MEMS technology has led to the development of new uncooled infrared imaging detectors. One type of these MEMS detectors consist of arrays of bi-metallic photomechanical pixels that tilt as a function of temperature associated with infrared radiation from the scene. The main advantage of these detectors is the optical readout system that measures the tilt of the beams based on the intensity of the reflected light. This removes the need for electronic readout at each of the sensing elements and reduces the fabrication cost and complexity of sensor design, as well as eliminates the electronic noise at the detector. The optical readout accuracy is sensitive to the uniformity of individual pixels on the array. The hypothesis of the present research is that direct measurements of the height change corresponding to tilt through holographic interferometry will reduce the need for high pixel uniformity. Measurements of displacements for a vacuum packaged detector with nominal responsivity of 2.4nm/K are made with a Linnik interferometer employing the four phase step technique. The interferometer can measure real-time, full-field height variations across the array. In double-exposure mode, the current height map is subtracted from a reference image so that the change in deflection is measured. A software algorithm locates each mirror on the array, extracts the measured deflection at the tip of a mirror, and uses that measurement to form a pixel of a thermogram in real-time. A blackbody target projector with temperature controllable to 0.001K is used to test the thermal resolution of the imaging system. The achieved minimum temperature resolution is better than 0.25K. The double exposure technique removes mirror non-uniformity as a source of noise. A lower than nominal measured responsivity of around 1.5nm/K combined with noise from the measurements made with the interferometric optical readout system limit the potential minimum temperature resolution. Improvements need to be made both in the holographic setup and in the MEMS detector to achieve the target temperature resolution of 0.10K.

In this investigation a number of post-genomic technologies have be applied to study the dermatological disorders of psoriasis and keloid disease. In spite of considerable research focus on these diseases the pathogenesis remains unclear and currently no cure is available however, both diseases are manageable by drug intervention. It is common place that patients who are suffering from skin disorders are diagnosed and the extent of the disease assessed by a dermatologist which may be subjective due to human error. The availability and application of methods to screen patients and quantify the level of disease or response to treatment has obvious benefits in disease management. The work has incorporated a two-pronged approach combining the spectroscopic analysis of excised tissue samples and the phenotypic profiling of a rapidly proliferating cell line in response to drug intervention. The initial analysis of psoriatic skin samples by MALDI-MS provided poor results which remain relatively unexplained; however similar problems have been observed by other research groups. In a complementary approach the HaCaT cell line was exposed to increasing concentrations of three anti-psoriatic drugs namely dithranol, methotrexate and ciclosporin and the cells profiled using both metabolomic and proteomic methods. A number of metabolic pathways were highlighted including glycolysis and the TCA cycle. This has resulted in a selection of potential biomarkers which could be investigated in further work. In a small follow on study a collection of plasma samples from patients undergoing methotrexate treatment were analysed. The level of patient metadata and the number of samples was relatively limiting however, a subset of metabolites were significantly altered between responders and non-responders and with further validation could be potential biomarkers of successful treatment. The analysis of excised keloid samples was conducted using FT-IR microspectroscopy where it was possible to successfully discriminate between keloid and normal tissue. The use of imaging FTIR illustrated the complex cellular composition within a keloid scar, with increased lipid, amide and phosphate levels being observed. These measurable variations could, in the future, be incorporated into surgical procedures to allow targeted excision ensuring all keloid areas are removed. Finally a SERS-based analysis was conducted to investigate the possibility of probing dynamic enzymatic processes. This was successful and with the use of varying reporter molecules could be a beneficial tool for the analysis of metabolic processes.This project has successfully used a number of bio-analytical techniques to investigate dermatological problems. While the ultimate goal would be the application of a single analytical technique to provide answers to biological questions, it has been found that a number of complimentary techniques and statistical data handling approaches can provide a valuable insight into the problems posed.

