The shape – morphing performance of magnetoactive soft materials

Magnetoactive soft materials (MSMs) are soft polymeric composites filled with magnetic particles that are an emerging class of smart and multifunctional materials with immense potentials to be used in various applications including but not limited to artificial muscles, soft robotics, controlled drug delivery, minimally invasive surgery, and metamaterials. Advantages of MSMs include remote contactless actuation with multiple actuation modes, high actuation strain and strain rate, self-sensing, and fast response etc. Having broad functional behaviours offered by the magnetic fillers embedded within non-magnetic matrices, MSMs are undoubtedly one of the most promising materials in applications where shape-morphing, dynamic locomotion, and reconfigurable structures are highly required. This review article provides a comprehensive picture of the MSMs focusing on the materials, manufacturing processes, programming and actuation techniques, behaviours, experimental characterisations, and device-related achievements with the current state-of-the-art and discusses future perspectives. Overall, this article not only provides a comprehensive overview of MSMs’ research and development but also functions as a systematic guideline towards the development of multifunctional, shape-morphing, and sophisticated magnetoactive devices

Light modulation of electric field driven semiconductor micromotors

The future micro/nanorobots require high degrees of freedom in motion control to perform complex tasks by individuals or by a swarm. It remains a great challenge to control the motions of an individual nanomachine amidst many, to switch the operation modes facilely, and it is even more difficult to actuate several components of a nanomachine coordinately for purposed actions. This high degree of versatility is essential for the future micro/nanorobots and requires investigation of innovative actuation mechanisms. In this dissertation, we report our recent finding about a new approach combining two types of stimulation to achieve such goal. The micromotors being studied are made of semiconductor silicon nanowires. Mechanical motion of the motors is driven by several types of AC electric field. Meanwhile, the electrical property of the nanowires can be locally and instantaneously modulated by visible light illumination in a reversible manner. We demonstrate that visible light is able to change the electric polarization of semiconductor nanowires under AC electric field, and reflected by the dramatic change of mechanical motions with very rich configurations. Under a rotating electric field, the rotation speed of semiconductor Si nanowires in electric fields can instantly increase, decrease, and even reverse the orientation by light illumination in the visible to infrared regime at various AC E-field frequencies. Under a linear AC electric field, instantaneous change of alignment direction and speed of semiconductor nanowires is observed under visible-light exposure. With theoretical analysis and simulation, the working principle can be attributed to the optically tuned imaginary-part (out-phase) and real-part (in-phase) electrical polarization of a semiconductor nanowire in aqueous suspension. Based on the understanding of this system, we further propose a new approach to control the semiconductor micromotor via light tunable dielectrophoresis. Localized control of collective behavior in a highly density silicon nanowire suspension is also investigated. Finally, we demonstrated how to utilize the mechanical motion at microscale for practical application of biosensing.Materials Science and Engineerin

Cancer Nanomedicine

This special issue brings together cutting edge research and insightful commentary on the currentl state of the Cancer Nanomedicine field

Plateforme pour le guidage de dispositifs thérapeutiques sub-millimétriques par IRM

