L’objectif de cette thèse est de concevoir et de réaliser un mobile piézoélectrique pour utilisation coopérative. Le terme mobile piézoélectrique est utilisé dans cette thèse pour décrire un robot piézoélectrique miniature. Ce robot miniature mobile est actionné par des matériaux piézoélectriques. L’objectif de la thèse est donc la conception et la réalisation d’un robot pouvant être miniaturisé et qui pourrait donc être utilisé dans le cadre du mimétisme des essaims biologiques (fourmis, abeilles…) pour un fonctionnement coopératif.Le robot réalisé est constitué d'un support mince et de patchs piézoélectriques. Les patchs piézoélectriques sont collés sur le support de façon intelligente afin de déplacer le support en milieu terrestre. Dans ce contexte, la thèse est divisée en trois parties.La première partie est consacrée à la modélisation d’un tel système (support mince avec des patches piézoélectriques sur une seule de ses faces). Une modélisation par la méthode des éléments finis est développée pour ce système en se basant sur le principe variationnel d’Hamilton et en considérant l'hypothèse de Love-Kirchhoff. L’originalité de cette modélisation réside dans l’utilisation de la notion du plan neutre pour modéliser ce système asymétrique. Cela permet de ne modéliser le système étudié que par un modèle éléments finis à deux dimensions (2D) tout en tenant compte de la troisième dimension dans le calcul. La deuxième partie présente le principe de fonctionnement du robot qui est inspiré des moteurs linéaire ultrasoniques à ondes progressive. Cette partie présente toutes les étapes de la conception optimale afin de créer les mouvements nécessaires. La conception optimale est étudiée en utilisant la modélisation par éléments finis obtenue dans la première partie. La troisième partie de cette thèse est dédiée à la réalisation d’un prototype expérimental. Le processus de fabrication ainsi que l’électronique associée au robot sont présentés dans cette partie. Le robot est caractérisé expérimentalement en mesurant la vitesse en fonction de la tension appliquée, la vitesse en fonction de masses embarquées par le robot et la vitesse en fonction de la force fournie par le robot. Ce robot est, par ailleurs, comparé avec d’autres systèmes de même nature. / The objective of this thesis is to design and realize a piezoelectric mobile for cooperative use. The term piezoelectric mobile is used in this thesis to describe a piezoelectric miniature robot. This mobile miniature robot is actuated by piezoelectric materials. The aim of the thesis is the design and the realization of a robot that can be miniaturized and could therefore be used in the context of biological mimicry swarms (ants, bees ...) for a cooperative operation.The realized robot consists of a thin support and piezoelectric patches. Piezoelectric patches are bonded on the support on an intelligent manner in order to move the support on land. In this context, the thesis is divided into three parts.The first part is devoted to the modeling of such a system (thin support with piezoelectric patches on one of its faces). Modeling by the finite element method is developed for this system based on the variational principle of Hamilton and considering the Love-Kirchhoff hypothesis. The originality of this model lies in the use of the concept of the neutral plane to model this asymmetric system. This allows modeling the system studied by a finite element model in two dimensions (2D), taking into account the third dimension in the calculation.The second part presents the operating principle of the robot which is inspired by the linear traveling wave ultrasonic motors. This section presents all the stages of the optimal design to create the necessary movements. The optimal design is investigated using finite element modeling obtained in the first part.The third part of this thesis is devoted to the realization of an experimental prototype. The manufacturing process and the associated electronics for the robot are presented in this section. The robot is characterized experimentally by measuring the speed according to the applied voltage, the speed versus mass loaded by the robot and the speed according to the force provided by the robot. This robot is also compared with other similar systems.