Infrared (IR) imaging is a key technology in a variety of military and civilian applications, especially for night vision and remote sensing. Compared with cryogenically cooled IR sensors, uncooled infrared imaging devices have the advantages of being low cost, light weight, and superior reliability. The electro-thermal analysis of a microbolometer pixel is critical to determine both device performance and reliability. To date, most microbolometer analysis research has focused on performance optimization and computation of thermal conductance directly from the geometry. However, modeling of the thermal distribution across the microbolometer pixel is critical for the comprehensive analysis of system performance and reliability. Therefore, this thesis investigates the electro-thermo-mechanical characteristics of a microbolometer pixel considering the effects of joule heating and incoming IR energy. The contributions of the present research include the electro-thermal models for microbolometer and methods of validating thermal distribution using experimental results. The electro-thermal models explain the effect of microbolometer material properties and geometry on device performance and reliability. The research also contributes methods of estimating the thermal conductivity of microbolometer, which take into account different heat transfer mechanisms, including radiation and convection. Previous approaches for estimating the thermal conductance of uncooled microbolometer consider heat conduction via legs from the geometry of the pixel structure and material properties [2]. This approach assumes linear temperature distribution in the pixel legs structure. It also leaves out the various electro-thermal effects existing for multilayer structures. In the present research, a different approach is used to develop the thermal conductance of microbolometer pixel structure. The temperature distribution in the pixel is computed from an electro-thermal model. Then, the average temperature in the pixel microplate and the total heat energy generated by joule heating is utilized to compute the thermal conductance of the structure. The thesis discusses electro-thermal and thermo-mechanical modeling, simulation and testing of Polysilicon Multi-User MEMS Process (PolyMUMPs®) test devices as the groundwork for the investigation of microbolometer performance and reliability in space applications. An electro-thermal analytical and numerical model was developed to predict the temperature distribution across the microbolometer pixel by solving the second order differential heat equation. To provide a qualitative insight of the effect of different parameters in the thermal distribution, including material properties and device geometry, first an explicit formulation for the solution of the electro-thermal coupling is obtained using the analytical method. In addition, the electro-thermal model, which accounts for the effect of IR energy and radiation heat transfer, spreading resistance and transient conditions, was studied using numerical methods. In addition, an analytical model has been developed to compute the IR absorption coefficient of a Thin Single Stage (TSS) microbolometer pixel. The simulation result of this model was used to compute absorbed IR energy for the numerical model. Subsequently, the temperature distribution calculated from the analytical model is used to obtain the deflections that the structure undergoes, which will be fundamental for the reliability analysis of the device. Finite element analysis (FEA) has been simulated for the selected device using commercial software, ANSYS® multiphysics. Finite element simulation shows that the electro-thermal models predict the temperature distribution across a microbolometer pixel at steady-state conditions within 2.3% difference from the analytical model. The analytical and numerical models are also simulated and results for a temperature distribution within 1.6% difference. In addition, to validate the analytical and numerical electro-thermal and thermo-mechanical models, a PolyMUMPs® test device has been used. The test results showed a close agreement with the FEM simulation deflection of the test device.

This thesis aims to design and develop camera electronics and image enhancement software for infrared detector arrays. It first discusses the camera electronics suitable for infrared detector arrays, then it concentrates on image enhancement software that are implemented including defective pixel correction, contrast enhancement, noise reduction and pseudo coloring. After that, testing and results of the implemented algorithms were presented. Camera electronics and circuit operation frequency are selected considering the available standard programmable devices and the output rate of the detector readout circuitry. The target device for implementation of algorithms was Xilinx Spartan &ndash / 3 XC3S1500 which is used in the camera tests at METU-MEMS Research and Applications Center. Considering the real time operation, the target clocking frequency for operation of the circuitry was selected as 2MHz. Image enhancement algorithms primarily aim to be implemented for 320 x 240 resolution detectors, however