In this study, we explore ultra-thin insulators of organic and inorganic composition and their potential role as high-speed rectifiers. Typical applications for these structures include IR sensing, chemical detection, high speed logic circuits, and MEMS enhancements. While there are many elements in the functional group required to create a rectifying antenna (rectenna), the primary thrust of this work is on the rectifier element itself. To achieve these research goals, a very good understanding of quantum tunneling was required to model the underlying phenomenon of charge conduction. The development of a multi-variable optimization routine for tunneling prediction was required. MATLAB was selected as the programming language for this application because of its flexibility and relative ease of use for simulation purposes. Modeling of physical processes, control of electromechanical systems, and simulation of ion implantation were also to be undertaken. To advance the process science, a lithographic mask set was made which utilized the information gleaned from the theoretical simulations and initial basic experiments to create a number of diode test structures. This came to include the creation of generations of mask sets--each optimizing various parameters including testability, alignment, contact area, device density, and process ease. Following this work, a complete toolset for the creation of "soft" contact top metals was required and needed to be developed. Ultra-flat substrates were needed to improve device reliability and measurement consistency. The final phase of research included measurement and characterization of the resultant structures. Basic DC electrical characterization of the organic monolayers would be accomplished using metal probes. Statistical studies of reliability and process yield could then easily be carried out. The rectification ratio (ratio of forward over reverse current at a given voltage magnitude) was found to be a reliable indicator of diode performance in the low frequency ranges. This would mean writing additional code in MATLAB to assist in the automatic analysis for the acquired IV curves. Progression to AC / RF measurements of tunneling performance was to be accomplished using relatively low frequencies (below 100 MHz). Finally, the organic films themselves would be studied for consistency, impedance characteristics, incidence of defects, and thickness by a variety of metrology techniques. This project resulted in a number of advances to the state-of-the-art in nanofabrication using organic monolayers. A very detailed review of the state of alkanethiol research was presented and submitted for publication. A single pot technique was developed to softly deposit metal nanoparticles onto a charged surface with a high degree of control. A temporary contact method using pure, sub-cooled gallium liquid metal was used to probe organic monolayers and plot IV curves with better understanding of surface states than before. An inkjet printer solution was devised for top contact printing which involved the development and production of a work-up free insulator ink which is water soluble and printable to resolutions of about 25 um. Localized selective chemical crosslinking was found to reduce printed ink solubility following deposition. Future work will likely include additional exploration of crosslinkable Langmuir-Blodgett films as MIM insulators. Stability and testing will hinge on the fabrication of enclosures or packages for environmental isolation.

Collective magnetic behavior in nanostructures is a phenomenon commonly observed in various magnetic systems. It arises due to competing inter/intra–particle interactions and size distribution and can manifest in phenomena like magnetic freezing, magnetic aging, and exchange bias (EB) effect. In order to probe these rather complex phenomena, conventional DC and AC magnetic measurements have been performed along with radio–frequency transverse susceptibility (TS) measurements. We also demonstrate the magnetic entropy change as a parameter sensitive to subtle changes in the magnetization dynamics of nanostructures. The focus of this dissertation is to study the collective magnetic behavior in core-shell nanostructures of Fe/γ–Fe2O3 and Co/CoO, La0.5Sr0.5MnO3 nanowires, and LaMnO3 nanoparticles. In the case of core/shell Fe/γ–Fe2O3, we found the particles to critically slow down below the glass transition temperature, below which they exhibit aging effects associated with a superspin glass (SSG) state. We demonstrate that it is possible to identify individual magnetic responses of the Fe core and the γ–Fe2O3 shell. Consistently, a systematic study of the magnetocaloric effect (MCE) in the Fe/γ–Fe2O3 system reveals the development of inverse MCE with peaks associated with the individual magnetic freezing of the core and the shell. From these obtained results, we establish a general criterion for EB to develop in core/shell nanostructures, that is when the core is in the frozen state and the magnetic moments in the shell begin to block. This criterion is shown to be valid for both ferromagnetic/ferrimagnetic (FM/FIM) Fe/γ–Fe2O3 and ferromagnetic/antiferromagnetic (FM/AFM) Co/CoO core–shell nanostructures. We also elucidate the physical origin of the occurrence of asymmetry in field-cooled hysteresis loops and its dependence on magnetic anisotropy in the Co/CoO system by performing a detailed TS study. We have performed a detailed magnetic study on hydrothermally synthesized single crystalline La0.5Sr0.5MnO3 nanowires. The temperature and field dependent evolution of the different magnetic phases leading to development of the inverse MCE and EB in the nanowires is discussed. Finally, we have studied the collective magnetic behavior of LaMnO3 nanoparticles synthesized by the sol–gel technique. The nanoparticle ensemble shows the unusual co–existence of super-ferromagnetism (SFM), as well as the SSG state, which we term the 'ferromagnetic superglass' (FSG) state. The existence of FSG and the characteristics of its magnetic ground state are discussed.

