Ce mémoire présente la conception d'un mini robot d'interaction rétroentraînable translationnel à trois degrés de liberté pour des tâches de finition de pièces métalliques, telles que le polissage et l'ébavurage. Le mini robot sert de tête de compliance, permettant l'adaptation d'un robot industriel à une pièce. Les propriétés physiques du mini robot permettent l'implantation d'un algorithme de commande en impédance lors de l'utilisation du système. La faible masse du mécanisme permet de l'installer à l'effecteur d'un robot industriel, formant ainsi un système de type macro-mini. Malgré la faible taille du mini robot, il peut exercer les forces de contact nécessaires pour effectuer des tâches de finition. Premièrement, un prototype d'un robot translationnel plan à deux degrés de liberté est préalablement conçu. Un algorithme de commande en impédance est développé et est ensuite testé conjointement avec le prototype afin de vérifier ses performances pour une tâche prédéfinie. Ensuite, un prototype du mini robot à trois degrés de liberté est conçu. Différentes architectures de robots translationnels à trois degrés de liberté sont comparées ; l'architecture la plus appropriée pour le projet est sélectionnée. Des paramètres géométriques sont sélectionnés pour le robot. Les capacités physiques de l'architecture sont prédites afin de s'assurer de respecter tous les critères de conception. Par après, l'algorithme de commande en impédance est adapté au mini robot. Celui-ci est installé sur un robot portique afin de former le système macro-mini. Des tests de sablage sont effectués afin de valider le fonctionnement du système et permettent d'identifier différentes problématiques du système. L'architecture du mini robot est modifiée afin de diminuer l'effet de ces problématiques. De nouveaux tests sont effectués afin de valider l'amélioration des performances du système avec cette nouvelle version du mini robot. Des recommandations sont formulées quant au concept de la tête de compliance et les limites d'utilisation de celle-ci sont établies. Le mini robot est comparé aux têtes de compliance actuellement sur le marché. Finalement, une méthode permettant d'évaluer l'amplitude des forces de friction du mécanisme est présentée. Une première ébauche d'un algorithme de compensation de la friction est aussi développée. / This Master's thesis presents the design process of a backdrivable three-degree-of-freedom translational mini robot used to control the interaction with a metallic part during finishing tasks, such as polishing and deburring. The mini robot acts as an active contact flange, allowing an industrial robot to adapt to a part. The physical properties of the mini robot make it possible to implement an impedance control algorithm when using the system. The low mass of the mechanism allows it to be installed at the end-effector of an industrial robot, forming a macro-mini system. Despite the small size of the mini robot, it can apply the necessary contact forces to accomplish the finishing tasks. Firstly, a prototype of a two-degree-of-freedom planar translational robot is first conceived. An impedance control algorithm is developed and is then tested using the planar robot to evaluate its performance when accomplishing a predefined task. Then, a prototype of the mini robot is designed. Different three-degree-of-freedom robot architectures are compared; the most suitable architecture for the project is selected. Geometrical properties are initially chosen for the robot. The physical capabilities of the architecture are predicted to ensure that the design criteria are satisfied. The impedance control algorithm is then adapted to the mini robot. The macro-mini system is formed by installing the mini robot on a gantry robot. Sanding tests are carried out in order to validate the performance of the system. The results of the tests reveal a few issues with the robotic system. The architecture of the mini robot is therefore modified in order to mitigate the impact of the issues previously identified. New tests are carried out with the intention of validating the improvement of this new version of the mini robot's performance. The results of the second series of tests are used to make recommendations about the contact flange's design and usage limitations are established. The mini robot is compared to other contact flanges already available on the market. Finally, a method allowing the determination of the magnitude of the mechanism's friction forces is presented. A first draft of a friction compensation algorithm is developed.

<p>Microrobots have a promising prospect to be used in healthcare and bioengineering applications due to their capability to gently access small and delicate body sites. Unfortunately, traditional materials used for the fabrication of microrobots are rigid, hindering safe operation due to the transfer of high stresses to the surrounding tissue. Additionally, traditional microrobots are often not biocompatible, which threatens the health of the patient if not properly retrieved. This dissertation describes the fabrication and actuation of small-scale (several micrometers in all dimensions) magnetic robots that are soft, biocompatible, and capable of moving over smooth and corrugated surface. <u>S</u>oft <u>M</u>agnetic <u>M</u>icro <u>R</u>obots (SMµRs) can carry payloads in their porous interior and release them using external magnetic inputs. SMµRs has therefore the potential to be used in a wide range of applications—including targeted drug release and remote biosensing and bio sampling—and access a number of difficult-to-reach sites in the human body, such as intestines or blood vessels. The structure of SMµRs consist of three thin layers: Two layers of polymer with embedded magnetic particles aligned along a preferential direction. One porous layer, in between the magnetic layers, where the SMµRs can accumulate and release payloads. SMµRs are small, light in weight, and fast and inexpensive to fabricate. Moreover, the manufacturing of SMµRs is compatible with large-scale production processes, facilitating their future commercial exploitation. Using external rotating magnetic fields, the position of the SMµRs can be controlled wirelessly <i>via</i> tumbling locomotion. We demonstrate two types of tumbling locomotion (length-wise and side-wise) as well as the possibility to release the internal payload of the SMµRs in a discrete or continuous manner using only changes in the intensity of the external magnetic field. We studied the performance of SMµRs under a variety of environmental conditions as well as their capability of overcoming obstacles.</p>

