objective of this thesis is to contribute to the understanding of the behavior of the liquid metal eutectic gallium/indium (EGaIn) in composite systems and provide a platform for the development of functional hybrid nanocomposites. Contributions are regarding (i) the investigation of the electromechanical coupling performance of EGaIn as electrodes in a soft electrostatic transducer and (ii) the effectiveness of organic surfactants to stabilize EGaIn nanoparticles in organic solvents. For the first portion, a completely soft dielectric elastomer actuator (DEA) using EGaIn electrodes was fabricated and evaluated. Experimental actuation of the DEA showed high agreement with a generalized NeoHookean constitutive law, assuming uniaxial pre-stretch and considering the device saddle deformation. The expected conductive behavior of the liquid alloy was confirmed, and further efforts have focused on the development and stabilization of EGaIn nanodroplets, which do not exhibit the problems associated with larger pools of EGaIn (such as leakage) and can be applied to soft multifunctional materials. A computational procedure was developed for calculating suspended EGaIn nanoparticle mass in order to determine reaction yields using applied Mie theory and optical characterization techniques (dynamic light scattering and UV/Vis spectrophotometry). This method calculated total mass to within 20% when applied to a known system. A systematic study evaluating particle yield as a function of aliphatic surfactant composition and concentration (and solvent type) revealed a pronounced dependence of nanodroplet formation on the solvent type as well as surfactant structure. Ethanol (EtOH) was found to be the most effective solvent for the formation and stabilization of EGaIn nanodroplets, in which only thiol-based surfactants were found to improve nanodroplet yield. Results suggest a stabilization mechanism other than the expected self-assembled monolayer (SAM) formation. The research has been extended to alternative (e.g. plant based) surfactant systems.

Soft electronics have become increasingly necessary for the implementation and integration of novel technologies in a variety of environments including aerospace, robotics, and healthcare. In order to develop these soft electronic devices, materials and manufacturing strategies are required for these soft, stretchable, and flexible systems. Further, the ability to effectively tune not only these mechanical properties but also their thermal and electrical properties is key to developing multifunctional materials for soft electronic applications. In this thesis, we present a method of printing highly tunable flexible and stretchable composites consisting of elastomers with liquid metal (LM) inclusions. We analyze the mechanical and functional behaviors and highlight the anisotropic properties that can be created via our printing system, and we apply this understanding to the development of a multiphase material with a programmable crack propagation path. Throughout this work we describe the process by which we use Direct Ink Write (DIW) technology, a type of additive manufacturing, to print 2D and 3D LM composites with tunable properties. The design map used to control LM microstructure in-situ is first outlined in Chapter 2. This tuning ability is used to print materials with varied LM microstructures and study the impact on mechanical, thermal, and electrical properties (Chapter 2, Chapter 3). We further study the elongated LM droplet inclusions for how their orientation with respect to loading may impact mechanical properties (Chapter 3). We further utilize these findings to control crack propagation along a specified path using only variations in printing parameters (Chapter 3). We provide concluding statements and outlooks on future work in Chapter 4. We then summarize our findings and detail the implications for the soft electronics field (Chapter 5). / Master of Science / Soft electronics have become increasingly necessary for the successful implementation and integration of novel technologies in a variety of environments including the spaces of aerospace, robotics, and healthcare. In order to develop these soft electronic devices, a new class of materials with soft, stretchable, and flexible properties is critical. Further, the ability to effectively tune not only these mechanical properties but also their thermal and electrical properties is key to developing high-functioning materials for soft electronic applications. In this thesis, we present a method of printing highly tunable flexible and stretchable materials with liquid metal (LM), known as liquid metal embedded elastomers (LMEEs). We analyze the mechanical properties and their direction-dependent nature that can be tuned via our printing system, and we apply this understanding to the development of a 2D material with a programmable path along which the material will tear. Throughout this work we describe the process by which we use Direct Ink Write (DIW) technology, a type of additive manufacturing, to print 2D and 3D LMEE structures with tunable properties. The design map used to control the LM microstructure in-situ is first outlined in Chapter 2. This tuning ability is used to print materials with varied LM microstructures and study the impact on mechanical, thermal, and electrical properties (Chapter 2, Chapter 3). We further study the elongated LM droplet inclusions for how their orientation with respect to loading may impact mechanical failure (Chapter 3). We further utilize these findings to control crack propagation along a specified path using only variations in printing parameters (Chapter 3). We provide concluding statements and outlooks on future work in Chapter 4. We then summarize our findings and detail the implications for the soft electronics field (Chapter 5)