Using experimental techniques along with computational fluid dynamics and electrodynamic simulations the performance of the first of three focusing elements in an electrospray macromolecular patterning system was assessed. The performance of this element, the ion funnel, was analyzed by varying the parameters and electric field applied to the system including electrospray emitter to atmosphere-vacuum interface capillary distance, temperature of the desolvating heater, injection rate of solution and the voltage applied to the jet disruption element. Results indicated that processes involved in injecting larger droplets into the chamber resulted in a less effective transmission of the ions through the funnel. Droplet diameter was increased by increasing flow rate and was decreased by increasing the desolvation heater. Varying the voltage applied to the jet disrupting element indicated a peak transmission voltage, when using a 20 mil interface capillary,of 175 V and when using the 30 mil capillary of 180 V. Numerical simulations were in agreement with these values although the widths of these transmission curves were much narrower than the experimental curves.

The advent of numerous tools, ease of techniques, and concepts related to nanotechnology, in combination with functionalization via simple chemistry has made gold important for various biomedical applications. In this dissertation, the development and characterization of planar gold surfaces with responsive hydrogel patterns for rapid point of care sensing and the functionalization of gold nanoparticles for drug delivery are highlighted. Biomedical micro- and nanoscale devices that are spatially functionalized with intelligent hydrogels are typically fabricated using conventional UV-lithography. Herein, precise 3-D hydrogel patterns made up of temperature responsive crosslinked poly(N-isopropylacrylamide) over gold were synthesized. The XY control of the hydrogel was achieved using microcontact printing, while thickness control was achieved using atom transfer radical polymerization (ATRP). Atomic force microscopy analysis showed that to the ATRP reaction time governed the pattern growth. The temperature dependent swelling ratio was tailored by tuning the mesh size of the hydrogel. While nanopatterns exhibited a broad lower critical solution temperature (LCST) transition, surface roughness showed a sharp LCST transition. Quartz crystal microbalance with dissipation showed rapid response behavior of the thin films, which makes them applicable as functional components in biomedical devices. The easy synthesis, relative biocompatibility, inertness, and easy functionalization of gold nanoparticles (GNPs) have made them useful for various biomedical applications. Although ATRP can be successfully carried out over GNPs, the yield of stable solution based GNPs for biomedical applications prove to be low. As an alternative approach, a novel method of ISOlating, FUnctionalizing, and REleasing nanoparticles (ISOFURE) was proposed. Biodegradable poly(β-amino ester) hydrogels were used to synthesize ISOFURE-GNP composites. ATRP was performed inside the composite, and the final hydrogel coated GNPs were released via matrix degradation. Response analysis confirmed that the ISOFURE method led to the increased stability and yield of the hydrogel coated ISOFURE-GNPs. The ISOFURE protocol was also utilized in functionalizing GNPs with enzyme catalase in the absence of a stabilizing reagent. Biotin-streptavidin affinity was used as the bioconjugation method. Activity analysis of the conjugated enzyme showed that the ISOFURE-GNPs showed enhanced biomolecular loading relative to solution based stabilizing reagent passivated GNPs.

