broad range of temperatures with high spatial resolution are not trivial. Thermal MEMS are devices in which the control and manipulation of temperature is necessary to perform a desired function, and are used in actuation, chemical sensing, nanolithography, thermal data storage, biological reactions and power generation. In order to properly design for reliability and performance issues amongst these devices and verify modeling accuracy, the temperature distribution under device operating conditions must be experimentally determined. Raman spectroscopy provides absolute temperature measurements with spatial scales below 1 micron, which is sufficient for most MEMS devices. In this work, a detailed study of Raman spectroscopy as an optical thermal metrology tool was performed. It is shown that a calibration of the Stokes shift with temperature yields a linear calibration for measurements up to 1000?n polysilicon. These coefficients were determined for polysilicon processed under various conditions (575-620?B and P doping) to assess the effects of microstructural variations on Raman spectra. The Stokes peak was also shown to shift linearly with an applied pure bending stress. In order to make stress-independent thermometry measurements, the ratio of the Stokes to anti-Stokes signal intensities and the Stokes linewidth were calibrated over the same temperature range. Using the calibration data, Raman spectroscopy was implemented for the evaluation of temperature of thermal MEMS. Heated AFM cantilevers and micro-beam heaters were chosen due to their wide range of applications. Different thermal and mechanical boundary conditions were considered by studying both the beams and cantilevers, resulting in varying levels of thermal stress. By using the three calibrations in a complementary fashion, the validity of Raman thermometry was explored. Device temperatures of up to 650?nd their corresponding uncertainties were found, and used to verify FEA modeling. Effects of thermally induced stresses were taken into account and analyzed. Possible uncertainties such as laser heating, spatial and spectral resolution, light collection efficiency, measurement uncertainty, and instrumental drift were reported and elucidated.

A comprehensive model for describing the fundamental mechanism dictating the interaction of ultrafast laser pulse with single crystalline silicon wafer is formulated. The need for establishing the feasibility of employing lasers of subpicosecond pulse width in Laser Induced Stress Waves Thermometry (LISWT) for single crystalline silicon processing motivated the work. The model formulation developed is of a hyperbolic type capable of characterizing non-thermal melting and thermo-elastoviscoplastic deformation as functions of laser input parameters and ambient temperature. A plastic constitutive law is followed to describe the complex elasto-viscoplastic responses in silicon undergoing Rapid Thermal Processing (RTP) annealing at elevated temperatures. A system of nine first-order hyperbolic equations applicable to describing 3-D elasto-viscoplastic wave motions in silicon is developed. The group velocities of certain selected frequency components are shown to be viable thermal indicators, thus establishing the feasibility of exploiting nanosecond laser induced propagating stress waves for the high-resolution thermal profiling of silicon wafers. Femtosecond laser induced transport dynamics in silicon is formulated based on the relaxation-time approximation of the Boltzmann equation. Temperature-dependent multi-phonons, free-carrier absorptions, and the recombination and impact ionization processes governing the laser model and carrier numbers are considered using a set of balance equations. The balance equation of lattice energy and equations of motion of both parabolic and hyperbolic types are derived to describe the complex thermo-elastoplastodynamic behaviors of the material in response to ultrafast laser pulsing. The solution strategy implemented includes a multi-time scale axisymmetric model of finite geometry and a staggered-grid finite difference scheme that allows both velocity and stress be simultaneously determined without having to solve for displacements. Transport phenomena initiated by femtosecond pulses including the spatial and temporal evolutions of electron and lattice temperatures, along with electron-hole carrier density, are found to be functions of laser fluence and pulse width. The femtosecond laser heating model that admits hyperbolic energy transport is shown to remedy the dilemma that thermal disturbances propagate with infinite speed. Non-thermal melting fluence is examined favorably against published experimental data. That it is feasible to explore femtosecond laser induced displacement and stress components for 1K resolution thermal profiling is one of the conclusions reached.

