Dissertations / Theses on the topic 'Chemical patterning'
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1
Zhang, Feng. "Chemical Vapor Deposition of Silanes and Patterning on Silicon." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2902.
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Self assembled monolayers (SAMs) are widely used for surface modification. Alkylsilane monolayers are one of the most widely deposited and studied SAMs. My work focuses on the preparation, patterning, and application of alkysilane monolayers. 3-aminopropyltriethoxysilane (APTES) is one of the most popular silanes used to make active surfaces for surface modification. To possibly improve the surface physical properties and increase options for processing this material, I prepared and studied a series of amino silane surfaces on silicon/silicon dioxide from APTES and two other related silanes by chemical vapor deposition (CVD). I also explored CVD of 3-mercaptopropyltrimethoxysilane on silicon and quartz. Several deposition conditions were investigated. Results show that properties of silane monolayers are quite consistent under different conditions. For monolayer patterning, I developed a new and extremely rapid technique, which we termed laser activation modification of semiconductor surfaces or LAMSS. This method consists of wetting a semiconductor surface with a reactive compound and then firing a highly focused nanosecond pulse of laser light through the transparent liquid onto the surface. The high peak power of the pulse at the surface activates the surface so that it reacts with the liquid with which it is in contact. I also developed a new application for monolayer patterning. I built a technologically viable platform for producing protein arrays on silicon that appears to meet all requirements for industrial application including automation, low cost, and high throughput. This method used microlens array (MA) patterning with a laser to pattern the surface, which was followed by protein deposition. Stencil lithography is a good patterning technique compatible with monolayer modification. Here, I added a new patterning method and accordingly present a simple, straightforward procedure for patterning silicon based on plasma oxidation through a stencil mask. We termed this method subsurface oxidation for micropatterning silicon (SOMS).
2
Nelson, Kyle A. "Chemical Templating by AFM Tip-Directed Nano-Electrochemical Patterning." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/3188.
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This work has examines the creation and use of chemical templates for nanocircuit and other nanodevice fabrication. Chemical templating can be useful in attachment, orientation and wiring of molecularly templated circuits. DNA origami provides a suitable method for creating molecularly templated circuits as DNA can be folded into complex shapes and functionalized with active circuit elements, such as semiconducting nanomaterials. Surface attachment of DNA origami structures can be accomplished by hybridization of dangling single-stranded DNA (ssDNA) on the origami structures with complementary surface-bound strands. Chemical templating provides a pathway for placing the patterned surface-bound attachment points needed for surface alignment of the molecular templates. Chemical templates can also be used to connect circuit elements on the surface by selectively metallizing the templates to form local wiring. AFM tip-directed nano-oxidation was selected as the method for patterning to create chemical templates. This project demonstrates new techniques for creating, continuous metallization of, and DNA attachment to nanochemical templates. Selective-continuous metallization of nanochemical templates is needed for wiring of circuit templates. To improve the metallization density and enable the continuous nano-scale metallization of amine-coated surfaces, the treatment of amine-coated surfaces with a plating additive prior to metallization was studied. The additive treatment resulted in a 73% increase in seed material, enabling continuous nano-scale metallization. A new method was developed to create amine nanotemplates by selective attachment of a polymer to surface oxide patterns created by nano-oxidation. The treatment of the templates with the additive enabled a five-fold reduction in feasible width for continuous metallization. Nano-oxidation was also used in the nanometer-scale patterning of a thiol-coated surface. Metallization of the background thiols but not the oxidized patterns resulted in a metal film that was a negative of the patterns. The resulting metal film may be useful for nanometer-scale pattern transfer. DNA-coated gold nanoparticles (AuNPs) were selectively attached to amine templates by an ionic interaction between the template and ssDNA attached to the particles. Only the ssDNA on the bottom of the AuNPs interacted with the template, leaving the top strands free to bind with complementary ssDNA. Attempts to attach origami structures to these particles were only marginally successful, and may have been hindered by the presence of complementary ssDNA in solution but not attached to the origami, or the by the low density of DNA-AuNPs attached to the templates. The formation of patterned binding sites by direct, covalent attachment of ssDNA to chemical templates was also explored. Initial results indicated that ssDNA was chemically bound to the templates and able to selectively bind to complementary strands; however, the observed attachment density was low and further optimization is required. Methods such as these are needed to enable nano-scale, site-specific alignment of nanomaterials.
