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1
Codan, Barbara. « New approaches for discrete and continuum analysis of the mechanical behaviour of cell ». Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3099.
Texte intégralRésumé :
2007/2008La tesi qui presentata riguarda la meccanica delle cellule. Negli ultimi anni l’interesse della comunità scientifica è stato rivolto a questo aspetto della biologia cellulare, perché, com’è stato dimostrato, all’interno della cellula stimoli meccanici e segnali biochimici sono strettamente correlati, ma ancora non è chiaro il meccanismo che li lega. Le tecniche disponibili si suddividono in due grandi categorie in base al numero di cellule analizzate, ovvero si differenziano in base allo studio su una popolazione cellulare o su singola cellula. Dopo un’attenta analisi delle metodologie disponibili, si è deciso di sviluppare due nuovi metodi. Il primo riguarda la deformazione di un gel poliacrilammidico su cui sono state depositate delle particelle fluorescenti. Questo metodo trae ispirazione dalla deformazione di substrati e dalla traction force microscopy, ovvero dallo studio dello spostamento delle particelle dovuto alla presenza della cellula è possibile ottenere informazioni sulle forze applicate da quest’ultima. Un nuovo dispositivo è stato realizzato ed ha permesso di tirare il gel e quindi deformare una singola cellula e di studiare la risposta alla deformazione. In parallelo a questi studi caratterizzati dall’impiego di un substrato continuo e macroscopico, si è deciso di sviluppare un nuovo dispositivo microelettromeccanico (MEMS), in cui l’aspetto più innovativo è la presenza sullo stesso dispositivo di attuatori, deputati alla deformazione della cellula, e di sensori, che permettono di leggere le componenti della forza esercitata dalla cellula in risposta alla deformazione esercitata con gli attuatori. Per entrambe queste componenti si è scelta la struttura del comb drive. Tale dispositivo è stato progettato seguendo i vincoli costruttivi della tecnologia SOIMUMPs®, che realizza dispositivi MEMS con tecnologia SOI, una delle più adatte allo studio cellulare. Sono state effettuate delle simulazioni agli elementi finiti, in particolare del sensore, in modo da poter valutare la sensibilità, che risulta essere dell’ordine dei µN. Durante la progettazione di questo dispositivo, è sorto il problema del posizionamento della cellula al centro del MEMS. La soluzione arriva dalla localizzazione di spot di proteine, che creano punti di ancoraggio per la cellula. In letteratura sono presenti alcuni lavori sul patterning di proteine, ma nessuno di questi soddisfa i vincoli imposti da un dispositivo tridimensionale quale il MEMS progettato. Un nuovo utilizzo di uno spettroscopio per microraman è stato sviluppato nell’ambito della litografia maskless. Tale tecnica permette di realizzare substrati patternati con risoluzione submicrometrica senza il vincolo di superfici piatte e la presenza di una maschera. Tale tecnica è stata utilizzata per depositare spot di proteine. Sono state testate positivamente la resistenza della fibronectina al processo litografico e la compatibilità di quest’ultima alle cellule dopo il trattamento della litografia. Il risultato finale è stata la realizzazione di spot proteici con geometrie definite dall’utente e dimensioni paragonabili a quelle dei complessi cellulari per l’adesione (focal adhesion).
The subject of this thesis is the mechanics of cell. Recent studies demonstrate that mechanical stimuli and biochemical signals are strictly interconnected in the cell, but these phenomena are not completely understood. Different techniques are available to study the mechanics of cell. They differ for the number of cells analyzed, from cells population to single cell techniques. After an exhaustive analysis of these available methods, two new techniques have been developed. The first one is a combination of substrate deformation and the traction force microscopy. By pulling a polyacrylamide gel, it is possible to obtain information about cell forces, looking at the displacement of fluorescent beads deposited on top of the gel. A new device has been devised and realized and the gel pulled. This technique permits to obtain information on the deformation of a single cell. While this project is characterized by a continuous and macroscopic substrate, a new microscopic device has also been developed. A micro electromechanical system (MEMS) is investigated. The most innovative aspect of the device is the introduction, on the same device, of actuators, which provide cell deformation, and sensors, which permit to read the cell response to the deformation. Both sensors and actuators present a comb drive structure. This new device follows the design rules of the SOIMUMPs® technique; this company provides MEMS device with SOI technology, suitable for the application here presented. The sensor and the actuator have been simulated by finite elements analysis, to evaluate the displacement and the sensitivity, that is in the range of µN. During the development of the MEMS, the problem of cell positioning in the center of the device arose. A solution can be found in the protein patterning. Proteins spots are the connection points between the cell and the substrate. Previous investigations present protein patterning methods, but none of them are suitable for the three dimensional structure of the MEMS and non-flat surfaces. Maskless lithography has been implemented with a Raman spectroscopy microprobe. This technique enables one to deposit proteins on three dimensional structures, such as the MEMS here developed. Tests on fibronectin resistance to the lithographic process and its compatibility with cells have been performed. The final result is proteins spots with geometries defined by the operator and dimensions similar to focal adhesion complex.
XXI Ciclo
1980
2
Jin, Di. « Phase-shifting techniques for laser direct write systems ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq24165.pdf.
Texte intégral
3
Sato, Taku. « Laser assisted ink consolidation for Direct Write Component Fabrication ». Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540068.
