L'essor de l'internet des objets (IoT) et des capteurs autonomes et communicants semble être retardé en raison du manque de source d’énergie fiable, sûre et à faible coût. Les récupérateurs d’énergies thermoélectriques présentent ces avantages clés. Le silicium présente les avantages d'être très abondant, moins polluant et de bénéficier d'installations et de procédés technologiques permettant la production en série de récupérateurs d’énergies thermoélectriques à faible coût par rapport aux matériaux conventionnel (alliages de tellure de bismuth). Toutefois, le silicium est un matériau thermoélectrique médiocre en raison de sa conductivité thermique élevée ( ). La possibilité de réduire la conductivité thermique tout en préservant la conductivité électrique et le coefficient Seebeck est la clé pour améliorer le silicium en tant que matériau thermoélectrique efficace. À cette fin, les efforts sont orientés vers la partie phononique du transport de chaleur, qui constitue la contribution dominante dans les semi-conducteurs. Les recherches menées au cours de cette thèse ont porté sur l'intégration des membranes de silicium nanostructurées de réseaux phononiques dans des démonstrateurs de récupérateurs d’énergies thermoélectriques et leur caractérisation au regard de l'état de l’art. Les résultats de ces études ont démontré la faisabilité d’un récupérateur d’énergie thermoélectrique à base de silicium présentant des performances (De quelques µW/cm2 pour ΔT~5-10K à quelques mW/cm2 pour ΔT>100K) suffisantes pour l’alimentation en énergie de nœuds de capteurs autonomes et des performances comparables à celles d’un récupérateur (état de l’art) à base de tellure de bismuth en fonction des conditions de refroidissement de ces derniers. De plus, cette thèse a démontré, outre la récupération d'énergie, la possibilité de développer des refroidisseurs thermoélectriques à base de silicium, ouvrant la voie à une possible intégration de refroidisseurs thermoélectriques dans des dispositifs micro-électroniques à base de silicium. / The lack of reliable, safe and low-cost energy source seems to delay the blooming of the internet of things (IoT) and wireless sensors nodes. Thermoelectric harvesters feature those key advantages. Silicon presents the advantages to be most abundant, less environmental harmful and to benefit from facilities and technological processes for low cost thermoelectric harvesters mass production compared to the conventional materials (bismuth telluride alloys). However, silicon is a poor thermoelectric material due to its high thermal conductivity ( ). The possibility to reduce the thermal conductivity while preserving electrical conductivity and Seebeck coefficient is the key to upgrade silicon as an efficient thermoelectric material. To that end, efforts are oriented towards the phononic part of heat transport, which is the dominant contribution in semiconductors. The researches carried out during this thesis dealt with the integration of phonon engineered silicon membranes into thermoelectric harvester demonstrators and their characterizations with respect to the state of the art. The results demonstrated the feasibility of a silicon based thermoelectric harvester exhibiting performance (from few µW/cm2 for ΔT~5-10K to few mW/cm2 for ΔT>100K) sufficient for autonomous sensor nodes’ power supplying and comparable performance with the bismuth telluride state of the art harvester according to the harvesters’ cooling conditions. Moreover, this thesis demonstrated, in addition to the energy harvesting, the possibility of developing silicon based thermoelectric coolers, opening the way to possible integration of thermoelectric coolers in silicon based micro-electronic devices.

Fiber optic temperature sensing has become a well-defined field in the past few decades [1] through the use of Fiber Bragg Gratings, Fabry-Perot interferometry, and pyrometry, to list several techniques in use today.  The use of fiber optics offers significant advantages over electronic sensing in terms of size and insensitivity to harsh conditions such as extreme temperatures and corrosive environments.  The availability of optical sapphire materials, including fibers, has allowed the creation of fiber optic sensing elements able to continuously operate at temperatures of 1600"C [2] or more, thus outstripping the abilities of many commonly used thermocouples (excluding platinum types R, S, and B) [3] which will also exhibit a sensitivity to electromagnetic fields. In addition to the aforementioned benefits, fiber optic sensing techniques provide a great deal of accuracy in temperature measurement over the entire working range of the sensor. The work documented in this thesis consists of efforts to minimize the overall footprint of a sapphire based extrinsic Fabry-Perot interferometry (EFPI) temperature sensing element, as well as strides made in multiplexing the same element and reducing the error potential from cross sensitivity of the thermometer with applied strain.  This work has been variously funded by Pratt & Whitney and the Department of Energy. / Master of Science

