A dependência com a temperatura dos tempos de relaxação nuclear e da forma da linha de ressonância dos núcleos F0, nos antiferromagnetos diluidos Fex Zn1-x F2 e Mnx Zn1-x F2, foram estudados na faixa TN&#8804;T&#8804;300K. Os tempos de relaxação spin, rede (1/T1) dos núcleos F0, os quais não estão acoplados aos spins Fe (ou Mn) através da interação hiperfina transferida, foram medidos e calculados teoricamente em função da concentração x. Os resultados teóricos apresentam uma boa concordância com os dados experimentais para concentrações na faixa 0.1&#8804;x&#8804;0.8. A dependência com a temperatura de 1/T1, para TN<T&#8804;300K foi entendido qualitativamente em ambos sistemas. Os resultados obtidos para 1/T1, em temperaturas próximas de TN foram utilizados para estudar os \"Efeitos de Campo Aleatório\" no comportamento crítico do Mn.65Zn.35 F2 com o campo aplicado paralelamente e perperdicularmente ao eixo fácil (C). Encontrou-se neste caso, que a temperatura de transição TN decresce substancialmente com o aumento da intensidade do campo somente quando H0 || C. Os resultados experimentais obtidos estão de acordo com as teorias do Efeito de Campos Aleatórios em antiferromagnetos anisotrópicos diluídos. A divergência crítica do segundo momento da linha de ressonância não homogeneamente alargada do F0 foi estudada acima de TN. Os resultados experimentais concordam com os cálculos de Heller para o alargamento não homogêneo causado por Efeitos de Campos Aleatórios. Observou-se que a forma da linha se altera na região crítica. Longe de TN ela é Gaussiana e para t&#8804;10-2 ela mostra uma tendência a se tornar Lorentziana. Abaixo de TN a sua meia largura aumenta, seguindo qualitativamente o aumento da magnetização das sub-redes. / The temperature dependence of the nuclear relaxation rates and line shapes of the F0 resonance in the diluted antiferromagnet Fex Zn1-x F2 and Mnx Zn1-x F2 are studied over a large temperature range TN&#8804;T&#8804;300K. The high (room) temperature spinlattice relaxation rates (1/ T1) of the F0 nuclei, which are not transfer hiperfine coupled to the Fe (or Mn) spins, have been measured and calculated as a function of the concentration x. Good agreement with experiment is found for the theoretical results, which have been obtained in the range 0.1&#8804;x&#8804;0.8. The temperature dependence of TN<T&#8804;300K was qualitatively understood \"Random Field Effects\" on the critical behavior of Mn.65Zn.35 F2, for fields applied parallel and perpendicular to the easy (C) axis. It was found that the transition temperature TN depressed substantially with field only for H0 || C. The experimental results are in general accord with the theory for Random Field Effects in desordered, anisotropic antiferromagnets. The critical divergence of the in homogeneously broadened F0 NMR was studied in Fe.6Zn.4F2 above TN. The experimental results agree with Heller\'s calculation of the NMR line broadening by Random Field Effects. With H0 || C the line shape changes from Gaussian towards Lorentzian for t&#8804;10-2 and below TN its line width increase qualitatively following increase in the sublattice magnetization.