Texte intégral
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Kingsley, David Michael. « Fabrication and Engineering of 3D Laser Direct Write Microenvironments ». Thesis, Rensselaer Polytechnic Institute, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10935067.
Texte intégralRésumé :
Three-dimensional (3D) bioprinting is a rapidly growing field that is particularly well suited for “bottom up” tissue engineering, largely due to its ability to control the 3D shape of the engineered construct, as well as its constituents (e.g., cells and/or material) and their spatial distribution. A variety of nozzle-based techniques have emerged for tissue engineering, and while these excel at building large 3D architectures, they suffer from moderate print resolution and limited printable materials, making them less attractive for smaller, high-resolution constructs. This is due in part to shearing effects and clogging of the nozzle. Thus, alternative printing methods are needed to create smaller constructs requiring high-spatial pattern resolution and size control.
Our laboratory has previously developed a laser-based biofabrication platform, gelatin-based laser direct-write (LDW) as a technique for bioprinting highly viable cells with spatial resolution unmatched by other printing techniques in 2D. In this thesis, a novel single-step technique was developed to extend this platform to fabricate and spatially pattern 3D alginate microbeads. With this new method, we demonstrate excellent size-control of fabricated microbeads by manipulating the beam diameter used for deposition. We further show that deposited beads have excellent pattern registry, and cells within LDW microbeads maintain high cellular viability. Additionally, we demonstrate that this technique is compatible with our laboratory’s 2D laser direct-writing of cells, illustrating the ability to fabricate spatially-precise, hybrid, 2D/3D cultures of cells and cell-loaded microbeads. Within cellular applications, the mechanical properties of the extracellular matrix have become an important feature for regulating behavior. To further develop our control over the cellular microenvironment, we demonstrate our ability to mechanically tune the stiffness of LDW-printed microbeads, by varying the crosslinking divalent cation and cation concentration used in the LDW microbead fabrication process. Microbead mechanical properties were determined using large printed arrays of microbeads (12 × 12 array) to amplify the resistance generated during traditional compression testing. Using this method, we demonstrated microbead mechanical properties could be tuned by adjusting fabrication and crosslinking parameters, to achieve a wide range of elastic moduli, from physiologic to pathologic values. While this was a valuable step to demonstrate our ability to control aspects of the engineered cellular microenvironment, our alginate structures were still largely limited for cellular interaction due to the lack of adhesion ligands. The inability for cells to interact with the alginate prevents migration within the matrix.
To overcome the limitations of the inert alginate of our microbeads, we used an established materials processing approach to produce core-shelled microcapsules. This technique consists of coating the printed microbead with a positively charged polymer (e.g., chitosan or poly-L-lysine), to produce a polyelectrolyte membrane around the bead, then chelating the calcium crosslinking the interior. This resulted in a polymeric shell with an aqueous core entrapping the cellular payload. We found that core-shelled microcapsules from LDW microbeads maintained their pattern fidelity through processing, and encapsulated cells retained high viability. Cancer cells and stem cells encapsulated within these structures were observed to self-assemble to form size-controlled 3D aggregates; tumor spheroids and embryoid bodies, respectively.
In addition to creating conventional core-shelled microcapsules, we demonstrate that LDW’s spatial precision can be leveraged to produce advanced core-shelled structures of customizable planar geometries, by utilizing single microbeads as voxels, and patterning these in overlapping arrays. Using this technique, we were able to create custom geometries, such as microstrands, bifurcations, rectangular mats, and rings, wherein aggregating cells self-assembled to make continuous three-dimensional aggregates that conform to the shape of the structure. Overall, this doctoral thesis research developed a powerful, laser-based method for engineering custom 3D microenvironments, with applications in tumor modeling and regenerative medicine. These advances hold great promise for fabricating the next generation in vitro diagnostics.
5
Ng, Sandy. « Ultrafast laser written bulk waveguides and gratings ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ53441.pdf.
Texte intégral
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Huang, Leilei. « Fabrication and characterisation of ultrafast direct laser written waveguides ». Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:7e40e1ee-fcc3-4797-953d-8be5c7af1334.
Texte intégralRésumé :
A novel ultrafast direct laser writing (DLW) system using adaptive optics is proposed and demonstrated. This system has the potential to generate high-quality three-dimensional (3D) optical waveguides and components. The experimental setup and procedures for the DLW process are studied, after which various optical waveguides are fabricated in different transparent materials. The resulting waveguides are characterised by the measurement of the near-field laser coupling profiles in combination with optical microscopy techniques. Quantum random number generation (QRNG) and the potential application of the DLW technique in quantum information is also discussed. To completely understand the fabrication procedures for the DLW system, the experimental equipment and effects of different fabrication parameters are studied and analysed. With the use of a liquid-crystal spatial light modulator (SLM) in the DLW system, dynamic control of phase modulation can be provided to correct aberrations adaptively. An SLM can also make the cross-sectional profile of the written waveguides more circular and facilitate the fabrication of more complex 3D structures. Experiments reveal that the shape of the focal spot can be improved dramatically with adaptive optics, resulting in higher-quality optical waveguides. The refractive-index information of the written waveguides and their optical properties are measured using the propagation-mode near-field method (PMNFM). Simulation results and experimental measurements of a commercial single-mode fiber and a waveguide sample are demonstrated and compared. Quantitative phase measurement is also applied via the transport of intensity equation (TIE) to monitor the refractive-index change during fabrication. The propagation losses of the waveguides are measured and discussed. Different optical waveguides are fabricated using DLW in fused silica, potassium dihydrogen phosphate (KDP), and lithium niobate (LiNbO3) crystals. Different materials have different characteristics and properties, requiring different fabrication parameters and resulting in waveguides exhibiting different properties. Waveguides at various depths are demonstrated both with and without effects of adaptive optics. Experimental results indicate great improvements in the quality of the written waveguides after aberration correction. With an understanding of the optical properties of the straight waveguides using the characterisation methods, modelling and fabrication of bend waveguides and y-splitters are presented and studied. A high-speed QRNG system is also demonstrated in this thesis, with potential implementation using the DLW technique for a more compact and stable system. Finally, the possibility of the DLW fabrication of complex 3D optical components and their applications are discussed for future work.