RÉSUMÉ L'utilisation des micro-robots en chirurgie minimalement invasive est un domaine de recherche très actif, et au potentiel très important. Il s'agit de doter les équipes médicales d'outils techniques leur permettant de surpasser les problèmes auxquels elles font face : traitement invasif, zones inaccessibles, infections nosocomiales, etc. Les micro-robots ont en effet le potentiel de pouvoir atteindre des endroits jusqu'ici inaccessibles par les chirurgiens tout en étant introduits dans le corps par une opération minime présentant de faibles risques. Ils peuvent être fonctionnalisés pour remplir une multitude de tâches : administration de médicament, prélèvement de cellules malades, pose de stent, ablation, etc. Miniaturiser un tel dispositif et lui fournir l'énergie nécessaire à son fonctionnement est un défi majeur. Nous proposons l'utilisation de forces magnétiques pour y répondre, la force peut ainsi être générée et contrôlée depuis l'extérieur du micro-robot. Notre méthode se base sur l'utilisation d'un scanner d'imagerie par résonance magnétique (IRM). Les scanners d'IRM sont des outils répandus dans les hôpitaux qui ont la particularité d'être composés d'un puissant champ magnétique permanent et de bobines de gradients magnétiques tridimensionnelles capable de moduler ce champ très rapidement et très précisément. Ces gradients peuvent générer la force dont nous avons besoin pour déplacer notre dispositif thérapeutique. Cette approche a été validée par des travaux de recherche précédents et nous souhaitons continuer à réduire la taille des micro-robots navigués. Cela entraîne un besoin de force magnétique supplémentaire qui se heurte aux capacités de l'IRM. Nous proposons alors de lui adjoindre du matériel capable d'engendrer une force magnétique 20 fois supérieure. Nous avons également besoin de connaître précisément l'emplacement du dispositif dans le système vasculaire pour mener à bien la navigation. Cette étape de localisation peut également être réalisée par une utilisation détournée du scanner d'IRM. Il se forme en effet une distorsion du champ magnétique lorsque l'on insère un élément métallique dans un IRM, nous pouvons exploiter ce phénomène pour isoler l'origine de la perturbation. L'IRM nous fournit donc à la fois un capteur et un actionneur. Le rôle du contrôleur pourra quant à lui être rempli par le personnel médical qui guidera le dispositif pour aux endroits appropriés. Le présent mémoire de maîtrise porte sur la mise en place d'une telle plateforme à l'École Polytechnique de Montréal. Nous proposons d'étudier le cas de la navigation d'un cathéter muni d'une bille métallique de 0.9 mm de diamètre. Pour parvenir à le naviguer magnétiquement, nous implémentons la technique de localisation présentée plus haut dans l'IRM du laboratoire de Nanorobotique. La mise en œuvre de cette technique est alors testée et validée pour le positionnement d'un cathéter (précision et linéarité du positionnement, influence des paramètres). Nous réalisons également la prise en main du nouveau système de génération de gradients magnétiques pour la propulsion. Ce matériel prototype est testé en profondeur afin de déterminer son adéquation à nos besoin et la façon d'en tirer partie au mieux. Nos expériences montrent que le matériel est adapté à des procédures de cathéters ou de fils-guides, mais qu'il présente des lacunes compromettant son utilisation pour la navigation en boucle fermée de dispositifs micrométriques. Nous réalisons enfin un ensemble de logiciels destinés à former une structure cohérente, mettant en relation nos capacités de localisation et de propulsion, au service de l'équipe médicale. Un serveur temps-réel est conçu pour prendre le contrôle du système de propulsion. Nous lui adjoignons une interface graphique cliente qui communique avec lui par réseau. Le système informatique est testé et amélioré au fur et à mesure des souhaits émis par les utilisateurs afin de parvenir à une plateforme conviviale et efficace. De nombreux tests en conditions in-vitro sont réalisés au cours de ce travail de maîtrise, tous les composants de la plateforme sont caractérisés et validés. Le projet de guidage magnétique prend tout son sens avec la réalisation d'expérimentation in-vivo, où nous parvenons à guider un fil-guide muni d'un embout magnétique de 0.9 mm de diamètre dans le système vasculaire de lapins vivants.---------ABSTRACT The use of microrobots in minimally invasive surgery is a very active research field where potential applications are numerous. The goal is to provide medical teams with technical tools in order to help them overcoming some of their current issues : invasive treatments, inaccessible areas, nosocomial infections, etc. Microrobots have indeed the potential to reach areas previously inaccessible by surgeons while being introduced into the body with a small incision with reduced risk. They can be functionalized to perform many kind of tasks: drug delivery, biopsy, stent deployment, ablation, etc. Reducing the size of such a device while providing the energy necessary for its operation is a major challenge. We propose the use of magnetic forces to this purpose, the force can be generated and controlled from outside the microrobot. Our method takes advantage of a magnetic resonance imaging scanner (MRI). MRI scanners are medical imaging tools widely used in hospitals. They have the key characteristic of being composed of a powerful permanent magnetic field and three-dimensional magnetic gradient coils which can apply variations on the main field very quickly and precisely. These gradients are able to generate the force we need to move a therapeutic device as it has been validated by previous research. We are looking to reduce the size of the navigated devices. This causes a need for additional magnetic force that conflicts with the capabilities of MRI. We propose to enhance the MRI with equipment capable of generating a magnetic force 20 times higher. Efficient navigation also needs the precise location of the device in the vascular system. This tracking part can also be performed by an alternate use of the MRI scanner. We take advantage of the magnetic field distortion caused by the ferromagnetic element to isolate the source of the phenomenon. With these two possibilities, the MRI provides us with both a sensor and an actuator. In the end, the role of the controller can be played by the medical team who will guide the device into the vessel network. This master's thesis focuses on the making of such a platform at École Polytechnique de Montréal. We propose to study the case of the catheter navigation with a 0.9 mm diameter metal tip. To achieve magnetic navigation, we implement the localization technique presented earlier in the MRI of the Nanorobotics Laboratory. The implementation of this technique is then tested and validated for the positioning of a catheter (positioning accuracy and linearity, influence of parameters). We also learn to use the new magnetic gradient equipment intended for propulsion. This prototype is tested to determine its suitability for our needs and how to take advantage of it. Our experiments show that the propulsion system may be used with catheter navigation procedures, however we identified issues that prevent it from running closed loop controlled particles steering procedures. We finally design and implement a set of software to assemble our tracking and propulsion system in a coherent platform to be used by a medical team. A real-time server is designed to take control of the propulsion system. We design a GUI client that communicates with him through network. The infrastructure is tested and improved with the feedback expressed by users in order to achieve an effective and user-friendly platform. Numerous tests in in-vitro conditions are achieved during this study, all platform components are characterized and validated. The proposed magnetic navigation procedure is brought to completion with in-vivo experiments where we navigate a guidewire with a 0.9 mm magnetic tip in the vasculature of live rabbits