Abstract In this thesis several novel inks based on dry inorganic powders enabling magnetic, piezoelectric and memory resistive (memristive) function were researched for printed electronics applications. Low curing temperature screen–printable magnetic inks for high frequency applications based on dry cobalt nanoparticles were developed in the first part of the work. Three publications were achieved. The first one concentrated on ink formulation and its process development, the second on the utilization of multifunctional surfactant, and the third on the development of the inks for plastic substrates. The magnetic inks developed were cured at 120 &#176;C. The electrical performance, microstructure, surface quality and mechanical durability of printed and cured layers were investigated. Relative permeability values up to 3 and related loss tangents up to 0.01 were achieved at 2 GHz frequency, as well as a pull–off strength of up to 5.2 MPa. The maximum loading level of cobalt nanoparticles was 60 vol–%, after which the stability of the ink started to degrade. The developed ink enabled the miniaturization of a patch antenna. In the second part of the thesis, the formulation of inks based on piezoelectric ceramic particles in powder form with ferroelectric polymers as a matrix material is introduced. The performance and quality of the printed inks and cured layers were investigated. The measured pull off –strength was up to 3.25 MPa, relative permittivity was up to 48 at 1 kHz and piezoelectric constant d31 up to 17 pm/V. The printed piezoelectric layer can be utilized in a pressure sensor. In the third part of the thesis, the development of inks for a novel printed memory component, a memristor, is researched. A synthesis route was developed for an organometallic precursor solution, which was formulated into inkjet–printable form. The printing tests were carried out in order to find the most feasible layer thickness with memristive behaviour. The influence of substrate materials and different thermal treatments on the components’ electrical properties, durability of read/erase –cycles and overall lifetime were also investigated. The prepared memristive patterns remained functional for up to 35 days, while the precursor solution remained usable for over a year. The memristive areas withstood up to 30 read/erase cycles and by utilizing heat treatments the shift in resistance value increased by up to three orders of magnitude. / Tiivistelmä Väitöstyössä kehitettiin epäorgaanisten kuivien jauhemaisten materiaalien pohjalta magneettisia, pietsosähköisiä ja memristiivisiä musteita käytettäviksi painettavan elektroniikan sovelluksissa. Työn ensimmäisessä osassa tutkittiin korkean taajuuden sovelluksissa käytettävien magneettisten, matalassa lämpötilassa kovetettavien, jauhemaisiin kobolttinanopartikkeleihin perustuvien silkkipainomusteiden valmistamista. Tulokset on esitetty kolmessa julkaisussa, joista ensimmäinen keskittyi musteen formulointiin, toinen monifunktionaalisen surfaktantin hyödyntämiseen ja kolmas musteen kehittämiseen muovialustalle sopivaksi. Työssä kehitettiin 120 &#176;C:ssa kovettuvia musteita, joista valmistettujen kalvojen suhteellisen permeabiliteetin maksimiarvoksi saatiin 3 ja häviöiden minimiarvoksi 0,01 kahden gigahertsin taajuudella. Pull–off –vetotestin tulokseksi saatiin jopa 5,2 MPa. Musteet säilyivät vakaina enimmillään 60 tilavuusprosentin metallipitoisuudella. Kehitettyä mustetta käytettiin tasoantennin miniatyrisoinnissa. Toisessa osassa kehitettiin pietsosähköisiä musteita, jotka pohjautuivat keraamijauheeseen ja matriisimateriaalina toimivaan ferrosähköiseen muoviin. Niistä valmistettujen kalvojen parhaaksi pull off –vetotestin tulokseksi saatiin 3,25 MPa, permittiivisyyden maksimiarvoksi 48 yhden kilohertsin taajuudella ja d31–pietsovakion maksimiarvoksi jopa 17 pm/V. Kehitettyjä painettuja rakenteita voidaan käyttää painettavissa paineantureissa. Kolmannessa osassa kehitettiin uudentyyppinen painettava muistikomponentti, memristori ja komponenttien valmistamiseksi uusi prekursoriliuoksen synteesi. Syntetisoitu liuos muokattiin mustesuihkutulostettavaksi. Painokokeiden avulla selvitettiin materiaalin paksuus, jolla saatiin aikaan muistivastukselle ominainen memristiivinen käyttäytyminen. Työssä tutkittiin substraattimateriaalien ja mahdollisten lämpökäsittelyjen vaikutusta komponenttien sähköisiin ominaisuuksiin, luku/kirjoitussyklien kestoon sekä käyttöikään. Valmistetut memristiiviset kalvot säilyivät toimivina 35 vuorokautta ja prekursoriliuos yli vuoden. Memristiiviset pinnat kestivät jopa 30 luku/kirjoitussykliä ja vastusarvon muutos saatiin lämpökäsittelyllä kolmea kertaluokkaa suuremmaksi.