We investigate the newly discovered, superconducting metal-mixed polymers made by embedding a surface layer of metal (a tin-antimony alloy) into a plastic substrate (polyetheretherketone - PEEK). Focusing initially on pre-implanted systems, we show that while the substrate morphology does affect the distribution of metal deposited on the surface, the morphology has no affect on the film's electrical properties. We find that the metal content can be characterised via the film's optical absorption, which along with the conductivity, scales with thickness. By conducting low temperature resistivity measurements we observe that the superconducting critical temperature, $T_c$, remains at that of bulk Sn but the transition broadens with decreasing film thickness. Studying N-implanted metal-mixed polymers, we find that the implant temperature can influence the electrical properties of these systems, as higher implant temperatures result in greater disorder, which in turn causes higher residual resistances and broader superconducting transitions. We observe peaks in the magnetoresistance of superconducting/insulating systems, which we attribute to the competition between superconductivity and weak localisation in a granular network. We determine that the substrate morphology does not influence the electrical properties of implanted systems. We investigate the role sputtering plays by implanting heavier ions (Sn) and show that this technique can be used to overcome the issue of inhomogeneity inherent with using thinner initial films. We study the effect the fabrication parameters of implant dose, beam energy and film thickness have on Sn-implanted metal-mixed polymers and find that with only minor changes in the fabrication conditions, it is possible to tune the conductivities of these materials between a zero-resistance superconducting state, through a metal-insulator transition, to a severely insulating state ($R_s > 10^{10}~\Omega/\Box$). We find that the electrical properties can be further controlled by annealing the samples, and that it is possible to induce optical changes at temperatures approaching the glass transition temperature of PEEK. We demonstrate that metal-mixed polymers are suitable for use in resistance-based temperature sensors by comparing their performance directly against commercially available products and find that the metal-mixed polymers perform at least as well as the commercial models and, indeed, pass the highest industry standards.

abstract: Presented in this thesis are two projects that fall under the umbrella of magnetically actuated electronics and robotics for medical applications. First, magnetically actuated tunable soft electronics are discussed in Chapter 2. Wearable and implantable soft electronics are clinically available and commonplace. However, these devices can be taken a step further to improve the lives of their users by adding remote tunability. The four electric units tested were planar inductors, axial inductors, capacitors and resistors. The devices were made of polydimethylsiloxane (PDMS) for flexibility with copper components for conductivity. The units were tuned using magnets and mobile components comprised of iron filings and ferrofluid. The characteristic properties examined for each unit are as follows: inductance and quality factor (Q-factor) for inductors, capacitance and Q-factor for capacitors, and impedance for resistors. There were two groups of tuning tests: quantity effect and position effect of the mobile component. The position of the mobile component had a larger effect on each unit, with 20-23% change in inductance for inductors (from 3.31 µH for planar and 0.44 µH for axial), 12.7% from 2.854 pF for capacitors and 185.3% from 0.353 kΩ for resistors. Chapter 3 discusses a magnetic needle tracking device with operative assistance from a six degree-of-freedom robotic arm. Traditional needle steering faces many obstacles such as torsional effects, buckling, and small radii of curvature. To improve upon the concept, this project uses permanent magnets in parallel with a tracking system to steer and determine the position and orientation of the needle in real time. The magnet configuration is located at the end effector of the robotic arm. The trajectory of the end effector depends on the needle’s path, and vice versa. The distance the needle travels inside the workspace is tracked by a direct current (DC) motor, to which the needle is tethered. Combining this length with the pose of the end effector, the position and orientation of the needle can be calculated. Simulation of this tracking device has shown the functionality of the system. Testing has been done to confirm that a single magnet pulls the needle through the phantom tissue. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2020

