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La récupération de l’énergie ambiante pour alimenter les systèmes électroniques devient de plus en plus une réalité grâce à la miniaturisation et la diminution importante de leur consommation. Dans ce but, nous avons développé une nouvelle famille de microgénérateurs thermoélectriques capables de produire quelques microwatts dès lors qu’une différence de température de quelques degrés est accessible. Ces microgénérateurs ont été réalisés avec des matériaux non polluants afin de tenir compte des contraintes environnementales qui apparaitront certainement dans un futur proche. Le principe de fonctionnement, classique, est basé sur l’effet Seebeck qui permet de convertir une différence de température en force électromotrice à l’aide d’une thermopile planaire réalisée en couches minces. Pour obtenir de bons résultats, il est nécessaire de concevoir puis de dimensionner précisément une structure tridimensionnelle permettant de transformer un flux de chaleur en une multitude de différences de température au niveau des thermocouples constituant la thermopile. La centrale de technologie silicium de l’IEMN nous a permis de fabriquer plusieurs familles des microgénérateurs correspondant à ces concepts en utilisant les procédés standards de micro-usinage du silicium. Bien sur, avant d’entreprendre une telle réalisation, un modèle analytique approché ainsi qu’un modèle numérique 3D ont été établis afin que le microgénérateur puisse délivrer le maximum de puissance électrique. Les dispositifs réalisés en centrale de technologie ont été caractérisés sur des bancs de mesure développés à cette fin et les résultats obtenus sont proches de ceux attendus. / Energy harvesting for the power supply of electronic systems becomes more and more a reality thanks to the miniaturization and the major reduction in their consumption. In this aim, we developed a new family of thermoelectric microgenerators able to produce a few microwatts when a temperature difference of a few degrees is accessible. These micro generators were carried out with non-polluting materials in order to take into account the environmental requirements which will certainly appear in a near future. The principle of operation is based on the Seebeck effect which makes it possible to convert a temperature difference into electromotive force using a planar thermopile fabricated with thin layers process. To obtain good performances it is necessary to design a three-dimensional structure to transform a heat flux into a multitude of temperature differences onto the thermocouples’ junctions of the thermopile. The silicon technology platform of IEMN enabled us to manufacture several families of micro generators corresponding to these concepts by using the standard processes of silicon micromachining. Of course, before undertaking such a realization, an approximate analytical model as well as a 3D numerical model was established in order to obtain the maximum of electrical power output that the microgenerator can deliver. The devices fabricated in our technology platform were characterized on specific set-up specially developed and experimental results are close to those expected.

The Thermal Radiation Group, a laboratory in the department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently working towards the development of a new technology for cavity-based radiometers. The radiometer consists of a 256-element linear-array thermopile detector mounted on the wall of a mirrored wedge-shaped cavity. The objective of this research is to provide analytical and experimental characterization of the proposed radiometer. A dynamic end-to-end opto-electrothermal model is developed to simulate the performance of the radiometer. Experimental results for prototype thermopile detectors are included. Also presented is the concept of the discrete Green's function to characterize the optical scattering of radiant energy in the cavity, along with a data-processing algorithm to correct for the scattering. Finally, a parametric study of the sensitivity of the discrete Green's function to uncertainties in the surface properties of the cavity is presented. / Master of Science