By combining new robot control systems with piezoelectric motors and micromechanics, we propose creating micromechanical systems which are small, cheap and completely autonomous. We have fabricated small - a few millimeters in diameter - piezoelectric motors using ferroelectric thin films and consisting of two pieces: a stator and a rotor. The stationary stator includes a piezoelectric film in which we induce bending in the form of a traveling wave. Anything which sits atop the stator is propelled by the wave. A small glass lens placed upon the stator becomes the spinning rotor. Using thin films of PZT on silicon nitride memebranes, various types of actuator structures have been fabricated.

Compliant mechanisms are flexible structures that utilize elastic deformation to achieve their desired motions. Using this unique mode of actuation, the compliant mechanisms have two distinct advantages over traditional rigid machines: (1) They can create highly repeatable motions that are critical for many high precision applications. (2) Their high degrees-of-freedom motions have the potential to achieve mechanical functionalities that are beyond traditional machines, making them especially appealing for miniature robots that are currently limited to only having simple rigid-body-motions and gripping functionalities. Unfortunately, despite the potential of compliant mechanisms, there are still several key challenges that restrict them from realizing their full potential. To facilitate this discussion, we first divide the compliant mechanisms into two categories: (1) the stiffer flexural mechanisms that are ideal for high precision applications, and (2) the more compliant miniature soft robots that can reshape their geometries to achieve highly complex mechanical functionalities. The key limitation for existing flexural mechanisms is that their stiffness and dynamic properties cannot be optimized when they have multi-degrees-of-freedom. This limitation has severely crippled the performance of flexural mechanisms because their stiffness and dynamic properties dictate their workspace, transient responses and capabilities to reject disturbances. On the other hand, miniature soft robots that have overall dimensions smaller than 1 cm, are unable to achieve their full potential because existing works do not have a systematic approach to determine the required design and control signals for the robots to generate their desired time-varying shapes.