with parametric implementation, they aim to support other resolutions, including 160 x 120 and 640 x 512. In addition, all implementations aim to be modular and reusable. Various different approaches are used for image enhancement software: (i) defective pixel correction is achieved by using a selective median filtering approach, (ii) contrast enhancement is achieved by employing contrast stretching and histogram based methods, and (iii) noise reduction is achieved by implementing a spatial filter. In addition to these, four types of pseudo coloring methods were applied and tested. Test results show that defective pixel correction algorithm operates at 20.0 MHz, with 0.0 x 10-3 RMS error from its MATLAB prototype, and contrast enhancement algorithms are able to operate at 3.3 MHz, with an average of 545.0 x 10-3 RMS error. Spatial filtering for noise reduction operates at 20.0 MHz, with a 2.6 x 10-3 RMS. Pseudo-coloring operates at 125.0 MHz, with a 0.0 x 10-3 RMS deviation from its MATLAB prototype,

Infrared (IR) imaging is a key technology in a variety of military and civilian applications, especially for night vision and remote sensing. Compared with cryogenically cooled IR sensors, uncooled infrared imaging devices have the advantages of being low cost, light weight, and superior reliability. The electro-thermal analysis of a microbolometer pixel is critical to determine both device performance and reliability. To date, most microbolometer analysis research has focused on performance optimization and computation of thermal conductance directly from the geometry. However, modeling of the thermal distribution across the microbolometer pixel is critical for the comprehensive analysis of system performance and reliability. Therefore, this thesis investigates the electro-thermo-mechanical characteristics of a microbolometer pixel considering the effects of joule heating and incoming IR energy. The contributions of the present research include the electro-thermal models for microbolometer and methods of validating thermal distribution using experimental results. The electro-thermal models explain the effect of microbolometer material properties and geometry on device performance and reliability. The research also contributes methods of estimating the thermal conductivity of microbolometer, which take into account different heat transfer mechanisms, including radiation and convection. Previous approaches for estimating the thermal conductance of uncooled microbolometer consider heat conduction via legs from the geometry of the pixel structure and material properties [2]. This approach assumes linear temperature distribution in the pixel legs structure. It also leaves out the various electro-thermal effects existing for multilayer structures. In the present research, a different approach is used to develop the thermal conductance of microbolometer pixel structure. The temperature distribution in the pixel is computed from an electro-thermal model. Then, the average temperature in the pixel microplate and the total heat energy generated by joule heating is utilized to compute the thermal conductance of the structure. The thesis discusses electro-thermal and thermo-mechanical modeling, simulation and testing of Polysilicon Multi-User MEMS Process (PolyMUMPs®) test devices as the groundwork for the investigation of microbolometer performance and reliability in space applications. An electro-thermal analytical and numerical model was developed to predict the temperature distribution across the microbolometer pixel by solving the second order differential heat equation. To provide a qualitative insight of the effect of different parameters in the thermal distribution, including material properties and device geometry, first an explicit formulation for the solution of the electro-thermal coupling is obtained using the analytical method. In addition, the electro-thermal model, which accounts for the effect of IR energy and radiation heat transfer, spreading resistance and transient conditions, was studied using numerical methods. In addition, an analytical model has been developed to compute the IR absorption coefficient of a Thin Single Stage (TSS) microbolometer pixel. The simulation result of this model was used to compute absorbed IR energy for the numerical model. Subsequently, the temperature distribution calculated from the analytical model is used to obtain the deflections that the structure undergoes, which will be fundamental for the reliability analysis of the device. Finite element analysis (FEA) has been simulated for the selected device using commercial software, ANSYS® multiphysics. Finite element simulation shows that the electro-thermal models predict the temperature distribution across a microbolometer pixel at steady-state conditions within 2.3% difference from the analytical model. The analytical and numerical models are also simulated and results for a temperature distribution within 1.6% difference. In addition, to validate the analytical and numerical electro-thermal and thermo-mechanical models, a PolyMUMPs® test device has been used. The test results showed a close agreement with the FEM simulation deflection of the test device.