Les technologies de type laboratoire sur puce (« lab on chip » LOC) mettent à profit la miniaturisation pour réaliser production, traitement, et analyse physico-chimiques sur un même substrat de petite taille avec comme résultat des dispositifs portables, plus rapides, demandant de plus petites quantités de réactifs, produits et opérés à plus faible coût. Les produits et les applications développés pour tirer profit de ces avantages ont le potentiel de transformer plusieurs secteurs comme ceux de la médecine et de la surveillance environnementale. Les mesures de calorimétrie revêtent un intérêt particulier pour l’intégration aux plateformes de type LOC notamment parce que la production de chaleur est un phénomène ubiquitaire. Or, cette intégration repose avant tout sur la capacité de produire des dispositifs miniaturisés suffisamment performants et compatibles avec la construction des plateformes LOC. La calorimétrie miniaturisée est un champ relativement peu développé même si, comme à l’échelle conventionnelle, elle permet d’obtenir des informations utiles pour la compréhension des phénomènes de transformations de la matière. Or, la calorimétrie miniaturisée fait face à un défi de taille. La taille réduite des échantillons résulte inévitablement en une diminution de la quantité de chaleur à mesurer. Possiblement pour faire face à cette limite, la grande majorité des calorimètres miniaturisés adopte une configuration planaire, car le positionnement du système cellule calorimétrique-échantillon sur membrane a pour effet de maximiser leur sensibilité. La configuration membranaire réduit la conduction thermique à travers le substrat ce qui, à puissance égale, résulte en davantage de signal. Cette configuration demande toutefois certains compromis. Elle pousse par exemple à construire les thermopiles à partir de films de plus en plus minces afin d’éviter d’annuler les gains. Or, des effets de « film mince », sont observés qui dégradent significativement les propriétés attendues des matériaux. Les gains apportés par la configuration membranaire peuvent aussi être annulés par la conduction thermique hors substrat qui est très sensible à la géométrie de la source de chaleur ainsi qu’aux conditions ambiantes. Ces deux phénomènes affectent significativement la sensibilité des calorimètres miniaturisés et peuvent résulter en une diminution de la précision des mesures. Dans le premier cas, on estime à 20-30% l’erreur évitée; dans le second cas, on estime à près de 30% l’erreur évitée. Les contributions présentées dans cette thèse proposent des moyens d’améliorer la précision des calorimètres miniaturisés, en renforçant la compréhension des compromis fondamentaux à négocier dans la conception de tels dispositifs et d’établir un « modèle » pour prédire avec une plus grande fidélité la performance de calorimètres miniaturisés à partir des paramètres de l’architecture. On peut donc plus précisément évaluer le potentiel de différents designs de calorimètres miniaturisés et explorer la manière de faire des calorimètres miniaturisés de bons candidats à l’intégration sur les plateformes LOC, que ce soit sur structure membranaire ou d’autres substrats.

This work seeks to apply the novel heat flux sensor called as the Atomic Layer Thermopile to measure high frequency heat flux in high speed and high temperature flows found in Gas Turbine combustors. To achieve this the sensor must be able to survive the harsh environment of high temperature and high pressure. To have any confidence in our measurement, it is also imperative that there are tools available for precise estimation of the measurement uncertainty. This works strives to achieve these objectives by developing calibration techniques for uncertainty estimation using both exposure to radiation and in convective environments by calibrating against power input in steady state flow and transient heat flux calculated using wall temperature measurement. The response of the sensor is then investigated in high speed flows by measuring the heat flux inside a supersonic nozzle when exposed to shock waves. The shock waves are generated using a fast throttle valve located at the entrance of the supersonic nozzle by generating sudden rise in pressure. Lastly a numerical study is carried out to design a cooling system that will allow the sensor to survive in high temperature conditions of 1000°C while the sensor film is maintained at 50°C. A one-dimensional model is used to provide initial design parameters and then a two-dimensional axisymmetric conjugate CFD analysis is carried out to obtain the desired geometry that can meet the design conditions. A static structural analysis is also carried out on this geometry to ensure that it will be able to survive and avoid distortion under the operational pressure required for providing the desired coolant mass flow.

