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Carmo, Cátia Vanessa Saldanha do Carmo. "Micro-and Nano-Technologies for Food Applications." Doctoral thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica António Xavier, 2016. http://hdl.handle.net/10362/58238.
Повний текст джерелаАнотація:
Dissertation presented to obtain the PhD degree in Chemistry-NanotechnologyNano- and microtechnology is one of the hottest topics in food science and technology. Current applications of nano- and microtechnology in the food sector includes the processing and formulation of food ingredients into nano- and micro- structures/-sized/-encapsulated or engineered particle additives. These systems have been incorporated in food to improve functionality, enhancing physical properties (i.e. colour, texture), protecting chemical ingredients from degradation (i.e antioxidants, flavour) and biological degradation (i.e. antimicrobials), and increasing bioavailability. Moreover, it has been used for the development of active/intelligent packaging, sensors and for encapsulation of bioactives, flavour and nutrients.(...)
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2
Berti, Francesca. "New micro-and nano-technologies for biosensor development." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4455.
Повний текст джерелаАнотація:
Recent advances in micro- and nanotechnology have produced a number of new materials which exhibit exceptional potential for the design of novel sensing strategies and to enhance the analytical performance of biosensing systems. In this thesis three different types of miniaturisation pathways were investigated for electrochemical biosensing applications. Vertically aligned carbon nanotube thin films were designed and tested as platforms for DNA immobilisation and for the development of a model electrochemical genosensor. The sensor format involved the immobilisation of oligoucleotide probes onto the sensor surface, hybridisation with the target sequence and electrochemical detection of the duplex formation. By combining such an electrode platform with an enzyme labeling, a detection limit of oligonucleotide targets in the nanomolar range was achieved. A novel magnetic particle-based microfluidic sensor was also realised by integrating a microfluidic platform with a new analytical procedure based on the use of paramagnetic beads for the detection of real PCR samples. The hybridisation reaction was carried out on probe-modified beads in a flow-through format, thus enhancing the surface area-to-volume ratio and consequently the sensitivity. Moreover, the magnetic properties of the beads greatly facilitated the delivery and removal of reagents through the microfluidic channels. This format allowed the detection of nanomolar levels of double-stranded DNA sequences, with high reproducibility and fast time of analysis. Finally, polyaniline nanotubes arranged in an ordered structure directly on gold electrode surfaces were realised and employed to create a model molecularly imprinted (MIP) polymer -sensor for catechol detection. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor that we had previously developed. A significantly lower limit of detection (one order of magnitude) was achieved, thus demonstrating that the nanostructures enhanced the analytical performance of the sensor.
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Jiang, Kyle. "Advanced micro and nano fabrications for engineering applications." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7052/.
Повний текст джерелаАнотація:
This document is a compilation of my selected research publications in micro and nano fabrications. The papers are largely arranged in chronological order to show the development of research interests. The research works are grouped into three sections. Section one consists of 34 research papers on micro fabrication in various materials. The research was motivated by the development of a finger nail sized micro engine as explained in Papers 1 and 2. Section two of the document includes some research activities and achievements on nanocomposite materials embedded in metallic and ceramic matrices. Section 3 includes the papers to reflect the research in developing nanostructure fabrication processes. The research contained in this DSc submission shows a continuous exploration and development of novel micro/nano fabrication processes. Although the submission covers research activities spanning 15 years, from 2000 to 2015, many of the research results represent the top technology of the time. They have contributed to the ever progressing manufacturing capability of the world. The research has encompassed both theoretical and experimental studies, contributing to the understanding of the processes and materials involved.
4
Yan, Jize. "Micro/nano-electro-mechanical resonators for signal processing." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613372.
Повний текст джерела
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Tang, Ying Kit. "A risk analysis methodology for micro/nano manufacturing." Thesis, University of Greenwich, 2012. http://gala.gre.ac.uk/8054/.
Повний текст джерелаАнотація:
This research concerns the development of a risk analysis and mitigation methodology for assessing the impact of uncertainties and complexity of the design requirements arising in new process and product developments in micro and nano manufacturing. The risk analysis methodology integrates different computational approaches for process and product analysis, including the reduced order modelling using design of experiments, risk analysis using sampling-based and analytical methods and optimisation techniques. The integrated risk analysis and optimisation methodology is applied to two applications: (1) the FIB sputtering process control, and (2) a flip chip design. Three different FIB processes using different ion sources were investigated in order to evaluate their process performance with respects to different process parameter uncertainties. A critical comparison of the process capability against the specification limits of different processes was studied. As parts of the research, a new modified computational model is developed for a material sputtering process using focused ion beam (FIB). This model allows the analysis of micro- and nano-structures shape with the FIB machine controlled through multiple beam scans and different beam overlapping. The FIB model related studies also address the modelling requirements for including material re-deposition effects that occur during FIB milling. The model has been validated using an experimental test case. Good agreement is observed between the analytical shape using the model and the actual experiment. The validated model enhances the accuracy of the dwell time prediction. This approach overcomes the dependence of a trial-and-error approach of the process control in nano-manufacturing industry. The proposed methodology is also used to address a design problem of a flip chip design. A novel method for the evaluation of the environmental impact of the flip chip design in a multi-disciplinary optimisation problem is proposed. The goal is to address materials constraints due to environmental regulations and to handle different types of requirements such as the reliability and cost. An optimal flip chip design reliability function is identified. The approach allows electronics manufacturers to consider the environmental impact amongst different design alternatives at an early stage of the design of the product before any real prototyping in order to reduce the total manufacturing life cycle.
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Sandison, Mairi Elizabeth. "Micro- and nano-electrode arrays for electroanalytical sensing." Thesis, Connect to e-thesis, 2004. http://theses.gla.ac.uk/1025/.
Повний текст джерелаАнотація:
Thesis (Ph.D.) - University of Glasgow, 2004.Includes bibliographical references (p. 183-203). Print version also available. Mode of access : World Wide Web. System requirements : Adobe Acrobat reader required to view PDF document.
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Li, Xue. ""Cage" Nano and Micro-particles for Biomedical Applications." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS316/document.
Повний текст джерелаАнотація:
Les systèmes à délivrance de médicaments sont des technologies conçues pour administrer des molécules actives de façon optimisée afin d’améliorer leurs effets thérapeutiques tout en minimisant les effets secondaires. En effet, ces systèmes permettent une libération au niveau d’une cible thérapeutique. Les particules de type «cage» ont récemment attiré une attention particulière en raison de leur capacité accrue à (co)incorporer et à protéger des molécules actives vis-à-vis de dégradations in vivo. Les cyclodextrines (CDs) sont des exemples type de molécules "cage", possédant une cavité hydrophobe et une surface extérieure hydrophile. Nous avons élaboré tout d’abord des assemblages supramoléculaires à base de CDs d'environ 100 nm par une méthode douce consistant à mélanger deux solutions aqueuses de polymères neutres : 1) polymère de β-CD et 2) dextrane greffé avec la benzophénone, molécule invitée formant des complexes d’inclusion avec les CDs. La procédure de préparation « verte» en une seule étape rend la formulation attractive, malgré sa relativement faible capacité d’encapsulation (5%pds). Afin d'améliorer cete charge, nous avons élaboré des particules hybrides organiques-inorganiques (MOFs) à base de CDs. Avantageusement, les CD-MOF comportent non seulement des cavités de CD, mais aussi de larges pores engendrés lors l’auto-assemblage de CDs. Le lansoprazole a été incorporé avec succès (23%pds) dans les CD-MOFs et nous avons montré que chaque CDs était capable d’accueillir une molécule de principe actif. Cependant, l’inconvénient majeur des CD-MOFs est leur faible stabilité en milieu aqueux, limitant leur domaine d’application. Une modification de surface est apparue donc nécessaire pour améliorer leur stabilité. Notre stratégie a été d’incorporer les CD-MOFs dans des matrices d'acide polyacrylique (PAA). Des microsphères composites d’environ 650 nm ont été élaborées avec succès et ont permis une bonne stabilité et une libération prolongée sur plus de 48 h. Avantageusement, ces particules composites n’étaient pas toxiques in vitro même à des concentrations élevées. Ainsi, nous nous sommes orientés vers l’étude comparative de MOFs plus stables dans l’eau, à base de trimesate de fer. Les MIL-100 (Fe) (Material of Institute Lavoisier) figurent parmi les premiers MOF étudiés en tant que nanomédicaments (nanoMOFs). Ces particules, parfaitement stables dans l'eau, se dégradent dans des milieux contenant des phosphates en perdant rapidement leur caractère cristallin et leurs ligands constitutifs. De façon étonnante, nous avons constaté que malgré leur dégradation, ces MOFs conservent leur taille intacte. Une analyse approfondie basée sur la microscopie de Raman a permis d’obtenir des informations pertinentes sur la morphologie et la composition chimique de particules individuelles. Ainsi, il a été montré qu’un front d'érosion délimitait nettement un cœur intact et une coquillé inorganique érodée. Cependant, ni l’encapsulation ni la modification de surface des MOFs n’altérait leur intégrité. Enfin, nous avons étudié la co-encapsulation de deux molécules actives utilisées en combinaison (amoxicilline et clavulanate de potassium) dans les nanoMOFs stables à base de MIL-100 (Fe). Les antibiotiques ont été incorporées par imprégnation et chaque molécule s’est localisée préférentiellement dans un compartiment (large ou petite cage) corroborant parfaitement les simulations par modélisation moléculaire. De plus, il a été découvert, de manière surprenante, qu’un grand nombre de nanoMOFs se localisait au voisinage des bactéries (S.aureus) dans des cellules infectées. En se dégradant dans ces cellules, les nanoMOFs contenant les antibiotiques ont réduit de manière importante la charge bactérienne intracellulaire. Ces études révèlent le potentiel des particules de type «cage» pour une incorporation efficace de molécules actives et leur libération contrôlée et ouvrent de nombreuses possibilités d’applicationDrug delivery systems are engineered technologies to administer pharmaceutical ingredients to improve their therapeutic effects, aiming at minimizing their side effects by means of targeted delivery and/or controlled release. “Cage” particles recently drew special attention since they could act as “drug containers” which potentially load large amount of drugs, improve their stability and offer the possibilities to co-encapsulate synergetic drugs. Cyclodextrins (CDs) are typical “cage” molecules with a hydrophobic cavity and a hydrophilic outer surface. Taking advantage of the host-guest interactions between β-CD and benzophenone (Bz), CD based nanoparticles (CD-NPs) were the first formulation investigated. CD-NPs of around 100 nm were instantaneously produced by mixing two aqueous solutions of neutral polymers: 1) poly-CD containing β-CDs, and 2) Bz grafted Dex (Dex-Bz). The “green” and facile preparation procedure makes it attractive formulation, whereas its limitation lies on the low drug payloads (~ 5 wt%). In order to improve the drug loading capacity of CDs, porous CD based metal organic frameworks (CD-MOFs) were synthesized, which contain not only CD cavities, but also large pores built up by CDs self-assembly. Lansoprazole (LPZ) was incorporated in CD-MOF microcrystals (~ 6 µm) reaching payloads as high as 23.2 ± 2.1% (wt). Remarkably, each CD cavity was able to host a drug molecule, offering new opportunities for the use of CD-MOFs for drug delivery purposes. However, these particles disassembled in aqueous media, which limits their application for oral and intravenous administration. Surface modification is therefore necessary to improve their stability in water. The drug loaded CD-MOF nanocrystals (~ 650 nm) were successfully embedded in polyacrylic acid (PAA) polymer matrices. The composite microspheres exhibited spherical shapes and sustained drug release over a prolonged period of time (over 48 h). Drug loaded MOF/PAA composite microspheres were not toxic in vitro (cell viability ~ 90%) even at very high concentrations up to 17.5 mg/mL. MOF/PAA composite microspheres constitute an efficient and pharmaceutically acceptable MOF-based carrier for sustained drug release. However, the process of surface modification was complicated and lead to larger particles and reduced drug payloads. Water-stable MOFs are a novel type of hybrid particles, showing a high potential as drug carriers. Iron trimesate MOFs, namely, MIL-100 (Fe) (MIL stands for Material of Institute Lavoisier) was among the first nano-scaled MOFs used for drug delivery. These particles were stable in water but degraded in phosphate buffer saline (PBS) losing their crystallinity and constitutive trimesate linkers. However, it was discovered that they kept their morphology intact. A thorough analysis based on Raman microscopy was carried on to gain insights on both the morphology and chemical composition of individual particles. It was evidenced the formation of a sharp erosion front during particle degradation. Noteworthy, the MOFs did not degrade during drug loading nor surface modification. Co-encapsulation of two synergic antibiotics (amoxicillin and potassium clavulanate) in MIL-100 (Fe) nanoMOFs was achieved following a “green” procedure by soaking nanoMOFs in aqueous solutions of both drugs. Molecular modelling showed that each drug preferentially located in a separate nanoMOF compartment. Surprisingly, nanoMOFs were prone to co-localize with bacteria once internalized in infected macrophages. NanoMOFs acted synergistically with the entrapped drugs to kill intracellular S. aureus, in vitro. These results pave the way towards the design of engineered nanocarriers in which each component synergistically plays a role in fighting the disease. These studies unravel the potential of “cage” particles for efficient drug entrapment and controlled release and open numerous possibilities for applications
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Zanchetta, Erika. "Innovative patternable materials for micro- and nano- fabrication." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423686.