Laser powder bed fusion is one of the most effective ways to achieve metal additive manufacturing. However, this method still suffers from deformation, delamination, dimensional error, and porosities. One of the most significant issues is poor printing accuracy, especially for small features such as turbine blade tips. The main reason for the shape inaccuracy is the heat accumulation caused by using constant laser power regardless of the shape variations. Due to the highly complex and dynamic nature of the laser powder bed fusion, improving the printing quality is challenging. Research gaps exist from many perspectives. For example, the lack of understanding of multi-physical melt pool dynamics fundamentally impedes the research progress. The scarcity of a customizable laser powder bed platform further restricts the possibility of testing the improvement strategies. Additionally, most state-of-the-art quality inspection techniques suitable for laser powder bed fusion are costly in economic and time aspects. Lastly, the rapid and chaotic printing process is hard to monitor and control. This dissertation proposes a complete research scheme including a fundamental physics study, process signature and quality correlation, smart additive manufacturing platform development, high-performance sensor development, and a robust real-time closed-loop control system design to address all these issues. The entire research flow of this dissertation is as follows: 1. This work applies and integrates three advanced sensing technologies: synchrotron X-ray imaging, high-speed IR camera, and high-spatial-resolution IR camera to characterize the melt pool dynamics, keyhole, porosity formation, vapor plume, and thermal evolution in Ti-64 and 410 stainless steel. The study discovers a strong correlation between the thermal and X-ray data, enabling the feasibility of using relatively cheap IR cameras to predict features that can only be captured using costly synchrotron X-ray imaging. Such correlation is essential for thermal-based melt pool control. 2. A highly customizable smart laser powder bed fusion platform is designed and constructed. This platform integrates numerous sensors, including but not limited to co-axial cameras, IR cameras, oxygen sensors, photodiodes, etc. The platform allows in-process parameter adjusting, which opens the boundary to test various control theories based on multi-sensing and data correlations. 3. To fulfill the quality assessment need of laser powder bed fusion, this dissertation proposes a novel structured light 3D scanner with extraordinary high spatial resolution. The spatial resolution and accuracy are improved by establishing hardware selection criteria, integrating the proper hardware, designing a scale-appropriate calibration target, and developing noise reduction procedures during calibration. Compared to the commercial scanner, the proposed scanner improves the spatial resolution from 48 µm to 5 µm and the accuracy from 108.5 µm to 0.5 µm. 4. The final goal of quality improvement is achieved through designing and implementing a real-time closed-loop system into the smart laser powder bed fusion platform. The system regulates the laser power based on the monitoring result from a novel thermal sensor. The desired printing temperature is found by correlating the laser power, the dimensional accuracy, and the thermal signatures from a set of thin-wall structure printing trails. An innovative high-speed data acquisition and communication software can operate the whole system with a graphic user interface. The result shows the laser power can be successfully controlled with 2 kHz, and a significant improvement in small feature printing accuracy has been observed. / Doctor of Philosophy / Laser powder bed fusion is one of the most effective ways to achieve metal additive manufacturing. However, this method still suffers from defects such as deformation, delamination, dimensional error, and porosities. Due to the highly complex and dynamic nature of the laser powder bed fusion, improving the printing quality is challenging. Research gaps exist from many perspectives, such as the lack of understanding of melt pool dynamics; the scarcity of a customizable laser powder bed platform; the need for suitable sensors; and the missing of a control system that can effectively regulate the rapid and chaotic printing process. This dissertation proposes a complete research scheme to address all these issues. The fundamental study characterizes the melt pool dynamics and discovers a strong correlation between the melt pool thermal and geometrical data, enabling thermal-based melt pool control. Following that, a highly customizable smart laser powder bed fusion platform is designed and constructed. The platform allows in-process parameter changes, opening the boundary to test various control theories. A novel structured light 3D scanner with an ultra-high spatial resolution was proposed to fulfill the quality assessment need. The final goal of quality improvement is achieved through designing and implementing a real-time closed-loop system into the smart laser powder bed fusion platform. The system regulates the laser power based on real-time thermal monitoring. The result shows the laser power can be successfully controlled with 2 kHz, and a significant improvement in printing accuracy is achieved.

No description available.