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Katis, Ioannis. « Laser direct write techniques for the fabrication of paper-based diagnostic devices ». Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/388397/.
Texte intégralRésumé :
We report on the use of laser direct-write techniques for the fabrication of point-of-care paper-based diagnostic sensors. These include laser-based deposition, laser ablation and laser-induced photo-polymerisation. Firstly, Laser Induced Forward Transfer (LIFT) was employed to deposit biomolecules from a donor film onto paper receivers. Paper was chosen as the ideal receiver because of its inherent properties which make it an efficient and suitable platform for point-of-care diagnostic sensors. Both enzyme-tagged and untagged antibodies were LIFT-printed and their viability was confirmed via a colorimetric enzyme-linked immunosorbent assay (ELISA). Secondly, we report on the laser-based structuring of paper-based fluidic devices. Laser-scanning the paper defines the areas that will be polymerised, thus creating barriers that keep the liquid solutions contained. Complicated devices are easy to fabricate and the flexibility of this technique allows for unique patterns, making it appropriate for rapid prototyping but also for large-scale production. Furthermore, the laser patterning technique allows control of the depth or degree of polymerisation, thereby allowing the liquid to wick through but also imposition of flow delays. Finally, the use of lasers for the fabrication of a 'master' which can be used for casting a PDMS mould for applications in micro-contact printing. The combination of the above mentioned techniques represent the platform technology for the rapid, precise and versatile laser-based fabrication of diagnostic point-of-care sensors.
8
Xu, Bojun. « Inkjet printing of silver for direct write applications ». Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/inkjet-printing-of-silver-for-direct-write-applications(8aaa64de-fd4f-4ffa-97df-0fca6977bfdc).html.
Texte intégralRésumé :
Direct Write (DW) defines an emerging group of technologies that allow the printing of electronic and other functional components out of vacuum, directly onto conformal surfaces. Both ink-jet and nozzle deposition technologies, which are seen to be complementary for the wide range of materials and processing required by industry, are employed in this project.Silver neodecanoate salt is sensitive to both light source, including ultra violet light (UV) and heat source, and is a good inkjet printing precursor when dissolved in xylene. We have studied the electrical properties of inkjet printed silver samples, derived from silver neodecanoate ink, and investigated the influence of UV treatment before thermal curing the silver samples. UV exposure at room temperature is believed to control the nucleation of silver particles. In addition we have studied the influence of thermal pre-treatment on the printed samples. This pre-treatment is thought to assist the neodecanoate precursor to form a uniform distribution of silver nanoparticles. The influence of UV exposure, thermal pre-treatment and the thermal curing conditions on subsequent track microstructure, and its influence on electrical resistivity is reported for glass substrates. Furthermore, a series of extruding experimental at different nozzle offset and pumping pressure settings are conducted based on the rheological property of silicone oil and silver paste to find the ideal condition for producing continuous tracks with good shape. These findings are used to simulate a computer model for further applications.
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Choi, Jiyeon. « Femtosecond laser Written Volumetric Diffractive Optical Elements and Their Applications ». Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6230.
Texte intégralRésumé :
Since the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features that can be exploited in fabricating photonic structures is the refractive index change which results from the localized energy deposition. The laser processing system for FLDW can be realized as a compact, desktop station, implemented by a laser source, a 3-D stage and focusing optics. Thus, FLDW can be readily adopted for the fabrication of the photonic devices. For instance, it has been widely employed in various areas of photonic device fabrication such as active and passive waveguides, couplers, gratings, opto-fluidics and similar applications. This dissertation describes the use of FLDW towards the fabrication of custom designed diffractive optical elements (DOE's). These are important micro-optical elements that are building blocks in integrated optical devices including on-chip sensors and systems. The fabrication and characterization of laser direct written DOEs in different glass materials is investigated. The design and performance of a range of DOE's is described, especially, laser-written embedded Fresnel zone plates and linear gratings. Their diffractive efficiency as a function of the fabrication parameters is discussed and an optimized fabrication process is realized. The potential of the micro-DOEs and their integration shown in this dissertation will impact on the fabrication of future on-chip devices involving customized DOEs that will serve great flexibility and multi-functional capability on sensing, imaging and beam shaping.Ph.D.