De nos jours, la modélisation numérique constitue un outil indispensable pour le prototypage de convertisseurs électromagnétiques. Les matériaux magnétiques jouent un rôle essentiel dans la conversion de l’énergie, il est donc nécessaire de maîtriser leur comportement et leur représentation. L’objectif de ce travail s’inscrit dans ce cadre et s’attache à élaborer des lois réalistes de comportement de matériaux afin de les inclure dans des simulateurs de circuits. Concernant le comportement statique, le modèle de Jiles-Atherton a été implémenté puis adapté, simplifié et modifié afin d’en améliorer la précision et l’implémentation. La modélisation dynamique du matériau a été effectuée grâce au modèle DWM élaboré au laboratoire Ampère. Ce modèle intègre les effets dynamiques excédentaires grâce à une loi « dynamique de matériau » implémentée au sein de l’équation de diffusion magnétique. Ce modèle a été ensuite homogénéisé afin d’en améliorer son implémentation future dans un simulateur de circuit. Chacun des différents modèles a été testé et validé sur plusieurs échantillons. / Nowadays, numerical modeling is an indispensable tool for the prototyping of electromagnetic converters. Magnetic materials play an essential role into the energy conversion so it is necessary to control their behavior as well as their modeling. The objective of this work is to develop realistic laws of material behavior for circuit simulators use. Regarding the static behavior, the Jiles-Atherton model has been implemented and adapted, simplified and modified to improve accuracy and implementation. Dynamic modeling of the material was performed using the model DWM developed into the Ampere laboratory. This model incorporates the excedentary dynamic effects thanks to a "dynamical material law" implemented into the magnetic diffusion equation. Then this model was homogenized to improve its future implementation in a circuit simulator. Each of the different models has been tested and validated on several samples.

Le travail présenté dans cette thèse porte sur l'application de la spectroscopie RMN pour l'étude de matériaux magnétiques moléculaires. Une attention particulière est consacrée aux systèmes magnétiques possédant des cyanures : des briques de construction, des complexes de cyanure polymétalliques et des réseaux étendus (analogues bleu de Prusse) à faible dimension. Par le biais d’exemples spécifiques, nous essayons de montrer que la spectroscopie RMN peut être utilisée comme une puissante sonde magnétique et structurale des systèmes paramagnétiques (chapitre 2, 4, 5). De plus, la RMN est également utilisée pour étudier l’équilibre de spin, en solution, d’une famille de complexes à transition de spin Fe(II) (chapitre 3). En dehors de la spectroscopie RMN, différentes techniques comprenant la spectroscopie FT-IR et UV-Vis (à l'état solide et solution), l’analyse thermogravimétrique (ATG), la diffraction aux rayons X, la résonance paramagnétique électronique (RPE), la diffraction de neutrons polarisés (uniquement pour le composé [Fe(Tp)(CN)3]-) et la magnétométrie SQUID sont utilisées afin d’obtenir une caractérisation structurale et électronique fiable des matériaux magnétiques sondés. Ces techniques permettent également de rationaliser et de soutenir les résultats obtenus à partir de spectroscopie RMN. Par ailleurs, des calculs théoriques de certains composés ont été effectués à l’aide de la méthode DFT (en collaboration avec les théoriciens) afin de soutenir les observations expérimentales. Le premier chapitre de la thèse revient sur quelques concepts de base de la spectroscopie RMN, à l'état solide et en solution, et expose brièvement quelques exemples d'études de systèmes paramagnétiques en RMN. La partie expérimentale de ce même chapitre met l'accent sur l'utilisation de la spectroscopie RMN 13C et 15N à l'état solide pour sonder les propriétés magnétiques locales, estimer la densité de spin et sa répartition sur les ligands cyanures. Une question fondamentale pour les magnéto-chimistes est ainsi soulevée : comment l'électron