3
Chen, Xiao Hua. "Patterning etch masks via the "Grafting-from polymerization." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/30768.
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Vuppalapati, Ragini. "Chemical Modification on Gold Slides to Gain Better Control of Patterning Techniques." TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/1129.
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Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip.
This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern techniques in order to create more intricate patterns such as interdigitated arrays, which can subsequently be used in sensors. An atomic force microscope (AFM) is used to pattern the prepared colloid-coated glass slides. Several compounds were used in the investigation, including sodium sulphate, potassium sulphate, magnesium sulphate, sodium fluoride, sodium chloride, sodium bromide, and sodium iodide, potassium chloride, potassium bromide, potassium iodide, potassium dihydrogen phosphate, and potassium hydrogen phosphate.
In Summary, the following were found as a result of this work:
The groups of sulphates were determined to require minimum patterning forces as indicated. Sodium sulphate took a force of 49 n Potassium sulphate took a force of 45 nN Magnesium sulphate took a force of 744.4 nN
The group of sodium and potassium halides were determined the minimum patterning forces as indicated. Sodium fluoride took a force of 8.42 nN Sodium chloride and potassium chloride took a force of 20.19 and 61.9nN Sodium bromide and potassium bromide took a force of 601.4 nN and 37.2 nN, respectively Sodium iodide and potassium iodide took a force of 953.7 nN and 47.2 nN, respectively
The phosphates were determined to require the minimum patterning forces as indicated. Potassium hydrogen phosphate took a force of 25nN Potassium dihydrogen phosphate took a force of 43 nN
5
Charest, Joseph Leo. "Topographic and chemical patterning of cell-surface interfaces to influence cellular functions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24621.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2007.Committee Chair: Dr. William P. King; Committee Member: Dr. Andres J. Garcia; Committee Member: Dr. F. Levent Degertekin; Committee Member: Dr. Hang Lu; Committee Member: Dr. Todd C. McDevitt.
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Sajid, N. "Chemical patterning and nano-mechanical measurements for understanding and controlling nerve growth." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/6976/.
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Hendricks, Troy Richard. "Polyelectrolyte multilayer coatings for conductive nanomaterials patterning and anti-wrinkling applications." Diss., Connect to online resource - MSU authorized users, 2008.
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8
Cai, Yangjun. "Simple Alternative Patterning Techniques for Selective Protein Adsorption." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1257386752.
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Tuft, Bradley William. "Photopolymerized materials and patterning for improved performance of neural prosthetics." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1410.
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Neural prosthetics are used to replace or substantially augment remaining motor and sensory functions of neural pathways that were lost or damaged due to physical trauma, disease, or genetics. However, due to poor spatial signal resolution, neural prostheses fail to recapitulate the intimate, precise interactions inherent to neural networks. Designing materials and interfaces that direct de novo nerve growth to spatially specific stimulating elements is, therefore, a promising method to enhance signal specificity and performance of prostheses such as the successful cochlear implant (CI) and the developing retinal implant.
In this work, the spatial and temporal reaction control inherent to photopolymerization was used to develop methods to generate micro and nanopatterned materials that direct neurite growth from prosthesis relevant neurons. In particular, neurite growth and directionality has been investigated in response to physical, mechanical, and chemical cues on photopolymerized surfaces. Spiral ganglion neurons (SGNs) serve as the primary neuronal model as they are the principal target for CI stimulation. The objective of the research is to rationally design materials that spatially direct neurite growth and to translate fundamental understanding of nerve cell-material interactions into methods of nerve regeneration that improve neural prosthetic performance.