Doctorate
Optics and Photonics
Optics
10
Suyal, Himanshu. « Direct laser-written polymer structures for guided-wave optical interconnects ». Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/2154.
Texte intégralRésumé :
This thesis describes the developments of guided-wave optical interconnects suitable for integration with printed circuit boards. The technology is based around direct laser writing of waveguides and other features in a newly developed multifunctional acrylate polymer system, using a He-Cd (325 nm) laser. It was demonstrated that, by writing with a laser spot having top-hat intensity profile, more sharply defined vertical and angled sidewalls could be achieved, compared to conventional methods using a Gaussian beam. Typical dimensions of the multimode waveguides were 50 x 50 J.lm, written with 50 J.lW of optical power with 100 J.lm/s scanning speed. The waveguide losses were measured, using the cut-back technique, to be -0.6 dB/em. A novel oil-immersion technique was developed to.overcome the limitations of refraction of the laser beam at the air / polymer inte~face and hence directly write 45° angled structures in the polymer. Metallised 45° out-of-plane mirrors were fabricated using these angled polymer structures and losses were measured to be ~ 0.8 dB per reflection. Successful coupling of optical signals between waveguides in different layers was also demonstrated in a double layer structure, in which the out-ofplane 45° mirrors provided the necessary optical connectivity. Direct laser writing was also employed to fabricate ~50 J.lm wide and 100 J.lm high polymer bumps for use in flip-chip bonding. Electroless gold plating was used to selectively metallise the polymer bumps and to produce electrical tracks on the substrate. Electrical resistances between the top of the bump and a lower metal pad were measured as less than ~5 ohms.
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RIZZUTI, ILARIA FRANCESCA. « STRENGTHEN OF DPNS FEATURES FOR THERANOSTIC APPLICATIONS AND MECHANICAL-CONTROL OF CHEMOTHERAPEUTIC EFFICACY THROUGH MODULATION OF CELL PROLIFERATION ». Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1000310.
Texte intégralRésumé :
Solid tumors are complex biological structures which are composed of cellular and matrix components, everything being perfused by blood vessels. During tumor development, modifications of both biochemical and mechanical parameters are observed and can feedback on one another. Cancer cells constantly interact with their mechanical environment and the whole tissue is mostly confined by its surrounding. Compressive mechanical stress develops in part from cell proliferation and could eventually result in the clamping of blood vessels leading to increased interstitial fluid pressure (hydrostatic pressure). The consequent hypoperfusion poses important obstacles to drug delivery and nanomedicines. In fact, the tortuous tumor microvasculature has blood velocities up to one order of magnitude lower compared to healthy capillary networks. Moreover, the fast angiogenesis during tumor progression leads to high vascular density in solid tumors, large gaps exist between endothelial cells in tumor blood vessels, and tumor tissues show selective extravasation and retention of macromolecular drugs (Enhanced Permeation Retention – EPR – effect). These effects have served as a basis for the development of drug delivery systems which are aimed at enhancing tumor tissue targeting and drug therapeutic effectiveness. Over the last 15 years, a plethora of materials and different formulations have been proposed for the realization of nanomedicines. Yet, drug-loading efficiency, sequestration by phagocytic cells, and tumor accumulation of nanoparticle-loaded agents - nanomedicines - are sub-optimal.
Starting from these considerations, during my PhD, I studied two complementary approaches: in the first two years my work was focused on implementing the characteristics of Discoidal Polymeric Nanoconstructs designed with controlled geometries and mechanical properties. In the last year, I investigated the role of mechanical stress on chemotherapeutic efficacy.
More precisely, this work first reviews the use of deformable discoidal nanoconstructs (DPNs) as a novel delivery strategy for therapeutic and imaging agents. Inspired by blood cell behavior, these nanoconstructs are designed to efficiently navigate the circulatory system, minimize sequestration by phagocytic cells, and recognize the tortuous angiogenic microvasculature of neoplastic masses. In this work, the synthesis, drug loading and release, and physico-chemical characterization of DPNs were enhanced with particular emphasis on the ability to independently control size, shape, surface properties, and mechanical stiffness. Two different loading strategies were tested, namely the straightforward “direct loading” and the “absorbance loading”. In the former case, the agent was directly mixed with the polymeric paste to realize DPNs whereas, in the latter case, DPNs were first lyophilized and then rehydrated upon exposure to a concentrated aqueous solution of the agent. Under these two loading conditions, the encapsulation efficiencies and release profiles of three different molecules and their corresponding prodrugs were systematically assessed (1,2-Distearoyl-sn-glycero-3-phosphorylethanolamine lipid chains or 1 kDa PEG chains were directly conjugated with Cy5.5 or methotrexate and Doxorubicin). Moderately hydrophobic compounds with low molecular weight showed encapsulation efficiencies of 80%, with absorption loading (direct loading has efficiencies around 1%). The DOX-DPN showed on triple negative breast cancer cells a toxicity comparable to free DOX. Preliminary in vivo preliminary studies conducted with directly loaded Cy5-DPN demonstrated a fairly solid integration of the imaging compound with the polymer matrix of the particles.