Повний текст джерелаАнотація:
The research activity of this thesis is focused on the development and optimization of new directly patternable organically modified TiO2, Al2O3 and ZrO2 based sol-gel materials whose peculiar characteristics and performances were optimized and exploited for the final specific application.
In particular, the main strategy that lies at the basis of all the thesis work is the combination of top down and- bottom up approach for the final device realization. In fact, special attention has been set to materials design and synthesis (bottom up) and subsequently to the micro- and nano- fabrication of patterns on the corresponding film surface with different lithographic techniques (top down) in order to achieve the required properties, according to the final application.
As it concerns the bottom up approach, the sol-gel has been assumed as the main synthetic method since, by mixing different organic-inorganic precursors, new materials with unique properties and microstructures can be created. In fact, by using organically modified precursors (such as trimethoxyphenylsilane, 3-glycidoxypropyltrimethoxysilane, 3-(Trimethoxysilyl)propyl methacrylate) or organic monomers it was possible to produce hybrid materials with the organic and inorganic components intimately mixed at a molecular scale, with the twofold effect of obtaining new properties and conferring them the patternability. Moreover, the addition of tetrafunctional precursors (Titanium isopropoxide, Zirconium butoxide, Aluminum-tri-sec-butoxide) allowed to increase the reticulation degree, taking part to the inorganic network formation, to improve the material mechanical properties (such as scratch, abrasion, plasma etching resistance) and to confer particular characteristics to the final materials, i.e. to modulate the refractive index.
On the other hand, as it regards the top down approach, different lithographic techniques (photolithography, X-ray lithography, electron beam lithography and nanoimprint lithography) have been exploited in the realization of high refractive index patterns, high selective etching masks features, adaptive-optics devices and stamps for microinjection moulding directly with the synthesized materials. The structural and chemical changes induced inside the material by the interactions with the source used in the lithographic process have been deeply investigated in order to optimize both the synthesis of the best sol-gel systems and the final lithographic procedures.
In conclusion the development of all the above mentioned advanced materials and innovative processing was pushed by the main target of improving, simplifying and decreasing costs and time of the overall micro- and nano- fabrication process in order to obtain better final features quality, with respect to traditional lithographic procedures.L’attività di ricerca del presente lavoro di tesi è stata finalizzata allo sviluppo e all’ottimizzazione di nuovi materiali sol-gel a base di ossidi di TiO2, Al2O3 e ZrO2, organicamente modificati, per diverse applicazioni, sfruttando alcune delle loro caratteristiche peculiari e ottimizzandone le prestazioni. Nella fase iniziale del lavoro particolare attenzione è stata rivolta alla sintesi e all’ingegnerizzazione dei materiali stessi (approccio bottom up). Nella fase successiva i materiali sviluppati sono stati micro- e nano- strutturati mediante tecniche litografiche differenti (approccio top down) al fine di valorizzarne proprietà specifiche a seconda della particolare applicazione finale. La combinazione tra l’approccio top down e quello bottom up è stata dunque la principale strategia adottata al fine di raggiungere gli obiettivi prefissati. Per quanto riguarda l’approccio bottom up, la strategia di sintesi adottata è stata il metodo sol-gel. Infatti, l’utilizzo di precursori organico-inorganici permette di sintetizzare nuovi materiali con proprietà e microstrutture uniche. Utilizzando precursori organicamente modificati, come ad esempio trimetossifenilsilano, glicidossipropiltrimetossisilano, metacrilossipropiltrimtossisilano, è stato possibile infatti ottenere materiali ibridi avanzati le cui componenti, organica e inorganica, sono intimemente mescolate a livello molecolare. Inoltre, in fase di sintesi, possono essere aggiunti precursori tetra funzionali, tra cui Titanio isopropossido, Zirconio butossido, Alluminio-tri-sec-butossido, per: aumentare il grado di reticolazione, poiché partecipano alla formazione del network inorganico, con relativo incremento delle proprietà meccaniche del materiale (resistenza al graffio, all’abrasione, all’attacco con plasma), e conferire particolari caratteristiche al materiale finale, come ad esempio la modulazione dell’indice di rifrazione. I materiali così sintetizzati sono stati quindi direttamente micro- e nano- strutturati mediante tecniche litografiche differenti (fotolitografia, litografia a raggi X e a elettroni, litografia nanoimprint), approccio top down, al fine di ottenere pattern ad elevato indice di rifrazione, maschere per il silicio altamente selettive, dispositivi per ottica adattiva e stampi per micro-iniezione. Uno studio approfondito dell’interazione del materiale con le sorgenti utilizzate nei vari processi litografici ha permesso inoltre di ottimizzare sia la sintesi dei sistemi sol-gel stessi sia i parametri di processo litografico. Quindi, lo sviluppo e l’ottimizzazione contemporanei dei materiali avanzati e dei processi litografici innovativi appena citati hanno permesso di ridurre in termini di costi e tempo l’intero processo di micro- e nano- fabbricazione dei dispositivi finali realizzati, rispetto al processo litografico tradizionale, ottenendo strutture qualitativamente superiori.
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Serrà, i. Ramos Albert. "New electrochemical strategies for synthesising micro- and nano- structures." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/399918.
Повний текст джерелаАнотація:
Nowadays, researchers have spent considerable effort on the development of new materials, with new properties and characteristics, and new methods of synthesis, in order to meet the demands of a market that is constantly evolving. In this sense, “New electrochemical strategies for synthesising micro- and nano-structures” proposes, generalizes and discusses the development of novel electrochemical methods, strategies or media to prepare different kinds of micro- and nanostructured materials. The leitmotiv could be focused on the possibility of preparing micro-patterned (Cu), nanoparticulated (Co, CoNi, CoPt), composited (CoPt-Ni), mesoporous (CoNi, CoPt, Pt, CoNi@Pt or CoNi@Au) or nanopowdered (CoPt) deposits with various shape (films, nanorods or nanowires) by using the proposed strategies (Electrochemical nano-Fabrication using Chemistry and Engineering (EnFACE) technology or classical/ionic liquid microemulsions as a soft electrodeposition templates) to obtain micro/nanomaterials for specific magnetic, catalytic or biomedical applications.
The present thesis is organized in eight chapters, in which several published scientific papers in international journals with our original results have been included in order to discuss and analyze our work. The first one introduces the electrodeposition (Chapter 1) – history, theoretical fundaments, advantages and disadvantages and introduce the state-of-the-art of electrochemical micro- and nano-fabrication –, which is fundamental in order to understand our work. The aims and the experimental details of our research are presented and detailed in chapter 2 and chapter 3, respectively. It is important emphasize that “New electrochemical strategies for synthesising
micro- and nano-structures” could be grouped into three main areas, according the aims introduced above:
(a) The optimization of EnFACE technology as an alternative method to classical masked-electrodeposition to prepare metallic microstructures on large conductive substrates, with the final objective of proposing this technology as a scalable, economic and environmentally-friendly synthesis approach to microfabrication; this could be relevant in the electronics and sensors industries. This work is presented in chapter 4;
(b) Proposing, discussing and analyzing the use of different types of classical microemulsions as new electrochemical media for synthesising nanostructures — that is, a new shape-controlled electrodeposition approach based on the use of soft-template systems. In this sense, the possibility of obtaining different types of Co-based structures with varied geometries and shapes as a function of the microemulsions conditions has been demonstrated. However, the low or moderate deposition rates and efficiencies leading us to explore and propose the use of alternative (water-in-ionic liquid) microemulsions as soft-template electrochemical media with improved conductivity and low environmental impact for shape-controlled electrodeposition. These electrodeposition media were tested to prepare magnetic nanostructured materials (nanoparticulated CoPt magnetic films or CoPt-Ni composites) with controlled size, composition and magnetism. Based on our results, the use of water –in-ionic liquid (W/IL) microemulsions have been revealed to be a versatile, green, simple and inexpensive approach to 1) synthesizing nanoparticles with controlled size and composition, and therefore magnetic behavior, by controlling the droplet size and aqueous solution concentration respectively, or 2) developing layers of composites using a one-step procedure, in which simultaneous electrodeposition from aqueous droplets and continuous ionic liquid components could take place. This work is presented in chapter 5;
(c) Proposing, generalizing and discussing new electrochemical strategies (electrodeposition in water-in-ionic liquid, bicontinuous and ionic liquid-in-water microemulsions) for synthesising mesoporous nanomaterials ((Pt, CoPt, CoNi, CoNi @Au or CoNi@Pt) for catalysis (the
electrooxidation of methanol or ethanol in order to propose competitive electrocatalysts with poor- Pt content for fuel cell reactions) or drug delivery with enhanced therapeutic effect as a consequence of their magnetic stimulation. This results are presented in chapter 6.
Lastly, to complete the thesis, the main conclusions obtained are collected in chapter 7, while a summary of the thesis in Catalan language is given in chapter 8.En aquesta tesi s’estudien i proposen noves estratègies de síntesi de micro- i nano-estructures metàl·liques amb potencials aplicacions en els camps de l’electrònica, catàlisi i alliberament de fàrmacs. El leitmotiv de la tesi serien (a) l’optimització de la preparació de micro-estructures de coure sobre grans àrees superficials, mitjançant la tecnologia EnFACE (Electrochemical nano-Fabrication using Chemistry and Engineering); demostrar, analitzar i generalitzar la viabilitat d’utilitzar (b) microemulsions clàssiques i (c) microemulsions base líquid iònic, com a plantilles toves, per a la síntesi diferents tipus de nano-estructures magnètiques (nanopartícules, compòsits, materials mesoporosos), permetent modular-ne les seves propietats, forma i característiques; i finalment (d) testar l’ús de les nano-estructures mesoporoses com a electro-catalitzadors per l’oxidació d’alcohols o vehicles intel·ligents per a l’alliberament de fàrmacs en medis cel·lulars. La tesi s’estructura en vuit capítols i inclou diverses publicacions en revistes científiques. En el primer capítol s’introdueix breument l’estat de l’art de l’electrodeposició de micro- i nano-materials, així com una breu ressenya històrica i els fonaments imprescindibles per a la comprensió del treball. El capítol 2 introdueix els objectius, mentre que en el capítol 3 es descriuen i detallen les condicions experimentals i equips emprats per a la síntesi, caracterització i aplicació dels materials fabricats. El capítol 4 es focalitza en la micro-fabricació fent una breu introducció a l’estat de l’art, així com discutir i optimitzar l’ús de la tecnologia EnFACE per a la micro-fabricació d’estructures de coure sobre substrats de grans dimensions. El capítol 5 es centra en la discussió i anàlisi de la viabilitat de l’ús de microemulsions clàssiques i base líquid-iònic per a l’electrodeposició amb forma controlada, basada en l’ús de plantilles toves. Finalment, el capítol 6 explora i estableix unes condicions de síntesi de nano-fils mesoporosos de diferents materials (base Co i Pt) per a la preparació d’electro-catalitzadors amb grans àrees superficials i alta activitat catalítica per a l’oxidació d’alcohols així com el seu ús com a vehicles dosificadors de fàrmacs. Finalment, el capítol 7 resumeix les conclusions de la tesi i el 8 presenta un resum en català.
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Perre, Emilie. "Nano-structured 3D Electrodes for Li-ion Micro-batteries." Doctoral thesis, Uppsala universitet, Institutionen för materialkemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-119485.