Indiana University-Purdue University Indianapolis (IUPUI) / A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nano fluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.

Recent advances in linear quantum optics have involved the development of unbiased, multi-port optical elements for use with pairs of identical photons, or biphotons, for the design of novel quantum devices. The unbiased counterpart of a conventional 50:50 beam-splitter is a particularly useful multiport, thanks to its unique algebraic properties when acting on both classical and quantum states of light. Dubbed the “Grover coin” due to its utility in the Grover’s Search quantum algorithm, the unbiased four-port behaves as a conventional beam splitter, but with two additional ports to provide a photon amplitude with four, equally-probable, spatially distinct paths through which it may propagate. While the Grover coin has been realized in the laboratory in the form of bulk optical elements, the formation of a network of Grover coins is impractical due to the meticulous alignment and large number of elements required for a single component. Therefore, the development of a small, chip-integrated embodiment of the unbiased four-port would enable experimentation with novel quantum optics theories, through the interconnection of multiple Grover coins over a small footprint. This thesis details the design and fabrication of photonic waveguide-based integrated circuit elements through numerical simulation, topology optimization and CMOS-compatible manufacturing processes. / 2025-06-08T00:00:00Z

The Terahertz region of the electromagnetic spectrum is the region between microwaves and infra-red, dubbed the terahertz 'gap' due to its relative underdevelopment in terms of technology. This region is marked by expensive and inconvenient sources that are bulky or that require cryogenic cooling for normal operation, therefore creating a need for cheap and easy to use terahertz sources. Carbon nanotubes have received considerable attention since their discovery due to their unique physical and electronic properties. Many applications have been proposed using especially Single-Walled Carbon Nanotubes (SWCNTs), and a number of commercial technologies exist. In this work, we have proposed to use SWCNTs as the basis for a cheap, compact and room temperature-operating Terahertz source. We have characterized the SWCNT source, and we present results on transport characteristics (I–V curves), radiation patterns, spectra, polarization as well as optical, SEM and AFM imaging. We show that the radiation spectrum is vi determined by integrated antennas coupled to the SWCNTs, and preliminary power calibration indicates that the radiated power exceeds the power predicated by the Nyquist formula.

Electrodeposition is one of the main techniques for fabricating conductive parts with one or two dimensions in the micron size range. This technique is utilized to coat surfaces with protective films of several micrometers thickness or fabricate standalone microstructures. In this process, an electrochemical reaction occurs on the electrode surface by applying an electric voltage, called overpotential. Different electrochemical practices were presented in the literature to obtain kinetic parameters of an electrochemical reaction but most of these practices are hard to implement for the reactions occur on a microelectrode. Toward addressing this issue, the first part of the dissertation work presents a combined experimental and analytical method which can more appropriately provides for the kinetic measurement on a microelectrode. Another issue which occurs for electrodeposition on microscale recessed areas is the deviation of the profile of the deposition front from the substrate shape. Non-uniform deposition front usually obtains for a deposit evolved from a flat substrate with microscale size. Consequently, a subsequent precision grinding process is required to level the surface of the electrodeposited microparts. In order to remove the need for this subsequent process, in the second and third parts of the dissertation work, multiphysics modeling was used to study the effects of the fabrication parameters on the uniformity of the deposit surface and suggest a design strategy. Surface texture of the deposit is another parameter which depends on the fabrication parameters. Several important characteristics of the electrodeposited coating including its wettability depend on the surface texture. The next part of the dissertation work presents an experimental investigation and a theoretical explanation for the effects of the overpotential and bath concentration on the surface texture of the copper deposit. As a result of this investigation, a novel two-step electrodeposition technique is developed to fabricate a superhydrophobic copper coating. In the last part of the dissertation work, similar investigation to the previous sections was presented for the effects of the fabrication parameters on the crystalline structure of the deposit. This investigation shows that nanocrystalline and superplastic materials can be fabricated by electrodeposition if appropriate fabrication parameters are applied. / Ph. D.