Organic electronic devices are becoming commonplace in many academic and industrial materials laboratories, and commercial application of these technologies is underway. To maximize our fundamental understanding of organic electronics, a wide array of molecular frameworks is necessary, as it allows for a variety of optical and electronic properties to be systematically investigated. With the ability to further tune each individual scaffold via derivatization, access to a broad spectrum of interesting materials is possible. Of particular interest in the search for organic semiconducting materials are the cyclopenta-fused polyaromatic hydrocarbons, including those based on the fully conjugated indenofluorene (IF) system, which is comprised of five structural isomers. This dissertation represents my recent contributions to this area of research. Chapter I serves as a historical perspective on early indenofluorene research and a review of more current research on their synthesis and applications in organic electronic devices. Chapters II and III cover our early work developing the synthesis of the fully-reduced indeno[1,2-b]fluorene scaffold, with the latter of these chapters showing the first example of its application in an organic electronic device, a field effect transistor. Chapter IV demonstrates the first syntheses of fully-reduced indeno[2,1-c]fluorene derivatives. Chapter V expands our research to encompass isoelectronic heteroatomic derivatives of that same scaffold, introducing the fully-reduced diindeno[2,1-b:1',2'-d]thiophene scaffold and showing that our synthetic methodology also can be used to produce a quinoidal thiophene core. Chapter VI concludes with a review of the similarities between the indeno[2,1-c]fluorene and diindeno[2,1-b:1',2'-d]thiophene molecular architectures and introduces benzo[a]indeno[2,1-b]fluorene derivatives, demonstrating the first example of a fully-reduced indenofluorene that possesses a non-quinoidal core, illustrating that the quinoidal core is not a prerequisite for the strong electron affinities seen across the families of fully-reduced indenofluorenes. This dissertation encompasses previously published and unpublished co-authored material. / 2015-10-10

No description available.

The field of soft electronics is rapidly growing as there is an increased demand for health monitoring using wearable electronics that conforms to biological tissue. To promote sustainability and reduce electronic waste, it is of interest to find ways to reuse low-value-added commodities, such as protein-rich byproducts, for materials in high-value-added technologies that are degradable at end of use. One recognised byproduct from meat production is the abundant protein collagen, or the hydrolysed derivative gelatine. To overcome the limited mechanical properties of gelatine, it can be functionalised with a polymer with previous use in tissue-engineering and battery encapsulation, namely Poly(Glycerol Sebacate)(PGS), to generate the copolymer PGS-G. The work described in this thesis focuses on PGS and PGS-G polymer characterisation by utilising ATR-FTIR and DSC, but also on material characterisation of mechanical and hydration properties, ionic conductivity, and degradation. The results indicate that the successfully synthesised PGS and PGS-G polymers should not be crosslinked completely to achieve the most flexible mechanical properties, but also that crosslinking density should be tuned to suit the application. Moreover, incorporation of gelatine in PGS resulted in increased hydrophilicity for PGS-G. Finally, it was concluded that PGS is suitable for encapsulation whereas PGS-G could be used as an active component. Future work should include degradation studies in vivo and under environmental aerobic conditions to ensure that the polymers are fully biodegradable. / Mjuk elektronik är ett nytt forskningsområde som utvecklas starkt i takt med den ökade efterfrågan på hälsoövervakning med innovativ elektronik som är mjuk och töjbar vilket möjliggör smidig integrering i biologisk vävnad. För att främja hållbarhet och minska elektroniskt avfall så är det av intresse att återanvända lågt värderade handelsvaror, såsom proteinrika restprodukter från industrin, till att skapa funktionella material för värdeskapande teknologier vilka är nedbrytbara efter användning. En välkänd restprodukt från köttproduktion är proteinet kollagen och dess hydrolyserade derivat gelatin. För att förbättra de mekaniska egenskaperna hos gelatin så kan det funktionaliseras med en polymer, vid namn Poly(Glycerol Sebacate)(PGS), som tidigare har använts för att skapa substitut till biologisk vävnad och batteriinkapsling. Denna reaktion genererar den nya polymeren PGS-G. I det här examensarbetet beskrivs karaktärisering av polymererna PGS och PGS-G, som utfördes med ATR-FTIR och DSC, samt karaktärisering av materialets mekaniska och hydrerande egenskaper men även dess ledningsförmåga och nedbrytbarhet. Resultaten indikerar att polymererna PGS och PGS-G ej bör tvärbindas fullständigt för att uppnå optimala mekaniska egenskaper med avseende på flexibilitet men också att tvärbindningen ska justeras beroende på tillämpningen. Vidare bidrar inkorporeringen av gelatin i PGS till en ökad hydrofilicitet i PGS-G. Slutligen visades det att PGS är lämpligt för inkapsling medan PGS-G kan användas som en aktiv komponent. Innan tillämpning behöver ytterligare studier genomföras med avseende på nedbrytbarhet, dels in vivo, dels i aerobiska förhållanden, för att säkerhetsställa att polymererna är fullständigt nedbrytbara.