non apparié, délocalisé de la source paramagnétique sur le ligand pontant, donne t-il naissance à l'interaction magnétique d'échange? Dans le troisième chapitre de la thèse, la spectroscopie RMN 1H paramagnétique en solution a été utilisée pour étudier des complexes mononucléaires Fe(II) commutables, c’est-à-dire pouvant subir un changement de leurs propriétés magnétiques (et optiques) sous l’influence de stimuli externes. L’équilibre de transition de spin thermo-induit des complexes [FeII(R-bik)3]2+ a été étudié par RMN 1H, à température variable, et les résultats ont été comparés à ceux obtenus avec des techniques différentes. Le quatrième chapitre traite de la caractérisation magnéto-structurale de certains complexes polynucléaires fondé sur la nouvelle brique de construction cyanurée [CoIII(Me2Tp)(CN)3]-. La spectroscopie RMN du noyau quadripolaire 59Co est employée comme sonde pour suivre à différente température, le comportement magnétique des systèmes moléculaires contenant du Co(III). La RMN 59Co permet par ailleurs, l’étude du mécanisme d'extension de spin sur le pont cyanure... / The work presented in this Ph.D. dissertation focuses on the application of NMR spectroscopy for studying molecular magnetic materials. A particular attention is devoted to cyanide-contaning magnetic systems: cyanide building blocks, low-dimensional polymetallic complexes and extended networks (Prussian blue analogues). Basically, we try to show through selected examples that NMR can be used as a powerful structural and magnetic probe to address a variety of questions related to paramagnetic materials (chapter 2, 4, 5). Besides, we also use here NMR to study spin equilibrium in solution in a family of Fe(II) spin-crossover complexes (chapter 3). Apart from the use of various NMR techniques, different physical techniques including FT-IR and UV-Vis spectroscopy (in solid-state and solution), TGA, X-ray diffraction, EPR spectroscopy, Polarized neutron diffraction (only for [Fe(Tp)(CN)3]- compound), and SQUID magnetometry are used to obtain reliable structural and electronic characterization of the probed magnetic materials and to rationalize and support the results obtained from NMR spectroscopy. Theoretical DFT calculations (in collaboration with theoreticians) are also performed on some selected compounds to support the experimental observations. The first chapter of the dissertation provides a short overview of some basic concepts of NMR spectroscopy in solid state and in solution and gives very briefly some few examples of NMR studies on a variety of paramagnetic systems. The first experimental chapter of the thesis focuses on the use of 13C and 15N solid-state NMR spectroscopy to probe local magnetic properties and to estimate the spin density and its distribution onto the cyanide ligands. It thus addresses a fundamental question for magnetochemists: how the unpaired electron delocalized from the paramagnetic source onto the bridging ligand to give rise to the magnetic exchange interaction? In the third chapter of the thesis, the solution state paramagnetic 1H NMR spectroscopy has been used to study Fe(II) mononuclear switchable complexes, which undergo a change of their magnetic (and optical) properties upon external stimuli. More specifically, the thermally-induced spin-crossover equilibria of the [FeII(R-bik)3]2+ complexes has been studied by variable temperature 1H NMR and the results are compared to those obtained by other techniques. The fourth chapter deals with the magneto-structural characterization of some polynuclear complexes based on the new cyanide-based [CoIII(Me2Tp)(CN)3]- building block. NMR spectroscopy of the quadrupolar 59Co nucleus is used as a probe for following the magnetic behaviour of these Co(III) containing molecular systems at different temperature. It also allows to investigate the spin extension mechanism over the cyanide bridge. Finally the chapter 5 intends to explore the use of 113Cd NMR spectroscopy as both a local structural and magnetic probe for studying Fe-Cd based molecular materials...

