Resonance-Based microwave technique for body implant sensing

There is an increasing need for safe and simple techniques for sensing devices and prostheses implanted inside the human body. Microwave wireless inspection may be an appropriate technique for it. The implanted device may have specific characteristics that allow to distinguish it from its environment. A new sensing technique based on the principle of differential resonance is proposed and its basic parameters are discussed. This technique allows to use the implant as a signal scattering device and to detect changes produced in the implant based on the corresponding change in its scattering signature. The technique is first tested with a canonic human phantom and then applied to a real in vivo clinical experiment to detect coronary stents implanted in swine animalsPeer ReviewedPostprint (published version

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches

The modulated scattering technique is based on the use of reconfigurable electromagnetic scatterers, structures able to scatter and modulate an impinging electromagnetic field in function of a control signal. The modulated scattering technique is used in a wide range of frequencies up to millimeter waves for various applications, such as field mapping of circuits or antennas, radio-frequency identification devices and imaging applications. However, its implementation in the terahertz domain remains challenging. Here, we describe the design and experimental demonstration of the modulated scattering technique at terahertz frequencies. We characterize a modulated scatterer consisting in a bowtie antenna loaded with a vanadium dioxide switch, actuated using a continuous current. The modulated scatterer behavior is demonstrated using a time domain terahertz spectroscopy setup and shows significant signal strength well above 0.5 THz, which makes this device a promising candidate for the development of fast and energy-efficient THz communication devices and imaging systems. Moreover, our experiments allowed us to verify the operation of a single micro-meter sized VO2 switch at terahertz frequencies, thanks to the coupling provided by the antenna

Terahertz integrated antenna arrays for imaging applications

Terahertz is the portion of the spectrum that covers a frequency range between 300 GHz - 3 THz. This frequency band has proven its potential for imaging applications thanks to the good compromise between spatial resolution and penetration; however, this push towards high frequencies contains many technological difficulties in all the subsystems involved in the signal generation, transmission and detection. The power budget restrictions and high losses that sources and receivers currently suffer at these frequencies require systems with a high level of integration among all the devices and components of the systems and subsystems. Therefore, the antennas needed for these systems require to be integrated within the same fabrication processes and technologies as the sensing and power converting devices that are used at their terminals. This doctoral thesis has focused on the development of integrated antenna arrays at Terahertz frequencies for imaging applications, for both near-field and focal-plane geometries, with a special emphasis on the technologies and the fabrication capabilities that can be potentially used and are currently available. The current imaging systems require large arrays of antennas in order to achieve the high-speed image acquisition that is required in most THz applications. This fact increases considerably the difficulty and complexity to achieve highly integrated and efficient antennas. This thesis has characterized and analyzed these difficulties and provided solutions to the development of antenna arrays at millimeter and submillimeter wave frequencies. The first part of this thesis has focused on the study of a planar antenna array, called retina, for a specific near-field imaging system based on the Modulated Scatterer Technique (MST) at millimeter and submillimeter-wave frequencies. This system has been selected for its capabilities to perform high-speed imaging and because it does not require a high frequency distribution line network. However, it is hindered by many technological difficulties: the selection of an antenna geometry that achieves high efficiency, the selection of the adequate active element and its integration with the antenna. In this thesis, these challenges have been addressed and studied in-depth, and a design methodology that integrates all the different aspects of the system has been developed. Because planar antennas at millimeter and submillimeter wave frequencies suffer from high losses due to the surface wave modes inside substrate, these losses have been analyzed and quantified for different antennas, and an antenna geometry that reduces significantly this problem has been developed. Different switching technologies currently or potentially available at these high frequencies have been considered in order to study and analyze their capabilities and their integration possibilities: PIN diodes, Schottky diodes and RF-MEMS. These technologies have been studied through the development of three retina prototypes, which have been fabricated using high precision fabrication processes such as laser micromachining and photolithographic. Different measurement set ups were fabricated and assembled to validate the different premises presented. The second part of the thesis is devoted to the study of integrated Focal Plane Arrays (FPA). The development of FPA at submillimeter wave frequencies is highly on demand due to the enormous progress in designing integrated heterodyne receivers. These receivers integrate arrays of submillimeter-wave diode-based mixers and multipliers with Monolithically Integrated Circuit (MIC) amplifiers on the same wafer stack. For this stackable multi-pixel terahertz camera technology to work, a leaky wave antenna with silicon micro-lenses has been developed, which allows wafer level integration compatible with silicon micro-fabrication techniques for bulk array manufacturing and has high directivity in order to illuminate a reflector efficiently. Detailed and thorough design guidelines for this antenna are presented. Two antenna prototypes were built in order to evaluate the two fabrication possibilities: advanced laser micro-fabrication and photolithographic fabrication. A study of the aberrations of the lens has been developed in order to evaluate the performance of the lens profile fabricated. Moreover, a set of radiation pattern measurements of the fabricated prototypes was performed in order to evaluate the performance of the antenna and its possibilities to be used as a FPA