The second part of the work dissect what happens to free drugs or to drugs carried by nanovectors once they reach the tumor site. As we mention above, the elevated mechanical stress derived from tumor progression could result in blood vessels clamping with consequent reduction of drug efficacy. It is quite obvious to imagine that if the drug fails to reach the tumor it cannot act on it. Indeed, mechanical stress within the tumor site is present from the early stages of the disease. Our goal was to understand what happens when mechanical stress is not yet so large enough to fully collapse the blood vessels. Are there mechanical alterations that can affect the efficacy of a chemotherapeutic? We studied how mechanical perturbations of the tumor microenvironment could contribute to the mechanical-form of Gemcitabine drug resistance.
Specifically, we developed a new in vitro strategy to mimic the mechanical compression stress induced by the stroma during tumor progression. We embedded pancreatic tumor spheroids into agarose polymeric matrix in order to demonstrate the effect of mechanical compressive stress on tumor proliferation. Then, we validated our results with other types of mechanical stresses. Finally, we investigated the therapeutic efficacy of a proliferation-based chemotherapy: Gemcitabine.
Collectively, having the physical cues of cancer in mind, it can be important to cross-fertilize the fields of physical oncology and nanomedicine.
12
He, Peijun. « Development of paper-based point-of-care biosensors by laser-based direct-write processes ». Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419484/.
Texte intégralRésumé :
The demand for low-cost alternatives to conventional point-of-care (POC) diagnostic tools has led to significant developments in the field of microfluidics in porous materials. Several approaches have already been reported for fabricating fluidic devices in such materials, which include photolithography, inkjet printing, wax printing etc. In this thesis, a new approach towards the fabrication of paper-based POC diagnostic sensors is proposed, which is a simple laser-based direct-write (LDW) procedure that uses polymerisation of a photopolymer to produce the required fluidic channels in porous substrates. Furthermore, this LDW technique is also further developed and explored for the introduction of a range of additional functionalities in paper-based microfluidic devices. Firstly, programmable flow control is enabled via two fluid delay mechanisms, namely, permeable barriers with variable porosity and impermeable barriers with variable depth. The generated flow delays can span times from minutes to over an hour. Secondly, the same LDW approach is also developed for stacking and sealing of multi-layer substrates, for assembly of backing layers for two-dimensional lateral flow devices (LFDs) and eventually for fabrication of three-dimensional devices. In addition, we also report an idea of enabling fluidic gating in paper-based devices via triggerable wax barriers. The printed wax barrier acts as triggerable fluidic gates, which can be switched on demand via the application of local heating. Finally, these LDW fabricated paper-based devices were validated via implementation of various clinical diagnostics and analytical chemistry assays using both artificial samples as well as real human bodily fluids. Overall, a huge number of advantages have been established with this approach for both device fabrication and enabling additional functionalities. Thus, we believe that this technique could be an ideal choice for fabrication of paper-based microfluidic devices.
13
Shang, Shuo. « A predictive thermal dynamic model for parameter generation in the laser assisted direct write process ». Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/10893/.
Texte intégralRésumé :
The Laser Assisted Direct Write (LADW) method can be used to generate electrical circuitry on a substrate by depositing metallic ink and curing the ink thermally by a laser. Laser curing has emerged over recent years as a novel yet efficient alternative to oven curing. This method can be used in-situ, over complicated 3D contours of large parts (eg. aircraft wings) and selectively cure over heat sensitive substrates, with little or no thermal damage. In previous studies, empirical methods have been used to generate processing windows for this technique, relating to the several interdependent processing parameters on which the curing quality and efficiency strongly depend. Incorrect parameters can result a track that is cured in some areas and uncured in others, or in damaged substrates. This thesis addresses the strong need for a quantitative model which can systematically output the processing conditions for a given combination of ink, substrate and laser source; transforming the LADW technique from a purely empirical approach, to a simple, repeatable, mathematically sound, efficient and predictable process. This thesis describes in detail a novel and generic Finite Element Method (FEM) model that for the first time predicts the evolution of the thermal profile of the ink track during laser curing and thus generates a parametric map which indicates the most suitable combination of parameters for process optimisation. Experimental data is compared with simulation results to verify the accuracy of the model. This study also theoretically and experimentally investigates the curing process under different intensity profiles obtained with the SunShaper, a novel beam shaping device invented by Dr Wellburn, and thus predicts the performance of curing with various circular shaped beams.
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Gleich, Joshua. « Write First, Ask Questions Later : Publishing and the Race to Tenure Track ». UNIV TEXAS PRESS, 2016. http://hdl.handle.net/10150/621069.
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Raja, Sandeep. « The systematic development of Direct Write (DW) technology for the fabrication of printed antennas for the aerospace and defence industry ». Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14930.