We study the magnetocaloric effect in two magnetic materials, an alloy intermetallic Dy2RhGa8 monocrystalline and polycrystalline manganite shaped the La0.99Pb0.01MnO3. These compounds were characterized by the methods of X-ray diffraction at room temperature and dc magnetization as a function of temperature and applied magnetic field. From the magnetic measurements we conclude that the La 0.99Pb0.01MnO3 has a ferromagnetic transition below 250 K and is antiferromagnetic Dy2RhGa8 to temperatures lower than 11 K. Study was conducted on the magnetocaloric effect in the compounds with the calculation of their variations of entropy for different magnetic fields. The sample Dy2RhGa8 ordering antiferromagnetically at 7 Tesla had an entropy change of 2.4 J / mol K when the applied field is parallel to the crystallographic c axis of 2.1 J / mol K when the field is perpendicular to the c direction. the results were compared with a theoretical modeling of the crystal field Hamiltonian for best fit of the experimental data and obtain satisfactory results. / Neste trabalho estudamos o efeito magnetocalórico em dois materiais magnéticos, uma liga intermetálica monocristalina de Dy2RhGa8 e uma manganita em forma policristalina de La0.99Pb0.01MnO3. Estes compostos foram caracterizados por métodos de difratometria de raios X à temperatura ambiente, e magnetização dc em função da temperatura e do campo magnético aplicado. Das medidas magnéticas concluímos que o La0.99Pb0.01MnO3 apresenta uma transição ferromagnética abaixo de 250 K e o Dy2RhGa8 é antiferromagnético para temperaturas menores de 11 K. Foi feito o estudo do efeito magnetocalórico nos compostos com o cálculo de suas respectivas variações de entropia para diferentes campos magnéticos. A amostra de Dy2RhGa8 que ordena antiferromagneticamente a 7 Tesla teve uma variação de entropia de 2,4 J/mol K quando o campo aplicado for paralelo ao eixo cristalográfico c e de 2,1 J/mol K quando o campo for perpendicular a direção c. os resultados foram comparados com um modelo teórico de modelagem da Hamiltoniana de campo cristalino para melhor ajuste dos dados experimentais e obtemos resultados satisfatórios.

We present results of an experimental and theoretical study of the magnetic properties of soft magnetic gels consisting of micron-sized magnetizable particles embedded in a polymer matrix. Experiments demonstrate hysteretic dependences of composite magnetization on an applied magnetic field and non-monotonic, with maximum, dependence of the sample susceptibilities on the field. We propose a theoretical approach which describes the main physical features of these experimental results.

<div>Rare circulating cells are becoming a subject of interest due to their potential clinical applications to replace invasive procedures. Due their low presence in blood (as low as 1 in 1 ml of blood) various platforms are developed to capture and isolate them. Common limitations of current platforms include the inability to process large volumes of blood without an initial volume reduction step such as centrifugation, reliance on a single antibody for the capture, and the difficulty of releasing and retrieving the captured cells with high purity. A rare cell retrieval platform with high throughput operation and high purity retrieval is needed to capture these rare cells by processing large volumes of blood.</div><div><br></div><div>In this thesis study, we have developed a two-tiered microchip system to capture and retrieve rare cells from blood samples with high purity. The first module of the system is a high throughput microfluidic interface that is used to immunomagnetically isolate targeted rare cells from whole blood, and discard > 99.999% of the unwanted leukocytes. The second module is a microwell array that furthers the purification by magnetically guiding each cell into a separate well concurrently, and allows individual retrieval of each cell. Even though the system we have developed is applicable to many fields pertaining to rare cell capture, here we demonstrate the proof-of-concept using model cell lines that represent circulating fetal trophoblasts. We describe the design, operation as well as the experimental characterization of the system. Our characterization results show that the process can be completed within 145 minutes from the very beginning till the retrieval of a target cell, and can provide efficiencies and purities that are as high as 100%. </div><div><br></div><div>In order to demonstrate a real-world use case for our device, we present preliminary experiments done with blood samples from pregnant women. We show that we are able to retrieve candidate fetal cells under 167 minutes. Future work will be focused on sequencing the candidate fetal cells retrieved from maternal samples to confirm their fetal origin as well as enhancing system performance in maximizing the number of cells captured.</div><div><br></div>