Conception et réalisation d'un nouveau capteur de gaz passif communicant à transduction RF

L'objectif de cette étude est de montrer la faisabilité d'un nouveau capteur de gaz a transduction RF, passif et sans fil. Ce nouveau capteur est composé de deux lignes coplanaires sur membrane et d'un résonateur diélectrique (RD). L'association de ces deux éléments permet de réaliser un filtre que nous excitons par une onde électromagnétique hyperfréquence en modes de galerie. Grâce à l'effet de " Relaxation Diélectrique ", nous pouvons détecter une variation de l'ambiance gazeuse par un décalage d'une fréquence de résonance du filtre. Les résultats de simulations électromagnétiques ont montré que la détermination de la fréquence de résonance d'un des modes de galerie permettait de détecter facilement la présence de gaz avec une grande sensibilité. Le développement de ce circuit simulé a été réalisé en deux étapes : la fabrication des lignes coplanaires sur membrane et l'élaboration du résonateur diélectrique à base d'un matériau sensible aux gaz. La réalisation d'un RD en TiO2 a été abordée en collaboration avec le CIRIMAT en utilisant la technique SPS (une voie prometteuse mais non encore maitrisée pour nos structures). Compte tenu des difficultés rencontrées, nous avons validé le concept du capteur en utilisant un résonateur en céramique (BaSmTiOxide) réalisé par Temex-Ceramics. L'assemblage des deux parties du capteur a permis d'obtenir les premiers dispositifs et de les caractériser sous différentes ambiances. Les résultats obtenus coïncident bien avec ceux de simulation ce qui valide le principe et la conception de ce nouveau capteur. Enfin, une dernière partie de l'étude est focalisée sur la communication sans fil de ce capteur passif à l'aide d'un RADAR FMCW.In this work, feasibility of gas sensors based on Titanium Dioxide (TiO2) dielectric resonator, operating with whispering-gallery modes, is presented. The gas or humidity adsorption modifies the TiO2 dielectric permittivity and such modification induces variation in the resonant frequencies of high-Q whispering-gallery modes in the millimeter-wave frequency range. Full-wave electromagnetic simulation demonstrates that the measurement of this variation allows the derivation of few parts-per-million (ppm) fluctuations in gas or humidity concentration. For validation purposes very first prototypes of resonator operating with whispering-gallery modes in the millimeter-wave frequency range are micro-machined. The measured performances confirm that such high-Q resonant modes are very sensitive to small variations in dielectric resonator permittivity. Moreover we validate experimentally that these small variations can be remotely detected from the RADAR interrogation of an antenna loaded by the whispering-gallery modes resonator

Conception d’antennes et méthode de caractérisation des systèmes RFID UHF en champ proche et en champ lointain