A novel, lipid-based platform nanotechnology has been designed to overcome limitations of in vivo fluorescent imaging, multidrug resistance (MDR) phenotypes hindering breast cancer chemotherapy, and shortcomings of magnetic resonance imaging (MRI) thermometry. Using this platform, three nanoparticle systems have been developed: QD-SLN (quantum dot-loaded solid lipid nanoparticles), DMsPLN (doxorubicin and mitomycin C co-loaded polymer-lipid hybrid nanoparticles), and HLN (hydrogel-lipid hybrid nanoparticles). Stealth, near-infrared emitting QD-SLN were developed for deep tissue fluorescence imaging, which were capable of extending the depth of penetration beyond 2 cm, with near complete probe clearance and good tolerability in vivo. The QD-SLN was used to evaluate the biodistribution of non-targeted SLN and actively targeted RGD-conjugated SLN. Non-targeted SLN accumulated in breast tumors and evaded liver uptake. The RGD-SLN showed prolonged retention in breast tumor neovasculature at the cost of lesser tumor accumulation due to enhanced liver uptake. With this information, a long circulating, non-targeted DMsPLN with a synergistic cancer chemotherapeutic combination of doxorubicin and mitomycin C was formulated to overcome MDR, enhancing breast cancer chemotherapy. Extensive tumor cell uptake and perinuclear trafficking of DMsPLN overcame the MDR phenotype of breast tumor cells in vitro. The DMsPLN provided the most efficacious chemotherapy reported in literature against aggressive mouse mammary tumors in vivo with significant reduction in whole animal and cardiotoxicity as compared to clinically applied liposomal doxorubicin. In establishing our tumor models, the impact of Matrigel™ on the tumor microenvironment was investigated, demonstrating altered tumor vascular and lymphatic anatomy and physiology, and significantly impacting nanomedicines assessment in mouse models of cancer. In all in vivo studies, tumors were established without use of Matrigel™. To guide thermotherapy of solid tumors, a novel HLN was formulated for use in MRI thermometry, presenting the first contrast agent capable of indicating a tunable, absolute two-point temperature window. In using specific limitations of therapeutic and imaging modalities to inform rational nanoparticle design, this lipid-based platform nanotechnology has extended the application of fluorescence imaging in vivo, enhanced the utility of nanoparticulate chemotherapeutics against breast cancer independent of MDR status, and provided novel functionality for MRI thermometry.

A novel, lipid-based platform nanotechnology has been designed to overcome limitations of in vivo fluorescent imaging, multidrug resistance (MDR) phenotypes hindering breast cancer chemotherapy, and shortcomings of magnetic resonance imaging (MRI) thermometry. Using this platform, three nanoparticle systems have been developed: QD-SLN (quantum dot-loaded solid lipid nanoparticles), DMsPLN (doxorubicin and mitomycin C co-loaded polymer-lipid hybrid nanoparticles), and HLN (hydrogel-lipid hybrid nanoparticles). Stealth, near-infrared emitting QD-SLN were developed for deep tissue fluorescence imaging, which were capable of extending the depth of penetration beyond 2 cm, with near complete probe clearance and good tolerability in vivo. The QD-SLN was used to evaluate the biodistribution of non-targeted SLN and actively targeted RGD-conjugated SLN. Non-targeted SLN accumulated in breast tumors and evaded liver uptake. The RGD-SLN showed prolonged retention in breast tumor neovasculature at the cost of lesser tumor accumulation due to enhanced liver uptake. With this information, a long circulating, non-targeted DMsPLN with a synergistic cancer chemotherapeutic combination of doxorubicin and mitomycin C was formulated to overcome MDR, enhancing breast cancer chemotherapy. Extensive tumor cell uptake and perinuclear trafficking of DMsPLN overcame the MDR phenotype of breast tumor cells in vitro. The DMsPLN provided the most efficacious chemotherapy reported in literature against aggressive mouse mammary tumors in vivo with significant reduction in whole animal and cardiotoxicity as compared to clinically applied liposomal doxorubicin. In establishing our tumor models, the impact of Matrigel™ on the tumor microenvironment was investigated, demonstrating altered tumor vascular and lymphatic anatomy and physiology, and significantly impacting nanomedicines assessment in mouse models of cancer. In all in vivo studies, tumors were established without use of Matrigel™. To guide thermotherapy of solid tumors, a novel HLN was formulated for use in MRI thermometry, presenting the first contrast agent capable of indicating a tunable, absolute two-point temperature window. In using specific limitations of therapeutic and imaging modalities to inform rational nanoparticle design, this lipid-based platform nanotechnology has extended the application of fluorescence imaging in vivo, enhanced the utility of nanoparticulate chemotherapeutics against breast cancer independent of MDR status, and provided novel functionality for MRI thermometry.

Abrupt, millennial-scale climate oscillations, known as Dansgaard-Oeschger (D-O) cycles, characterized the climate system during the last ice age. Proxy evidence suggests these climate oscillations resulted in global-scale reorganizations in the hydrological cycle. For this study, Mg/Ca-paleothermometry and stable isotope measurements were combined on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC26 (24*19.61'N, 83*15.14'W; 546 m depth) to reconstruct a high-resolution record of sea surface temperature and delta18OSW (a proxy for upper water column salinity) during Marine Isotope Stages 2 and 3 from 20-35.45 ka BP. As additional proxies for upper water column salinity change, Ba/Ca ratios in G. ruber were also measured to determine the relative contribution of local riverine input on the delta18OSW record and a faunal abundance count record of the planktonic foraminifera N. dutertrei abundance was developed. These results show that rapid upper water column salinity changes occurred across D-O events in the Florida Straits, coeval with climate change in the high-latitude North Atlantic. Furthermore, the G. ruber Ba/Ca record suggests that riverine-derived meltwater from the Gulf of Mexico did not significantly impact surface salinity in the Florida current, calling into question the role of Mississippi River discharge on Atlantic Meridional Overturning Circulation (AMOC) during MIS 2 and 3. Instead, the most likely cause of MIS 2 and 3 salinity changes in the Florida Straits were variations in the strength and position of the Intertropical Convergence Zone. Finally, the timing of surface salinity change was compared with the benthic delta18OC record from the same core. A recent study showed that benthic delta18OC changes on the Florida Margin can be combined with contemporaneous records from the Bahamas Margin to reconstruct Florida Current transport related to AMOC variability. These results show that atmospheric circulation changes lead AMOC changes on the transition out of cold stadial events, suggesting the trigger for these abrupt climate events may reside in the tropics rather than in the high-latitude North Atlantic as previously thought.