Повний текст джерелаАнотація:
A new challenging application for Li-ion battery has arisen from the rapid development of micro-electronics. Powering Micro-ElectroMechanical Systems (MEMS) such as autonomous smart-dust nodes using conventional Li-ion batteries is not possible. It is not only new batteries based on new materials but there is also a need of modifying the actual battery design. In this context, the conception of 3D nano-architectured Li-ion batteries is explored. There are several micro-battery concepts that are studied; however in this thesis, the focus is concentrated on one particular architecture that can be described as the successive deposition of battery components (active material, electrolyte, active material) on free-standing arrays of nano-sized columns of a current collector. After a brief introduction about Li-ion batteries and 3D micro-batteries, the electrodeposition of Al through an alumina template using an ionic liquid electrolyte to form free-standing columns of Al current collector is described. The crucial deposition parameters influencing the nucleation and growth of the Al nano-rods are discussed. The deposition of active electrode material on the nano-structured current collector columns is described for 2 distinct active materials deposited using different techniques. Deposition of TiO2 using Atomic Layer Deposition (ALD) as active material on top of the nano-structured Al is also presented. The obtained deposits present high uniformity and high covering of the specific surface of the current collector. When cycled versus lithium and compared to planar electrodes, an increase of the capacity was proven to be directly proportional to the specific area gained from shifting from a 2D to a 3D construction. Cu2Sb 3D electrodes were prepared by the electrodeposition of Sb onto a nano-structured Cu current collector followed by an annealing step forcing the alloying between the current collector and Sb. The volume expansion observed during Sb alloying with Li is buffered by the Cu matrix and thus the electrode stability is greatly enhanced (from only 20 cycles to more than 120 cycles). Finally, the deposition of a hybrid polymer electrolyte onto the developed 3D electrodes is presented. Even though the deposition is not conformal and that issues of capacity fading need to be addressed, preliminary results attest that it is possible to cycle the obtained 3D electrode-electrolyte versus lithium without the appearance of short-circuits.
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Williams, Benjamin Heathcote. "Nano- and micro-scale techniques for electrical transport measurements." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:09c73d9f-b68d-4f06-9ffe-cbb29d200809.
Повний текст джерелаАнотація:
This thesis outlines the development of two new techniques that exploit very small structures, on the micro- and nano-scale, to enable innovative electrical transport measurements on a variety of materials of current interest in condensed matter physics. The first technique aims to apply the versatility of electron-beam lithography for micro-fabrication of patterned electronic circuitry to the problem of performing transport experiments on individual crystallites taken from a typical powder sample. We show that these small samples, tens of microns in size, are actually often very high quality single crystals and can be exploited for measurements of electrical transport in materials of which no larger crystals are available. By way of demonstration, we present the results of preliminary transport measurements on a crystallite of the layered oxide chalcogenide Sr2MnO2Cu1.5Se2. We report a phase transition in the resistivity at 213K which may correspond to the onset of previously reported short-range order in copper and vacancy sites in the Cu1.5Se2 planes. The second technique is designed to investigate the topological protection of surface transport in 3-D topological insulators. We decorate the surfaces of single-crystal samples with two different species from a well-characterised family of single-molecule magnets. The two coatings have an electrostatically identical influence on the sample surface, but differ in that one species carries a spin and the other is spinless. The spinless molecule acts as a control, to allow us to cleanly determine the influence of the magnetic component of a scattering potential on transport in the surface. With this technique we investigate proposed topological Kondo insulator SmB6. We find that the surface state dominates low-temperature transport and demonstrate that the momentum relaxation is very sensitive to a spin degree of freedom in the scatterer, in keeping with expectations of a topological insulator.
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Otanocha, Omonigho. "Laser surface micro/nano patterning for improving aerodynamic performance." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/laser-surface-micronano-patterning-for-improving-aerodynamic-performance(f78b8df4-fa5d-4dd8-9d93-88e1068c5857).html.
Повний текст джерелаАнотація:
The use of ultrafast lasers in material surface engineering has gained pre-eminence in recent years. This is due to optimal utility arising from their versatility, better process control, repeatability and high precision fabrication, without need for post processing. Reported in this thesis are experimental results on the use of picosecond laser to produce micro-patterns on cyclone components and their effects on flow characteristics. Results show that micro- dimples achieved reduction in dust accumulation within a multi-cyclone system considered, up to 78%. These micro-dimples when applied on the cyclone roof effected a 3% reduction in inlet velocity and 5% reduction on the dynamic pressure across the cyclone, without dust introduction. Results support the possibility for energy savings, without compromise on cyclone overall separation efficiency. Findings further demonstrated the effects of micro-riblets on cyclonic airflow at the wall boundary. Research outcomes supported the view that surface roughness of the cyclone roof could contribute on its dust separation capacity. Injection moulding was used to produce bumps on ABS plastic materials utilising picosecond laser machined micro-dimples on H13 tool steel. A statistical model detailing the interactions between the critical factors involved with picosecond laser interaction with H13 for micro-patterning was proposed. Critical factors identified were laser fluence, scanning speed and number of laser scans. In addition, results demonstrated the suitability of predicting depth of 40 - 100 µm for H13 tool steel, with 96% accuracy. The findings in this research could be explored to develop embedded micro/nano-wires within riblets through injection moulding, to effect electrically biased charging within the internal walls of a cyclone to aid dust separation processes.
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Badami, Muhammad Ali. "Design of a FEEP Thruster for Micro-/Nano-Satellites." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75615.
Повний текст джерелаАнотація:
CubeSat development has seen a rise since the first launch in 2003 due to faster design process and low launch costs. It has played a vital role in providing access to space to small start-ups and academic organizations with low budgets. It has also enabled the testing of different upcoming technologies in space and has helped in providing hands-on experience to students taking part in design of such platforms. University of Pisa, in collaboration with SITAEL, has also taken an initiative to design and develop a CubeSat to test the FEEP thruster, design of which is presented in the thesis. A FEEP system was designed to fit within 1U dimensions and with a dry mass of approximately 820 grams. The system is based on slit emitter which provides an advantage over already available technologies in the market which uses needle emitters. Slit emitter scan achieve multiple Taylor cones without the need of clustering as used in needle emitters and also have a higher Thrust to Power Ratio. A propellant comparison was done considering all the properties required for an ideal propellant for a FEEP system. This comparison led to the selection of indium as working propellant which has an atomic mass of 114.8 u and a melting point of 156.6 °C. The FEEP system was designed keeping in mind easy assembling and modularity of thruster for ease in changing parts. The design consists of three different modules that are assembled separately and then joined together to complete the assembling of the system. The propellant tank, which also houses the emitter, has an internal volume of 32.75 cm3 and can hold approximately 240 grams of indium, which has a density of 7.31 g/cm3. During mission analysis, a 600km altitude orbit was proposed by analyzing the amount of propellant required for drag compensation and de-orbit maneuver at different altitudes with worst case values for ballistic coefficient and Thrust to Weight Ratio. At this altitude, the propellant requirement is 254.4 grams, 14.4 grams more than that of what can fit in the propellant tank of the designed thruster. However, both design of the system and mission analysis are ongoing processes and changes would be made in the future to either one or both to meet the requirements.
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WETTERBORG, MALIN. "Micro and nano sized textile topography for improved water repellence." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18006.
Повний текст джерелаАнотація:
Water repellent fabrics with superhydrophobic properties have been constructed during this diploma work. First the fabrics were woven using six different weft yarns creating micro roughness and then a nanoparticle and surface energy lowering treatment was made. Contact angle measurements, contact angle hysteresis measurements, roll-off angle measurements and spray tests were made on the fabrics to investigate the hydrophobicity and water repellence. Also the durability was tested to examine the fastness of the treatments. It was found that the nanoparticles boosted the hydrophobicity of the hydrophobic treatments. Also by varying the size of textile filaments in yarns, the hydrophobicity of the material was affected. In this study, it was found how small textile parameters in the fabric could be changed to increase both durability and water repellence.Program: Textilingenjörsutbildningen
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Iyengar, Ananth Shalvapulle. "Synthesis and characterization of micro/nano material for thermoelectric applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1276182370.
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Yan, Huan. "MICRO- AND NANO-MATERIALS FOR DRUG DELIVERY AND BIOIMAGING APPLICATIONS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1428155172.
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Hung, Ming-Tsung. "Heat transport in polymer thin films for micro/nano-manufacturing." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1459914931&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Wang, Chenguang. "Nano and micro structured transparent conductors for organic photovoltaic applications." Thesis, University of Bristol, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738327.
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Giacomazzo, Sujatha. "Integrated Micro and Nano Systems for Photonic Detection in Liquids." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3425703.
Повний текст джерелаАнотація:
The aim of this Ph.D. work was the study of functional materials and micro/nano structures for the realization of optical sensors for chemical or biological species in liquid media. The research was focused on two different areas of interest: biology and food industry. A disorder of zinc metabolism is closely associated with severe diseases, including diabetes. Functional and porous sol-gel films, doped with a fluorescent molecule, able to detect Zn2+ down to the nanomolar range were engineered. The systems allow to detect dynamic concentrations in time, showing selectivity overall other ions, stability provided by covalent binding of the fluorophore, and most relevantly reversibility. The second part of the dissertation is focused on the detection of residual antibiotics.
The concern for food safety in milk industry has determined definition of residue levels of antibiotics in milk samples. Strong interest is evident in the development of high sensitivity optical sensors, giving reliable responses and allowing in situ multiple antibiotics detection. Two different plasmonic architectures for performing high-sensitive, selective and cost-effective detection of residual antibiotics in milk, and in particular of ampicillin, were developed. An SPR-based sensing strategy which consists in the combination of resonant optical and magnetic properties in a single nanostructure, and a plasmonic sinusoidal grating coupling supporting the propagation LRSPPs were studied. Selectivity is achieved by functionalization with specific aptamers.
Even if further in-depth investigations are needed, this work has provided awareness and competence of the fabrication techniques and analytical instruments for characterization and use of the developed devices.Lo scopo di questo lavoro è stato lo studio di materiali funzionali e strutture micro / nano per la realizzazione di sensori ottici per la rilevazione di specie chimiche o biologiche in mezzi liquidi. La ricerca è stata incentrata su due diverse aree di interesse: la biologia e l'industria alimentare. Un disturbo del metabolismo di zinco è strettamente associato a gravi malattie, tra cui il diabete. Film sol-gel funzionali e porosi, drogati con una molecola fluorescente, in grado di rilevare Zn2 + fino alla range del nanomolare sono stati ingegnerizzati. I sistemi permettono di rilevare le concentrazioni di ioni zinco dinamicamente nel tempo, mostrando selettività rispetto ad altri ioni, stabilità derivante dal legame covalente del fluoroforo con la matrice, e soprattutto reversibilità. La seconda parte della tesi è focalizzata sul rilevamento di antibiotici residui. La preoccupazione per la sicurezza alimentare nel settore del latte ha determinato la definizione dei livelli residui di antibiotici in campioni di latte. C'è un forte interesse nello sviluppo di sensori ad alta sensibilità ottica, che diano risposte affidabili e permettano il rilevamento di più antibiotici in situ. Due diverse architetture plasmoniche per il rilevamento ad alta sensibilità, selettività ed economicamente conveniente di antibiotici residui nel latte, ed in particolare di ampicillina, sono stati sviluppati. Sono state studiate una strategia basata su SPR che consiste nella combinazione di proprietà di risonanza ottica e magnetiche in un unica nanostruttura, e un grating sinusoidale plasmonico che supporta la propgazione LRSPPs. La selettività è il risultato di una funzionalizzazione con aptameri specifici. Anche se sono necessari ulteriori indagini, questo lavoro ha fornito la consapevolezza e la competenza delle tecniche di fabbricazione e degli strumenti analitici per la caratterizzazione e l'uso dei dispositivi sviluppati.
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Shen, Cai. "Self-assembled monolayers of thiolates as templates for micro/nano fabrication." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/603.
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Agustí, Batlle Jordi. "Nonlinear micro/nano-optomechanical oscillators for energy transduction from IR sources." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285101.
Повний текст джерелаАнотація:
En aquesta tesi es proposa un nou dispositiu que combina antenes òptiques i micro/nanoestructures mecàniques amb l'objectiu de transformar energia electromagnètica en energia mecànica. El principal objectiu de la feina realitzada és l'estudi dels mecanismes de transducció implicats. El principi de funcionament d'aquest nou dispositiu es pot resumir de la manera següent: les antenes absorbeixen la radiació electromagnètica en l'espectre infraroig i la transformen en una distribució de temperatura en l'estructura mecànica, a causa de les propietats tèrmiques del material estructural la resposta tèrmica es converteix en una deflexió mecànica que eventualment pot conduir a l'autooscil·lació del dispositiu.
Donades les transformacions d'energia involucrades, el modelatge de les físiques acoblades esdevé un pas fonamental per tal de dissenyar, fabricar i caracteritzar un dispositiu de prova de concepte. La conversió d'energies es demostra que és més eficient quan el dispositiu autooscil·la. No obstant això, a causa de la naturalesa altament no lineal d'aquest fenomen, saber exactament si aquesta oscil·lació es pot aconseguir utilitzant el dispositiu de prova de concepte implica caracteritzar-lo físicament per tal d'aplicar el model desenvolupat.In this thesis, a new device merging optical antennas and micro/nano-mechanical structures is proposed with the aim to transform electromagnetic energy into mechanical energy. The study of the involved transduction mechanisms is the main objective of the presented work. The working principle of this new device can be summarized as follows: the antennas acting as absorbers in the infrared spectrum capture the electromagnetic radiation and transform it into a temperature field in the mechanical structure. Due to the thermal properties of the structural material the thermal response is converted to a mechanical deflection which eventually can lead to the self-oscillation of the device. Given the involved energy transformations, the modeling of the coupled physics becomes a fundamental step in the path of designing, fabricating and characterizing a proof-of-concept device. The energy conversion is shown to be more efficient when the device auto-oscillates. However, due the the highly nonlinear nature of such phenomenon precisely knowing if such oscillation can be achieved using the proof-of-concept device imply its physical characterization in order to apply the developed model.