Les microrobots MEMS sont des éléments miniaturisés qui peuvent capter et agir sur l'environnement. Leur taille est de l'ordre du millimètre et ils ont une faible capacité de mémoire et une capacité énergétique limitée. Les microrobots MEMS continuent d'accroître leur présence dans notre vie quotidienne. En effet, ils peuvent effectuer plusieurs missions et tâches dans une large gamme d'applications telles que la localisation d'odeur, la lutte contre les incendies, le service médical, la surveillance, le sauvetage et la sécurité. Pour faire ces taches et missions, ils doivent appliquer des protocoles de redéploiement afin de s'adapter aux conditions du travail. Ces algorithmes doivent être efficaces, évolutifs, robustes et ils doivent utiliser de préférence des informations locales. Le redéploiement pour les microrobots MEMS mobiles nécessite actuellement un système de positionnement et une carte (positions prédéfinies) de la forme cible. La solution traditionnelle de positionnement comme l'utilisation d'un GPS consommerait trop d'énergie. De plus, l'utilisation de solutions de positionnement algorithmique avec les techniques de multilatération pose toujours des problèmes à cause des erreurs dans les coordonnées obtenues.Dans la littérature, si nous voulons une auto-reconfiguration de microrobots vers une forme cible constituée de P positions, chaque microrobot doit avoir une capacité mémoire de P positions pour les sauvegarder. Par conséquent, si P est de l'ordre de milliers ou de millions, chaque noeud devra avoir une capacité de mémoire de positions en milliers ou millions. Parconséquent, ces algorithmes ne sont pas extensibles ou évolutifs. Dans cette thèse, on propose des protocoles de reconfiguration où les noeuds ne sont pas conscients de leurs positions dans le plan et n'enregistrent aucune position de la forme cible. En d'autres termes, les noeuds ne stockent pas au départ les coordonnées qui construisent la forme cible. Par conséquent, l'utilisation de mémoire pour chaque noeud est réduite à une complexité constante. L'objectif desalgorithmes distribués proposés est d'optimiser la topologie logique du réseau des microrobots afin de chercher une meilleure complexité pour l'échange de message et une communication peu coûteuse. Ces solutions sont complètement distribués. On montre pour la reconfiguration d'une chaîne à un carré comment gérer la dynamicité du réseau pour sauvegarder l'énergie, on étudie comment utiliser le parallélisme de mouvements pour optimiser le temps d'exécution et lenombre de mouvements. Ainsi, on propose une autre solution où la topologie physique initiale peut être n'importe quelle configuration initiale. Avec ces solutions, les noeuds peuvent exécuter l'algorithme indépendamment du lieu où ils sont déployés, parce que l'algorithme est indépendant de la carte de la forme cible. En outre, ces solutions cherchent à atteindre la forme de la cible avec une quantité minimale de mouvement. / MEMS microrobots are miniaturized elements that can capture and act on the environment. They have a small size, low memory capacity and limited energy capacity. These inexpensive devices can perform several missions and tasks in a wide range of applications such as locating odor, fighting against fires, medical service, surveillance, search, rescue and safety. To do these tasks and missions, they have to carry out protocols of redeployment to adapt to the working conditions. These algorithms should be efficient, scalable, robust and should only use local information. Redeployment for mobile MEMS microrobots currently requires a positioning system and a map (predefined positions) of the target shape. Traditional positioning solutions such as using GPS consumes a lot of energy and it is no applicable in the micro scale. Also, the use of an algorithmic solution positioning with multilateration techniques causes problems due to errors in the coordinates obtained. In the literature works, if we want a microrobots self-reconfiguring to a target shape consisting of P positions, each microrobot must have a storage capacity of at least P positions to save them. Therefore, if P equals to thousands or millions, every node must have a storage capacity of thousands or millions of positions. However, these algorithms are notscalable. In this thesis, we propose protocols of self-reconfiguration where nodes are not aware of their position in the plane and do not record the positions of the target shape. Therefore, the memory space required for each node is significantly reduced at a constant complexity. The purpose of these distributed algorithms is to optimize the logical topology of the network of mobile MEMS microrobots to seek a better complexity for message exchange and inexpensive communication.In this work, we show for the reconfiguration of a chain into a square, how to handle the dynamicity of the network to save energy, and we study how to use parallelism in motion to optimize the execution time and the number of movements. Furthermore, another solution is proposed where the initial physical topology may be any connected configuration. With thesesolutions the nodes can execute the algorithm regardless of where they are deployed, because the algorithm is independent of the map of the target shape. Furthermore, these solutions seek to achieve the shape of the target with a minimum amount of movement.

Η χειρουργική δια μέσου φυσικών οπών ή NOTES (Natural Orifice Transluminal Endocopic Surgery) αποτελεί σήμερα ίσως το πιο ενδιαφέρον επίτευγμα της χειρουργικής από πλευράς τεχνικής. Η ανάπτυξη της τεχνολογία των υπολογιστών και της ρομποτικής αποτελεί ένα δυνατό εργαλείο για το σύγχρονο χειρουργό. Η πρόοδος της μικρο-ρομποτικής στις μέρες μας είναι αλματώδης. Συνεχώς κατασκευάζονται από ομάδες επιστημόνων όλο και μικρότερα σε μέγεθος ρομπότ με όλο και περισσότερες δυνατότητες κίνησης και επεξεργασίας σήματος ικανά να εισέλθουν στο ανθρώπινο σώμα δια μέσου των φυσικών οπών του, στην περιτοναϊκή κοιλότητα. Η τεχνική NOTES είναι ίσως η ιδανική για χρήση μικρο-ρομποτικής. Ο συνδυασμός αυτός ίσως φέρει επανάσταση και στην τηλεχειρουργική. Σκοπός τις εργασίας μας είναι να αναδείξουμε το ρόλο της ιατρικής πληροφορικής κατά τη χρήση μικρο-ρομποτ στη χειρουργική δια μέσου φυσικών οπών. Σχεδιάσαμε και εξομοιώσαμε ένα μοντέλο αρθρωτού μικρο-ρομποτ αποτελούμενου από υπομονάδες (modular robot) που θα μπορεί να εισέλθει δια μέσω των φυσικών οπών στο γαστρεντερικό σωλήνα ή και στην περιτοναϊκή κοιλότητα και θα έχει δυνατότητα κίνησης και χειρουργικών χειρισμών εξ αποστάσεως καθώς και παροχή πληροφοριών στο χρήστη από αισθητήρες. / Natural Orifice Transluminal Endocopic Surgery (NOTES) is perhaps the most interesting achievement of today’s surgery in terms of technique. The development of computer technology and robotics is a powerful tool for the modern surgeon. The progress of micro-robotics today is remarkable. Robotic working teams continuously produce smaller in size robots with more potential motion and signal processing that can enter into the peritoneal cavity through the body’s natural orifices. NOTES surgery is perhaps ideal for use of micro-robots. This combination could be a revolution for the Telesurgery. The aim of our work is to highlight the role of medical informatics in the use of micro-robots in NOTES surgery. We designed and simulated a model of an articulated micro-robot composed of subunits (modular robot) that can enter the gastrointestinal tract or the peritoneal cavity through the body’s natural orifices. It is capable of motion and surgical manipulations and can also provide sensor information to the user.-