A rapid, single-step photopolymerization method was developed to fabricate micro and nanopatterned physical cues on methacrylate surfaces by selectively blocking light with photomasks. Feature height is readily tuned by modulating parameters of the photopolymerizaiton including initiator concentration and species, light intensity, separation distance from the photomask, and radiation exposure time. Alignment of neural elements increases significantly with increasing feature amplitude and constant periodicity, as well as with decreasing periodicity and constant amplitude. SGN neurite alignment strongly correlates with the maximum feature slope. Neurite alignment is compared on unpatterned, unidirectional, and multidirectional photopolymerized micropatterns.
The effect of substrate rigidity on neurite alignment to physical cues was determined by maintaining equivalent pattern microfeatures, afforded by the reaction control of photopolymerization, while concomitantly altering the composition of several copolymer platforms to tune matrix stiffness. For each platform, neurite alignment to unidirectional patterns increases with increasing substrate rigidity. Interestingly, SGN neurites respond to material stiffness cues that are orders of magnitude higher (GPa) than what is typically ascribed to neural environments (kPa).
Finally, neurite behavior at bioactive borders of various adhesion modulating molecules was evaluated on micropatterned materials to determine which cues took precedence in establishing neurite directionality. At low microfeatures aspect ratios, neurites align to the pattern direction but are then caused to turn and repel from or turn and align to bioactive borders. Conversely, physical cues dominate neurite path-finding as pattern feature slope increases, i.e. aspect ratio of sloping photopolymerized features increases, causing neurites to readily cross bioactive borders. The photopolymerization method developed in this work to generate micro and nanopatterned materials serves as an additional surface engineering tool that enables investigation of cell-material interactions including directed de novo neurite growth. The results of this interdisciplinary effort contribute substantially to polymer neural regeneration technology and will lead to development of advanced biomaterials that improve neural prosthetic tissue integration and performance by spatially directing nerve growth.
10
Parry, Kristina Louise. "A novel plasma source for surface chemical patterning and spatial control of cell adhesion." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408370.
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Trujillo, Nathan J. (Nathan Jeffrey). "Environmentally focused patterning and processing of polymer thin films by initiated chemical vapor deposition (iCVD) and oxidative chemical vapor deposition (oCVD)." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62139.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
The new millennium has brought fourth many technological innovations made possible by the advancement of high speed integrated circuits. The materials and energy requirements for a microchip is orders of magnitude higher than that of "traditional" goods, and current materials management requirements for EHS friendly low-k processing require a 10% annual increase in raw materials utilization. Initiated Chemical Vapor Deposition (iCVD) is a low-energy, one step, solvent-free process for producing polymeric thin films This thesis describes the deposition of a novel low-k iCVD precursor, 1,3,5,7-tetravinyltetramethylcylcotetrasiloxane (V4D4). The high degree of organic content in the as-deposited film affords the ability to tune the film's properties by annealing. The incorporation of atmospheric oxygen at high temperatures enhances the mechanical and electrical properties of the films. Films annealed at 410'C have a dielectric constant of 2.15, hardness and modulus of 0.78 GPa and 5.4 GPa, respectively. These values are comparatively better than previously reported results for CVD low-k films. Environmentally friendly low-k processing encompasses materials and energy management in the entire integration process, including lithography. Colloidal lithography was combined with iCVD and capillary force lithography to create spatially addressable grafted polymer pattern nanostructures, without the need for expensive lithography tools. Using this method, we pattern our novel low dielectric constant polymer down to 25 nm without the need for environmentally harmful solvents. Furthermore, these grafted patterns were produced for a broad material set of functional organic, fluorinated, and silicon containing polymers. A variation of this process created amine functionalized biocompatible conducting polymer nanostructure patterns for biosensor applications. These were fabricated using grafting reactions between oxidative chemical vapor deposition (oCVD) PEDOT conducting polymers and amine functionalized polystyrene (PS) colloidal templates. Carboxylate containing oCVD copolymer patterns were used to immobilized fluorescent dyes. Fluorescent colloidal particles were assembled within dyed PEDOT-co-TAA copolymer nanobowl templates to create bifunctional patterns for optical data storage applications. Finally, UV and e-beam lithography were used to pattern covalently tethered vinyl monolayers for resist-free patterning of iCVD and oCVD polymers, using environmentally innocuous solvents.
by Nathan J. Trujillo.