Zielstellung dieser Arbeit ist die experimentelle Aufklärung und computergestützte Simulation von Phasengleichgewichten im binären System Kupfer-Sauerstoff und im quaternären System Eisen-Samarium-Zirkonium-Molybdän. Damit wird ein Beitrag zu Phasendiagrammen in den Stoffgruppen der keramischen Materialien und der Seltenerd-basierenden magnetischen Materialien geleistet. Zur Charakterisierung der einzelnen Systeme und ihrer Subsysteme nach der CALPHAD-Methode werden die Stöchiometrie der einzelnen Phasen, ihre Phasenanteile in den jeweiligen Legierungen sowie ihre druckabhängige und thermische Stabilität unter angenäherten Gleichgewichtsbedingungen betrachtet. Zusammen mit den kristallographischen und magnetischen Eigenschaften der Phasen ergeben sich daraus thermodynamische Modelle, die durch ihre parametrisierte Darstellungsweise eine Optimierung an die jeweiligen experimentellen Befunde gestatten. Durch Extra- und Interpolation der so gewonnenen Zustandsfunktionen der einzelnen Phasen ergibt sich ein möglichst weitgehendes Bild aller wesentlichen, das stoffliche Gesamtsystem charakterisierenden thermodynamischen Zustände, welches auch über die experimentellen Einschränkungen hinaus noch Aussagen über die Phasenkonstitution, etwa die Primärkristallisation von Phasen bei hohen Drücken und Temperaturen sowie die Phasenstabilität in höherkomponentigen Systemen, ermöglicht. Schließlich werden die thermodynamischen Funktionen in einer Datenbank zusammengefasst, womit auch die Möglichkeit ihrer Weiterverwendung in anderen Systemen besteht. Die Arbeit kann in den Bereich der Grundlagenuntersuchungen zu den behandelten Stoffsystemen mit werkstoffwissenschaftlichem Hintergrund eingeordnet werden.

Les paliers magnétiques actifs auto-détecteurs sont des transducteurs électromécaniques permettant de réaliser deux fonctions simultanées: une fonction puissance assurant le positionnement du rotor et une fonction capteur de position permettant d'estimer la taille de l'entrefer et la position du rotor. Dans cette thèse nous nous sommes intéressés au développement de modèles électromagnétiques de paliers magnétiques actifs auto-détecteurs pour leur conception et leur optimisation. Différents modèles ont ainsi été produits durant ces travaux de thèse:- Un modèle haute fréquence d'un matériau feuilleté et polarisé construit à partir d'une mesure de la perméabilité réversible et d'un modèle formel de diffusion haute fréquence;- Un modèle de simulation des courants induits dans un rotor feuilleté générés par la rotation de celui-ci. Ce modèle permet alors de déterminer les pertes par courants induits ainsi que l'effet de la rotation sur l'estimation de la position;- Enfin, un modèle de l'impédance haute fréquence d'un circuit magnétique feuilleté, saturable et polarisé. Cette modélisation se réalise en 3 étapes : calcul magnétostatique non linéaire, intégration du modèle haute fréquence et calcul magnétodynamique linéaire. Ces différentes approches de modélisation ont été validées expérimentalement au moyen d'un cadre d'Epstein et sur deux types de paliers magnétiques. L'ensemble de ces modèles ont ensuite été exploités dans un outil pour la conception optimale de paliers magnétiques actifs auto-détecteur. Finalement, une optimisation multivariable bi-objective a été réalisée de façon à concevoir un palier magnétique actif auto-détecteur optimal à la fois d'un point de vue capteur et d'un point de vue puissance. / Active magnetic bearings with a self-sensing approach are electromechanical transducers. They realize two different functions at the same time: power function for moving the rotor, and sensor function for estimating the size of the air gap and the position of rotor. In this thesis, we developed an electromagnetic model for conception and optimization of these active magnetic bearing. In order to achieve this goal, different models were developed during this thesis:- A high frequency model of a laminated and polarized material builds with a reversible permeability measure and an homogenization model for high frequency;- A simulation model induced currents in a laminated rotor created by its own rotation. This one permits eddy current losses determination and the impact of rotation on the position estimation;- Finally, a high frequency impedance model for a laminated, saturated and polarized magnetic circuit. This model computes in 3 steps: nonlinear magnetostatic calculation, integration of high frequency model and linear magnetodynamic calculation. These different approaches were validated experimentally with an Epstein frame and with two different magnetic bearings. All these models were then exploited in a tool for optimal conception of active magnetic bearings with a self-sensing approach. Finally, a bi-objective multivariable optimization was realized to design an optimal active magnetic bearing to both estimate position and create force.

