Computer-assisted diagnosis of wireless-capsule endoscopic images using neural network based techniques

Computerised processing of medical images can ease the search of the representative features in the images. The endoscopic images possess rich information expressed by texture. In this paper schemes have been developed to extract texture features from the texture spectra in the chromatic and achromatic domains for a selected region of interest from each colour component histogram of images acquired by the new M2A Swallowable Capsule. The implementation of advanced learning-based schemes and the concept of fusion of multiple classifiers have been also adopted in this paper. The preliminary test results support the feasibility of the proposed methodology

Design and fabrication of a microsystem to handle biological objects

Biological particle microhandling is a common operation in medicine and microbiology, and a lot of research work has been addressed to develop faster, cheaper and more efficient manipulation techniques. In this way, microsystem technologies play an important role because they can be used to fabricate microparticle manipulators. This paper describes the design and fabrication of a microsystem to handle biological objects, based on the dielectrophoretic effects. The development of the right technological option among the possibilities at disposal is also discussed. The proposed design, a whole microsystem including electrical, optical and fluidic interfaces, was developed employing gold and platinum metals, silicon micromachining, and photoresin patterning techniques. Furthermore, the structure of the utilized microelectrode arrays, as well as the resulting microchip are also reported

Diseño y fabricacion de un microsistema para la manipulacion de objetos biologicos

La micromanipulación de partículas biológicas es una operación frecuente en medicina y microbiología, y se ha dedicado una gran cantidad de trabajo para desarrollar técnicas de manipulación mas rápidas, baratas y eficientes. En este sentido, la tecnología de microsistemas juega un papel importante ya que se puede utilizar para fabricar manipuladores de micropartículas. En este artículo se describe el diseño y fabricación de un microsistema para la manipulación de objetos biológicos, basado en el efecto dielectroforetico. También se discute la selección de la alternativa tecnológica mas adecuada dentro de las disponibles. El diseño propuesto, es un microsistema completo que incluye interfases eléctrica, óptica y fluidica, y se desarrolló empleando oro y platino como metales para los electrodos, micro mecanizado del silicio y técnicas de fotocurado de resinas fotosensibles. De la misma forma se describe la estructura de los microelectrodos desarrollados al igual que el circuito integrado resultante

Investigation and Integration of Piezoresistive Silicon Nanowires for MEMS applications

Ph.DDOCTOR OF PHILOSOPH

Contribution au développement d'actionneurs électroactifs pour l'assistance circulatoire - Application à la mise au point d'une fonction antithrombotique

Cette étude se place dans le cadre d'une collaboration entre le Groupe de Recherche en Electrodynamique de l'INPT/ENSEEIHT/CNRS et le Service de Chirurgie Thoracique et Cardiovasculaire de l'APHP Pitié-Salpêtrière de Paris. L'objectif de ce travail est d'envisager l'apport des nouveaux matériaux électroactifs dans les dispositifs d'assistance circulatoire. Ces systèmes ont pour rôle de remplacer temporairement la fonction de pompe jouée par le coeur (coeur artificiel et système de circulation extracorporelle). Dans ces conditions, le sang est confronté à deux problèmes favorisant la formation de caillots (thrombose) : contact avec des surfaces artificielles et perturbation de son écoulement. L'étude proposée envisage la possibilité de réaliser une fonction antithrombotique avec un actionneur électroactif. La première partie est consacrée à la définition des principaux matériaux actifs. Quelques applications présentes dans le domaine médical sont aussi décrites. La deuxième étape consiste à déterminer, par simulations fluidiques, les zones privilégiées pour la formation de caillots dans une géométrie de type divergente (raccord en Y) en tenant compte des propriétés non newtoniennes du sang. De plus, une étude représentant l'agrégation de plaquettes sanguines est réalisée en utilisant de fines particules de fer immobilisées avec un aimant dans la divergence étudiée, dans lequel circule un fluide. Ainsi, l'influence de déformations pariétales sur le décollement d'une particule a pu être modélisée. A partir des données accumulées dans le chapitre précédent, des actionneurs constitués de céramiques multicouches piézoélectriques sont dimensionnés et caractérisés (fréquence de résonance et déformation créée sur le raccord). Enfin, un circuit permettant de reproduire la formation de caillots dans le raccord en Y, basé sur un modèle de circulation extracorporelle, a été réalisé. En intégrant les actionneurs dans ce modèle, le décollement des particules par vibrations pariétales a pu être vérifié expérimentalement. De plus, une étude a permis de déterminer l'influence des vibrations sur les temps de formation des caillots dans le raccord, ouvrant la voie à la mise au point d'une fonction antithrombotique. ABSTRACT : This study is placed within the framework of collaboration between the Electrodynamics Research Group of the INPT/ENSEEIHT/CNRS and the Thoracic and Cardiovascular Surgery Service of the APHP Pitié-Salpêtrière of Paris. The objective of this work is to consider the contribution of new electroactive materials in the devices of mechanical circulatory support. These systems replace temporarily the pump function played by the heart (artificial heart and device of extracorporeal circulation). Under these conditions, blood is confronted with two problems supporting the clot formations (thrombosis) : contact with artificial surfaces and disturbance of its flow. The study suggested considers the possibility of fulfilling an antithrombotic function with an electroactive actuator. The first part is devoted to the definition of principal active materials. Some applications present in the medical field are also described. The second stage consists in determining, by fluidic simulations, the zones privileged for the clot formations in a divergent type geometry (Y-shaped connection) by taking into account the non newtonian blood properties. Moreover, a study representing the blood platelet aggregations is carried out by using fine iron particles immobilized with a magnet in the studied divergence, in which a fluid circulates. Thus, the influence of parietal deformations on the separation of a particle could be modelled. From the data accumulated in the preceding chapter, actuators made up of piezoelectric multi-layer ceramics are dimensioned and characterized (resonance frequency and deformation created on the Y-shaped connector). Finally, a circuit allowing to reproduce the clot formations in the Y-shaped connector, based on a model of extracorporeal circulation, was carried out. By integrating the actuators in this model, the separation of the particles by parietal vibrations could be check in experiments. Moreover, a study made it possible to determine the influence of the vibrations on the clot formation times in the connection, opening the way to the development of an antithrombotic function