Indiana University-Purdue University Indianapolis (IUPUI) / It is increasingly recognized that mechanical properties of substrates play a pivotal role in the regulation of cellular fate and function. However, the underlying mechanisms of cellular mechanosensing still remain a topic of open debate. Traditionally, advancements in this field have been made using polymeric substrates of adjustable stiffness with immobilized linkers. While such substrates are well suited to examine cell adhesion and migration in an extracellular matrix environment, they are limited in their ability to replicate the rich dynamics found at cell-cell interfaces. To address this challenge, we recently introduced a linker-functionalized polymer-tethered multi-bilayer stack, in which substrate stiffness can be altered by the degree of bilayer stacking, thus allowing the analysis of cellular mechanosensitivity. Here, we apply this novel biomembrane-mimicking cell substrate design to explore the mechanosensitivity of C2C12 myoblasts in the presence of cell-cell-mimicking N-cadherin linkers. Experiments are presented, which demonstrate a relationship between the degree of bilayer stacking and mechanoresponse of plated cells, such as morphology, cytoskeletal organization, cellular traction forces, and migration speed. Furthermore, we illustrate the dynamic assembly of bilayer-bound N-cadherin linkers underneath cellular adherens junctions. In addition, properties of individual and clustered N-cadherins are examined in the polymer-tethered bilayer system in the absence of plated cells. Alternatively, substrate stiffness can be adjusted by the concentration of lipopolymers in a single polymer-tethered lipid bilayer. On the basis of this alternative cell substrate concept, we also discuss recent results on a linker-functionalized single polymer-tethered bilayer substrate with a lateral gradient in lipopolymer concentration (substrate viscoelasticity). Specifically, we show that the lipopolymer gradient has a notable impact on spreading, cytoskeletal organization, and motility of 3T3 fibroblasts. Two cases are discussed: 1. polymer-tethered bilayers with a sharp boundary between low and high lipopolymer concentration regions and 2. polymer-tethered bilayers with a gradual gradient in lipopolymer concentration.

Construction of radiotherapy treatments for cancer is a laborious and time consuming task. At the same time, when presented with a treatment plan, an oncologist can quickly judge whether or not it is suitable. This means that the problem of constructing these treatment plans is well suited for automation. This thesis investigates a novel way of automatic treatment planning. The treatment planning system this pipeline is constructed for provides dose mimicking functionality with probability density functions of dose–volume histograms (DVHs) and spatial dose as inputs. Therefore this will be the output of the pipeline. The input is historically treated patient scans, segmentations and spatial doses. The approach involves three modules which are individually replaceable with little to no impact on the remaining two modules. The modules are: an autoencoder as a feature extractor to concretise important features of a patient segmentation, a distance optimisation step to learn a distance in the previously constructed feature space and, finally, a probabilistic spatial dose estimation module using sparse pseudo-input Gaussian processes trained on voxel features. Although performance evaluation in terms of clinical plan quality was beyond the scope of this thesis, numerical results show that the proposed pipeline is successful in capturing salient features of patient geometry as well as predicting reasonable probability distributions for DVH and spatial dose. Its loosely connected nature also gives hope that some parts of the pipeline can be utilised in future work. / Skapandet av strålbehandlingsplaner för cancer är en tidskrävande uppgift. Samtidigt kan en onkolog snabbt fatta beslut om en given plan är acceptabel eller ej. Detta innebär att uppgiften att skapa strålplaner är väl lämpad för automatisering. Denna uppsats undersöker en ny metod för att automatiskt generera strålbehandlingsplaner. Planeringssystemet denna metod utvecklats för innehåller funktionalitet för dosrekonstruktion som accepterar sannolikhetsfördelningar för dos–volymhistogram (DVH) och dos som input. Därför kommer detta att vara utdatan för den konstruerade metoden. Metoden är uppbyggd av tre beståndsdelar som är individuellt utbytbara med liten eller ingen påverkan på de övriga delarna. Delarna är: ett sätt att konstruera en vektor av kännetecken av en patients segmentering, en distansoptimering för att skapa en distans i den tidigare konstruerade känneteckensrymden, och slutligen en skattning av sannolikhetsfördelningar med Gaussiska processer tränade på voxelkännetecken. Trots att utvärdering av prestandan i termer av klinisk plankvalitet var bortom räckvidden för detta projekt uppnåddes positiva resultat. De estimerade sannolikhetsfördelningarna uppvisar goda karaktärer för både DVHer och doser. Den löst sammankopplade strukturen av metoden gör det dessutom möjligt att delar av projektet kan användas i framtida arbeten.