The Radiofrequency Identification technology (RFID) has had a huge growth these last years, due to its versatility and the uncountable possibilities to integrate this technology in many different application (tracking and inventory of goods, access control, supply chain, etc.), and in particular the brand new context of internet of things projects. For some years, the near field UHF RFID applications has been developed in order to overcome the problems related to degradations of tag's read range when needing to use it in a perturbing environment. The research work presented in this thesis come as a study of the UHF RFID in near field and far field zones. This study focus more particularly on the design of reader and tag antennas and on the characterization method in near field and far field zones. A study on the characteristics of fields outgoing from an antenna has been made, in order to underline the important criteria for the design of performant UHF RFID reader antennas in near field zone. From the state of art about tag antennas design and classical methodologies, we propose a new approach that aims improving the design of tag antennas in a more suitable point of view that is getting the expected power level in a given application. Finally, with an objective to characterize UHF RFID tags, we first propose a new approach enabling the identification of tag families, and then propose a new innovating power transfer efficiency measurement procedure, that has been validated experimentally.La technologie d'identification par radiofréquence (RFID) a eu un essor très important ces dernières années notamment grâce à sa configuration polyvalente et aux innombrables possibilités d'intégration offertes par cette technologie notamment avec l'apparition d'un nouveau contexte applicatif celui des objets connectés. Depuis quelques années, des applications de la RFID UHF en champ proche ont été notamment développées afin de surmonter les problèmes liés à la dégradation de lecture des tags lorsqu'ils sont placés dans des milieux fortement perturbateurs. Les travaux de recherche présentés dans cette thèse s'intéressent à l'étude de la technologie RFID UHF en zones de champ proche et de champ lointain. Les études portent plus particulièrement sur la conception d'antennes lecteur et d'antennes tag ainsi que sur les méthodes de caractérisation des systèmes RFID en zones de champ proche et de champ lointain. Une étude sur les caractéristiques des champs rayonnées par une antenne est réalisée afin de souligner les critères les plus pertinents en vue de concevoir des antennes pour les lecteurs RFID, performantes en zone de champ proche. A partir de l'état de l'art sur les antennes tags et les méthodologies de conception classiques, une nouvelle approche de conception est développée qui vise à améliorer la conception d'antennes tags en intégrant une vision appropriée pour tenir compte du niveau de puissance espéré dans une application donnée. Enfin avec pour objectif la caractérisation des tags RFID UHF, d'une part une approche est proposée permettant l'identification de familles de tags, et d'autre part, une procédure innovante pour la mesure de l'efficacité du transfert de puissance est proposée et validée expérimentalement

Reconfigurable electronics based on metal-insulator transition:steep-slope switches and high frequency functions enabled by Vanadium Dioxide

The vast majority of disruptive innovations in science and technology has been originated from the discovery of a new material or the way its properties have been exploited to create novel devices and systems. New advanced nanomaterials will have a lasting impact over the next decades, providing breakthroughs in all scientific domains addressing the main challenges faced by the world today, including energy efficiency, sustainability, climate and health. The electronics industry relied over the last decades on the miniaturization process based on the scaling laws of complementary metal-oxide semiconductors (CMOS). As this process is approaching fundamental limitations, new materials or physical principles must be exploited to replace or supplement CMOS technology. The aim of the work in this thesis is to propose the abrupt metal-insulator transition in functional oxides as a physical phenomenon enabling new classes of Beyond CMOS devices. In order to provide an experimental validation of the proposed designs, vanadium dioxide (VO2) has been selected among functional oxides exhibiting a metal-insulator transition, due to the possibility to operate at room temperature and the high contrast between the electrical properties of its two structural phases. A CMOS-compatible sputtering process for uniform large scale deposition of stoichiometric polycrystalline VO2 has been optimized, enabling high yield and low variability for the devices presented in the rest of the thesis. The high quality of the film has been confirmed by several electrical and structural characterization techniques. The first class of devices based on the MIT in VO2 presented in this work is the steep-slope electronic switch. A quantitative study of the slope of the electrically induced MIT (E-MIT) in 2-terminal VO2 switches is reported, including its dependence on temperature. Moreover, the switches present excellent ON-state conduction independently of temperature, suggesting MIT VO2 switches as promising candidates for steep-slope, highly conductive, temperature stable electronic switches. A novel design for the shape of the electrodes used in VO2 switches has been proposed, targeting a reduction in the actuation voltage necessary to induce the E-MIT. The electrothermal simulations addressing this effect have been validated by measurements. The potential of the MIT in VO2 for reconfigurable electronics in the microwave frequency range has been expressed by the design, fabrication and characterization of low-loss, highly reliable, broadband VO2 radio-frequency (RF) switches, novel VO2 tunable capacitors and RF tunable filters. The newly proposed tunable capacitors overcome the frequency limitations of conventional VO2 RF switches, enabling filters working at a higher frequency range than the current state-of-the-art. An alternative actuation method for the tunable capacitors has been proposed by integrating microheaters for local heating of the VO2 region, and the design tradeoffs have been discussed by coupled electrothermal and electromagnetic simulations. The last device presented in this work operates in the terahertz (THz) range; the MIT in VO2 has been exploited to demonstrate for the first time the operation of a modulated scatterer (MST) working at THz frequencies. The proposed MST is the first THz device whose working principle is based on the actuation of a single VO2 junction, in contrast to commonly employed VO2 metasurfaces