Ph.D.
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Schumacher, Joshua David. "Design and Construction of Plasma Enhanced Chemical Vapor Deposition Reactor and Directed Assembly of Carbon Nanotubes." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000214.
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Tiu, Brylee David Buada. "Conducting Polymers for Molecular Imprinting and Multi-component Patterning Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1449227860.
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Carroll, Keith Matthew. "Modeling and controlling thermoChemical nanoLithography." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52962.
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Thermochemical Nanolithography (TCNL) is a scanning probe
microscope (SPM) based lithographic technique modified with a
semi-conducting cantilever. This cantilever is capable of locally
heating a surface and with a well-engineered substrate, this spatially
confined heating induces chemical or physical transformation. While
previous works focused primarily on proof of principle and binary
studies, there is limited research on controlling and understanding the
underlying mechanisms governing the technique. In this thesis, a
chemical kinetics model is employed to explain the driving mechanisms
and to control the technique. The first part focuses on studying
surface reactions. By coupling a thermally activated organic polymer
with fluorescence microscopy, the chemical kinetics model is not only
verified but also applied to control the surface reactions. The work is
then expanded to include 3D effects, and some preliminary results are
introduced. Finally, applications are discussed.
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Ghosh, Souvik. "ATMOSPHERIC-PRESSURE in situ PLASMA REDUCTION AND PATTERNING OF METAL-ION CONTAINING POLYMERS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1490872201148598.
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Atwood, Matthew Paul. "Analysis and patterning of thin films of YBa₂Cu₃O₇₋ₓ deposited by metal organic chemical vapour deposition." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627464.
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Kumar, Girish. "Cell Engineering: Regulating Cell Behaviors Using Micropatterned Biomaterials." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1225816129.
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Wesser, Andrea Suzette. "User-defined patterning of neural progenitor cells on 3D micropillar arrays using round cross-sectional geometry, specific dimensions and thiol-based chemical adhesion." Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002054.
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Orozco, Nieto Pedro Francisco. "Manufacturing strategy for high current cold field emission cathodes : floating catalyst chemical vapour deposition grown carbon nanotube fibres and films enhanced by laser patterning and laser purification process." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278104.
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The aim of this work is to produce a manufacturing strategy for high current (>10 mA) field emission (FE) devices for military (microwave generation) and civilian (particle accelerator electron beam) applications using carbon nanotubes (CNT) as base material. With a particular focus on the relationship of the laser time pulse duration used for cutting CNTs and how this affects the field emission performance. Material selection for this work was narrowed to CNT as they possess unique characteristics such as: high aspect ratio; high thermal conductivity; high chemical stability and high current carrying capacities up to a theoretical limit of 1,200 MA∙cm-1 making them an ideal material for FE. The CNT material studied in this work is produced in two distinct forms, fibres (∅~7-10 μm) and films (h~30 μm), using a floating catalyst chemical vapour deposition process which produces high quantities of CNT material with mixed mechanical and electrical properties. The material is difficult to handle because of its dimensions and is susceptible to environmental changes i.e. electrostatic forces. In order to reduce the variability in electrical properties, a laser purification process was developed. The process consists of locally irradiating an infra-red (IR) laser several microseconds directly at the material. A percentage is vaporised (mainly non-conductive or defective material) and the remaining CNT material shows very high crystallinity with an increase of up to ten times (G/D ratio > 100) compared to the original material and electron mean free path is increased by an order of magnitude. The production strategy is based on directly coating the CNT material with copper using an electroplating process. This allowed for CNT fibre and film to be easily handled and improved the overall electrical contact. Emitter geometry was customised by a laser cutting process to achieve increased enhancement factor geometries, in this case, triangles with 29 tips whilst reducing FE variability. FE performance was quantified by testing the devices in a continuous DC mode with a sweep up to 1,000 V until the material suffered catastrophic failure. The gap distance between the tip of the triangles and the anode was varied to increase the electric field until failure. FE results using the production strategy improved more than 400% compared to untreated material. Applications for these devices are intended to be in the creation of high energy electron beam lines and generation of high powered directed microwaves.