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Zhang, Xing. "Electrospun tri-layer micro/nano-fibrous scaffold for vascular tissue engineering." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2010r/zhang.pdf.
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Ketterl, Thomas P. "Micro- and nano-scale switches and tuning elements for microwave applications." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001559.
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LI, BO. "UV-LIGA COMPATIBLE ELECTROFORMED NANO-STRUCTURED MATERIALS FOR MICRO MECHANICAL SYSTEMS." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2269.
Повний текст джерелаАнотація:
UV-LIGA is a microfabrication process realzed by material deposition through microfabricated molds. UV photolithography is conducted to pattern precise thick micro molds using UV light sensitive materials, mostly SU-8, and electroforming is performed to fabricate micro metallic structures defined by the micro molds. Therefore, UV-LIGA is a bottom-up in situ material-addition process. UV-LIGA has received broad attention recently than LIGA – a micro molding fabrication process using X-ray to pattern the micro molds. LIGA is an expansive and is limited in access. In comparing to LIGA, the UV-LIGA is a cost effective process, and is widely accessible and safe. Therefore, it has been extensively used for the fabrication of metallic micro-electro-mechanical-systems (MEMS). The motivation of this research was to study micro mechanical systems fabricated with nano-structured metallic materials via UV-LIGA process. Various micro mechanical systems with high-aspect-ratio and thick metallic structures have been developed and are presented in this desertation. A novel micro mechanical valve has been developed with nano-structured nickel realized with UV-LIGA fabrication technique. Robust compact valves are crucial for space applications where payload and rubstaness are critically concerned. Two types of large flow rate robust passive micro check valve arrays have been designed, fabricated and tested for robust hydraulic actuators. The first such micro valve developed employs nanostructured nickel as the valve flap and single-crystal silicon as the substrates to house inlet and outlet channels. The Nano-structured nickel valve flap was fabricated using the UV-LIGA process developed and the microchannels were fabricated by deep reactive etching (DRIE) method. The valves were designed to operate under a high pressure (>10MPa), able to operate at high frequencies (>10kHz) in cooperating with the PZT actuator to produce large flow rates (>10 cc/s). The fabricated microvalves weigh 0.2 gram, after packing with a novel designated valve stopper. The tested results showed that the micro valve was able to operate at up to 14kHz. This is a great difference in comparison to traditional mechanical valves whose operations are limited to 500 Hz or less. The advantages of micro machined valves attribute to the scaling laws. The second type of micro mechanical valves developed is a in situ assembled solid metallic (nickel) valves. Both the valve substrates for inlet and outlet channels and the valve flap, as well as the valve stopper were made by nickel through a UV-LIGA fabrication process developed. Continuous multiple micro molds fabrication and molding processes were performed. Final micro mechanical valves were received after removing the micro molds used to define the strutures. There is no any additional machining process, such as cutting or packaging. The alignment for laminated fabrication was realized under microscope, therefore it is a highly precise in situ fabrication process. Testing results show the valve has a forward flow rate of19 cc/s under a pressure difference of 90 psi. The backward flow rate of 0.023 cc/s, which is negligible (0.13%). Nano-structured nickel has also been used to develop laminated (sandwiched) micro cryogenic heater exchanger with the UV-LIGA process. Even though nickel is apparently not a good thermal conductor at room temperature, it is a good conductor at cryogentic temerpature since its thermal conductivity increases to 1250 W/k·m at 77K. Micro patterned SU-8 molds and electroformed nickel have been developed to realize the sandwiched heat exchanger. The SU-8 mold (200mm x 200mm x50mm) array was successfully removed after completing the nickel electroforming. The second layer of patterned SU-8 layer (200mm x 200mm x50mm, as a thermal insulating layer) was patterned and aligned on the top of the electroformed nickel structure to form the laminated (sandwiched) micro heat exchanger. The fabricated sandwiched structure can withstand cryogenic temperature (77K) without any damages (cracks or delaminations). A study on nanocomposite for micro mechanical systems using UV-LIGA compatible electroforming process has been performed. Single-walled carbon nanotubes (SWNTs) have been proven excellent mechanical properties and thermal conductive properties, such as high strength and elastic modulus, negative coefficient of thermal expansion (CTE) and a high thermal conductivity. These properties make SWNT an excellent reinforcement in nanocomposite for various applications. However, there has been a challenge of utilizing SWNTs for engineering applications due to difficulties in quality control and handling – too small (1-2nm in diameter). A novel copper/SWNT nanocomposite has been developed during this dissertational research. The goal of this research was to develop a heat spreader for high power electronics (HPE). Semiconductors for HPE, such as AlGaN/GaN high electron mobility transistors grown on SiC dies have a typical CTE about 4~6x10-6/k while most metallic heat spreaders such as copper have a CTE of more than 10x10-6/k. The SWNTs were successfully dispersed in the copper matrix to form the SWNT/Cu nano composite. The tested composite density is about 7.54 g/cm3, which indicating the SWNT volumetric fraction of 18%. SEM pictures show copper univformly coated on SWNT (worm-shaped structure). The measured CTE of the nanocomposite is 4.7 x 10-6/°C, perfectly matching that of SiC die (3.8 x 10-6/°C). The thermal conductivity derived by Wiedemann-Franz law after measuring composit's electrical conductivity, is 588 W/m-K, which is 40% better than that of pure copper. These properties are extremely important for the heat spreader/exchanger to remove the heat from HPE devices (SiC dies). Meanwhile, the matched CTE will reduce the resulted stress in the interface to prevent delaminations. Therefore, the naocomposite developed will be an excellent replacement material for the CuMo currently used in high power radar, and other HPE devices under developing. The mechanical performance and reliability of micro mechanical devices are critical for their application. In order to validate the design & simulation results, a direct (tensile) test method was developed to test the mechanical properties of the materials involved in this research, including nickel and SU-8. Micro machined specimens were fabricated and tested on a MTS Tytron Micro Force Tester with specially designed gripers. The tested fracture strength of nanostructured nickel is 900±70 MPa and of 50MPa for SU-8, resepctively which are much higher than published values.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Miljkovic, Nenad. "Development and characterization of micro/nano structured surfaces for enhanced condensation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84403.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 159-168).
Micro/nanostructures have long been recognized to have potential for heat transfer enhancement in phase-change processes by achieving extreme wetting properties, which is of great importance in a wide range of applications including thermal management, building environment control, water harvesting, desalination, and industrial power generation. This thesis focuses on the fundamental understanding of water vapor condensation on superhydrophobic surfaces, as well as the demonstration of such surfaces for enhanced condensation heat transfer performance. We first studied droplet-surface interactions during condensation on superhydrophobic surfaces to understand the emergent droplet wetting morphology. We demonstrated the importance of considering local energy barriers to understand the condensed droplet morphologies and showed nucleation-mediated droplet-droplet interactions can overcome these barriers to develop wetting states not predicted by global thermodynamic analysis. To minimize these droplet-droplet interactions and ensure the formation of favorable morphologies for enhanced condensation heat transfer, we show that the structure length scale needs to be minimized while ensuring the local energy barriers satisfy the morphology dependent criteria. This mechanistic understanding offers insight into the role of surface-structure length scale and provides a quantitative basis for designing surfaces optimized for condensation in engineered systems. Using our understanding of emergent droplet wetting morphology, we experimentally and numerically investigated the morphology dependent individual droplet growth rates. By taking advantage of well-controlled functionalized silicon nanopillars, the growth and shedding behavior of both suspended and partially wetting droplets on the same surface during condensation was observed. Environmental scanning electron microscopy was used to demonstrate that initial droplet growth rates of partially wetting droplets were 6 times larger than that of suspended droplets. A droplet growth model was developed to explain the experimental results and showed that partially wetting droplets had 4-6 times higher heat transfer rates than that of suspended droplets. Based on these findings, the overall performance enhancement created by surface nanostructuring was examined in comparison to a flat hydrophobic surface. These nanostructured surfaces had 56% heat flux enhancement for partially wetting droplet morphologies, and 71% heat flux degradation for suspended morphologies in comparison to flat hydrophobic surfaces. This study provides fundamental insights into the previously unidentified role of droplet wetting morphology on growth rate, as well as the need to design nanostructured surfaces with tailored droplet morphologies to achieve enhanced heat and mass transfer during dropwise condensation. To create a unified model for condensation capable of predicting the surface heat transfer for a variety of surface length scales, geometries, and condensation conditions, we incorporated the emergent droplet wetting morphology, individual droplet heat transfer, and size distribution. The model results showed a specific range of characteristic length scales (0.5 - 2 ptm) allowing for the formation of coalescence-induced jumping droplets with a 190% overall surface heat flux enhancement over conventional flat dropwise condensing surfaces. This work provided a unified model for dropwise condensation on micro/nanostructured superhydrophobic surfaces and offered guidelines for the selection of ideal structured surfaces to maximize heat transfer. Using the insights gained from the developed model and optimization, a scalable synthesis technique was developed to produce functionalized oxide nanostructures on copper surfaces capable of sustaining superhydrophobic condensation. Nanostructured copper oxide (CuO) films were formed via chemical oxidation in an alkaline solution resulting in dense arrays of sharp CuO nanostructures with characteristic heights and widths of -1 pm and -300 nm, respectively. Condensation on these surfaces was characterized using optical microscopy and environmental scanning electron microscopy to quantify the distribution of nucleation sites and elucidate the growth behavior of individual droplets with characteristic radii of -1 to 10 pm at supersaturations < 1.5. Comparison of the measured individual droplet growth behavior showed good agreement with our developed heat transfer model. We subsequently studied the macroscopic heat transfer performance during water condensation on superhydrophobic CuO tube surfaces in a custom built experimental chamber. The results experimentally demonstrated for the first time a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement, but promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation. In addition to demonstrating enhanced heat transfer performance, we discovered electrostatic charging of jumping droplets on CuO. With the aid of electric fields, the charge on the droplets was quantified, and the mechanism for the charge accumulation was studied. We demonstrated that droplet charging was associated with the formation of the electric double layer at the droplet-surface interface, and subsequent separation during coalescence and jumping. The observation of droplet charge accumulation and electric double layer charge separation provides important insight into jumping droplet physics. Furthermore, this work is a starting point for more advanced approaches for enhancing jumping droplet surface performance by using external electric fields to control droplet jumping. Finally, we demonstrated electric-field-enhanced (EFE) condensation, whereby an external electric field was used to force charged departing droplets away from the surface and limit their return. With the CuO surfaces, we studied EFE condensation heat transfer performance during water condensation. The results experimentally demonstrated a 50% higher overall heat transfer coefficient compared to the no-field jumping surface at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement, it offers insights into new avenues for improving the performance of self-cleaning and anti-icing surfaces, as well as thermal diodes. This thesis presents improved fundamental understanding of wetting and condensation on micro/nanostructures as well as practical implementation of these structures for enhanced condensation heat transfer. The insights gained demonstrate the potential of new surface engineering approaches to improve the performance of various thermal management and energy production applications.
by Nenad Miljkovic.
Ph.D.
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Fowley, Colin Paul. "Nano/micro particle conjugates for use in photodynamic and sonodynamic therapy." Thesis, Ulster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.692835.
Повний текст джерелаАнотація:
Photodynamic therapy (PDT) has been used as a clinical treatment since the early 1990s and utilizes a photosensitising drug (PS), molecular oxygen and light of a specific wavelength, (usually visible light below 700nm) to generate singlet oxygen and other reactive oxygen species which are highly cytotoxic. Originally used as a treatment for superficial skin cancer it is now emerging as a treatment for other forms of cancer such as head, neck, lung and prostate cancers. There are however, several limitations which have prevented PDT obtaining wide spread clinical use. For example currently approved PS drugs absorb light in the visible region limiting tissue depth penetration to a few mm rendering the treatment unsuitable for deep seated tumours. Secondly, PS molecules also tend to be hydrophobic and can aggregate in aqueous solutions, leading to a reduction in singlet oxygen production. The focus of this PhD seeks to take advantage of the photophysical properties of conventional cadmium selenide quantum dots (QDs) (chapter 3) and the relatively new carbon based nano material known as carbon quantum dots (CQDs) (chapter 4), to address some of the difficulties currently faced with the use of conventional PS drugs in PDT. This strategy shall involve the synthesis, in vitro and in vivo evaluation of suitable nano-particlePS conjugates. In addition to the synthesis of conjugates for PDT implications, microbubblesensitiser conjugates were also developed for use in sonodynamic therapy (SDT). SDT refers to the ultrasound dependent cytotoxic effect of certain compounds (sonosensitisers). Ultrasound having far superior tissue dept penetration than light, overcoming the major limitation of poor tissue depth penetration observed in PDT. However there are still some undesirable characteristics associated with SDT. The accumulation of sonosensitisers in healthy tissue has been one such drawback, as sonosentisers (SS) are generally also PS this can lead to photosensitivity of the skin. In order to achieve a greater degree of selectivity the use of microbubble-SS conjugates was investigated (chapter 5). Lipid based microbubbles (MBs) are currently approved for use as contrast agents in diagnostic ultrasound applications and have also been investigated as potential drug / gene delivery vehicles. In chapter 5 Rose Bengal, a well known SS, was covalently attached to the surface of a lipid coated MB. The overall objective of this strategy was to investigate the potential of this MB-SS conjugate as a therapeutic for highly targeted, minimally invasive treatment of deep seated tumours.