Formulation faible, formulation forte et méthodes de calcul numérique du champ magnétique en vue de la modélisation d'une prothèse innovante pour l'assistance circulatoire

L'objectif de ce travail est d'améliorer les méthodes numériques de calcul de champ magnétique en vue de l'estimation de la répartition des forces magnétiques dans les actionneurs, notamment ceux conçus sur de nouveaux concepts à base de matériaux magnétoactifs. Cette étude se place dans le cadre d'une collaboration entre le groupe de recherche en Electrodynamique du laboratoire LAPLACE et le service de chirurgie Cardiovasculaire et Thoracique de l'AP-HP Pitié-Salpêtrière de Paris. En effet, au cours de ces dernières décennies de nombreux progrès ont été réalisés dans le domaine de l'assistance circulatoire. Toutefois, l'implantation permanente de ces nouveaux systèmes se heurte encore à de nombreuses barrières : encombrement, difficulté et lourdeur de l'implantation, fiabilité, systèmes non physiologiques n'assurant que des débits continus, efficacité insuffisante. Ainsi, de nouveaux concepts de pompes sont aujourd'hui à l'étude, en vue d'assurer un débit pulsé physiologique à l'aide d'un système totalement implantable. L'approche privilégiée dans notre étude est basée sur le "morphing" électroactif d'un corps déformable rempli de fluide magnétorhéologique, dont le déplacement et la conformation spatiale sont contrôlés, par l'intermédiaire du champ magnétique, par des bobines externes. Des simulations par éléments finis ont été réalisées pour montrer la faisabilité des principaux concepts et ont permis le dimensionnement d'un premier démonstrateur. Lors de ces simulations numériques réalisées avec ANSYS Multiphysics, nous avons eu besoin de connaître très précisément la répartition du champ magnétique sur le corps déformable pour calculer la distribution des forces s'y exerçant et ainsi, déterminer sa déformation. Une analyse approfondie des résultats de calcul a mis en évidence une discontinuité importante de la composante tangentielle du champ d'excitation magnétique au niveau de l'interface de deux matériaux de perméabilité différente. Bien que constituant une limite bien connue de la formulation faible utilisée couramment pour le calcul par éléments finis du champ magnétique, la discontinuité de cette composante n'a pas été étudiée de manière systématique jusqu'à présent. Or, dans la plupart des méthodes de calcul de force magnétique, l'expression de la densité de force s'exerçant à la surface du corps polarisé fait intervenir cette composante et la discontinuité constatée peut entraîner des erreurs importantes. ABSTRACT : This thesis focuses on the improvement of numerical methods to compute the magnetic field in order to estimate the distribution of magnetic forces in actuators, including those designed on innovative concepts based on the use of magnetoactive materials. Thus, in the field of mechanical circulatory support, new implantable cardiac prosthesis are under consideration to ensure a pulsating flow. Here, the approach is based on the electroactive "morphing" of a deformable body, so the displacement and the deformation can be modified at distance. The repartition of magnetic field around the deformable body must be precisely known to compute the repartition of forces and to determine its deformation. An analysis of the results obtained from finite element method, highlighted a discontinuity of the tangential component of magnetic field excitation at the interface of two materials of different magnetic permeability. To understand this problem due to the use of a weak formulation, a precise study was led in order to analyze this discontinuity and its influence on the calculation of the magnetic force density. To overcome this problem, the proposed solution is to develop a code using a strong formulation. A comparative study between the two formulations and experimental value has been completed to show the superiority of the strong formulation. The solution is a valuable tool to initiate the optimization studies of the new concept of prosthesis presented at the beginning of the thesis