Texte intégralRésumé :
Low profile, conformal antennas have considerable advantages for Aerospace and Military platforms where conventional antenna system add weight and drag. Direct Write (DW) technology has been earmarked as a potential method for fabricating low profile antennas directly onto structural components. This thesis determines the key design rules and requirements for DW fabrication of planar antennas. From this, three key areas were investigated: the characterisation of DW ink materials for functionality and durability in harsh environments, localised processing of DW inks and the optimisation of DW conductive ink material properties for antenna fabrication. This study mainly focused on established DW technologies such as micro-nozzle and inkjet printing due to their ability to print on conformal surfaces. From initial characterisation studies it was found that silver based micro-nozzle PTF inks had greater adhesion then silver nano-particle inkjet inks but had lower conductivity (2% bulk conductivity of silver as opposed to 8% bulk conductivity). At higher curing temperatures (>300??C) inkjet inks were able to achieve conductivities of 33% bulk conductivity of silver. However, these temperatures were not suitable for processing on temperature sensitive surfaces such as carbon fibre. Durability tests showed that silver PTF inks were able to withstand standard aerospace environments apart from Skydrol immersion. It was found that DW inks should achieve a minimum conductivity of 30% bulk silver to reduce antenna and transmission line losses. Using a localised electroplating process (known as brush plating) it was shown that a copper layer could be deposited onto silver inkjet inks and thermoplastic PTF inks with a copper layer exhibiting a bulk conductivity of 66% bulk copper and 57% bulk copper respectively. This was an improvement on previous electroless plating techniques which reported bulk copper conductivities of 50% whilst also enabling DW inks to be plated without the need for a chemical bath. One of the limitations of many DW ink materials is they require curing or sintering before they become functional. Conventional heat treatment is performed using an oven which is not suitable when processing DW materials onto large structural component. Previous literature has investigated laser curing as means of overcoming this problem. However, lasers are monochromatic and can therefore be inefficient when curing materials that have absorption bands that differ from the laser wavelength. To investigate this, a laser diode system was compared to a broadband spot curing system. In the curing trials it was found that silver inks could be cured with much lower energy density (by a factor of 10) using the broadband white light source. Spectroscopy also revealed that broadband curing could be more advantageous when curing DW dielectric ink materials as these inks absorb at multiple wavelengths but have low heat conductivity. Themodynamical modelling of the curing process with the broadband heat source was also performed. Using this model it was shown that the parameters required to cure the ink with the broadband heat source only caused heat penetration by a few hundred micro-metres into the top surface of the substrate at very short exposure times (~1s). This suggested that this curing method could be used to process the DW inks on temperature sensitive materials without causing any significant damage. Using a combination of the developments made in this thesis the RF properties of the DW inks were measured after broadband curing and copper plating. It was found that the copper plated DW ink tracks gave an equivalent transmission line loss to a copper etched line. To test this further a number of GPS patch antennas were fabricated out of the DW ink materials. Again the copper plated antenna gave similar properties to the copper etched antenna. To demonstrate the printing capabilities of the micro-nozzle system a mock wireless telecommunications antenna was fabricated on to a GRP UAV wing. In this demonstrator a dielectric and conductive antenna pattern was fabricated on to the leading edge of the wing component using a combination of convection curing and laser curing (using an 808nm diode laser).
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Zimmerman, Elizabeth Farrell. « God’s Teachers : Women Writers, Didacticism, and Vernacular Religious Texts in the Later Middle Ages ». The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244059446.
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Onanuga, Temitope [Verfasser], Andreas [Akademischer Betreuer] Erdmann et Bernhard [Gutachter] Schmauß. « Process modeling of two-photon and grayscale laser direct-write lithography / Temitope Onanuga ; Gutachter : Bernhard Schmauß ; Betreuer : Andreas Erdmann ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1186380640/34.
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Landowski, Alexander [Verfasser]. « Integration of Strong Fluorescent Nanodiamonds into Direct Laser Written Polymer Waveguides for Quantum Sensing / Alexander Landowski ». München : Verlag Dr. Hut, 2019. http://d-nb.info/1181514711/34.
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Dottermusch, Stephan [Verfasser], et B. [Akademischer Betreuer] Richards. « Direct Laser Written Nano- & ; Micro-Optical Textures for Photovoltaics Applications / Stephan Dottermusch ; Betreuer : B. Richards ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1200471075/34.
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Hamilton, William Derek. « The use of radiocarbon and Bayesian modelling to (re)write later Iron Age settlement histories in east-central Britain ». Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/9066.
Texte intégralRésumé :
This thesis focuses on the use of radiocarbon dating and Bayesian modelling to develop more precise settlement chronologies for later prehistoric settlements over an area extending from the Tees valley in the south to the Firth of Forth in Scotland and bounded by the Pennines to the west. The project has produced a corpus of 168 new radiocarbon dates from nine sites and used these, together with dates that were already available for another 10 sites to develop new chronological models for 18 settlements representative of different parts of the study area. The results of the modelling underline the dynamic character of later prehistoric social organization and processes of change in east-central Britain over a period of several centuries. A widespread shift from nucleated settlements to dispersed farmsteads apparently occurred over a period of no more than a generation on either side of 200 cal BC, with a subsequent move back to open sites in the period following Caesar’s invasions in 55/54 BC. It is not yet clear why the settlement pattern became more focused on enclosed settlements around 200 cal BC, but whatever the cause, this seems to form a single archaeological horizon all the way from the Forth to the Tees. The shift to open settlement around 50 cal BC seems, however, to be tied to new economic forces developing in the region as southern England becomes more focused on economic and diplomatic relations with Rome in the century leading up to the Roman occupation of northern England shortly after AD 70. Questions of duration are also explored, related more specifically to the lifespan of settlements and even of individual structures or enclosure ditches. These questions lead to ones of tempo, whereby the cycle of rebuilding a roundhouse or redigging a ditch is examined.
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Du, Mao-feng, et 杜茂楓. « Laser direct writer with light intensity modulation ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/99858019108303321159.