Elastin like polypeptides (ELPs) are a class of naturally derived biomaterials that are non-immunogenic, genetically encodable, and biocompatible making them ideal for a variety of biomedical applications, ranging from drug delivery to tissue engineering. Also, ELPs undergo temperature-mediated inverse phase transitioning, which allows them to be purified in a relatively simple manner from bacterial expression hosts. Being able to genetically encode ELPs allows for the incorporation of bioactive peptides and functionalization of ELPs. This work utilizes ELPs for regenerative medicine and drug delivery. The goal of the first study was to synthesize a biologically active epidermal growth factor-ELP (EGF-ELP) fusion protein that could aid in the treatment of chronic wounds. EGF plays a crucial role in wound healing by inducing epithelial cell proliferation and migration, and fibroblast proliferation. The use of exogenous EGF has seen success in the treatment of acute wounds, but has seen relatively minimal success in chronic wounds because the method of delivery does not protect exogenous EGF from degradation, or prevent it from diffusing away from the application site. We created an EGF-ELP fusion protein to combat these issues. As demonstrated through the proliferation of human skin fibroblasts in vitro, the EGF-ELP may be able to aid in the treatment of chronic wounds. Furthermore, the ability of the EGF-ELP to self-assemble near physiological temperatures could allow for the formation of drug depots at the wound site and minimize diffusion, increasing the bioavailability of EGF and enhancing tissue regeneration. The objective of the second study was to create an injectable hydrogel platform that does not require conjugation of functional moieties for crosslinking or biological activity. Hydrogels are three-dimensional polymer networks that are able to absorb water and biological fluids without dissolving. Their high water content gives them physical properties similar to soft tissues, making them useful as scaffolds for cell migration and drug delivery vehicles. Injectable hydrogels that crosslink in situ are particularly useful because they can form to the shape of the defect, providing a near perfect fit. However, many hydrogel platforms cannot be crosslinked in situ because cytotoxic crosslinking reagents are required. Additionally, hydrogels typically require the chemical conjugation of crosslinking domains and bioactive peptides to the polymer backbone, adding more steps and time required for hydrogel production. We devised an injectable hydrogel platform that can be synthesized in a single step using photoreactive ELPs as the polymer backbone. Leucine auxotrophic Eshcherichia coli expressed ELPs containing photoleucine, a leucine analog and photoreactive diazirine crosslinker, which is substituted for leucine periodically throughout the ELP sequence. Upon exposure to ultraviolet radiation (~370 nm), photoleucine is able to form covalent crosslinks with amino acid side chains, forming a polymer network for hydrogel formation. Additionally, recombinant growth factors and morphogens can be encoded into the ELP sequence providing a simple method of hydrogel functionalization for regenerative medicine applications. The potential for this platform was demonstrated through in vivo crosslinking of photoreactive ELPs in the expression hosts. Though the production of the photoreactive ELP was not as forthright as originally assumed. The substitution of noncanonical amino acids typically requires the auxotrophic expression hosts to be starved of the amino acid that they are auxotrophic for. A noncanonical analog of said amino acid can then be supplemented into expression media, maximizing incorporation. In this investigation, it was found the addition of photoleucine alone inhibited photoreactive ELP expression. ELP expression only occurred in the presence of photoleucine if valine or leucine was also present in the media. Furthermore, valine was found to aid the production of ELPs as much as leucine. It was postulated the bacterial translational machinery might need to be altered for optimal ELP expression.

Lactic acid is widely existing in human bodies, animals and microorganisms. Recently, using biosensor to detect the concentration of lactic acid and diagnose disease have attracted great research and development interests. Nanocomposites is one of the best material used for biosensor because their wonderful conductivity, optical and electrochemical properties. In the study, MoS2 and polypyrrole (PPY) are used for the composite material electrode. To determine whether lactate oxidase (LOD) was helpful for the biosensor’s detective properties, both PPY-MoS2 film with LOD and PPY-MoS2 film without LOD are being tested. The fourier transform infrared spectroscopy (FTIR) and Raman spectroscopic techniques have been used to understand the chemical bonds in the nanocomposite film. The X-ray diffraction (XRD) technique has been performed to understand the crystallographic structure of the MoS2 -PPY film. The morphologies were confirmed by scanning electron microscopy (SEM). The UV-vis spectroscopy has been used to determine the band structure of composite film. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were used to analyze in different concentration of solution, under different scan rate to obtain stability and work efficiency. These results were compared with PPY-MoS2 film with and without lactate oxidase conditions. The chronoamperometric technique has been used to detect the concentration of lactic acid.

Quadratic optimization problems arise in various real world application domains including engineering design, microeconomics, genetic algorithms, integrated circuit chip design, probabilistic graphical models and computer vision. In particular, there are many problems in computer vision that require binary quadratic optimization such as motion segmentation, correspondences, figure-ground segmentation, clustering, grouping, subgraph matching, and digital matting. The objective of an optimization algorithm can be related to the state of a physical system, where the goal is to bring the initial arbitrary state of the system to a state with minimum possible energy. By recognizing that the Hamiltonian of nanomagnets can be expressed in a quadratic form, we exploit the energy minimization aspect of these nanomagnets to solve the quadratic optimization problem in a direct manner. Most hard problems especially in computer vision can be naturally cast as energy minimization problems and solving these using traditional techniques like simulated annealing, graph cuts evidently associate with exorbitant computational efforts. In this dissertation, transcoding the conceptual crossover between the magnetic Hamiltonian and the optimization problem, we envision a nanomagnetic coprocessor with a grid of nanomagnets embracing an optimization heuristic enabling to solve energy minimization in a single clock cycle. We will essentially be solving an optimization problem with each input-and-readout cycle as compared to orders of magnitude more clock cycles that would be needed in a Boolean logic circuit. The dissertation presents results for quadratic minimization problem in the context of perceptual organization of edges in computer vision and compare quality of results using traditional optimization methods and that expected from magnetic computing. The dissertation also presents image processing algorithms for analysis of results produced by actual fabrication of the magnetic systems.