Le nano-moteur qui se trouve à la base des flagelles des bactéries est une merveille de part sa structure et son rôle dans la survie des bactéries. Il permet la mise en rotation rapide (300Hz) d'un long filament à l'extérieur de la bactérie, filament qui va jouer un rôle comparable à une hélice de sous marin. Malgré sa taille, 45 nm dans son plus grand diamètre, cette nano-bio-machine est composée de milliers de protéines, briques essentielles à la vie. Ces protéines travaillent de concert afin de faire tourner le flagelle bactérien et permettre à la bactérie de se mouvoir dans son environnement au gré du milieu dans lequel elle évolue. Malgré son importance dans la vie bactérienne, son fonctionnement précis reste encore relativement flou aujourd'hui. Sa découverte il y a plus de 30 ans a permis l'accumulation de données qui permettent d'esquisser la structure de certaines des protéines, leur emplacement ou le rôle joue par certaines parties de ces mêmes protéines. D'autres expériences ont permis de déduire des caractéristiques mécaniques, comme les relations couple/vitesse de ce moteur. Cependant, sa description à l'échelle nanométrique reste a ce jour limité et sujette à précautions. Dans le cadre de ma thèse, deux approches parallèles et complémentaires ont été développé afin de répondre à ce défi : le réassemblage de manière contrôlé in vitro d'une partie du moteur crucial pour le fonctionnement du moteur, l'étude à grande échelle des interactions entre les protéines identifiées comme étant essentielles à la rotation du flagelle. De nombreux outils qui n'avaient jamais été utilisés pour l'étude du moteur ont été mis à profit : le microscope à force atomique, afin de visualiser dans un environnement proche du milieu natif les parties du moteur réassemblées, et la Micro Balance à Quartz pour les études d'interactions. Des nouvelles données ont pu être obtenues et synthétisées dans une nouvelle hypothèse de fonctionnement du Nano-moteur flagellaire des bactéries q ui sera présentée.

The main objective of the present research work is to fabricate three dimensional photonic nanostructures in photo-sensitive polymers using a novel diffractive optical element (DOE) based lithography technique. A diffractive optical element is a promising alternative device for 3D fabrication where one DOE creates multiple laser beams in various diffraction orders that are inherently phase-locked and stable for reproducible creation of 3D near-field diffraction patterns from a single laser beam. These near-field patterns are captured inside a photosensitive material like photoresist to fabricate 3D photonic crystal templates. We have demonstrated fabrication of a wide range of 3D structures having different crystal symmetries and different relative crystal axis ratios. The present work has provided 3D photonic crystal nanostructures with uniform optical and structural properties over large sample area (~3-4 mm diameter) and through large 15-50 micron thickness with large number of layers (> 40) having period 550 nm - 650 nm and feature sizes between 200 nm and 300 nm. The short exposure time and small number of process steps shows promise for scaling to very large volume fabrication, dramatically improving the throughput, quality and structural uniformity of 3D periodic nanostructures, especially over that provided by tedious and costly semiconductor processing technology. The diffractive optics lithography is a parallel processing method that is easily scalable to generate centimeter-scale 3D nanostructures having large number of layers in several seconds. Due to low refractive index contrasts these polymer templates possess partial stopgaps along several crystallographic directions which can be practically used in several device or sensor applications where complete bandgap is not necessary. The potential usefulness of these partial stopbands for refractive index sensing of liquids has been demonstrated. These low refractive index polymer structures have been inverted with amorphous silica to convert a "soft" polymer structure to a robust "hard" structure. Further, few preliminary tests were done in fabricating 3D nanostructures into micro-fluidic channels for potential chromatography applications. The practical merits of this 3D fabrication technique will enable new practical manufacturing methods for optical and MEMS applications of 3D micro and nano structures.