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Richardson, Elliot J. W. "Micro- and nano-soft lithography for the fabrication of photonic devices." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27964.
Повний текст джерелаАнотація:
This thesis presents the application of two soft lithographic tools for direct patterning of (soft) photonic materials at the micro- and nano-scale. Inkjet printing and Dip-Pen Nanolithography, respectively, have been used to pattern organic molecules, photoresists, and conductive inks to create optically active structures and devices. A series of light emitting polymers (LEPs), blended with a photo-curable host system, have been integrated as colour converters with an array of matrix-addressable gallium nitride (GaN) micro LEDs to form a red-green-blue (RGB) emitting array. Surface structure and conversion efficiency have been explored in detail with peak colour conversion efficiencies of 31.6% being obtained. Inkjet printing of silver conductive inks has been used in conjunction with mask-free ultraviolet direct writing to generate an 8 x 8 GaN LED array. The smallest feature achieved with the mask-free writing set up is 1 μm and the conductive ink was used to form a contact with the n-GaN to enable wire-bonding and characterisation of the LED. This mask-free process is attractive as fabrication of conventional masks for photolithography is both costly and lengthy. Possessing the ability for define LED patterns “free form” on photoresist and subsequently producing a common n-contact with the silver ink allows for rapid prototyping for novel and experimental LED designs. Two techniques were explored for utilising the potential of Dip-Pen Nanolithography; deposition of liquid inks (positive) and removal of dried material (negative). Photoresist inks were used to generate nanoscale features (560nm) on a planar LED structure. Subsequent exposure to a CHF3 plasma treatment deactivated the Mg doped GaN which was not protected by the photoresist; LEDs with 3 μm diameter at full-width half-maximum were fabricated in this manner. Utilising dip-pen nanolithography for negative patterning allows for grating structures to be created via the displacement and removal of material. 1D and 2D structures were generated using a lasing polymer as the optically active gain medium. When optically pumped it was found that these structures lased and the grating structures acted as Distributed Bragg Reflectors (DBRs).Key advantages for the techniques used throughout this thesis are that they allow the patterning of sensitive materials that otherwise would not survive classical lithography due to aggressive chemical treatment or high UV exposure. In addition all of the techniques used are readily programmable and require no masks to be fabricated thus allowing for rapid prototype production and experimental designs to be implemented without delays or incurring extra costs.
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Chichenkov, Aleksandr. "Electrokinetic manipulation of micro to nano-sized objects for microfluidic application." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/15933/.
Повний текст джерелаАнотація:
This thesis describes experimental and numerical investigations of various electrokinetic techniques on fluorescent particles, bacteria and protein motors. The aim of this work is to extend the knowledge on the object manipulation, which is an essential part of a practical microfluidic device. The dissertation consists of three major sections that contain novel approaches to object manipulation using electric fields. The effect of dielectrophoretic force on fluorescent particles is analysed first. Using an experimental setup with a controlled switch for the input signal, the theoretical framework for amplitude modulated responce of dielectrophoretic force is developed. Also presented is the image processing software for quantitative particle motion analysis. Another analysis of various electrokinetic techniques (dielectrophoresis, AC electroosmosis, AC electrothermal flow and electrophoresis) was carried out on Pseudomonas Fluorescence bacteria in a solution that supports its growth. These bacteria usually live in geometrically restricted spaces and so spatially confined transparent channels were created to mimic their natural environment. It was noted that in these conditions the motile bacteria do not experience the effect of dielectrophoretic force. The minimum frequency that can be applied to the solution without forming bubbles is too high to distinguish AC electroosmotic effect. Using the numerical simulation, however, the experimental setup that utilises the observed effect of electrophoresis and AC electrothermal flow is designed. The final study was carried out on protein molecular motors. The novel experimental setup to investigate the effect of the electric field on the actin filament motility on five different surfaces, covered with myosin II motors, was developed. The application of higher external electric fields resulted in different velocity increases on different surfaces. Using the numerical simulation, this difference is quantitatively explained by the variation of the number of motors on surfaces. Also presented is a novel method that enables determining the forces exerted by the population of active and resistive motors without the need of expensive equipment.
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DO, JAEPHIL. "A DISPOSABLE POLYMER LAB-ON-A-CHIP WITH MICRO/NANO BIOSENSOR FOR MAGNETIC NANO BEAD-BASED IMMUNOASSAY." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1164035684.
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Tulli, Domenico. "Micro-nano structured electro-optic devices in LiNbO3 for communication and sensing." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/81118.
Повний текст джерелаАнотація:
A material that is enabling integrated optics is the ferroelectric crystal Lithium Niobate (LiNbO3), which has excellent electro-optical, acousto-optical and nonlinear optical properties. Moreover, it can be doped with laser-active ions and allows for simple fabrication of low-loss optical waveguides.
The broad aim of this work is to develop and introduce advanced micro- and nano-fabrication techniques for LiNbO3 and a new class of integrated based telecommunication and sensing devices. The techniques developed include precise micro-domain inversion, etching, bonding and thin film fabrication.
From a device point of view, domain inversion is used to improve the electro-optic response of LiNbO3 waveguide modulators in terms of bandwidth and driving voltage. With respect to standard single-domain structures, larger bandwidths and lower driving voltages can be obtained, thus achieving figure of merits for the electro-optic response that are up to 50% larger. As a demonstration, a chirp-free modulator, having ~2V switching voltage and bandwidth of 15 GHz, was fabricated by placing the waveguide arms of a Mach-Zehnder interferometer in opposite do- main oriented regions. The modulator could be driven in a single-drive configuration with inexpensive low-voltage drivers, e.g. a SiGe based RF amplifier, typically used for electro-absorption devices.
A further aspect of this work focuses on the development of devices for the precise measurement of strong electric fields, which are typically generated in power stations and transmission lines. Therefore, two new integrated electric field sensors are proposed, each of which exploits the aforementioned micro-fabrication techniques. The first device is based on a proton-exchange waveguide at cut-off, centered on a few microns wide domain-inverted region in a z-cut LiNbO3 substrate. The sensor’s performance is demonstrated by detecting DC fields up to 2.6 MV/m and high-frequency (1.1 GHz) fields ranging from 19 V/m to 23 kV/m. The second proposed device is fabricated by direct bonding a z-cut LiNbO3 substrate on top of a cut-off proton-exchanged waveguide centered on the domain-inverted region. It is possible to detect electric fields as high as 2 MV/m at low frequency with improved sensitivity compared to the previous device. These features make the devices suitable for use in high electric field and harsh conditions without endangering the operator. The conclusions section of the Thesis presents possible future developments which will contribute to increase the impact of the work in the optical telecommunication and sensing industries.
After a brief introduction, the second chapter describes the basic properties of the material used in the thesis work: Lithium Niobate (LiNbO3). This includes the properties related to its ferroelectric crystal structure and the subsequent applications. Chapter three presents the micro-fabrication techniques, over 3 inch LiNbO3 wafers, developed at ICFO during this work. The chapter begins with a description of waveguides fabrication by Annealed Proton Exchange (APE). The mid-part of the chapter outlines the fabrication procedure for domain inversion using electric field poling technique and liquid electrodes while the last part describes the bonding technique to permanently join LiNbO3 with different substrates, namely Si, SiO2 and another LiNbO3. Moreover, lapping and polishing techniques for thin plate fabrication are presented. The forth chapter firstly introduces the
fundamentals and main characteristics of travelling-wave LiNbO3 Mach-Zehnder modulators. Secondly, a new modulator design is proposed. It is based on domain inverted LiNbO3, with improved performance with respect to existing devices. The modulator characterization and the results obtained from the new design are presented. The chapter five begins with a literature review about DC and low frequency electric field optical sensors. Afterwards, two novel all-optical electric field sensors are presented. Both devices are based on a proton-exchange, domain inversion and bonding techniques. The sensors characterization, including the test set-up and the performance results are discussed. Finally, in chapter six, several conclusions on the thesis work and possible future work directions are presented.Uno de los materiales que permite el avance de la tecnología de dispositivos ópticos integrados es el niobato de litio (LiNbO3). Se trata de un cristal ferro-eléctrico, con excelentes propiedades electro-ópticas, acusto-ópticas y no lineales. Además, es posible fabricar guías de onda de bajas pérdidas mediante las técnicas de intercambio protónico (PE) y difusión de titanio. El objetivo principal de este trabajo es el desarrollo y la introducción tanto de las técnicas avanzadas de micro-nano fabricación para el niobato de litio como de nuevos dispositivos ópticos integrados para las comunicaciones ópticas y la detección de campo eléctricos de alto voltaje. La técnicas de fabricación desarrolladas incluyen inversión de dominios mediante la técnica de poling de alto voltaje, grabado, bonding y capas delgadas. Desde el punto de vista de los dispositivos, la inversión de dominios ha sido utilizada para mejorar la respuesta electro-óptica de los moduladores en LiNbO3 en términos de ancho de banda (BW) y voltaje de control (Vπ). En comparación con los moduladores comerciales actuales de un único dominio, con esta técnica es posible obtener mayores anchos de banda y menores voltajes de control resultando en un aumento del 50% del producto BW·Vπ. Para demonstrar la eficacia de la técnica desarrollada, se ha fabricado un modulador Mach-Zehnder chirp-free poniendo los brazos del interferómetro en dos regiones de dominios opuestos. De las mediciones efectuadas se han obtenidos valores de voltaje de control de 2V y ancho de banda de 15 GHz. Estos resultados muestran que los dispositivos desarrollados pueden reducir el coste total de funcionamiento, ya que permiten el uso de controladores económicos de Si-Ge que operan en el rango de los 2V. Otro aspecto de este trabajo se enfoca en el desarrollo de dispositivos para medir, de forma exacta, altos campos eléctricos, que normalmente son generados en las centrales eléctricas y en las líneas de transmisión. Por este motivo, se han desarrollado dos sensores de campo eléctrico mediante las técnicas de micro-fabricación anteriormente mencionadas. El primer dispositivo está basado en una guía fabricada mediante intercambio protónico en LiNbO3 z-cut, diseñada a la frecuencia de corte y centrada en una región de dominio invertido de 10 micras de ancho y 10mm de largo. El rendimiento del dispositivo se ha demostrado detectando campos a baja frecuencia con amplitudes de hasta 2.6MV/m y campos a la frecuencia de 1.1GHz con amplitudes desde 19V/m hasta 23kV/m. El segundo dispositivo se ha fabricado mediante bonding directo de un sustrato de LiNbO3 encima de una guía PE diseñada a la frecuencia de corte y centrada en una región de dominio invertido de 10 micras de ancho y 10mm de largo. El dispositivo se ha caracterizado a baja frecuencia y ha sido posible medir campos eléctricos de hasta 2MV/m con un aumento de sensibilidad comparado con el primer dispositivo fabricado sin la técnica del bonding. Estos resultados muestran que los dispositivos desarrollados pueden ser utilizados para mediciones de campos eléctricos intensos en condiciones peligrosas sin ningún riesgo para el operador. Después de una breve introducción en el Capítulo 1 de esta Tesis, las propiedades del LiNbO3 se discuten en el Capítulo 2, prestando especial atención a sus características ópticas y electro-ópticas. El Capítulo 3 presenta las técnicas de micro fabricación desarrolladas durante este trabajo sobre sustratos de 3 pulgadas. En particular, se presentan las técnicas de fabricación de guías mediante intercambio protónico, de inversión de dominios mediante poling de alto voltaje, de bonding de LiNbO3 con diferentes sustratos (LiNbO3 , SiO2, Si) y la fabricación de capas delgadas. El Capítulo 4 ofrece una introducción sobre los moduladores interferométricos Mach-Zehnder de onda propagada, presentando sus principales características. Además se presenta una nueva estructura de modulador basada sobre inversión de dominios y los resultados obtenidos. El Capítulo 5 empieza con una introducción sobre los sensores de campo eléctrico y después se presentan dos nuevos sensores de campo eléctrico completamente ópticos fabricados en LiNbO3 z-cut. Los dispositivos están basados en las técnicas de intercambio protónico, inversión de dominios y bonding directo. Finalmente, en el Capítulo 6 se presentan las conclusiones y posibles desarrollos futuros que pueden contribuir al aumento del impacto de este trabajo en las industrias de comunicaciones ópticas y de detección.