Fabricación de medios fotónicos para el control de la emisión y transporte de luz

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de lectura: 15-07-2015This thesis is devoted to the development of advanced photonic materials and their potential implementation in multifunctional systems. It reports the fabrication and characterization of two dimensional photonic crystals, specifically inverse monolayers of silica. A fabrication protocol introducing some novelties is presented, which allows to grow composite monolayers in a one step method and porous membranes, by sacrificing one of the components. This work is partially extended in an attempt towards the fabrication of porous membranes of silicon. The growth of three dimensional photonic crystals by self-assembly methods is discussed. Composite opals are grown by vertical deposition and coassembly techniques and several doping strategies with Rare Earth elements are tested. The aim of this work is to search for photonic effects, in the infrared region of trivalent erbium photoluminescence, induced by the presence of a pseudogap in silica inverse opals or by a full photonic bandgap in silicon ones. We further describe a replica molding procedure, adequate to imprint two dimensional gratings in the surface of shape memory polymers, by using self-assembled colloidal monolayers as templates. The obtained crystals are characterized with different techniques to assess their structural and optical properties. Their applicability in new multifunctional photonic devices with programmable and self-healing capabilities is ascertained. The possibility of using shape memory polymers to fabricate new nanocomposites containing titania nanoparticles that may perform as functional photonic white paints is additionally explored. Furthermore, their potential use as shape programmable active media is verified by doping them with organic dyes. Systematic photoluminescence studies are performed

Cyber-Human Systems, Space Technologies, and Threats

CYBER-HUMAN SYSTEMS, SPACE TECHNOLOGIES, AND THREATS is our eighth textbook in a series covering the world of UASs / CUAS/ UUVs / SPACE. Other textbooks in our series are Space Systems Emerging Technologies and Operations; Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD); Disruptive Technologies with applications in Airline, Marine, Defense Industries; Unmanned Vehicle Systems & Operations On Air, Sea, Land; Counter Unmanned Aircraft Systems Technologies and Operations; Unmanned Aircraft Systems in the Cyber Domain: Protecting USA’s Advanced Air Assets, 2nd edition; and Unmanned Aircraft Systems (UAS) in the Cyber Domain Protecting USA’s Advanced Air Assets, 1st edition. Our previous seven titles have received considerable global recognition in the field. (Nichols & Carter, 2022) (Nichols, et al., 2021) (Nichols R. K., et al., 2020) (Nichols R. , et al., 2020) (Nichols R. , et al., 2019) (Nichols R. K., 2018) (Nichols R. K., et al., 2022)https://newprairiepress.org/ebooks/1052/thumbnail.jp

Interfacial phenomena between bacterial or mammalian cells and orthopaedic biomaterials

Adhesion as a scientific phenomenon has been researched for the past 70 years, as the notion of two entities contacting effects a huge expanse of daily activities, from writing to sophisticated cellular and bacterial interactions essential for growth and survival. Inherently, a robust and adequate model of adhesion was acquired, one in which biological aspects were considered. Initially, the methodology required was optimised using the atomic force microscope (AFM) by testing a model bone substrate against ultra-high molecular weight polyethylene (UHMWPE), a material commonly found in the articulating acetabular cup. Once a force mapping technique was established experimentation continued to bacterial adhesion against model bone samples of various roughness, establishing that the adhesion phenomena occurs at a scale dependency due to the alterations in the topography of the surface at the micro to nano level. Aseptic loosening and osteolysis are major causes of failures in implanted biomedical devices at the hip. These issues are governed by the deterioration of the moving components, producing particles known as wear debris associated with the metals, bone cement, and UHMWPE materials initiating an immune response which is detrimental to the surrounding cells and tissues adjacent to the implant. The notion of mechanical aspects altering the health of mammalian cells has been ignored throughout the research of implantations and their effect on the cells by foreign bodies; the only concept studied to date is the viability and functionality post exposure. Therefore, this thesis aims at observing ii mesenchymal and osteoblast (both rodent and human) cells associated to wear debris (metal and polymeric particles of various sizes and compositions) exposure and the effect this has on cell nanomechanical and adhesive properties using the AFM techniques. The data obtained indicated that Cobalt nanoparticles were more damaging on all cell types than Titanium and polymeric particles