Integrated packaging solutions and hotplates for a miniature atomic clock and other microsystems

This thesis aimed at developing innovative packaging solutions for a miniature atomic clock and other microsystems in the cm-scale, i.e. somewhat larger than what is practical for full "chip-scale" device-package integration using clean-room technologies for fabrication of microelectromechanical systems (MEMS). Besides well-defined and robust mechanical attachment, such packaging solutions must provide reliable electrical interconnection with the other system components, and, if needed, additional functions such as local temperature control, insulation from electrical magnetic or temperature perturbations, chemical separation (hermeticity). In order to accomplish this objective, different packaging technologies and modules were developed, fabricated and characterized in the frame of this thesis, with particular emphasis on the packaging of a miniature double-resonance (DR) rubidium atomic clock, which is an ideal demonstration platform given the associated large variety of requirements. First, the possibility of encapsulating the reactive Rb metal in ceramic / glass substrates using soldering was explored, with the aim to achieve simple and reliable fabrication of miniature atomic clock elements such as the reference cell and the Rb lamp. After a thorough literature review investigation of the metallurgical interactions between rubidium and materials used in packaging such as solder (Sn, Pb, Bi..) and thick-film metallizations metals (Ag, Pd, Au, 2 Pt...), an innovative design for a Rb reference cell (dimensions 10 × 12 mm ) is presented. The cell is based on a multifunctional low-temperature cofired ceramic (LTCC) spacer, closed by two glass windows allowing light transmission and acting as lids. Bonding is achieved by low-temperature soldering, avoiding exposing Rb to high temperatures. The use of LTCC as the main substrate material for Rb vapor cells in principle allows further integration of necessary functions for the Rb lamp and reference cell, such as temperature regulation, excitation / microwave resonator electrodes, impedance-matching passive components (lamp), and coil for static magnetic field generation (reference). In this work, to test the hermeticity of the bonding, a pressure sensor was integrated into the cell by replacing one of the glass windows by a membrane comprising an integrated piezoresistive Wheatstone bridge. In this frame, a new lamination technique for LTCC is proposed. The technique consists in applying a hot-melt adhesive on top of the LTCC green tape, and allows good bonding of the tapes even at low lamination pressure. This technique is particularly attractive for the lamination of LTCC microfluidic devices or membrane pressure sensors, because the low pressure applied during lamination does not affect the shape of the channels in a microfluidic device, or the membrane of the sensor. The resulting cells are shown to be hermetic, and a Rb response could be measured by the project partners. However, heating resulted in loss of this response, indicating Rb depletion by undesired reactions between Rb and the sealing metals or contaminants. This result is somewhat in line with studies made in parallel with the present work on low-temperature indium thermocompression bonding. Therefore, although the results are promising, further optimisation of metallizations, solders and package design is required. An important generic function that may be integrated into LTCC is temperature control. In this frame, a multifunctional LTCC hotplate was designed, fabricated and studied. This device allows controlling the temperature of any object in the cm-scale, such as the abovementioned Rb vapor cells (reference or lamp) and other temperature-sensitive elements used in miniature atomic clocks such as lasers and impedance-matching passive components. Full thermal analysis, mathematical calculations, finite-element simulations and laboratory experiments were performed. The excellent structurability and modest thermal conductivity of LTCC make it much better suited than standard alumina for integrated hotplates, resulting in conduction losses in the LTCC structure being small compared to surface losses by conduction and convection. It is therefore concluded that insulation and/or vacuum packaging techniques are necessary to achieve optimized low-power operation. Although we have seen that LTCC is an excellent integrated packaging platform, there are some limitations for carrying relatively massive components such as the DR atomic clock resonator cavity structure, which in general is a solid metal part. Therefore, an alternative hotplate technology platform, was developed, based on the combination of standard fiberglass-reinforced organic-matrix printed-circuit board (PCB), combined with thick-film alumina heaters. The PCB acts as high-strength, low-cost and readily available mechanical carrier, electrical interconnect and thermal insulator, and the thick-film heaters provide local temperature regulation, with the high thermal conductivity of alumina ensuring good local temperature uniformity. Therefore, such a hybrid PCB-Al2O3 platform constitutes an attractive alternative to LTCC hotplates for benign operating conditions. In conclusion, this work introduced several innovative packaging solutions and techniques, which were successfully applied to various dedicated modules carrying the elements of miniature atomic clocks. Beyond this application, these developments allow us to envision efficient packaging of a wide variety of new miniature devices. Also, new areas for further investigations are suggested, such as long-term metallurgical interactions of alkali metals with solders, hermeticity, optimization of temperature distribution and thermal insulation techniques, as well as reliability at