This thesis investigates inkjet-printed flexible antennas fabricated on paper substrates as a system-level solution for ultra-low-cost and mass production of RF structures. These modules are designed for the UHF Radio Frequency Identification (RFID) Tags and Wireless Sensor Nodes (WSN); however the approach could be easily extended to other microwave and wireless applications. Chapter 1 serves as an introduction to RFID technology and its capabilities while listing the major challenges that could potentially hinder RFID practical implementation. Chapter 2 discusses the benefits of using paper as a substrate for high-frequency applications, reporting its very good electrical/dielectric performance up to at least 1 GHz. The dielectric properties are studied by using the microstrip ring resonator. Brief discussion on Liquid Crystal Polymer (LCP) is also given in this chapter. Chapter 3 gives details about the inkjet printing technology, including the characterization of the conductive ink, which consists of nano-silver-particles, while highlighting the importance of this technology as a fast and simple fabrication technique especially on flexible organic (e.g.LCP) or paper-based substrates. Chapter 4 focuses on antenna designs. Four examples are given to provide: i) matching techniques to complex IC impedance, ii) proof of concept of inkjet printing on paper substrate through measurement results, iii) demonstration of a fully-integrated wireless sensor modules on paper and show a 2D sensor integration with an RFID tag module on paper. Chapter 5 concludes the thesis by explaining the importance of this work in creating a first step towards an environmentally friendly generation of "green" RF electronics and modules.

No description available.

Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment. The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.

The objective of this research is to explore the possibilities of developing transmit/receive (T/R) modules using silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) BiCMOS technology to integrate with organic liquid crystal polymer (LCP) packages for the next-generation phased-array radar system. The T/R module requirements are low power, compact, lightweight, low cost, high performance, and high reliability. All these requirements have provided a very strong motivation for developing fully monolithic T/R modules. SiGe HBT BiCMOS technology is an excellent candidate to integrate all the RF circuit blocks on the T/R module into a single die and thus, reducing the overall cost and size of the phase-array radar system. In addition, this research also investigates the effects and the modeling issues of LCP package on the SiGe circuits at X-band.

abstract: Scientists have used X-rays to study biological molecules for nearly a century. Now with the X-ray free electron laser (XFEL), new methods have been developed to advance structural biology. These new methods include serial femtosecond crystallography, single particle imaging, solution scattering, and time resolved techniques. The XFEL is characterized by high intensity pulses, which are only about 50 femtoseconds in duration. The intensity allows for scattering from microscopic particles, while the short pulses offer a way to outrun radiation damage. XFELs are powerful enough to obliterate most samples in a single pulse. While this allows for a “diffract and destroy” methodology, it also requires instrumentation that can position microscopic particles into the X-ray beam (which may also be microscopic), continuously renew the sample after each pulse, and maintain sample viability during data collection. Typically these experiments have used liquid microjets to continuously renew sample. The high flow rate associated with liquid microjets requires large amounts of sample, most of which runs to waste between pulses. An injector designed to stream a viscous gel-like material called lipidic cubic phase (LCP) was developed to address this problem. LCP, commonly used as a growth medium for membrane protein crystals, lends itself to low flow rate jetting and so reduces the amount of sample wasted significantly. This work discusses sample delivery and injection for XFEL experiments. It reviews the liquid microjet method extensively, and presents the LCP injector as a novel device for serial crystallography, including detailed protocols for the LCP injector and anti-settler operation. / Dissertation/Thesis / Doctoral Dissertation Physics 2015