Over the last six decades, the field of drug delivery has advanced considerably, from sustained oral release technology to pH-responsive polymers. Innovation in the space has progressed alongside the development of new categories of drugs, as well as improvements in electronics and material science which have enabled new modalities of external stimulation. Nevertheless, the traditional challenges of drug delivery persist, including the need to reduce off-target toxicity, minimize invasiveness of administration, and bypass biological barriers; these challenges are particularly apparent for drug delivery applications in difficult-to-reach areas of the body, such as tumors or areas beyond the blood-brain barrier. Furthermore, as therapeutics become more targeted, the need for corresponding delivery methods becomes even more vital to ensure treatment effectiveness with minimal side effects. In this dissertation, we aim to demonstrate a new strategy for on-demand and localized drug delivery which is easy to fabricate and delivers a large payload relative to device size, is responsive to external stimulation for triggered release, and can be integrated into a system for real-time actuation during a physiological process. In Aim 1, we developed a microfluidic fabrication technique for making biphasic microcapsules loaded with model drug. This method relied on microfluidic droplet methods, with sufficient interfacial tension between two on-chip phases to cause droplet formation. Typically, these systems rely on an aqueous-oil interface for sufficient interfacial tension; to fabricate a biocompatible microcapsule, we formed biphasic microcapsules composed of an aqueous-based inner and outer phase, without an oil intermediate phase, with aqueous two-phase system properties. Additionally, we incorporated on-chip photopolymerization, designing the microfluidic chip and light source to minimize refracted ultraviolet exposure. The resulting drug-loaded microcapsules were stable, with minimal background leakage. This fabrication technique can produce a high-throughput supply of monodisperse microcapsules, which can be modified for a variety of therapeutic payloads and easily injected in targeted region in the body. In Aim 2, we adapted these drug-loaded microcapsules for ultrasound-triggered release. Focused ultrasound (FUS) is a minimally-invasive method of stimulating release from a device, which can penetrate deep within the body and is compatible with a variety of materials; when applied at sufficient intensity and duration, it can induce heating, cavitation, or both. We tuned the applied ultrasound parameters to minimize temperature increases in surrounding tissue phantoms, while inducing step-like release profiles from the microcapsules over the course of multiple cycles of pulsed FUS. Under these applied conditions, we detected acoustic signatures consistent with inertial cavitation and visually observed structural breakdown of the microcapsules corresponding to cavitation-related effects. This release strategy is highly targeted, inducing drug release from microcapsules within a narrow focal area with minimal risk to surrounding tissue. Finally, in Aim 3, we performed in vitro demonstrations of drug-loaded actuators, as initial demonstrations towards a system of integrated sensors, actuators, and adaptive learning algorithms for closed-loop control over physiological processes involved in wound healing. We experimented with both the aforementioned microcapsules and with a liposome-loaded scaffold as drug-loaded actuators, and tested both actuators with three ultrasound transducers which offered a range of portability, intensity ranges, and imaging capacities. Next, we developed in vitro testing setups incorporating the actuators with either a cell monolayer or a three-dimensional cell construct, mimicking a wound site, and validated ultrasound-triggered drug-release with minimal cell damage. To demonstrate cell uptake of the released therapeutic agents, we modified the microcapsules’ payload, performed the in vitro release experiments, and then observed correlating cell response over the following week of culturing. These demonstrations have provided guidance towards a more integrated system, which will validate the impact of the localized actuators in stimulating enhancing wound healing rates. More broadly, the eventual integrated system, incorporating both sensors and the adaptive algorithm, will be able to sense and respond to physiological changes within a wound in real-time. This work explores how wireless, deep-tissue devices coupled with external control modalities will facilitate interventions with high spatiotemporal accuracy; when combined with sensing and regulating algorithms, it will empower real-time monitoring and interventions in physiological processes. Aim 1 focused on the fabrication of such implantable microcapsule devices and Aim 2 demonstrated a method for triggering the devices using an external control modality. In Aim 3, we investigated a use case for these microcapsules to promote rapid wound healing, alongside flexible electronics, sensors, and additional actuators. To provide additional context on implantable microdevices and biocompatibility, we provide a framework for designing medical microrobotics in Appendix I and an application of a thermally-responsive hydrogel coating in Appendix II. Overall, the sum of this work illustrates the potential impact of soft microdevices for localized and on-demand applications, towards a future of spatiotemporally-targeted biological interventions.