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Choi, Hae Woon. "Femtosecond laser material processing for micro-/nano-scale fabrication and biomedical applications." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1184883900.
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Chiang, Chung-Yi. "Assembly of biological building blocks for nano- and micro-fabrication of materials." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44391.
Повний текст джерелаАнотація:
Includes bibliographical references (p. 132-137).Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.
Experimental studies were performed to fabricate various material structures using genetically engineered M13 bacteriophage. This virus template showed superior controls of material syntheses from nanoscale to microscale. Structures including nanowires, nanoparticle arrays, hetero-particle arrays, and micro-fibers were fabricated using the engineered MI3 virus as the building block and mineralization platform. The mineralization mechanisms were revealed by alternating the types and amounts of peptide motifs displayed on the viral templates. The results showed the importance of a fused peptide motif to mediate the mineralization process of a material, which was dominated by either physical absorption or chemical nucleation. The potential applications of the materials synthesized using the viral template, including energy generation and biosensors, were also demonstrated. For the first time, several types of highly engineered MI 3 virus were used to fabricate nanostructures such as nanowires, nano-arrays, hetero-particle arrays, and complex nanowires. A type 8 phage library was reported to screen peptide motifs for making nanowires. A multi-functionalized viral template, type 8-3 virus, was engineered and demonstrated to create a variety of nano-archietetures. A type 8+8 virus was used to create complex nanowires embedded with different materials. In addition, the mechanical properties of virus-based materials were evaluated and characterized for the first time. The tunable functionalities and mechanical performances of virus-based materials showed promising capabilities not only to manipulate material syntheses and structures but also to be integrated with other synthetic materials using current processing techniques.
by Chung-Yi Chiang.
Ph.D.
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Vladov, Nikola. "Strategies for application of focused ion beams in micro and nano manufacturing." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664274.
Повний текст джерелаАнотація:
This thesis presents a new methodology for high precision nanoscale machining using Focused Ion Beam (FIB) processes. The methodology is supported by several novel models and methods developed during the PhD project. Gallium focused ion beam instruments are capable of processing virtually any material with a nanometre resolution. This has established FIB based instruments as invaluable specimen preparation tools in material science and circuit editing and failure analysis tools in the semiconductor industry. So far, the technique has had limited application in nano and micro- manufacturing, due to the high cost of the equipment and the long process cycle times required . Nonetheless in recent years it has been demonstrated that FIB can be a viable manufacturing technology if employed in the fabrication of high precision replication tools and it has the potential to replace existing electron and photon lithography techniques. One of the current problems is that the existing FIB procedures developed for material science are often not optimised for quality and efficiency or not applicable in manufacturing. A new machining methodology has been proposed that can be used as a guide to optimise FIB processes for improved efficiency and production quality. The methodology systematically looks into the material selection, the choice of gas precursor and the optimisation of the scanning parameters. To accomplish this several new models and methods are developed. A raster scanning model is proposed that links the probe current, the dwell time, the number of loops and the step with the key process parameters of refresh time, exposure time, dose, and dose distribution. Furthermore, a new term apparent beam size and a method for its measurement are suggested as an alternative to the commonly used "knife edge diameter". The apparent beam size is found to be material and precursor dependent and together with the overlap is accounted for as a key factor in the dose uniformity criterion formulated in the project.
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Sinjab, Faris. "Integrated AFM-Raman for molecular characterization of peptide nano- and micro-tubes." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28411/.
Повний текст джерелаАнотація:
This work is focused on exploring a unique integration of techniques, Raman micro-spectroscopy and atomic force microscopy (AFM), which when combined offer more than the sum of their respective parts. The non-invasive chemical specificity afforded by Raman spectroscopy, combined with the nanoscale-resolution topographic imaging of AFM offer much individually. The physics underlying the practical application of each technique is very general; Raman spectroscopy detects molecular vibrational shifts using light, and AFM uses a physical probe to interact with a surface to provide topographic (and mechanical) information. As a result, there are few restrictions to the possible samples that can be studied with these techniques, from semiconductors and geological crystals, through to simple organic chemical structures all the way to complex biological molecules and systems such as cells and tissue. In this work, a synthetic biomaterial composed of diphenylalanine (FF) peptide units which self-assemble into strong tubular structures is used as a sample of interest when exploring the different possibilities available from a combined Raman-AFM instrument. First, the combined system was set up in order to perform tip-enhanced Raman spectroscopy (TERS), a technique promising Raman spectroscopic imaging at the resolution of AFM imaging. A relatively young technique, TERS has huge potential in extending the reach of Raman spectroscopic imaging to the nanoscale, at a regime where a great deal of structure exists, but is usually blurred by conventional diffraction-limited Raman microspectroscopy. A major focus in this work is addressing a current problem with TERS: the fabrication of suitable probes. TERS typically utilizes AFM tips modified to have a silver nanoparticle, capable of locally enhancing the Raman signal, attached at the probe apex. A new method is presented here that promises several improvements over existing approaches, as the entire fabrication can be performed in-situ on the instrument. Tips produced in this way are then characterized by electron microscopy and tested on FF nanotubes. Following this, several techniques for the synthesis of silver nanoparticles are explored for use in TERS. Here, the focus is particularly on decahedral nanoparticles, which can be grown into rod shaped particles with well- defined shapes and sizes. These are important considerations for obtaining the desired enhancing properties for TERS probes. Finally, the AFM-Raman instrument is used to investigate the mechanical properties of FF tubes using several methods. AFM force spectroscopy of tubes suspended across a gap can be used in conjunction with a bending beam theory to measure the Young's modulus of individual tubes. A new type of co-localized experiment using polarized Raman spectroscopy on a suspended tube under various forces from the AFM is tested, and subsequently information relating to the hydrogen bonding network is used, in conjunction with existing X-ray data, to determine the molecular contributions to the modulus using a simple model for amyloid fibrils. Each experiment operates at the single fibril level, with the same fibrils being used, such that different methods can be compared for a single FF tube.
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Marzorati, S. "PT-FREE NANO- AND MICRO-STRUCTURED CARBONS FOR ELECTROCHEMICAL OXYGEN REDUCTION REACTION." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/332529.
Повний текст джерелаАнотація:
Oxygen reduction reaction (ORR) catalysts are of crucial importance in developing low- and medium-temperature fuel cells, as PEMFCs (Polymer Electrolyte Membrane Fuel Cells), from which sizeable energy saving and reduction of greenhouse gas emission are expected in comparison with the use of coal and oil based fuels in thermal engines. The same electrochemical oxygen reduction reaction takes place in oxygen depolarized cathodes (ODC) in chlor-alkali electrolysis, replacing the conventional hydrogen evolving cathode, gaining about 30% energy consumption reduction in the overall process. At present carbon-supported Pt and Pt-rich alloys are best credited to the ORR purpose. However, Pt-based catalysts are not free from certain drawbacks, such as oxide formation and Pt particle coarsening through Ostwald ripening, that decrease the overall cell energy conversion efficiency. Furthermore, attendant problems concerning natural availability, geographic distribution and cost of platinum, render platinum supply strategic and fuel cells hardly scalable to mass production. At present, projections on platinum usage for PEMFCs are estimated at ~15 ton y-1 in addition to the current ones, at a cost of ~40 $ g-1.
Therefore, non-precious metal catalysts are actively searched for, such as to meet already established operational benchmarks for conventional platinum PEMFC vehicular requirements (0.5 W cm-2; 5500 h durability) with the additional target of significant cost reduction.
Several papers on non-precious ORR catalysts have been published after a first report by Jasinski in 1964 demonstrating the ORR activity of metal substitutes-phthalocyanines. Then, research on metal-nitrogen macrocycles significantly expanded, leading to the picture that ORR catalytic activity can be related to N4-Me and N2-Me moieties. However, for precursors cost and unsatisfactory lifetime performance, research was steered toward more simple nitrogen-containing reactants and preparation procedures. Significant steps in this direction were obtained by Dodelet et al. who demonstrated that ORR overpotentials almost linearly decrease with increasing nitrogen content in carbon. Positive results were obtained on a series of samples prepared by high temperature treatment of carbon precursors in NH3/H2/N2 mixtures; doping of these modified carbons with iron rather than cobalt salts was shown to be preferable for better efficiency in oxygen reduction, even though still lower than that of platinum. Further improvements both in terms of incipient ORR potentials and currents were obtained by Maruyama et al. using carbons from hemoglobin and adenine-glucose pyrolysis in the presence of added Fe(II) and Cu(II)/Fe(II) mixtures, respectively. The ORR promoting role of nitrogen in carbon was independently demonstrated both theoretically and experimentally. Indeed, it was found that substitutional nitrogen at a few, specific, peripheral positions of graphene layers in well-ordered carbon nanostructures is in itself able to promote ORR activity even in the absence of accompanying metal centers.
Besides the above examined composition-dependent factors, catalyst activity also depends on structural and morphological carbon support features. In fact, many electrocatalytic reactions show faster kinetics on carbon edge planes compared with basal ones. This is related to the ability of the edges to more readily chemisorb O2 (this is the same reason why O2 combusts faster from edges and defects). On the other hand, an optimized porosity of carbon supports is beneficial for an easy access of the oxygen to the catalyst layer in contact with the proton exchange electrolyte membrane. Despite carbon materials of different textural morphology are widely used at an industrial level as supports for precious metal catalysts, in the PEMFC field, electrocatalysts are by far supported on the same VULCAN XC72 carbon. Given that improved catalytic activity of Pt-based catalysts has been achieved by the use of carbons with pore size centered in the mesoporous region, even developed with advanced synthesis, including template methods, such strategy should be pursued also for Pt-free catalytic systems.
In this project a number of Pt-free N-doped C-based catalysts have been synthesized on the basis of different synthetic and templating strategies aiming to understand how compositional, morphological and textural aspects of the end material can affect the electrochemical behaviour of ORR. Materials have been characterized using different physico-chemical methods including a study of the kinetics and mechanism of the electrochemical oxygen reduction reaction. Electrochemical results were obtained by rotating disk electrode (RDE) and rotating ring disk electrode (RRDE). Surface and bulk analyses have been performed by BET technique, XPS and XRPD (sometimes data were recorded at synchrotron facilities). (HR) TEM, SEM (combined with FIB milling) imaging was also performed to characterize samples morphology.
Many types of samples have been synthesized, starting with mesoporours N-, Fe- doped carbons obtained by heat treatment of a solution of precursors, using silica as a templating agent. Outstanding results in terms of ORR electroactivity in acidic and alkaline conditions have been recorded. Some samples, especially in alkaline media, catalyze ORR even better than commercial Pt-based catalysts. Then, attempting to prepare materials with a precise and defined order and trying to emphasize some of their properties such as surface area and conductivity, ordered carbonaceous nano- and microstructures were synthesized. By chemical vapor deposition N-, Fe- doped carbon nanotubes (N-CNTs) were prepared and some interesting aspects related to the aging of the Fe-doped MgO catalyst used to grow N-CNTs were evidenced. Then, a modified method, but very similar to that used in the synthesis of nanotubes, surprisingly allowed the synthesis of innovative N-doped hollow carbon nanocubes (N-CNCs). This is the great novelty of the work. Due to nanocubes endothermal transformation, happening at 37°C, as detected by DSC, and to the empty space available in the internal part of each cube, many applications can be thought for example involving cubes as nano-reactors that can be opened/close in correspondence of body’s temperature changes. This feature could be taken into considerations for medical applications, after testing and verifying the biocompatibility of nanocubes. Finally, a completely different technique, an ultraspray pyrolysis method (USP) was used to obtain N-, Fe- doped carbon microspheres. The inherent scalability of continuous flow methods such as USP represents a significant advantage compared to alternative synthetic strategies requiring batch processing or surface catalyzed deposition of nanostructured carbon materials (e.g. CVD growth), this feature might be useful in order to improve electrode packing and, consequently, mass transport electrocatalytic applications.
The last results section, apparently diverging from the main goals of the present work, was thought to better understand the electronic C-surface behavior in charge transfer reactions. This is actually strongly connected to the oxygen reduction reaction, for which all the catalysts, hereby synthesized, were designed. However, instead of starting from complicated systems involving porous and doped-carbons, the choice was addressed to the simplest but closest material: annealed and non-annealed amorphous carbon thin films prepared by DC-magnetron sputtering technique.