De la RFID à la MMID 60 GHz : contribution au développement de l'identification par onde radiofréquence en bande millimétrique

With the opening of the 57-66 GHz band in Europe, new high data-rate wireless communication technologies are currently under development. Numerous advantages linked to the frequency band conducted to consider the transposition of the radiofrequency identificaion (RFID) principle to the millimeter frequency band: the MMID. The international regulations provide a common bandwidth of 5 GHz allowing universal solutions. Moreover, the communication security of point-to-point networks and the directivities of the antennas present interesting perspectives.The presented work in this thesis looks for contributing to the development of MMID. The work underlines the principal locks of this technology and it presents the different proposed solutions covering multiple aspects: conception of antennas and antennas arrays, conception of MMID tags prototypes, characterization and measurement methodology including the complete conception of a measurement bench in V-band, improvement of the tags performances and study of sensing functionalities integrated in the tags. Different prototypes of MMID tags are fabricated and passive communications based on the backscattering of the tags were demonstrated up to 20 cm. In addition, humidity and pressure sensing functionalities were proved by experimentations. The overall of these results pave the way for new perspectives for the wireless communication domain and sensors networks in the millimeter-wave band.Avec l'ouverture de la bande 57-66 GHz en Europe, de nouvelles technologies de communication sans fil à haut débit sont en cours de développement. De nombreux avantages liés à cette bande de fréquence ont notamment conduit à envisager la transposition du principe de l'identification par radiofréquence (RFID) en bande millimétrique : la MMID. Les réglementations internationales font notamment apparaître une bande passante commune de 5 GHz qui permettrait la mise en place de solutions universelles. De plus la sécurisation des communications point-à-point et la directivité des réseaux d'antennes offrent des perspectives intéressantes.Les travaux présentés dans cette thèse visent à contribuer au développement de la MMID. Ils soulignent les principaux verrous de cette technologie et présentent les différentes solutions proposées qui couvrent de multiples aspects : conception d'antennes et de réseaux d'antennes, conception de prototypes de tags MMID passifs, caractérisation et méthodologie de mesure dont la conception intégrale d'un banc de mesure en bande V, amélioration des performances des tags, et étude de fonctionnalités de capteur intégrées aux tags. Les différents prototypes de tags MMID fabriqués ont permis de réaliser des communications passives de type rétro-modulation jusqu'à 20 cm. De plus, des fonctions de capteur d'humidité et capteur de pression intégrées aux tags MMID ont été montrées expérimentalement. L'ensemble de ces résultats ouvre la voie à de nouvelles perspectives pour les domaines des télécommunications et des réseaux de capteurs en bande millimétrique