Texte intégralRésumé :
碩士國立中央大學
機械工程研究所
90
Traditionally, the diffractive optical element (ODE) is made by using the multiple binary-level lithography processes to enhance the diffractive efficiency. Due to the multiple exposures, the manufactory error will be included and more complicate processes is need to be considered. Therefore, to overcome these problems, the grey level mask can be used, in which only one exposure is needed to fabricate the optical element. This project presents that a laser machine with light intensity modulation to fabricate grey level masks. In the writer system, a solid-state laser with the power of 180 mw is used as the working light source. The processed target is laser direct write glass developed by the Canyon Material company. An acoustic-optics modulator (AOM) is used to modulate the laser intensity. To make sure the result of the processed mask, a measurement system is built. The laser direct writer system is already out of the binary methods to manufacture optical mask. The optical elements designer can use the LDW system to design any appropriate mask. Thus, the LDW system is a quite useful system for the ODEs.
22
Liu, Cheng-Lin, et 劉長霖. « Design and implement of a laser writer ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8g84z4.
Texte intégralRésumé :
碩士國立交通大學
機械工程系所
102
The laser writer is designed for research goal that can write patterns to the photoresist on the photomask or wafer. The design of the laser writer is using optical fiber with wavelength of 405 nm as the laser writing source and the 100X objective lens with numerical aperture of 0.90 as the focusing lens. The focus system is using a laser displacement detector with wavelength of 650 nm and a stepping motor Z-stage, which enables compensation for the thickness error from wafer and photoresist. The laser writer can successfully write lines to photoresist on wafer surface, which line width can be controlled and the minimum line width is 1μm.
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Wen, Ming-Hua, et 溫明華. « Design and Construction of Laser Based Mask Writer ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/97298278860641089035.
Texte intégralRésumé :
碩士國立臺灣大學
應用力學研究所
90
Twenty-first century is the age of information digitization, and the optical storage plays a very important role in the optical information technology. The key technology of high dense optical storage becomes the objective of internal and even abroad relative industries to aspire after. The widespread applications of this technology are beyond the scope of the development in CD-ROM. However, the market of CD-ROM is gradually replaced by DVD-ROM as a result of the violent competition of price and skills. Therefore, the demand of high capacity is turning into the tendency. The disk capacity of the secondary generation DVD-ROM will be achieved to be larger than 15 GB/side, i.e. HD-DVD, and the selected wavelengths of laser beam are within the range of blue light, about 430 nm. With larger numerical aperture (NA) of optical head, for example 0.6 ~ 0.8, the light spot diameter will be at the level of 0.25 mm ~ 1.8 mm. To make a comprehensive survey of HD-DVD ROM system and key technology within it, the technology of Laser Based Mask Writer system in demand, like high-speed auto-focusing system (response frequency higher than 1 KHz) to correct defocusing exposure due to misalignment, the optimized thickness of photoresist, the parameters of lithography process, dynamic control of nano-scale precision bearing and so on, certainly can conform to the technical roadmap in industrial development of optical storage. For that reason, the Laser Based Mask Writer system of this research can be regarded as a guide investigation on the development of key components in the HD-DVD ROM system. In the progression of this research of the Laser Based Mask Writer system, from the choices and purchases of system components, opto-mechanical design, the construction of whole system, to the connection of control interface, under the manpower and resources in the laboratory, each mechanisms of full system has successfully be started, constructed and linked. Besides the fundamental conditions of exposure and development have been quantitatively determined, we also get good experimental results, for example, a linear grating with grating period 2.5 mm (linewidth 1.5mm, space 1mm), a radial grating with minima grating period 4mm (linewidth 2mm) and some simple geometrical patterns. Furthermore, if we optimize the time-sequence control between acousto-optical modulator system and motion stage, and add program transform data and pattern for industrial use, then we can substantially expand the ways of Laser Based Mask Writer system.
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Liao, Hong-Zong, et 廖宏榮. « Design and Construction of A Laser Writer : A mask writer for semiconductor and micro-optomechatronic systems ». Thesis, 1998. http://ndltd.ncl.edu.tw/handle/15768175256830396124.
Texte intégralRésumé :
博士國立臺灣大學
應用力學研究所
86
A low cost prototype laser writer has been designed, constructed and demonstrated all within a limited budget. This novel laser writer includes a definition of the system specifications, components, development of the control codes, design of the optical layout, data processing procedures and construction of the database for the manufacturing process. In addition, problems of system vibration, allocation error and recombination have been examined and resolved. In the laser writer system, a 10 mW He-Cd laser with the wavelength of 442 nm was used as the working light source while a parfocal microscope was used as the foundation of the optical system. An acoustic optical control system was introduced to control the laser beam intensity, on/off conditions, and scanning bands. To make sure the exposure condition remains consistent, an autofocus system was incorporated to make the system in focus across the full working area. A novel code based on LabVIEW was developed and incorporated in a motion control card to control the stepping motors and to drive the corresponding stages. The newly developed working algorithm drives the stages at a constant speed while the scanning mechanism steers the laser beam to expose the photoresist in a straight line. The starting point for exposure of the system is determined by a preset value. Once the system compares it with its current position reading from a rotary encoder on the motor, and the two readings match, the system starts to operate. In regards to the precision and accuracy of this novel laser writer, the system has the ability to master with a spot resolution of one micrometer and can scan 1 cm2 in an hour. Thus, with its low cost, high accuracy and ease-of-use, this type of laser writer should be highly sought after for micro-opto-electromechanical systems and its manufacturing processes as it offers much potential.
