A study of optical propagation in polymer liquid crystal nanocomposites for photolithography applications

Technology devices today are rapidly growing in complexity while shrinking in physical size as exemplified by the ultra slim laptops and music players currently available on the market. With the downsizing of packaging and the increase in components, innovative new lithography techniques designed to push the density limit of the digital functions on a chip are becoming more available. Though many di erent forms of lithography exist, all with individual benefits, there currently exists no photolithography tool that can completely eliminate alignment error over a series of exposures; a tool that can bring the industry into the next phase of nanometer photo-patterning. The device that can achieve this goal is designed using digitally adaptable polymer light-valve films to spatially control exposure transmission creating a photomask with an arbitrary and dynamically adjustable pattern.This thesis presents the fundamental engineering behind the design of this novel photomasking application that uses a nanostructured composite. The material used is holographically-formed polymer-dispersed liquid crystal (H-PDLC) film and it is a photosensitive material formed with an interference pattern to contain layers of liquid crystal molecules held in a polymer matrix. With control over individual regions of film in a patterned electrode configuration, areas can be user defined as opaque or transmissive to resist exposing light. When used in a photomasking application, the light and dark fields can be real-time adjusted for rapid mask debugging, mask testing, and multiple exposures with no realignment. To truly understand the microscopic optical behavior of this device, aspects of propagation through the nanostructured film are investigated. Diffractive and edge interference effects are simulated and measured. In addition to this study, transmissive wavefront, scattering, coherence, intensity, and absorption are examined to assess factors limiting imaging due to transmission through the nanostructured thin film. To this point, there have been no investigations into imaging through an H-PDLC as it pertains to patterning photoresist, and limited studies regarding optical propagation within the film. Shown in this work is compelling evidence not only of the practicality of a liquid crystal adaptable photomask but also a study of the optical transmission properties within this type of thin film.Ph.D., Electrical Engineering -- Drexel University, 200

Mass Transport via Thermoplasmonics

When a metallic nanoparticle is illuminated with light under resonant conditions, the free electron gas oscillates in such a way that substantial amplification of the local electric field amplitude is achieved – this is known as a plasmonic resonance. This resonance enhances both the optical scattering as well as absorption. In many applications, the enhanced scattering can facilitate efficient coupling between the near-field and the far-field, which enables optical interrogation of nanoscale volumes. Simultaneously, however, the enhanced absorption results in localized heating and substantial temperature gradients. The resulting temperature profile can drive other thermal processes, some beneficial others detrimental. Thermoplasmonics is the study of these plasmonically enhanced thermal processes. Elevated temperatures increase the Brownian motion of small particles. Moreover, if large temperature gradients are present, then a process known as thermophoresis is likely to occur. Thermophoresis tends to cause a local depletion of Brownian particles around a hot region. From the context of “conventional” plasmonic applications (like molecular sensing), these thermally driven mass transport mechanisms are adverse side effects since they reduce the interaction rate between the plasmonic system and the analyte. An investigation of thermal effects in plasmonic optical tweezers showed that the increased Brownian motion essentially negated the optical tweezing effect, resulting in an overall insensitivity between the resonance condition of the antenna and the particle confinement when evaluated in terms of the local temperature increase. Additionally, a significant thermophoretic depletion of analytes occurred, extending tens of microns from the plasmonic structure. This depletion acts in opposition to the plasmonically enhanced optical forces, which are restricted to a region of only a few hundred nanometres.However, thermoplasmonic effects can also be used for advantageous means. Once example is by driving thermocapillary flows directed towards the plasmonic system, thereby facilitating the efficient accumulation of analytes. One method of employing this effect is to superheat a plasmonic particle to a high enough temperature such that a bubble is nucleated. Once a bubble is formed, thermocapillary effects at the bubble interface drive fluid motion with a flow profile similar to that of a Stokeslet. This fluid flow can be utilized for analyte accumulation near the plasmonic structure. In addition to the thermocapillary induced flow, it was found that even more intense flow speeds were achieved immediately upon nucleation due to the mechanical action of the bubble. This transient peak in flow speed was approximately an order of magnitude faster than the subsequent persistent (thermocapillary) flow. By designing the plasmonic nanoparticle so that the Laplace pressure restricted the ultimate bubble size, these bubbles could be kept small enough to permit high modulation rates and maximize the relative effect of the peak transient flow