Die Arbeit behandelt ausgewählte Aspekte der Ausbildung strömungsinduzierter Orientierungen und deren Auswirkung auf die mechanischen Eigenschaften in spritzgegossenen LCP-Formteilen. Es werden die Grundlagen zum rheologischen Verhalten von LCP, zum Füllvorgang und zur Orientierungsausbildung beim Spritzgießen sowie zu den Methoden der Orientierungsuntersuchung zusammengefaßt. Rheologische Untersuchungen werden aus der Sicht der praktischen Kennwertermittlung durchgeführt. Dabei wird die Abhängigkeit der Viskosität von der Düsenlänge und von der thermo-rheologischen Vorgeschichte analysiert sowie eine Viskosimeter-Vorrichtung für die Spritzgießmaschine vorgestellt und erprobt. Die umfangreiche Analyse verarbeitungsinduzierter Formteileigenschaften behandelt schwerpunktmäßig Orientierungsphänomene in der Wanddickenrichtung. Die Orientierungseffekte werden durch Grauwertmessungen erfaßt. Ein Meßaufbau mit einer kalibrierten Mikroskop-Digitalkamera-Kombination ermöglicht die reproduzierbare, effektive Messung der Grauwerte in hoher Ortsauflösung und damit eine über die bisher bekannten qualitativen Vergleiche hinausgehende quantitative Auswertung. Anhand der Grauwertverläufe wird der Einfluss technologischer und konstruktiver Parameter auf die Orientierungsstruktur dargelegt und mit Ergebnissen der Computersimulation verglichen. Durch parallele Messung anisotroper mechanischer Kennwerte und Orientierungsmerkmale werden richtungsabhängige Struktur-Eigenschafts-Beziehungen bestimmt.

The advances in modern communication systems have brought about devices with more functionality, better performance, smaller size, lighter weight and lower cost. Meanwhile, the requirement for newer devices has become more demanding than ever. Tunability and flexibility are both long-desired features. Tunable devices are ‘smart’ in the sense that they can adapt to the dynamic environment or varying user demand as well as correct the minor deviations due to manufacturing fluctuations, therefore making it possible to reduce system complexity and overall cost. It is also desired that electronics be flexible to provide conformability and portability. Previously, tunable devices on flexible substrates have been realized mainly by dicing and assembling. This approach is straightforward and easy to carry out. However, it will become a “mission impossible” when it comes to assembling a large amount of rigid devices on a flexible substrate. Moreover, the operating frequency is often limited by the parasitic effect of the interconnection between the diced device and the rest of the circuit on the flexible substrate. A recent effort utilized a strain-sharing Si/SiGe/Si nanomembrane to transfer a device onto a flexible substrate. This approach works very well for silicon based devices with small dimensions, such as transistors and varactor diodes. Large-scale fabrication capability is still under investigation. A new transfer technique is proposed and studied in this research. Tunable BST (Barium Strontium Titanate) IDCs (inter-digital capacitors) are first fabricated on a silicon substrate. The devices are then transferred onto a flexible LCP (liquid crystalline polymer) substrate using iv wafer bonding of the silicon substrate to the LCP substrate, followed by silicon etching. This approach allows for monolithic fabrication so that the transferred devices can operate in millimeter wave frequency. The tunability, capacitance, Q factor and equivalent circuit are studied. The simulated and measured performances are compared. BST capacitors on LCP substrates are also compared with those on sapphire substrates to prove that this transfer process does not impair the performance. A primary study of a reflectarray antenna unit cell is also conducted for loss and phase swing performance. The BST thin film layout and bias line positions are studied in order to reduce the total loss. Transferring a full-size BST-based reflectarray antenna onto an LCP substrate is the ultimate goal, and this work is ongoing at the University of Central Florida (UCF). HFSS is used to simulate the devices and to prove the concept. All of the devices are fabricated in the clean room at UCF. Probe station measurements and waveguide measurements are performed on the capacitors and reflectarray antenna unit cells respectively. This work is the first comprehensive demonstration of this novel transfer technique.