I det här arbetet presenteras ett system som utvecklats i syfte att kunna räkna personer. Systemet är tänkt att användas i mötesrum för upp till tio personer och använder sig av infraröd teknik i form av thermopile arrayer. I arbetet har tre olika sensorer använts för utvärdering. Sensorerna som använts är Panasonic Grid-EYE med pixelupplösningen 8×8 och detekteringsvinkeln 60°×60° samt två stycken Heimann 32x32d, båda med upplösningen 32×32 pixlar, men med detekteringsvinkeln 90°×90° respektive 105°×105°. Systemet är programmerat med hjälp av utvecklingskortet STM32L476RG och är skrivet i språket C. I systemet används två metoder för att beräkna antalet personer. Den ena metoden jämför temperaturförändringen i ett rum i förhållande till då rummet är tomt och den andra metoden använder sig av bildbehandlingsmetoder som interpolering, filtrering och beräkning av area. Sensorerna utvärderas även individuellt utifrån egenskaper som noggrannhet, strömförbrukning och implementationskostnad. Script har även skapats i MATLAB som, i kombination med mikrokontrollern, används för att grafiskt presentera temperaturvärdena från sensorerna. Den sensor som visade sig vara bäst lämpad för att räkna personer är Heimann 32×32d med detekteringsvinkeln 105°×105°. Detta tack vare den större detekteringsvinkeln som resulterar i en större detekterbar yta samt upplösningen på totalt 1024 pixlar som sammantaget ger en högre noggrannhet för personräkning. Denna sensor kräver dock mer komplexa och tidskrävande beräkningar för behandling av data än Grid-EYE. Dessa skillnader är ändå marginella, där noggrannheten och den större detekterbara arean väger upp nackdelarna. De experimentella resultaten visar att Heimann 32×32d med 105°×105° ger en noggrannhet på c:a 98.3 % vid mätning på höjden 2.45 m. Detta motsvarar en yta på c:a 39.1 m2 och systemet kan räkna upp till minst 4 personer. För Grid-EYE och samma höjd har ej noggrannheten fastställts, men har endast en detekterbar yta på c:a 7.7 m2 där maximalt 4 personer bedöms kunna räknas. / In this work, a system is being developed with the purpose of counting people. The system is intended for use in meeting rooms for up to ten persons and utilizes infrared technique using thermopile arrays. For this work, three different sensor have been used for evaluation. A Panasonic Grid-EYE with a resolution of 8×8 and a Field of View (FoV) of 60°×60°, and two Heimann 32×32d sensors, both having a resolution of 32×32, but with the FoV 90°×90° and 105°×105° respectively. The system has been programmed using the microcontroller STM32L476RG, and with the programming language C. In this system, two methods for people counting has been implemented. The first method compares the total change in temperature of a room in relation to when the room is empty and the other method uses image processing methods, such as interpolation, filtering and area calculations. The sensors are also being evaluated individually, based on characteristics such as accuracy, current consumption and implementation cost. To graphically display the temperature values of the sensors, scripts has been made for MATLAB that uses information sent by the microcontroller. The sensor which seem to be best suited for counting people is the Heimann 32×32d with the FoV 105°×105°. The main advantage of this sensor is its wider FoV, covering a larger area, and its higher resolution, which overall yields a higher accuracy when counting people. However, this sensor requires more complex and time-consuming calculations when processing data than the Grid-EYE. Still, these differences are marginal where the accuracy and the larger detectable area for the HTPA outweighs its disadvantages. The experimental results shows that the Heimann sensor with 105°×105° FoV can achieve an accuracy of ≈98.3 % measuring at a height of 2.45 m. At this height, the detectable area for the sensor is ≈39.1 m2 and is being able to count up to at least 4 persons. As for the Grid-EYE and with the same scenario, the accuracy has not been determined, but has a detectable area of ≈7.7 m2 and is estimated being able to count up to a maximum of 4 persons.

abstract: In the search for chemical biosensors designed for patient-based physiological applications, non-invasive diagnostic approaches continue to have value. The work described in this thesis builds upon previous breath analysis studies. In particular, it seeks to assess the adsorptive mechanisms active in both acetone and ethanol biosensors designed for breath analysis. The thermoelectric biosensors under investigation were constructed using a thermopile for transduction and four different materials for biorecognition. The analytes, acetone and ethanol, were evaluated under dry-air and humidified-air conditions. The biosensor response to acetone concentration was found to be both repeatable and linear, while the sensor response to ethanol presence was also found to be repeatable. The different biorecognition materials produced discernible thermoelectric responses that were characteristic for each analyte. The sensor output data is presented in this report. Additionally, the results were evaluated against a mathematical model for further analysis. Ultimately, a thermoelectric biosensor based upon adsorption chemistry was developed and characterized. Additional work is needed to characterize the physicochemical action mechanism. / Dissertation/Thesis / M.S. Bioengineering 2011