L'histologie tridimensionnelle (3D) est un nouvel outil avancé de cancérologie. L'ensemble du profil chimique et des caractéristiques physiologiques d'un tissu est essentiel pour comprendre la logique du développement d'une pathologie. Cependant, il n'existe aucune technique analytique, in vivo ou histologique, capable de découvrir de telles caractéristiques anormales et de fournir une distribution3D à une résolution microscopique. Nous présentons ici une méthode unique de microscopie infrarouge (IR) à haut débit combinant une correction d'image automatisée et une analyse ultérieure des données spectrales pour la reconstruction d'image 3D-IR. Nous avons effectué l'analyse spectrale d'un organe complet pour un petit modèle animal, un cerveau de souris avec une tumeur de gliome implantée. L'image 3D-IR est reconstruite à partir de 370 coupes de tissus consécutives et corrigée à l'aide du tomogramme à rayons X de l'organe pour une analyse quantitative précise du contenu chimique. Une matrice 3D de spectres IR 89 x 106 est générée, ce qui nous permet de séparer la masse tumorale des tissus cérébraux sains en fonction de divers paramètres anatomiques,chimiques et métaboliques. Nous démontrons pour la première fois que des paramètres métaboliques quantitatifs (glucose, glycogène et lactate) peuvent être extraits et reconstruits en 3D à partir des spectres IR pour la caractérisation du métabolisme cérébral / tumoral (évaluation de l'effet de Warburg dans les tumeurs). Notre méthode peut être davantage exploitée en recherchant l'ensemble du profil spectral, en distinguant différents points de repère anatomiques dans le cerveau.Nous le démontrons par la reconstruction du corps calleux et de la région des noyaux gris centraux du cerveau. / Three-dimensional (3D) histology is a new advanced tool for cancerology. The whole chemical profile and physiological characteristics of a tissue is essential to understand the rationale of pathology development. However, there is no analytical technique, in vivo or histological, that is able to discover such abnormal features and provide a 3D distribution at microscopic resolution.Here, we introduce a unique high- throughput infrared (IR) microscopy method that combines automated image correction and subsequent spectral data analysis for 3D-IR image reconstruction. I performed spectral analysis of a complete organ for a small animal model, a mouse brain with animplanted glioma tumor. The 3D-IR image is reconstructed from 370 consecutive tissue sectionsand corrected using the X-ray tomogram of the organ for an accurate quantitative analysis of thechemical content. A 3D matrix of 89 x 106 IR spectra is generated, allowing us to separate the tumor mass from healthy brain tissues based on various anatomical, chemical, and metabolic parameters. I demonstrate for the first time that quantitative metabolic parameters (glucose, glycogen and lactate) can be extracted and reconstructed in 3D from the IR spectra for the characterization of the brain vs. tumor metabolism (assessing the Warburg effect in tumors). Our method can be further exploited by searching for the whole spectral profile, discriminating different anatomical landmarks in the brain. I demonstrate this by the reconstruction of the corpus callosum and basal ganglia region of the brain.

La technologie des microbolomètres est à ce jour la plus avancée pour l'imagerie IR non refroidie. Le LETI développe une technologie basée sur l'utilisation du silicium amorphe comme matériau thermistor. L'introduction d'un matériau alternatif doit permettre de poursuivre l'amélioration des performances. Cette étude considère une solution alternative à base de films minces d'oxydes nanocristallins. Deux procédés sont envisagés : le dépôt IBS et le dépôt MOCVD. L'étude des procédés ainsi que la caractérisation des matériaux ont permis la maîtrise et la compréhension des évolutions structurales et fonctionnelles mises en jeux. Des caractérisations électriques (résistivité, TCR, bruit en 1/f) sur dispositifs ont permis de débattre de l'intérêt de ces nouveaux matériaux. Une réflexion a été menée sur les relations microstructure-propriétés. / Microbolometers FPAs are nowadays the most advanced technology for uncooled IR imaging. Developments at CEA-LETI are based on the use of amorphous silicon as thermistor material. Introduction of an alternative material is necessary to keep on improving detectors performances. This study considersnanocrystalline oxides thin films as an alternative material. Two deposition techniques have been studied : IBS and MOCVD. Process studies as well as materials characterizations allowed us to control and understand the involved micro-structural evolutions. Electrical characterizations (resistivity, TCR, 1/f noise) on integrated devices were achievedin order to estimate the potential of these new materials. Microstructure-property relationships are also discussed.