The main objective of the present research work is to fabricate three dimensional photonic nanostructures in photo-sensitive polymers using a novel diffractive optical element (DOE) based lithography technique. A diffractive optical element is a promising alternative device for 3D fabrication where one DOE creates multiple laser beams in various diffraction orders that are inherently phase-locked and stable for reproducible creation of 3D near-field diffraction patterns from a single laser beam. These near-field patterns are captured inside a photosensitive material like photoresist to fabricate 3D photonic crystal templates. We have demonstrated fabrication of a wide range of 3D structures having different crystal symmetries and different relative crystal axis ratios. The present work has provided 3D photonic crystal nanostructures with uniform optical and structural properties over large sample area (~3-4 mm diameter) and through large 15-50 micron thickness with large number of layers (> 40) having period 550 nm - 650 nm and feature sizes between 200 nm and 300 nm. The short exposure time and small number of process steps shows promise for scaling to very large volume fabrication, dramatically improving the throughput, quality and structural uniformity of 3D periodic nanostructures, especially over that provided by tedious and costly semiconductor processing technology. The diffractive optics lithography is a parallel processing method that is easily scalable to generate centimeter-scale 3D nanostructures having large number of layers in several seconds. Due to low refractive index contrasts these polymer templates possess partial stopgaps along several crystallographic directions which can be practically used in several device or sensor applications where complete bandgap is not necessary. The potential usefulness of these partial stopbands for refractive index sensing of liquids has been demonstrated. These low refractive index polymer structures have been inverted with amorphous silica to convert a "soft" polymer structure to a robust "hard" structure. Further, few preliminary tests were done in fabricating 3D nanostructures into micro-fluidic channels for potential chromatography applications. The practical merits of this 3D fabrication technique will enable new practical manufacturing methods for optical and MEMS applications of 3D micro and nano structures.

In this thesis, intrinsic Josephson junctions, naturally formed in the strongly anisotropic high-temperature superconductor Bi2Sr2CaCu2O8 (Bi-2212), are studied experimentally. For this purpose, small mesa structures are fabricated on the surface of single crystals using micro- and nano-fabrication tools, focused ion beam is used to reduce the area of the mesa-structures down to ≈ 1 × 1 μm2. The properties of charge transport across copper-oxide layers inside the mesas are studied by intrinsic tunneling spectroscopy. Temperature, bias and magnetic field dependences of current-voltage characteristics are examined. In the main part of the thesis, the behavior of intrinsic Josephson junctions in magnetic fields B parallel to the copper-oxide planes is studied. Parallel magnetic fields penetrate the junctions in the form of Josephson vortices (fluxons). At high magnetic fields, fluxons are arranged in a regular lattice and are accelerated by a sufficient high transport current. As the fluxon lattice is moving through the mesa, it emits electromagnetic waves in the important THz frequency range. Properties of Bi-2212 mesas in this flux-flow regime are studied in this thesis. The following new observations were made during the course of this work: a crossover from thermal activation above Tc to quantum tunneling below Tc is seen in the interlayer transport-mechanism, the Fraunhofer pattern of Ic(B) is observed clearly in Bi-2212, superluminal electromagnetic cavity resonances and phonon-polaritons are observed in Bi-2212. It is argued that the employed technique for miniaturization of mesas and the obtained results can be useful for a better understanding of fundamental properties of high-temperature superconductors and for the realizations of coherent flux-flow oscillators and coherent phonon-polariton generators in the important THz frequency range. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Manuscript.