Hybrid structures for molecular level sensing

With substantial molecular mobility and segment dynamics relative to metals and ceramics, all polymeric materials, to some extent, are stimuli-responsive by exhibiting pronounced chemical and physical changes in the backbone, side chains, segments, or end groups induced by changes in the local environment. Thus, the push to incorporate polymeric materials as sensing/responsive nanoscale layers into next-generation miniaturized sensor applications is a natural progression. The significance and impact of this research is wide-ranging because it offers design considerations and presents results in perhaps two of the most critical broad areas of nanotechnology: ultrathin multifunctional polymer coatings and miniaturized sensors. In this work, direct evidence is given showing that polymer coatings comprised of deliberately selected molecular segments with very different chemistry can have switchable properties, and that the surface composition can be precisely controlled, and thus properties can be tuned: all in films on the order of 20 nm and less. Furthermore, active sensing layers in the form of plasma-polymerized polymers are successfully incorporated into actual silicon based microsensors resulting in a novel hybrid organic/inorganic materials platform for microfabricated MEMS sensors with record performance far beyond contemporary sensors in terms of detection sensitivity to various environments. The results produced in this research show thermal sensors with more than two orders of magnitude better sensitivity than what is attainable currently. In addition, a humidity response on the order of parts per trillion, which is four orders of magnitude more sensitive than current designs is achieved. Molecular interactions and forces for organic molecules are characterized at the picoscale to optimize polymeric nanoscale layer design that in turn optimize and lead to microscale hybrid sensors with unprecedented sensitivities

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

New advances in vehicular technology and automotive engineering

An automobile was seen as a simple accessory of luxury in the early years of the past century. Therefore, it was an expensive asset which none of the common citizen could afford. It was necessary to pass a long period and waiting for Henry Ford to establish the first plants with the series fabrication. This new industrial paradigm makes easy to the common American to acquire an automobile, either for running away or for working purposes. Since that date, the automotive research grown exponentially to the levels observed in the actuality. Now, the automobiles are indispensable goods; saying with other words, the automobile is a first necessity article in a wide number of aspects of living: for workers to allow them to move from their homes into their workplaces, for transportation of students, for allowing the domestic women in their home tasks, for ambulances to carry people with decease to the hospitals, for transportation of materials, and so on, the list don’t ends. The new goal pursued by the automotive industry is to provide electric vehicles at low cost and with high reliability. This commitment is justified by the oil’s peak extraction on 50s of this century and also by the necessity to reduce the emissions of CO2 to the atmosphere, as well as to reduce the needs of this even more valuable natural resource. In order to achieve this task and to improve the regular cars based on oil, the automotive industry is even more concerned on doing applied research on technology and on fundamental research of new materials. The most important idea to retain from the previous introduction is to clarify the minds of the potential readers for the direct and indirect penetration of the vehicles and the vehicular industry in the today’s life. In this sequence of ideas, this book tries not only to fill a gap by presenting fresh subjects related to the vehicular technology and to the automotive engineering but to provide guidelines for future research. This book account with valuable contributions from worldwide experts of automotive’s field. The amount and type of contributions were judiciously selected to cover a broad range of research. The reader can found the most recent and cutting-edge sources of information divided in four major groups: electronics (power, communications, optics, batteries, alternators and sensors), mechanics (suspension control, torque converters, deformation analysis, structural monitoring), materials (nanotechnology, nanocomposites, lubrificants, biodegradable, composites, structural monitoring) and manufacturing (supply chains). We are sure that you will enjoy this book and will profit with the technical and scientific contents. To finish, we are thankful to all of those who contributed to this book and who made it possible.info:eu-repo/semantics/publishedVersio