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Villefranc, Jacques A. "Two Distinct Modes of Signaling by Vascular Endothelial Growth Factor C Guide Blood and Lymphatic Vessel Patterning in Zebrafish: A Dissertation." eScholarship@UMMS, 2011. https://escholarship.umassmed.edu/gsbs_diss/557.
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Vascular Endothelial Growth Factor Receptor-3 (VEGFR3/Flt4) and its ligand Vegfc are necessary for development of both blood and lymphatic vasculature in vertebrates. In zebrafish, Vegfc/Flt4 signaling is essential for formation of arteries, veins, and lymphatic vessels. Interestingly, Flt4 appears to utilize distinct signaling pathways during the development of each of these vessels. To identify components of this pathway, we performed a transgenic haploid genetic screen in zebrafish that express EGFP under the control of a blood vessel specific promoter. As a result, we indentified a mutant allele of vascular endothelial growth factor c (vegfc), vegfcum18. vegfcum18 mutants display defects in vein and lymphatic vessel development but normal segmental artery (SeA) formation. Characterization of this allele led to the finding that the primary defect in vegfcum18 mutants was a general failure in vein and lymphatic vessel sprouting. Further genetic and biochemical analysis of this mutant revealed profound paracrine defects, which likely result in the observed loss of lymphatic and venous structures. Furthermore, double mutant analysis demonstrated that defects during SeA formation in vegfcum18 mutants were masked by inputs from the Vegfa signaling pathway. Endothelial cell autonomous expression of vegfcum18 induced angiogenic effects on blood vessels while endothelial cells lacking vegfc displayed defects in tip cell occupancy, suggesting a cell autonomous-autocrine role for Vegfc during developmental angiogenesis. Finally, we present genetic evidence that links processing of Vegfc by Furin during the formation of lymphatics in zebrafish. Together the data presented here suggest two discrete modes of signaling during blood and lymphatic vessel development, thus implying that regulation of Vegfc secretion and processing may play a pivotal role in the formation of these distinct vessel types in zebrafish.
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Pokpas, Keagan William. "Microfluidic graphenised-paper electroanalytical devices (μGPED) for adsorptive cathodic stripping voltammetric detection of metal contaminants." University of the Western Cape, 2017. http://hdl.handle.net/11394/5506.
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Philosophiae Doctor - PhDThe need for clean, non-toxic drinking water supplies, free of pollutants and metal contamination is vital in impoverished areas and the developing world alike. With this in mind, the development of accurate, inexpensive, portable and simple devices for remote sensing applications is therefore pivotal for early detection and the prevention of illnesses. Over the last two decades, adsorptive stripping voltammetry (AdSV) has emerged as a superior detection method over common analytical techniques due to its low-cost instrumentation, unskilled labour and ability to detect a wide range of analytes.
2020-08-31
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Driscoll, Peter F. "Bioanalytical Applications of Chemically Modified Surfaces." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-dissertations/465.