high-temperatures and under severe thermal cycling.This thesis aimed at developing innovative packaging solutions for a miniature atomic clock and other microsystems in the cm-scale, i.e. somewhat larger than what is practical for full "chip-scale" device-package integration using clean-room technologies for fabrication of microelectromechanical systems (MEMS). Besides well-defined and robust mechanical attachment, such packaging solutions must provide reliable electrical interconnection with the other system components, and, if needed, additional functions such as local temperature control, insulation from electrical magnetic or temperature perturbations, chemical separation (hermeticity). In order to accomplish this objective, different packaging technologies and modules were developed, fabricated and characterized in the frame of this thesis, with particular emphasis on the packaging of a miniature double-resonance (DR) rubidium atomic clock, which is an ideal demonstration platform given the associated large variety of requirements. First, the possibility of encapsulating the reactive Rb metal in ceramic / glass substrates using soldering was explored, with the aim to achieve simple and reliable fabrication of miniature atomic clock elements such as the reference cell and the Rb lamp. After a thorough literature review investigation of the metallurgical interactions between rubidium and materials used in packaging such as solder (Sn, Pb, Bi..) and thick-film metallizations metals (Ag, Pd, Au, 2 Pt...), an innovative design for a Rb reference cell (dimensions 10 × 12 mm ) is presented. The cell is based on a multifunctional low-temperature cofired ceramic (LTCC) spacer, closed by two glass windows allowing light transmission and acting as lids. Bonding is achieved by low-temperature soldering, avoiding exposing Rb to high temperatures. The use of LTCC as the main substrate material for Rb vapor cells in principle allows further integration of necessary functions for the Rb lamp and reference cell, such as temperature regulation, excitation / microwave resonator electrodes, impedance-matching passive components (lamp), and coil for static magnetic field generation (reference). In this work, to test the hermeticity of the bonding, a pressure sensor was integrated into the cell by replacing one of the glass windows by a membrane comprising an integrated piezoresistive Wheatstone bridge. In this frame, a new lamination technique for LTCC is proposed. The technique consists in applying a hot-melt adhesive on top of the LTCC green tape, and allows good bonding of the tapes even at low lamination pressure. This technique is particularly attractive for the lamination of LTCC microfluidic devices or membrane pressure sensors, because the low pressure applied during lamination does not affect the shape of the channels in a microfluidic device, or the membrane of the sensor. The resulting cells are shown to be hermetic, and a Rb response could be measured by the project partners. However, heating resulted in loss of this response, indicating Rb depletion by undesired reactions between Rb and the sealing metals or contaminants. This result is somewhat in line with studies made in parallel with the present work on low-temperature indium thermocompression bonding. Therefore, although the results are promising, further optimisation of metallizations, solders and package design is required. An important generic function that may be integrated into LTCC is temperature control. In this frame, a multifunctional LTCC hotplate was designed, fabricated and studied. This device allows controlling the temperature of any object in the cm-scale, such as the abovementioned Rb vapor cells (reference or lamp) and other temperature-sensitive elements used in miniature atomic clocks such as lasers and impedance-matching passive components. Full thermal analysis, mathematical calculations, finite-element simulations and laboratory experiments were performed. The excellent structurability and modest thermal conductivity of LTCC make it much better suited than standard alumina for integrated hotplates, resulting in conduction losses in the LTCC structure being small compared to surface losses by conduction and convection. It is therefore concluded that insulation and/or vacuum packaging techniques are necessary to achieve optimized low-power operation. Although we have seen that LTCC is an excellent integrated packaging platform, there are some limitations for carrying relatively massive components such as the DR atomic clock resonator cavity structure, which in general is a solid metal part. Therefore, an alternative hotplate technology platform, was developed, based on the combination of standard fiberglass-reinforced organic-matrix printed-circuit board (PCB), combined with thick-film alumina heaters. The PCB acts as high-strength, low-cost and readily available mechanical carrier, electrical interconnect and thermal insulator, and the thick-film heaters provide local temperature regulation, with the high thermal conductivity of alumina ensuring good local temperature uniformity. Therefore, such a hybrid PCB-Al2O3 platform constitutes an attractive alternative to LTCC hotplates for benign operating conditions. In conclusion, this work introduced several innovative packaging solutions and techniques, which were successfully applied to various dedicated modules carrying the elements of miniature atomic clocks. Beyond this application, these developments allow us to envision efficient packaging of a wide variety of new miniature devices. Also, new areas for further investigations are suggested, such as long-term metallurgical interactions of alkali metals with solders, hermeticity, optimization of temperature distribution and thermal insulation techniques, as well as reliability at high-temperatures and under severe thermal cycling