[pt] Em 1990, com a adoção da Escala Internacional de Temperatura de 1990, o termopar de platina e platina/ródio deixou de ser o instrumento de interpolação entre 630 graus Celsius e 1064 graus Celsius, em virtude de sua pouca estabilidade, sendo a partir daí utilizados o termômetro de resistência de platina de alta temperatura (TRPAT) e o termômetro de radiação. Este estudo realiza uma investigação prática das características de um termopar de ouro e platina, ambos com pureza superior a 99,999 por cento, no que diz respeito à sua estabilidade termoelétrica e à homogeneidade de seus termoelementos, questionando a possibilidade de seu uso como alternativa ao emprego do TRPAT em processos de medição que exijam grande exatidão com custo mais baixo. Neste trabalho, o termopar estudado foi submetido a temperaturas próximas ao seu limite máximo de operação, que é de 1000 graus Celsius, por mais de 1500 horas, sendo avaliadas a sua estabilidade e a sua homogeneidade em função do tempo de uso, com o auxílio de uma célula de ponto fixo da prata do Inmetro, que é um padrão primário de temperatura. / [en] In 1990, with the adoption of the International Temperature Scale of 1990, the platinum/platinum-rhodium thermocouple was removed as the interpolation instrument between 630 graus Celsius and 1064 Celsius degrees, due its low stability, in favor of the high temperature standard platinum resistance thermometer (HTSPRT) and the radiation thermometer. In this work, it is performed a practical investigation of the characteristics of a 99,999 percent purity gold-platinum thermocouple, concerning its thermoelectric stability and homogeneity of its thermoelements, questioning the possibility of its use as an alternative to the HTSPRT in measurement processes requiring high accuracy with lower costs. In this work, the test thermocouple was exposed to temperatures close to its upper limit (1000 Celsius degrees) for more than 1500 hours, being its stability and homogeneity evaluated as function of time, with aid of a silver fixed point cell from Inmetro, that is a temperature primary standard.

Polymer extrusion is an energy intensive process whereby the simultaneous action of viscous shear and thermal conduction are used to convert solid polymer to a melt which can be formed into a shape. To optimise efficiency, a homogeneous melt is required with minimum consumption of process energy. In this work, in-process monitoring techniques have been used to characterise the thermal dynamics of the single screw extrusion process with real-time quantification of energy consumption. Thermocouple grid sensors were used to measure radial melt temperatures across the melt flow at the entrance to the extruder die. Moreover, an infrared sensor flush mounted at the end of the extruder barrel was used to measure non-invasive melt temperature profiles across the width of the screw channel in the metering section of the extruder screw. Both techniques were found to provide useful information concerning the thermal dynamics of the extrusion process; in particular this application of infrared thermometry could prove useful for industrial extrusion process monitoring applications. Extruder screw geometry and extrusion variables should ideally be tailored to suit the properties of individual polymers but in practise this is rarely achieved due the lack of understanding. Here, LDPE, LLDPE, three grades of HDPE, PS, PP and PET were extruded using three geometries of extruder screws at several set temperatures and screw rotation speeds. Extrusion data showed that polymer rheology had a significant effect on the thermal efficiency on the extrusion process. In particular, melt viscosity was found to have a significant effect on specific energy consumption and thermal homogeneity of the melt. Extruder screw geometry, set extrusion temperature and screw rotation speed were also found to have a direct effect on energy consumption and melt consistency. Single flighted extruder screws exhibited poorer temperature homogeneity and larger fluctuations than a barrier flighted screw with a spiral mixer. These results highlighted the importance of careful selection of processing conditions and extruder screw geometry on melt homogeneity and process efficiency. Extruder scale was found to have a significant influence on thermal characteristics due to changes in surface area of the screw, barrel and heaters which consequently affect the effectiveness of the melting process and extrusion process energy demand. In this thesis, the thermal and energy characteristics of two single screw extruders were compared to examine the effect of extruder scale and processing conditions on measured melt temperature and energy consumption. Extrusion thermal dynamics were shown to be highly dependent upon extruder scale whilst specific energy consumption compared more favourably, enabling prediction of a process window from lab to industrial scale within which energy efficiency can be optimised. Overall, this detailed experimental study has helped to improve understanding of the single screw extrusion process, in terms of thermal stability and energy consumption. It is hoped that the findings will allow those working in this field to make more informed decisions regarding set conditions, screw geometry and extruder scale, in order to improve the efficiency of the extrusion process.