Part of the work described was carried out at Trinity College Dublin in the laboratory of Prof. Colavita as a part of an academic collaboration and 5 months exchange granted by the European LLP Erasmus Program.
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Bancaud, Aurélien. "Technologies for genomic and epigenomic analysis: a new frontier for micro- and nano-fluidics." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00997069.
Повний текст джерелаАнотація:
Les sciences de la vie et de la santé sont aujourd'hui au centre d'intérêts scientifiques et économiques. Les aspects économiques sont présidés par le développement de nouveaux outils de diagnostic fiables, reposant sur des mesures parallélisées d'interaction moléculaires au niveau de l'ADN ou des protéines. L'intérêt scientifique est très pluridisciplinaire, car les mécanismes de la vie impliquent des réactions physico-physiques multiples, que l'on aborde avec des technologies nouvelles et des approches de modélisation encore à développer. Dans ce panorama, les micro- et nano-technologies sont appelées à apporter de nouvelles solutions car elles permettent de manipuler des cellules ou des molécules avec une grande précision temporelle et spatiale. Elles sont en outre complémentaires avec les outils classiques de la biologie cellulaire et moléculaire, qui permettent des analyses sur des échantillons de grande dimension. Pourtant les exemples de succès scientifiques à l'interface des sciences de la vie et de la biologie restent plutôt rares. Dans ce manuscrit, nous faisons un tour d'horizon sur l'émergence de nouvelles technologies dédiées à l'analyse du génome. Nous présentons certaines de nos contributions, et proposons quelques pistes pour de futures recherches, principalement focalisées sur l'étude des mécanismes d'instabilité du génome réalisée dans des populations contenant seulement quelques cellules.
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Caccamo, Sebastiano. "Innovative techniques for conformal doping of semiconductors for applications in micro- and nano-electronics." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/4171.
Повний текст джерелаАнотація:
This Ph.D. thesis is intended to provide a contribution to understanding some aspects of doping by MD through systematic experimental work.
In chapter 1, in order to better understand this work, the main aspects of semiconductor properties, the techniques commonly used for doping these materials and the MD are briefly recalled.
In chapter 2 some aspects of MD are discussed. In particular a physico-chemical characterization of molecular precursors in standard conditions, the role of the surface treatments and the role of the dilution of the precursor solution was examined.
In chapter 3, the results about the role of the deposition parameters in MD are discussed, focusing on the role of coating time and sampling time and on the role of the solvent and the molecular precursor.
Chapter 4 examines the results obtained by studying the effects of the post-deposition treatments. The following aspects are discussed in detail: the role of the annealing parameters: Temperature and time, the competition between evaporation and diffusion and the role of the cap layer.
In chapter 5 an example of application of MD to Si nanowires are investigated.
Finally, the results of this work and the perspectives of this activity are discussed and possible experimental approaches for the study of some unclear aspects in this thesis work are proposed.
These aspects were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), transmission electronic microscopy (TEM) and Raman Spectroscopy, electrical measurements were performed by spreading resistance profiles (SRP).
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Galán, Cascales Teresa. "Conducting polymers for micro and nano electrodes. Application to biomolecule sensing and release." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/297432.
Повний текст джерелаАнотація:
This thesis aims at providing a better understanding of the micro- and nanofabrication of conducting polymers for biomedical devices and presents novel processes that widen the application range of conducting polymers in this field.
The thesis is divided in four chapters, namely “Materials and Methods”, “Biocatalytically-produced polypyrrole thin films and microelectrodes on insulating surfaces”, “Azide-PEDOT electrodes. Application to DNA sensors” and “Fabrication of polypyrrole single nanowire devices”.
Chapter 1, entitled “Materials and Methods”, describes the materials used in this work and the fabrication and characterization methods required for the development of the thesis. Here, theoretical and experimental details about the techniques employed, are provided.
Chapter 2, entitled “Biocatalytically-produced polypyrrole thin films and microelectrodes on insulating surfaces”, presents a new on-surface biocatalytical procedure for the fabrication of polypyrrole microelectrodes on insulating surfaces, with resolutions comparable to the ones of conventional photolitography. This is an environmentally respectful microfabrication method that allows the entrapment of biomolecules during the polymer synthesis in a single step. As a proof of concept, biotin was trapped in the polypyrrole matrix and then released in a controlled way through electrical stimulation. It was proven that the polymer keeps its electroactivity after the fabrication and functionalization processes. This biocatalytical-based technique represents a straightforward method for the microfabrication of biological-active conducting polymers, which could be implemented in implantable devices for remotely controlled tissue interactions.
Chapter 3, entitled “Azide-PEDOT electrodes. Application to DNA sensors”, describes the fabrication and testing of an electrochemical label-free DNA hybridization sensor, based on novel azidomethyl-modified poly(3,4-ethylenedioxythiophene) electrodes (azide-PEDOT electrodes). These azide-PEDOT electrodes were used as platforms for the immobilization of acetylene-DNA probes, complementary to the “Hepatitis C” virus. The acetylene-DNA probes were covalently grafted to the polymer backbone via the robust “Click” reaction, which a part from being a very selective functionalization method, preserves DNA from denaturation during the synthesis of the polymer. DNA hybridization was detected by Differential Pulse Voltammetry (DPV), where the electrochemical change of the polymer behaviour, produced by the recognition event, was directly evaluated. This fabrication procedure is a powerful tool for the preparation of label-free DNA sensors able to selectively recognize a specific DNA sequence, down to the nanomolar range.
Finally, Chapter 4, entitled “Fabrication of polypyrrole single nanowire devices”, discusses the fabrication of polypyrrole at the nanoscale. Two fabrication techniques were investigated here, namely dip pen nanolithography and electrochemical polymerization on template-assisted surfaces. On one hand, the dip pen nanolithography proved to be a simple deposition technique with good control over size and location of the polypyrrole nanowires. On the other hand, the electrochemical polymerization on template-assisted surfaces provided as well nanoscaled polypyrrole, but added the possibility to chemically manipulate the polymer. This chemical manipulation was translated into polymer devices with different electrical properties. By the use of these techniques, the capability of fabricating single nanowire devices (ready to use in different applications) and arrays of ordered nanowires based on conducting polymers is demonstrated.
Additionally, two appendixes can be found at the end of the thesis: Appendix A: “Fabrication of azide-PEDOT microwire-based devices” and Appendix B: “Fabrication of nanopatterns by electron-sensitive silanes”. They provide short experimental results obtained during the course of this work, which are first steps for future investigations.
A general conclusions section can be found at the end of the thesis, where a summary of the main achievements and contributions of this thesis are listed.Aunque los polímeros conductores se presentan como una alternativa viable a los materiales convencionalmente usados en aplicaciones biomédicas, las técnicas de fabricación adaptadas a ellos y el aprovechamiento de sus propiedades están lejos de ser completos. Existen importantes limitaciones en la fabricación de micro y nano estructuras basadas en polímeros conductores. Debido a la agresividad de las técnicas tradicionalmente usadas en microelectrónica, se hace necesaria la búsqueda de nuevas estrategias de fabricación adaptadas a polímeros conductores, así como de nuevos procesos que puedan mejorar el rendimiento de los dispositivos diseñados. En esta tesis titulada “Conducting polymers micro and nano electrodes. Application to biomolecule sensing and release”, se han investigado nuevas técnicas de fabricación y de funcionalización de polímeros conductores, poniendo un especial interés en su aplicación biomédica. Una nueva técnica de fabricación de microestructuras de polipirrol por método biocatalítico sobre superficies aislantes ha sido desarrollada con resoluciones comparables a las de la litografía óptica. Dicha técnica es compatible con la incorporación de biomoléculas durante el proceso de síntesis, lo que garantiza su utilización en entornos biológicos. Esto fue demostrado mediante la incorporación de biotina durante el proceso de polimerización y su posterior liberación, mediante estimulo eléctrico. También se ha desarrollado un nuevo sensor de ADN sin marcaje basado en electrodos de azida-PEDOT, para la detección de secuencias basadas en la “Hepatitis C”. Estos electrodos, permiten la directa y covalente funcionalización con secuencias de ADN, modificadas con grupos acetileno, por medio de la química “Click”. La hibridación fue detectada mediante la evaluación de la electroactividad del polímero tras el suceso de reconocimiento. Esta novedosa modalidad de sensores demostró ser selectiva y sensible, siendo capaz de detectar secuencias complementarias en el rango nM, sin necesidad de marcajes, ni complejas técnicas de microfabricación. Finalmente, se estudiaron dos técnicas de fabricación de nanohilos de polímero conductor: nanolitografía de dip-pen y electropolimerización sobre superficies con plantillas. Estos estudios proveen al incompleto campo de la fabricación de nanoestructuras de polímeros conductores de resultados adicionales, que amplían el campo de aplicación de dichos materiales.
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Estrada, Leypón Oscar Emilio. "Micro-Nano-Bio Systems for on-line monitoring of in vitro biofilm responses." Doctoral thesis, Universitat Ramon Llull, 2015. http://hdl.handle.net/10803/300595.
Повний текст джерелаАнотація:
El treball presentat en aquesta tesi doctoral te com objectiu principal la contribució en el camp de la microbiologia per entendre el biofilms i el possible control de desenvolupament mitjançant l’ús de mètodes i enfoc multidisciplinari. Els biofilms estan definits com comunitats de microorganismes que creixen envoltats en una matriu exopolisacárida i s’adhereixen a una superfície inert o teixit viu. La formació dels biofilms bacterians tenen un gran interès en microbiologia clínica degut al desenvolupament d’infeccions que son causades pel contacte directe o per colonització de dispositius mèdics implantats i pròtesis. Actualment es consideren causa de més del 60 % de les infeccions bacterianes. El problema dels biofilms bacterians a nivell clínic es que mostren millor resistència a antibiòtics arribant inclús a ser de 500 a 5000 cops més resistents a agents antimicrobians comparant amb la mateixa bactèria planctònica (bactèria en suspensió). Hi ha hagut moltes temptatives d’adaptar mètodes a laboratoris clínics on es reprodueixen les condicions pel desenvolupament de biofilms, però encara no s’ha arribat a obtenir òptims protocols estàndard per a aquest propòsit de monitoritzar la formació i toxicitat a temps real. Ha crescut l’interès en disseny, desenvolupament i utilització de dispositius de microfluídica que poden emular els fenòmens biològics que ocorren amb diferents geometries, dinàmica de fluids i restriccions de transport de biomassa en microambients fisiològics.
La recerca descrita en aquesta tesis s’ha dut a terme amb diferents mètodes “label-free” basats en la variació acústica y/o propietats elèctriques per a la monitorització de biofilms. El treball presentat en la monografia descriu un dispositiu “custom-made” per a la utilització d’Espectroscòpia de impedància electroquímica com a eina útil per a l’obtenció d’informació d’adherència i formació de biofilms. El fet d’afegir nanopartícules com a segon biosensor permet la correlació de biofilm amb la seva toxicitat a temps real per a la detecció del punt òptim de tractament de biofilms. Finalment el disseny d’aquesta tecnologia s’utilitza per l’assaig de la resposta de biofilms a antibiòtics com a model in vitro d’infeccions causades per biofilms.El trabajo presentado en esta tesis doctoral tiene como principal objetivo la contribución en el campo de la microbiología para entender los biofilms y el posible control de desarrollo mediante el uso de métodos y enfoque multidisciplinar. Los biofilms están definidos como comunidades de microorganismos que crecen embebidos en una matriz exopolisacárida y se adhieren a una superficie inerte o tejido vivo. La formación de los biofilms bacterianos tiene un gran interés en microbiología clínica debido al desarrollo de infecciones que son causadas por contacto directo o por colonización de dispositivos médicos implantados y prótesis. Actualmente se consideran la causa de más del 60 % de las infecciones bacterianas. El problema de los biofilms bacterianos a nivel clínico es que muestran mejor resistencia a antibióticos llegando incluso a ser de 500 a 5000 veces más resistentes a agentes antimicrobianos comparado a la misma bacteria planctónica (bacteria en suspensión). Ha habido muchas tentativas de adaptar métodos a laboratorios clínicos donde se reproducen las condiciones para el desarrollo de biofilms, pero aún no se ha llegado a obtener óptimos protocolos estándar para este propósito de monitorizar la formación y toxicidad en tiempo real. Ha crecido el interés en diseño, desarrollo y utilización de dispositivos de microfluídica que puedan emular los fenómenos biológicos que ocurren con diferentes geometrías, dinámica de fluidos y restricciones de transporte de biomasa en microambientes fisiológicos. La investigación descrita en esta tesis se lleva a cabo con diferentes métodos “label-free” basados en variación acústica y/o propiedades eléctricas para la monitorización de biofilms. El trabajo presentado en esta monografía describe un dispositivo “custom-made” para la utilización de Espectroscopia de impedancia electroquímica como herramienta útil para obtener información de adherencia y formación de biofilms. El hecho de añadir nanopartículas como segundo biosensor permite la correlación de biofilm con su toxicidad en tiempo real para la detección del punto óptimo del tratamiento de biofilms. Finalmente el diseño de esta tecnología es usada para el ensayo de la respuesta de biofilms a antibióticos como modelo in vitro de infecciones causadas por biofilms.