We develop biohybrid magnetic microrobots by electrostatic self-assembly of nonmotile sperm cells and magnetic nanoparticles. Incorporating a biological entity into microrobots entails many functional advantages beyond shape templating, such as the facile uptake of chemotherapeutic agents to achieve targeted drug delivery. We present a single-step electrostatic self-assembly technique to fabricate IRONSperms, soft magnetic microswimmers that emulate the motion of motile sperm cells. Our experiments and theoretical predictions show that the swimming speed of IRONSperms exceeds 0.2 body length/s (6.8 ± 4.1 µm/s) at an actuation frequency of 8 Hz and precision angle of 45°. We demonstrate that the nanoparticle coating increases the acoustic impedance of the sperm cells and enables localization of clusters of IRONSperm using ultrasound feedback. We also confirm the biocompatibility and drug loading ability of these microrobots, and their promise as biocompatible, controllable, and detectable biohybrid tools for in vivo targeted therapy.

Systemic chemotherapy remains the backbone of many cancer treatments. Due to its untargeted nature and the severe side effects it can cause, numerous nanomedicine approaches have been developed to overcome these issues. However, targeted delivery of therapeutics remains challenging. Engineering microrobots is increasingly receiving attention in this regard. Their functionalities, particularly their motility, allow microrobots to penetrate tissues and reach cancers more efficiently. Here, we highlight how different microrobots, ranging from tailor-made motile bacteria and tiny bubble-propelled microengines to hybrid spermbots, can be engineered to integrate sophisticated features optimised for precision-targeting of a wide range of cancers. Towards this, we highlight the importance of integrating clinicians, the public and cancer patients early on in the development of these novel technologies.

<p dir="ltr">Murine, or small rodent, models can provide valuable and translatable insights into human pathophysiology. Specifically, we are looking to combine murine models and high-frequency ultrasound to non-invasively investigate microrobot drug delivery systems, cardiac effects of lactation on the mother during postpartum, and cardiac remodeling due to the combination of pregnancy and hypertension.</p><p dir="ltr">Currently, we are looking at the applications of microrobots within the colon to provide targeted treatment for patients suffering from inflammatory bowel disease (IBD). IBD is an overarching term encompassing chronic inflammation of the digestive tract tissue. The standard treatment of IBD includes oral and injectable treatments depending on disease severity. The drawbacks of these therapeutics are the associated systemic toxicity, non-specific treatment allocation, and degradation of the treatment in proximal portions of the gastrointestinal (GI) system. The goal of this research is to use an external magnetic torque to cause the microrobots to tumble to targeted areas of inflammation and release a drug payload. Retroactive locomotion of these microrobots can avoid degradation in the proximal GI tract. Therefore, these microrobots need a smaller drug payload to provide the same efficacy as traditional treatments.</p><p dir="ltr">The cardiovascular system adapts to meet the growing physiological demands of pregnancy. Although this change has been greatly studied, it is unclear if this change in shape and function returns to prepregnant values during postpartum. Previous research has also shown that lactation affects the mother’s hemodynamics during postpartum, but its impact on cardiac morphology is still not completely understood. To study this further, we longitudinally tracked cardiovascular changes using ultrasound and blood pressure measurements in C57BL6/J mice during pregnancy and postpartum that were either lactating or not.</p><p dir="ltr">Chronic hypertension affects approximately 1 in 20 pregnancies and its prevalence in pregnancies continues to increase. The maternal cardiovascular system goes through dynamic changes during pregnancy to meet the demands of perfusing the gestation, especially during the exponential growth seen later in pregnancy. Studies with female C57BL6/J mice demonstrate comparable cardiovascular changes during pregnancy to those observed in humans. Additionally, a study using rats showed the cardioprotective properties of pregnancy against angiotensin II-induced fibrosis. The objective of this study is to characterize non-invasive cardiac remodeling in a small animal model of hypertensive disorders in pregnancy. We used a combination of ultrasound imaging and noninvasive blood pressure measurements to longitudinally monitor the physiological adaptations that occur during pregnancy with superimposed hypertension.</p>