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"The design and development of chemically modified surfaces for bioanalytical applications is presented. Chemical surface modification is demonstrated to be a method to control surface properties on the molecular level by selecting the appropriate substrate, linking chemistry, and terminal group functionality. These systems utilize spontaneous interactions between individual molecules that allow them to self-assemble into larger, supramolecular constructs with a predictable structure and a high degree of order. Applications investigated in this thesis include: surface patterning, switchable surface wettability, and biological sensor devices that combine surface based molecular recognition, electrochemical detection methods, and microfluidics. A multilayered approach to complex surface patterning is described that combines self-assembly, photolabile protecting groups, and multilayered films. A photolabile protecting group has been incorporated into molecular level films that when cleaved leaves a reactive surface site that can be further functionalized. Surface patterns are created by using a photomask and then further functionalizing the irradiated area through covalent coupling. Fluorophores were attached to the deprotected regions, providing visual evidence of surface patterning. This approach is universal to bind moieties containing free amine groups at defined regions across a surface, allowing for the development of films with complex chemical and physico-chemical properties. Systems with photoswitchable wettability were developed by fabricating multilayered films that include a photoisomerizable moiety, cis-/trans- dicarboxystilbene. When this functionality was incorporated into a multilayered film using non-covalent interactions, irradiation with light of the appropriate wavelength resulted in a conformational change that consequently changed the hydrophobicity of the substrate. Methods were investigated to increase the reversibility of the photoswitching process by creating surface space between the stilbene ligands. Utilizing mixed monolayers for spacing resulted in complete isomerization for one cycle, while the use of SAMs with photolabile groups produced surfaces that underwent isomerization for three complete cycles. A microfluidic device platform for ion sensing applications has been developed. The platform contains components to deliver small volumes of analyte to a surface based microelectrode array and measure changes in analyte concentration electrochemically in an analogous method to that used in conventional electrochemical cells. Crown ether derivatives that bind alkali metal ions have been synthesized and tested as ionophores for a multi-analyte device of this type, and the sensing platform was demonstrated to measure physiological relevant concentrations of potassium ions. Advantages of this design include: high sensitivity (uM to mM), small sample volumes (less than 0.1 mL), multi-analyte capabilities (multiple working electrodes), continuous monitoring (a flow through system), and the ability to be calibrated (the system is reusable). The self-assembled systems described here are platform technologies that can be combined and used in molecular level devices. Current and future work includes: photopatterning of gold and glass substrates for directed cell adhesion and growth, the design and synthesis of selective ion sensors for biological samples, multi-analyte detection in microfluidic devices, and incorporating optical as well as electrochemical transduction methods into sensor devices to allow for greater sensitivity and self-calibration."
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Malkoc, Veysi. "Micropatterning Neuronal Networks on Nanofiber Platforms." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1367508074.
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Sy, Piecco Kurt Waldo. "Chemically-Patterned Substrates via Sequential Photoinitiated Thiol-ene Reactions asTemplates for the Deposition of Molecules and Materials on Surfaces." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1553174280949411.
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Srinivasan, Charan Horn Mark William Weiss Paul S. "Hybrid strategies for nanolithography and chemical patterning." 2008. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2468/index.html.
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Ye, Jia. "Nanoscale patterning of chemical order introduced by displacement cascades in irradiated alloys /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3243036.
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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6684. Adviser: Pascal Bellon. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.
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Kim, Hyun Suk. "Macroscopic patterning via dynamic self-assembly and wrinkling instability." 2012. https://scholarworks.umass.edu/dissertations/AAI3545951.