The maximum sensitivity of a thermal IR sensor can be available either by means of the sensor material, having its own absorbing properties, or by the deposition of an additional absorber structure on the detector surface. In this thesis, the theory of two absorption structures is discussed. The first is called the interferometric absorber structure. The second structure under investigation uses a lead selenide layer for the IR absorption. In the interferometric structure, a new epoxy material SU8-2002 was used as a dielectric medium. This material has a very low thermal conductivity of 0.3 W/mK, which makes it suitable for thermal detectors. The interferometric structure is based on three layers, a 40–60 Å thick Ti layer, a SU8–2002 layer with a thickness of 2000 Å thick and a 2000Å Al layer. Using standard cleanroom processing an interferometric structure was fabricated. Transfer matrix theory was used in order to simulate the interferometric structure and the lead selenide was fabricated by means of an argon-plasma sputtering process. Both fabricated samples were characterized through Fourier transfer infrared (FTIR) spectroscopy together with a specular reflectance accessory. The thicknesses of the added layers were measured using Atomic force microscopy (AFM) for both the interferometric and lead selenide structure.  It was determined  that by changing the reflective index value of the SU8-2002 from the reported value of 1.575 to about 2.40 that this provided a better agreement with the experimental results. The absorption results for the interferometric structure were determined to be approximately 82–98% for the wavelength region of 2-20µm at 30 degree. The PbSe absorption spectra showed 30%–50% absorption for the wavelength region 2.5 – 6.67μm.

During the last decades, great steps have been taken to decrease passenger fatality in cars. Systems such as ABS and airbags have been developed for this purpose alone. But not much effort has been put into pedestrian safety. In traffic today, pedestrians are one of the most endangered participants and in recent years, there has been an increased demand for pedestrian safety from the European Enhanced Vehicle safety Committee and the European New Car Assessment Programme has thereby developed tests where pedestrian safety is rated. With this, detection of pedestrians has arised as a part in the automotive safety research. This thesis provides some of this research available in the area and a brief introduction to some of the sensors readily available. The objective of this work is to detect pedestrians in front of a vehicle by using thermoelectric infrared sensors fused with short range radar sensors and also to minimize any missed detections or false alarms. There has already been extensive work performed with the thermoelectric infrared sensors for this sole purpose and this thesis is based on that work. Information is provided about the sensors used and an explanation of how they are set up during this work. Methods used for classifying objects are given and the assumptions made about pedestrians in this system. A basic tracking algorithm is used to track radar detected objects in order to provide the fusion system with better data. The approach chosen for the sensor fusion is a central-level fusion where the probabilities for a pedestrian from the radars and the thermoelectric infrared sensors are combined using Dempster-Shafer Theory and accumulated over time in the Occupancy Grid framework. Theories that are extensively used in this thesis are explained in detail and discussed accordingly in different chapters. Finally the experiments undertaken and the results attained from the presented system are shown. A comparison is made with the previous detection system, which only uses thermoelectric infrared sensors and of which this work continues on. Conclusions regarding what this system is capable of are drawn with its inherent strengths and weaknesses.

<p>During the last decades, great steps have been taken to decrease passenger fatality in cars. Systems such as ABS and airbags have been developed for this purpose alone. But not much effort has been put into pedestrian safety. In traffic today, pedestrians are one of the most endangered participants and in recent years, there has been an increased demand for pedestrian safety from the European Enhanced Vehicle safety Committee and the European New Car Assessment Programme has thereby developed tests where pedestrian safety is rated. With this, detection of pedestrians has arised as a part in the automotive safety research.</p><p>This thesis provides some of this research available in the area and a brief introduction to some of the sensors readily available. The objective of this work is to detect pedestrians in front of a vehicle by using thermoelectric infrared sensors fused with short range radar sensors and also to minimize any missed detections or false alarms. There has already been extensive work performed with the thermoelectric infrared sensors for this sole purpose and this thesis is based on that work.</p><p>Information is provided about the sensors used and an explanation of how they are set up during this work. Methods used for classifying objects are given and the assumptions made about pedestrians in this system. A basic tracking algorithm is used to track radar detected objects in order to provide the fusion system with better data. The approach chosen for the sensor fusion is a central-level fusion where the probabilities for a pedestrian from the radars and the thermoelectric infrared sensors are combined using Dempster-Shafer Theory and accumulated over time in the Occupancy Grid framework. Theories that are extensively used in this thesis are explained in detail and discussed accordingly in different chapters.</p><p>Finally the experiments undertaken and the results attained from the presented system are shown. A comparison is made with the previous detection system, which only uses thermoelectric infrared sensors and of which this work continues on. Conclusions regarding what this system is capable of are drawn with its inherent strengths and weaknesses.</p>