This dissertation presents a free-space, long-range, passive optical communication system that uses electrostatically modulated microelectromechanical systems (MEMS) structures coupled with a glass total internal reflection (TIR)-type corner cube retroreflector (CCR) as a non-emitting data transmitter. A CCR consists of three mirrors orthogonal to each other, so that the incident beam is reflected back to the incident beam, source. The operational concept is to have a MEMS modulator fusion with TIR CCR, such that the modulators are working periodically to disrupt the evanescent waves at the air interface of one of the three back glass faces of a TIR CCR. The MEMS chip has two primary components: (1) an array of movable light scattering silicon structures with nano roughness and (2) a glass lid with a transparent conductive indium tin oxide (ITO) film. The MEMS structures are bonded to a glass lid using flip-chip bonding. Once bonded, the MEMS structures can be modulated either toward or away from the glass lid, thus disrupting evanescent energy delivered from a probing laser beam. The MEMS structure is precisely bonded to the TIR CCR with an accuracy of 10-30 arc-seconds using a Michelson interferometry feedback system. This is a novel step by which an existing passive commercial CCR can be converted into a modulating active CCR. This CCR-MEMS unit acts as the key element of the transmitter. To illustrate the concept of a low-power, unattended, sensor-monitoring system, we developed a sensor board containing temperature, humidity, and magnetic sensors along with a microprocessor and other electronics. The sensor board and CCR board are packed together and act as the transmitter unit. We developed a benchtop system and an improved portable receiver system. The receiver system contains the laser (as source), a collimating lens (to collect retroreflected signal), an optical, narrow band pass filter, and a detector. The detector signal was amplified and filtered and sent either to the oscilloscope, a lock-in-amplifier, or a laptop to display the sensor data. Using the receiver system, a sensor-CCR-based transmitter unit, and receiver with 635 nm as source, we achieved retroreflective communication over a distance of 300 m.

Polyvinylidene difluoride (PVDF) is a functional polymeric material that can be used for a wide variety of applications. There are many new future applications that were recently suggested for electrospun PVDF fibers. Electrospinning is a process capable of producing nano to micro sized PVDF fibers in a web. It is important to control the structure of the web during electrospinning because by controlling the structure of the web it is possible for the PVDF fiber web to have increased performance in comparison to other common forms of PVDF. While past scientific literature focused on applications of PVDF fibers, little was known on how to control structure of PVDF fiber webs during production. Even though defects can alter the structure and performance of the web only a few studies reported defect occurrence and how to reduce the occurrence of defects in fiber webs. This research investigated the defect free production space of electrospun PVDF and provided streamlined guidelines for manufacturers to use for electrospinning PVDF webs. Many studies looked at influencing fiber diameter and beading with one factor at a time experimentation; this work was foundational and was able to identify many important electrospinning parameters. But this methodology neglected the possibility of parameter interactions and often did not look at the effects of parameters on the occurrence of defects and the structure of those defects. Therefore a systematic understanding that included all of the important electrospinning parameters in relation to fiber and defect structure was needed to present a clear picture of the possibilities for controlling the structure of electrospun PVDF webs. This research explored ways to control the structure of PVDF fiber webs. The production space and control of web structure was explored by using a regression analysis to identify important parameters and interactions. Then the regression analysis was used to determine the effects of the important parameters that influenced the web structure. This research showed that the web structure can be controlled using solution parameters and processing parameters and monitored by system parameters. In addition, this study showed that by controlling the web structure it was possible to influence the porosity and piezoelectric properties of PVDF fiber webs. In its entirety, this research presents a systematic approach to producing PVDF fibers for tailored web performance.

Chemotherapy Induced Peripheral Neuropathy (CIPN) is a common problem among cancer patients who receive a wide range of chemotherapy. This problem causes a decline in quality of life and increased disabilities. CIPN assessment instruments are either subjective, objective, or a combination of both. So far, there is no agreement on the best way for assessment. The goal of this study was to explore the relationships among subjective and objective CIPN assessment instruments. Specifically, this study aimed to 1) evaluate the relationship between the Total Neuropathy Score-reduced (mainly objective) and patients’ function, as measured by the interference scale of the Chemotherapy-Induced Peripheral Neuropathy Assessment Tool (subjective); and 2) evaluate the relationship between the Total Neuropathy Score-reduced and neuropathy symptom experience, as measured by the symptom experience scale of the Chemotherapy-Induced Peripheral Neuropathy Assessment Tool (Subjective). To achieve those aims, a secondary data analysis for 56 participants who participated in a study entitled: Group Acupuncture for Treatment of Neuropathy from Chemotherapy was done. After Pearson correlations were calculated, the study found that there is a positive, weak relationship between the TNSr and the symptom experience scale of the CIPNAT(r=0.34). A positive, week relationship was found between the TNSr and the interference with activity scale of the CIPNAT(r=0.28). These results suggest that objective and subjective assessment are not highly correlated, and likely measure different aspects of CIPN. A comprehensive assessment approach is needed for decision making in the clinical oncology setting.