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My PhD work focuses on developing new methods to create the macroscopic patterns in a simple, robust, and versatile way. For macroscopic pattern formation, we first use flow coating as an assembly technique, uniquely balancing two driving forces: (i) evaporative deposition of nonvolatile solutes at a three-phase contact line and (ii) precision movement of a confined meniscus layer. This balance leads to the formation of line-based patterns that range in height and width from nanometers to microns, with lengths greater than centimeters. Moreover, we couple this deposition methodology with functional ligand chemistry on the nanoparticle surface, which allows us to create complex nanoparticle structures. By lifting crosslinked nanoparticle ribbons and ropes, exceptionally intriguing structures emanate from this process. The nanoparticle ribbons and ropes demonstrate a leap forward in nanomaterials fabrication, since the nanoscale properties are embedded within a macroscale object that can be manipulated with conventional methods and engineered into advanced technologies. Using mechanical instability, we fabricate a simple, robust stimuli-responsive surface with periodic structures over a large area based upon osmotically-driven surface wrinkling. Although surface wrinkling has received considerable attention in the scientific literature, only a handful of papers have shown the ability to harness perhaps the greatest potential attribute of surface wrinkles: their active reversible nature. The ability to precisely control surface topographic morphologies in accordance with established scaling relationships opens a wide array of advanced materials applications, which do not rely upon cost-limiting fabrication techniques. Specifically, the surfaces respond to solvent exposure by developing well-defined topographic structures over laterally extensive areas due to osmotically-driven differential strains between a surface layer and underlying soft substrate. The observed wrinkling occurs spontaneously, forming hierarchical morphologies with controlled dimensions, and vanishes upon removal of the solvent driving force. The combined responsiveness and reversibility of wrinkling allow for the realization of functional devices, such as smart windows, smart microlens arrays, reversible channels in microfluidic devices. Moreover, by using thermal and osmotic approaches, we study the influence of geometry and material properties on surface instability such as cracking and wrinkling in a trilayer system consisting of a thin film on a soft foundation supported by a rigid substrate.
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Lin, Meng-Hsien, and 林孟賢. "Plasma Modification of Self-Assembled Monolayers for Chemical Patterning and Fabrication of Large-Area 3D Plasmonic Supercrystals." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34801414462583826120.
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博士國立清華大學
奈米工程與微系統研究所
99
Nanotechnology has been developed as a reliable technology for producing minimal components to perform more precise functions. In particular, the availability of nanolithography and nanostructure fabricating processes is important in the fields of photonics, electronics, biotechnology, and metamaterial. In our research, we present a generic and efficient chemical patterning method, compared with conventional photolithography this approach is without diffraction limit. Base on this approach, we expand a method for synthesizing three-dimensional (3D) gold and silver nanoparticle supercrystal films. Since nanoparticles have unique properties of surface plasmon, this technology will offer a pathway to designer plasmonic metamaterials. We fabricate chemical pattern based on local plasma-induced conversion of surface functional groups on self-assembled monolayers. Here, spatially controlled plasma exposure is realized by elastomeric poly(dimethylsiloxane) (PDMS) contact masks or channel stamps with feature sizes ranging from nanometer, micrometer, to centimeter, and an achievable resolution is down to the 50 nm range. This chemical conversion method has been comprehensively characterized by a set of techniques, including contact angle measurements, X-ray photoelectron spectroscopy (XPS), scanning photoelectron microscopy (SPEM), scanning electron microscopy (SEM), and scanning Kelvin probe microscopy (SKPM). In particular, XPS and SPEM can be used to distinguish regions of different surface functionalities and elucidate the mechanism of plasma-induced chemical conversion. Based on plasma-induced conversion, we expand a simple and efficient method for synthesizing large-area (>cm2), three-dimensional (3D) gold and silver nanoparticle supercrystal films. In this approach, Janus nanoparticle (top face solvent-phobic and bottom face solvent-philic) films with an arbitrary number of close-packed nanoparticle monolayers can be formed by using layer-by-layer (LbL) assembly from suspensions of thiolate-passivated gold or silver colloids. Furthermore, we demonstrate that these films can act as true 3D plasmonic crystals with strong transverse (intralayer) and longitudinal (interlayer) near-field coupling. In contrast to conventional polyelectrolyte-mediated LbL assembly processes, this approach allows multiple longitudinal coupling modes with a conspicuous spectral dependence on the layer number. We have found a universal scaling relation between the spectral position of the reflectance dips related to the longitudinal modes and the layer number. This relation can be understood by the presence of a plasmonic Fabry-Pérot nanocavity along the longitudinal direction, allowing the formation of standing plasmon waves under plasmon resonance conditions. The realization of 3D plasmonic coupling enables broadband tuning of collective plasmon response in a wide spectral range (visible and near-infrared) and a key pathway to designer plasmonic metamaterials.