Il y a à l'heure actuelle un grand besoin d'antennes reconfigurables dans la bande des 60 GHz pour des applications de télédétection et de télécommunications sans fil très hauts débits. Les solutions traditionnelles de reconfiguration sont basées sur des semiconducteurs ou des composants RF-MEMS, qui connaissent un coût, une complexité et des pertes croissantes en bande millimétrique. Dans cette thèse, une approche originale a été développée : elle est basée sur la reconfiguration mécanique d'antennes et dispositifs millimétriques microrubans sur substrat élastomère ultrasouple PDMS grâce à des actionneurs MEMS grands déplacements. Premièrement, les choix de conception, la technique de simulation éléments finis (HFSS), et surtout la microfabrication d'antennes sur membrane PDMS ainsi que les techniques de mesure en impédance et rayonnement sont abordés.Deux axes ont ensuite été étudiés : les antennes accordables en fréquence, et les antennes et composants pour le balayage angulaire (déphaseurs et antennes à balayage mécanique de type scanner). Des procédés technologiques innovants ont été développés (reports de métallisations épaisses biocompatibles et d'aimants permanents en couches minces sur membrane PDMS) et différentes techniques d'actionnement (pneumatique, magnétique, par électromouillage) ont été mises en œuvre. Les performances en terme d'accord en fréquence (8,2 %) et de balayage angulaire (-90/+100°) dépassent l'état de l'art des antennes du même type en bande millimétrique, et ceci en utilisant une technologie peu complexe, ultra bas-coût et prometteuse pour la montée en fréquence. / There is currently an increasing need for reconfigurable antennas in the 60 GHz band for remote sensing applications and wireless communications. Traditional reconfiguration solutions are based on semiconductors or RF-MEMS but these components face cost, complexity and losses issues at millimeter-waves.In this thesis, an original approach was developed: it is based on the mechanical reconfiguration of millimeter-wave microstrip antennas and devices printed on ultrasoft PDMS substrates, thank to large displacements MEMS actuators. First, the design choices, the finite element simulation technique (HFSS), and the microfabrication of antennas supported by PDMS membranes as well as the impedance and radiation measurements techniques have been discussed. Two axis have then been studied: frequency-tunable antennas, and beam-steering components (phase shifters and "scanner" type antennas). Innovative technological processes were developed (transfer of biocompatible metal patterns and permanent magnet thin films on PDMS membranes) and several actuation techniques (pneumatic, magnetic, electrowetting) were implemented. Performances in terms of frequency tuning (8.2%) and scan angles (-90 / 100 °) are beyond the state of the art for similar antennas in the millimeter-wave band, and are achieved by using a very simple, ultra low-cost technique that is expected to be effective at even higher frequencies.