Abstract The uniformity of conductive materials is an important property in thin film electronic applications such as solar cells and light emitting diodes (LED). Such uniformity variations are often very small, invisible or below the surface of the film and thus are difficult to detect even when using high-resolution characterization devices. Thus, surface measurement instruments such as profilometer, atomic force microscope, or scanning electron microscope can all encounter remarkable challenges. The uniformity of films can also be analyzed by conductivity measurements. However, they do not provide the precise spatial uniformity information of a large area sample. To be able to investigate systematically the defects of conductive thin films an appropriate sample preparation method was constructed. In addition, a synchronized heating and IR-imaging based system (called synchronized thermography = ST) was developed to overcome the limitations of existing characterization methods. ST performance was tested and analyzed by measuring the single and multi-layer structures. In this work, Indium Tin Oxide (ITO) and poly(3,4-ethylenedioxy-thiopene):poly(styrene-sulfonate) (PEDOT: PSS) were used as examples of conductive thin films. Obtained results show that ST is capable of localizing even small defects from thin film structures based on a single IR-image. In order to make automatic identification of the defect locations and the sizes of the defects, a data processing algorithm was implemented. The performed experiments have proven ST capable of determining the conductivity of the films and the critical bending curvature of ITO. Based on thin film multi-layer PEDOT:PSS measurements, the results suggest use of the ST-method is also suitable for thickness measurements. ST with automatic data processing is a simple method to localize small defects in large-area thin film structures. This approach opens up new possibilities in measuring industrial scale manufacturing processes. / Tiivistelmä Johtavien materiaalien tasalaatuisuus on tärkeä ominaisuus ohutkalvoelektroniikan sovelluksissa kuten aurinkokennoissa ja valoa emittoivissa diodeissa (LED). Tasalaatuisuuserot ovat usein erittäin pieniä, näkymättömiä tai ne sijaitsevat pinnan alla, joten niiden havaitseminen on vaikeaa jopa korkean resoluution karakterisointivälineillä. Niinpä pintaa mittaavat laitteet kuten profilometri, atomivoimamikroskooppi ja skannaava elektronimikroskooppi kohtaavat merkittäviä haasteita. Pinnan tasalaatuisuutta voidaan analysoida myös johtavuusmittauksilla. Ne eivät kuitenkaan anna täsmällistä spatiaalista informaatiota suurista näytteistä. Johtavien ohutkalvojen rikkoutumien systemaattista tutkimista varten kehitettiin oma näytteiden käsittelymenetelmä. Lisäksi kehitettiin synkronoituun lämmitykseen ja infrapunakuvantamiseen perustuva mittaussysteemi (menetelmän nimi: synkronoitu termografia = ST), jolla pyritään ratkaisemaan nykyisten menetelmien rajoitukset. ST-menetelmää testattiin ja analysoitiin mittaamalla yksi- ja monikerroksisten kalvojen rakenteita. Indiumtinaoksidia (ITO) ja poly(3,4-etyleenidioksi-tiofeeni):poly(styreeni-sulfonaatti):a (PEDOT: PSS) käytettiin esimerkkeinä johtavista kalvoista. Tulokset osoittavat, että ST kykenee paikallistamaan pienetkin virheet ohutkalvorakenteista jopa yhden infrapunakuvan perusteella. Automaattisen tiedonkäsittelyn algoritmi implementoitiin identifioimaan virheiden paikkariippuvuuksia ja kokoja. Tehdyt kokeet osoittavat, että ST-menetelmä soveltuu kalvojen johtavuuden ja ITO:n kriittisen taivutussäteen määrittämiseen. Monikerroksisiin PEDOT:PSS rakennemittauksiin perustuen ST-menetelmä näyttäisi soveltuvan myös ohutkalvojen paksuuksien määrittämiseen. ST-menetelmä yhdistettynä automaattiseen mittaustiedon prosessointiin on yksinkertainen menetelmä paikallistamaan pieniä virheitä suuripinta-alaisilla näytteillä. Tämä lähestymistapa avaa uusia mittausmahdollisuuksia teollisuuden tuotantoprosesseihin.