The work presented in this thesis has the main aim to contribute in the field of clinical microbiology to understand the biofilms and the possible of development through the use of methods with multidisciplinary approach. Biofilms are defined as communities of microorganisms that grow embedded in a matrix of exopolysaccharides and adhering to an inert surface or living tissue. The formation of bacterial biofilms has an interest in clinical microbiology with the development of infections that usually arise from either direct contact or the colonization of implanted medical devices and prostheses. Currently they are considered the cause of over 60% of bacterial infections. The problem of bacterial biofilms at clinical level is showing great resistance to antibiotics, so that the biofilm bacteria are 500 to 5000 times more resistant to antimicrobial agents that the same bacteria grown in planktonic cultures (bacteria in suspension). There have been attempts to adapt methods to clinical laboratories where they reproduce the conditions of biofilms, but have not yet adopted an optimal standard protocol for this purpose to follow-up the formation and toxicity in real-time. There has been a growing interest in design, development and utilization of microfluidic devices that can emulate biological phenomena that occur in different geometries, fluid dynamics and mass transport restrictions in physiological microenvironments. The research described in this thesis deals with different label-free methods based on variation of acoustic and electric properties for biofilm monitoring. The work presented in this monograph describe a custom-made device for using electrochemical impedance spectroscopy (EIS) as useful tool to obtain information of adherence and formation of biofilms. The addition of nanoparticles as toxicity biomarker allows the correlation of biofilm formation with its toxicity in real-time for detention of the optimal point for biofilm treatment. Finally the design of this technology is used for testing the biofilm response to antibiotic as in vitro model of biofilm-related infection.
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Simpson, Brian Keith Jr. "Strain engineering as a method for manufacturing micro- and; nano- scale responsive particles." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34728.
Повний текст джерелаАнотація:
Strain engineering is used as a means of manufacturing micro- and nano- scale particles with the ability to reversibly alter their geometry from three dimensional tubes to two dimensional flat layers. These particles are formed from a bi-layer of two dissimilar materials, one of which is the elastomeric material polydimethylsiloxane (PDMS), deposited under stress on a sacrificial substrate. Upon the release of the bi-layer structure from the substrate, interfacial residual stress is released resulting in the formation of tubes or coils. These particles possess the ability to dramatically alter their geometry and, consequently, change some properties that are reversible and can be triggered by a stimulus. This work focuses on the material selection and manufacturing of the bi-layer structures used to create the responsive particles and methods for characterizing and controlling the responsive nature of the particles. Furthermore, the potential of using these particles for a capture/release application is explored, and a systematic approach to scale up the manufacturing process for such particles is provided. This includes addressing many of the problems associated with fabricating ultra-thin layers, tuning the size of the particles, understanding how the stress accumulated at the interface of a bi-layer structure can be used as a tool for triggering a response as well as developing methods (i.e. experiments and applications) that allow the demonstration of this response.
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Mohammadi, Saeed. "Phononic band gap micro/nano-mechanical structures for wireless communications and sensing applications." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/41069.
Повний текст джерелаАнотація:
Because of their outstanding characteristics, micro/nano-mechanical (MM) structures have found a plethora of applications in wireless communications and sensing. Many of these MM structures utilize mechanical vibrations (or phonons) at megahertz or gigahertz frequencies for their operation.
On the other hand, the periodic atomic structure of crystals is the fundamental phenomenon behind the new era of electronics technology. Such atomic arrangements lead to a periodic electric potential that modifies the propagation of electrons in the crystals. In some crystals, e.g. silicon (Si), this modification leads to an electronic band gap (EBG), which is a range of energies electrons can not propagate with. Discovering EBGs has made a revolution in the electronics and through that, other fields of technology and the society.
Inspired by these trends of science and technology, I have designed and developed integrated MM periodic structures that support large phononic band gaps (PnBGs), which are ranges of frequencies that phonons (and elastic waves) are not allowed to propagate.
Although PnBGs may be found in natural crystals due to their periodic atomic structures, such PnBGs occur at extra high frequencies (i.e., terahertz range) and cannot be easily engineered with the current state of technology. Contrarily, the structures I have developed in this research are made on planar substrates using lithography and plasma etching, and can be deliberately engineered for the required applications. Although the results and concepts developed in this research can be applied to other substrates, I have chosen silicon (Si) as the substrate of choice for implementing the PnBG structure due to its unique properties.
I have also designed and implemented the fundamental building blocks of MM systems (e.g., resonators and waveguides) based on the developed PnBG structures and have shown that low loss and efficient MM devices can be made using the PnBG structures. As an example of the possible applications of these PnBG structures, I have shown that an important source of loss, the support loss, can be suppressed in MM resonators using PnBG structures. I have also made improvements in the characteristics of the developed MM PnBG resonators by developing and employing PnBG waveguides.
I have further shown theoretically, that photonic band gaps (PtBGs) can also be simultaneously obtained in the developed PnBGs structures. This can lead to improved photon-phonon interactions due to the effective confinement of optical and mechanical vibrations in such structures.
For the design, fabrication, and characterization of the structures, I have developed and utilized complex and efficient simulation tools, including a finite difference time domain (FDTD), a plane wave expansion (PWE), and a finite elements (FE) tool, each of which I have developed either completely from scratch, or by modification of an existing tool to suit my applications. I have also developed and used advanced micro-fabrication recipes, and characterization methods for realizing and characterizing these PnBG structures and devices. It is agued that by using the same ideas these structures can be fabricated at nanometer scales to operate at ultra high frequency ranges.
I believe my contributions has opened a broad venue for new MM structures based on PnBG structures with superior characteristics compared to the conventional devices.
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Sotomayor-Rivera, Alexis. "Modification of nano and micro-phase diamond powder for enhancement of hydrogen storage." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6004.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 16, 2007) Vita. Includes bibliographical references.
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Partington, Matthew William. "Development of a molecular-based micro/nano platform for blood stream infection diagnostics." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582168.
Повний текст джерелаАнотація:
Blood Stream Infections (BSIs) are a massive burden to health services worldwide, present culture based diagnostic methods identify microorganisms phenotypically, based upon physical characteristics such as morphology, growth or not in a specific medium. These methods require up to 4 days for a complete analysis of a clinical sample in order to determine the cause of the infection and define an appropriate antimicrobial chemotherapy. This standard culturing approach is time consuming, complex, costly and diagnostically limited. Yet reliability, reproducibility and broad use of these methods provide a real world 'Gold Standard' in microbiology that molecular techniques have yet to surpass in the clinical setting. A well-defined molecular approach can theoretically overcome the limitations of the culture-based methodology. A molecular technique could be faster, being able to provide a clinically relevant diagnosis at the point-of-care e.g. the patient's bedside and more accurate providing information about the infection based upon primary molecular data within the sample not on a secondary culture from that clinical sample. When translated to the real world these advantages mean that; the patient can be accurately diagnosed upon presentation to a physician allowing the treatment to be delivered without the need for a long hospital stay or a broad-spectrum antibiotic therapy. This reduces costs and evolutionary pressure upon bacteria to develop resistance to antimicrobial chemotherapies. A molecular approach also allows a simplification of the diagnostic process by employing a lab-on-a-chip framework. By integrating the core components of the molecular approach the infrastructural requirements of health care provider such as; well trained staff, expensive laboratory equipment buildings and resources etc could be reduced to a simple hand held device. This thesis details the multidisciplinary work undertaken to thoroughly define the nature of the problem and the requirements of a solution. The research in defining that solution was conducted within three disciplines, bioinformatics, molecular biology and nanotechnology.
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Li, Xiangping [Verfasser], and Andreas [Akademischer Betreuer] Manz. "Micro- and Nano Engineering for Polymerase Chain Reaction / Xiangping Li ; Betreuer: Andreas Manz." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2018. http://d-nb.info/1166654257/34.
Повний текст джерела
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Ahmad, Zakiah. "Nano-and micro-particle filled epoxy-based adhesives for in-situ timber bonding." Thesis, University of Bath, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478940.
Повний текст джерела
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Alasadi, Alaa. "Development of laser direct writing for fabrication of micro/nano-scale magnetic structures." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22820/.
Повний текст джерелаАнотація:
Traditional lithographic techniques used to fabricate a magnetic structure are often complex, time consuming, dependent on other techniques and expensive. Laser direct writing (LDW) can potentially overcome many of these drawbacks and may be a cheaper, faster and easier route to fabricating technique micro-/nano-magnetic structures. The main aim of this project is to fabricate magnetic structures through LDW. Two types of LDW were used to fabricate magnetic structures: subtractive LDW (LDW-) and laser-induced forward transfer (LIFT). LIFT was used to transfer permalloy (Ni81Fe19) using three laser systems. Numerous parameters were varied, including thin film thickness, scanning speed, pulse energy, distance between donor/acceptor and acceptor material. These attempts did not succeed in transferring the magnetic materials as a uniform shape. The differences of heat conductivity between the permalloy and acceptor substrate (glass and silicon), shock wave effects and the landing speed of material on the acceptor are the most possible reasons that the uniform structures and the magnetic properties were lost. LDW- was used to successfully pattern 90nm thick Permalloy into 1-D and 2-D microstructures. Magnetic wires with a range of widths, arrays of squares, rectangles with a range of aspect ratios and rhombic elements were patterned. These structures were fabricated using an 800-picosecond pulse laser and a 0.75 NA lens to give a 1.85µm diameter spot. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures compared with lower levels of pulse overlap. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 150 nm - 6.7µm and showed coercivity reducing across this range from 47 Oe to 10 Oe. Squares, rectangles and diamonds These elements demonstrated shape-sensitive magnetic behaviour with increasing the shape aspect ratio. Wires of different width were also fabricated by LDW- and their anisotropic magnetoresistance (AMR) determined to show a simple width-dependent magnetic field response, making them interesting as magnetic field sensors. This approach is extremely rapid and does not requires masks or chemical processing as part of the patterning procedure. The time required to patterned 1-D area of 4 x 0.18 mm was 85 s and the average fabrication time per element of 2-D structures was 4.7x10 4 s. The microstructures may be of use for AMR sensors or for biological applications, such as cell trapping.
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Gun, S. "Electrohydrodynamic atomization forming of micro and nano-scale magnetic particles for biomedical applications." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1468713/.
Повний текст джерелаАнотація:
Production of polymeric magnetic micro and nano-particles is a rapidly emerging area in pharmaceutical and biomedical science. In this thesis, the capability of the electrohydrodynamic atomization (EHDA) process for preparing biodegradable polymeric magnetic particles with different sizes was explored. The EHDA processing method offers several advantages over conventional coprecipitation and emulsification techniques for the preparation of magnetic particles. Most significant are the process efficiency and preservation of the iron oxide nanoparticles and/or therapeutic agents functionality, as complex multistep processing involving harsh solvents, additives and elevated temperatures or pressure are avoided. The first part of the thesis describes a detailed investigation of how the size, morphology and shape of the particles generated can be controlled through the operating parameters; specifically the flow rate and applied voltage. The particle diameter was greatly influenced by flow rate and applied voltage. The mean size of the particles changed from1.6µ m to 17.8µm as the flow rate increased from 100µl/min-1 to 400µl/min-1. The research also focuses on the effects of these parameters on the jetting modes of the E H DA process, in particular the con-jet mode operation. Magnetic nanospheres were also produced using single needle processing with mean size of 56nm with a corresponding polydispersivity index of 16%. Nanospheres exhibited a high saturation magnetization at room temperature (67emu/g). Chlorotoxin, a scorpion venom was chosen as the therapeutic agent model because it is non-toxic, non-immunogenic along with other favourable characteristics such as small size high stability and most importantly only binds to tumour cells and not healthy cells. Scorpion venom loaded magnetic microspheres were produced using single needle processing, with a particle size of 2µm. This work demonstrates a powerful method of generating micro and nano magnetic polymeric particles, with control over the size of particles prepared.
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Qin, Zhenpeng. "Modeling of Ion Transport for Micro/Nano Size Particles in Coulter Counter Application." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1240858653.
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Jung, Hyunchul. "Design, Fabrication and Characterization of Micro/Nano Electroporation Devices for Drug/Gene Delivery." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316541070.
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Bushman, Sarah Mansfield. "The Development of Micro- and Nano-scale Techniques for Studying Cancer Cell Invasion." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492775878121827.
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