3D printed muscle-powered bio-bots

Complex biological systems sense, process, and respond to a range of environmental signals in real-time. The ability of such systems to adapt their functional response to dynamic external signals motivates the use of biological materials in other engineering applications. Recent advances in 3D printing have enabled the manufacture of complex structures from biological materials. We have developed a projection stereolithographic 3D printing apparatus capable of patterning cells and biocompatible polymers at physiologically relevant length scales, on the order of single cells. This enables reverse engineering in vitro model systems that recreate the structure and function of native tissue for applications ranging from high-throughput drug testing to regenerative medicine. While reverse engineering native tissues and organs has important implications in biomedical engineering, the ability to “build with biology” presents the next generation of engineers with both a unique design challenge and opportunity. Specifically, we now have the ability to forward engineer bio-hybrid machines and robots (bio-bots) that harness the adaptive functionalities of biological materials to achieve more complex functional behaviors than machines composed of synthetic materials alone. Perhaps the most intuitive demonstration of a “living machine” is a system that can generate force and produce motion. To that end, we have designed and 3D printed locomotive bio-bots, powered by external electrical and optical stimuli. In addition to being the first demonstrations of untethered locomotion in skeletal musclepowered soft robots, these bio-hybrid machines have served as meso-scale models for studying tissue self-assembly, maturation, damage, remodeling, and healing in vitro. Bio-hybrid machines that can dynamically sense and adaptively respond to a range of environmental signals have broad applicability in healthcare applications such as dynamic implants or targeted drug delivery. Advanced research in exoskeletons and hyper-natural functionality could even extend the useful application of such machines to national defense and environmental cleanup. We have developed a modular skeletal muscle bioactuator that can serve as a fundamental building block for such machines, setting the stage for future generations of bio-hybrid machines that can self-assemble, self-heal, and perhaps even self-replicate to target grand engineering challenges. Furthermore, we present a robust optimized protocol for manufacturing 3D printed muscle-powered biological machines, and a mechanism to incorporate biological “building blocks” into the toolbox of the next generation of engineers and scientists

Developing novel nonlinear materials for metaphotonics device applications

Recent advancements in flat-optics, metamaterials research, and integrated optical devices have established the need for more efficient, spectrally tunable, and Si-compatible optical media and nanostructures with designed linear/nonlinear responses that can enable high-density integration of ultrafast photonic-plasmonic functionalities on the chip. Traditional methodologies for nanoscale photon manipulation utilize lossy materials, such as noble metals, which lack significant optical tunablility and compatibility with complementary metal-oxide-semiconductor technologies. In this dissertation, we propose, develop, and characterize alternative plasmonic materials that overcome these limitations while providing novel opportunities for significant optical nonlinear enhancement. Specifically, we investigate the plasmonic resonant regime and the nonlinear optical responses of Si- and O2- doped titanium nitride, SiO2- doped indium oxide, and Sn-doped indium oxide with engineered structural and optical dispersion behavior. We study a number of novel passive metaphotonic devices that leverage refractive index control in low-loss materials for near-field engineering and nanoscale nonlinear optical enhancement. Moreover, we integrate the developed alternative plasmonic materials into active metaphotonic surfaces for electro-optical modulation, enhanced light absorption, and ultrafast photon detection. Furthermore, utilizing the double-beam accurate Z-scan technique, we characterize the intrinsic nonlinear susceptibility χ(3) of optical nanolayers with epsilon-near-zero behavior as a function of their microstructural properties that we largely control by post-deposition annealing. A main objective of this work is to establish robust structure-property relationships for the control of optical dispersion, Kerr nonlinearity, and near-field resonances that extend from the visible to the infrared. This work substantially expands and diversifies the reach of plasmonics, flat-optics, and nonlinear optics across multiple spectral regions within scalable and Si-compatible novel material platforms