This thesis focuses on transport properties and durability of liquid crystalline polymers (LCP)and fibre reinforced plastics (FRP) with regard to application in industrial process equipment.In the first part of the study the possibility of using a thermotropic LCP of type Vectra A950as lining material for FRP process equipment was investigated. Its performance wascompared to that of a fluorinated ethylene propylene copolymer (FEP) with respect tochemical and permeation resistance. Transport property and chemical resistance data wereestablished for different types of LCP film (compression molded, uniaxially and biaxiallyoriented film) exposed to selected chemicals chosen to represent typical industrial processenvironments. Annealing of the LCP, which may reduce the disclination density and henceimprove the barrier properties, induced a crystallinity increase, but did not significantlyimprove the barrier and chemical resistance properties. Different surface treatments toincrease the bonding between the LCP and FRP were explored. The conclusion was that LCPhas potential to serve as lining material for FRP in contact with water, organic solvents andnon-oxidizing acid environments, although certain issues, such as jointing techniques, stillhave to be evaluated. The second part of the study focused on transport and long-termproperties of commercial thermoset and FRP materials for industrial process equipment inaqueous environments (50 – 95 °C, water activity 0.78 – 1, exposure time ≤ 1000 days). Thewater transport properties in different thermosets were related to their chemical structureusing the solubility parameter concept. The transport of water in the thermosets with differentchemical structures could be predicted from the water activity, regardless of the actual type ofionic or non-ionic solute in the solution. An empirical relationship, independent of boththermoset chemistry and temperature, was established to describe the water concentration inthe thermoset as a function of water activity and the water concentration in pure water. Inlong-term, the water concentration in the thermosets increased with exposure time. Thisseemed to be primarily related to stress relaxation processes induced by water absorption andcertain leaching effects. The effects of hydrolysis seemed to be small. The glass fibrereinforcement may to various extents affect the water transport properties by capillarydiffusion and additional absorption around fibre bundles. The extent of such processesseemed to depend on temperature, water activity and the type of thermoset and reinforcement.The present work may be a useful contribution to an increased understanding of water effectsand durability of FRP process equipment. However, open questions still remain for a morecomprehensive durability analysis. / QC20100629

Wireless communications have been an indispensable aspect of everyday life, and there is an increasing consumer demand for accessing several wireless communication technologies from a single, compact, mobile device. System-on-package (SOP) technology is an advanced packaging technology that has been proven to realize the convergence of multiple functions into miniaturized, high-performance systems to meet this demand. With the advancements in the SOP technology, the miniaturization of the front-end module has been achieved using embedded passives in multilayer packages. However, the integration of the antenna directly on the module package is still the barrier to achieve a fully-integrated, high-performance RF SOP system. The main reason for this missing link is that integrating the antenna on the package requires miniaturizing the antenna, which is a difficult task. The focus of this dissertation is to design high-performance antennas along with developing techniques for miniaturization and system-on-package (SOP) integration of these antennas to achieve fully-integrated SOP systems using advanced multilayer organic substrates and thin-film magneto-dielectric materials. The targeted spectrum for the antenna designs are 2.4/5 GHz WLAN/WiMAX and 60 GHz WPAN bands. Several novel antenna designs and configurations to integrate the antenna on the package along with the module are discussed in this dissertation. The advanced polymers used in this research are Liquid Crystalline Polymer (LCP), RXP, and thin-film magneto-dielectrics.

This study investigated the relationship of out-of-class English use and proficiency gains. It also explored the relationship of gender, proficiency level and native language and the possible effect of these demographics on out-of-class English use and language gains in English. Though some studies have shown that those who spend more out-of-class time using the target language have higher language gain (Seliger, 1977), other studies have not found this to be true (Day, 1985; Freed 1990; Spada, 1986). Some reasons for the discrepancy in findings may be differences in the length of the time data is collected, samples of study participants and types of tests used to measure proficiency. Sixty-one students at an intensive English language program came from 12 different language backgrounds and 4 proficiency levels. They participated in a 31-week-long study. Participants took a proficiency pre- and posttest (Elicited Imitation Test) and responded to a questionnaire designed to elicit information about out-of-class language use (Language Contact Profile). In addition to the questionnaire, six students participated in semi-structured interviews that offered additional support for the data gathered by the questionnaire. Data obtained from the questionnaire and interviews was compared to gains in proficiency between the pre- and posttest. The results suggest that using English out-of-class helps improve oral proficiency. In addition, the study shows that gender, proficiency level and native language are not significant predictors of out-of-class English use and proficiency gains. These findings are discussed in light of what teachers and school administrators can do to help their students use the target language in and out of class for best results.