This thesis seeks to advance the field of microrobotics by leveraging Bayesian principles and computational tools to design system parameters for information gain and microrobot propulsion. Inspired by living cells, the development of mobile robots on the micron scale (microrobots) promises new capabilities for advancing human health, renewable energy, and environmental sustainability. To help pave the way towards this goal we develop practical recipes for applying computational and analytical tools to physics-based dynamical models of our microrobot experiments. We apply methods of criticism and validation to identify robust models for the motion of magnetic particles at curved interfaces, and identify optimal conditions for propulsion in our model system. We then develop tools for identifying optimal experimental conditions for most efficiently learning model parameters. By studying microscale actuation in depth, we seek to provide a roadmap of how to apply these computational tools to other microrobot design challenges, accelerating the scientific process. In Chapter 1, we focus on the actuation of magnetic particles adsorbed at curved liquid interfaces by external fields, a phenomenon that can be utilized for applications such as droplet mixing or propulsion. To optimize these behaviors, the development and validation of predictive models are essential. We employ Bayesian data analysis as a principled approach to infer model parameters from experimental observations, assess the capabilities of candidate models, and select the most plausible among them. Specifically, we identify and validate a dynamical model which accounts for the effects of gravity and tilting of the particle, a Janus sphere, at the interface. We show how this favored model can predict complex particle trajectories with micron-level accuracy across the range of driving fields considered. Chapter 2 builds on this modeling to develop the optimal properties of a mobile liquid droplet, driven by an adsorbed magnetic particle. This configuration enables the design of responsive emulsions, which can be actuated by a magnetic field. This work develops the properties of such a swimmer and validates our findings with an experimental realization of a ferromagnetic ellipsoid adsorbed onto a stationary water droplet in decane. Accounting for geometric differences, the model developed in the previous chapter is demonstrated to be accurate for this new system. We find that the configuration of the magnetic moment of our ellipsoid prohibits swimming of the assembly, but if it can be modified during fabrication, propulsion is possible. In Chapter 3 we show how automated experiments based on Bayesian inference and design can accurately and efficiently characterize another microscale propulsion system, the acoustic field within resonant chambers used to propel acoustic nanomotors. Repeated cycles of observation, inference, and design are guided by a physical model that describes the rate at which levitating particles approach the nodal plane. We show how this iterative process serves to discriminate between competing hypotheses and efficiently converges to accurate parameter estimates using only a few automated experiments. This work demonstrates how Bayesian methods can learn the parameters of nonlinear hierarchical models used to describe video microscopy data of active colloids. Finally, the forward-looking perspective in Chapter 4 illustrates how best to leverage these techniques and models to provide a path forward for self-guided microrobots. Existing microrobots based on field-driven particles rely on knowledge of the particle position and the target destination to control particle motion through fluid environments. These external control strategies are challenged by limited information and global actuation, where a common field directs multiple robots with unknown positions. We discuss how time-varying magnetic fields can be used to encode self-guided behaviors of magnetic particles conditioned on local environmental cues. Programming these behaviors is framed as a design problem: we seek to identify the design variables (e.g. particle shape, magnetization, elasticity, stimuli-response) that achieve the desired performance in a given environment. We discuss strategies for accelerating the design process using the methods developed in this thesis—including automated experiments, computational models, and statistical inference—as well as other approaches such as machine learning. Based on the current understanding of field-driven particle dynamics and existing capabilities for particle fabrication and actuation, we argue that self-guided microrobots with potentially transformative capabilities are close at hand. This research offers a unique contribution by demonstrating the practicality and efficiency of Bayesian computational methods in microrobot design, and provides a template that is applicable anywhere that physics-based dynamical models can be used to guide experimental effort.