25
Chan, Hsu-Chi, et 詹勛智. « Home-Made Direct Laser Writer and Demonstration of Graphene Oxides Reduction ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y6u696.
Texte intégralRésumé :
碩士國立交通大學
理學院應用科技學程
106
Within decades, three dimensional (3D) printer has become a very popular machine for rapid production since it quickly make samples and help to correct the product shortcomings in the designing stage. In addition, the cost of 3D printer is very low so using 3D printer for machine design is not only easy and affordable for the general public. Following this concept, we try to develop a low cost and micrometer scale writer to make electronic circuits. Based on the 3D printer and Arduino as a controller, we employ the precision screw, linear slider and step motor to build up a laser writing machine. The shortest distance (single step) of the moving stage can reach ~50 nm. We demonstrate the reduction of graphene oxide by using the home-made laser writer. It is checked that the diameter of the laser spot is about 12 micrometers. After laser irradiation, we check the resistance of the reduction of graphene oxides. We vary three conditions of laser writing, including the coating thickness of graphene oxides, the time of laser exposure, and the power of the laser spot. Then, we discuss the change of resistance as a function of the three conditions. Our results show that the best condition for reduction is to use the laser with a power of 5 mW, a wavelength 523 nm integrated with the objective lens of 10X to irradiate the graphene oxide film of ~3 nm in thickness for ~2 minutes.
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Cheng, Tsung-Dar, et 鄭琮達. « Research and Development of a Sub-wavelength Nondiffracting Beam Laser Writer : Theory and Fabrication of Nano-optical Components to System Verification ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/05954837545669514728.
Texte intégralRésumé :
博士國立臺灣大學
應用力學研究所
97
Traditional optical systems are affected by diffraction limit which its focal spot size is limited by the incident wavelength and numerical aperture of the system. In 1987, Durnin and the coworkers firstly demonstrated the concept of nondiffracting beam which its depth of focus was larger than traditional Gaussian beam 10 to 100 times. However, the minimum spot size of nondiffracting beam still remained in the range of several microns. In thesis, we demonstrate the simulations and numerical calculations of beaming light from bull’s eye structure and SAA optical head. We also performed experiments to verify the optical properties and feasibilities of optical head continuously. A Bessel beam writer system which is integrated with SAA optical head is designed and performed the ability of fabricating high-aspect-ratio structure on photoresist. We examine the optical properties such as propagation modes, focal length, sidelobes, etc. of metallic sub-wavelength annular apertures (SAA) and use finite-difference time-domain (FDTD) simulation to compare our experimental findings. Using two different metals, silver and tungsten, we examine the different optical transmission properties of the two metallic SAA structures. The far-field propagation of the silver SAA structure is found to be a type of quasi-Bessel beam when compares with a quasi-Bessel beam generated by a perfect axicon. The propagation characteristics of these two beams were found to match qualitatively. The far-field transmitted light generated by the silver SAA structure is found to possess a 390 nm sub-micron focal spot with a 24 μm depth of focus, which is much smaller than the focal spot generated by a perfect axicon. We also find that a tungsten SAA structure can generate a sub-micron quasi-Mathieu beam. Utilizing radially polarized and azimuthally polarized beam, we can generate higher-order quasi-Bessel beam from SAAs. We use Bessel beam writer system to fabricate the high-aspect-ratio structure on AZP4620 positive photoresist with 1 μm line width and aspect ratio 5:1.
27
Lin, Guo-Hui, et 林國輝. « Precision Laser Direct-Write Sintering Technology for Silver Nanoparticles ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/qt375h.
Texte intégralRésumé :
碩士國立虎尾科技大學
光電與材料科技研究所
100
The film display technology is growing mature, so the size of films is growing larger as well. It is very wasteful and resources unwise to generate circuit wire only in part of the area by plating the whole panel with mask. Therefore, we improve that disadvantage by adopting laser direct-write technique on the glass substrate to implant silver wire. The laser direct-write technique uses the blue-ray optical pickup as the resource of light, and it is a focusing lens with 405nm wavelength and 0.85 N.A. (numerical aperture). The characteristics above make it able to shrink the resource of light to 19% of the red-ray optical pickup. The sample specimen used in the experiment needed to coat the nano-silver solution on the glass substrate first, and then took advantage of the PDIC (photo diode integrated circuit) inside of the optical pickup to receive the FES (focus error signal) reflected by the glass substrate. It is used to distinguish whether the laser spot is on the positive focus and it can further achieve the atomization of the lock focus with VCM (voice coil motor) and with Labview program which controls the up and down displacement. It can shorten the manufacture process and decrease errors by human tuning. The patterned substrate is contained on the nano-platform and it controls the light energy of the optical pickup by the platform mobile and programs to get the effect of direct-write silver solution. The line width can up to 400 nm according to our test result.
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Chang, Hao-Wen, et 張皓雯. « Development of Blue Ray Laser Direct-Write Lithography System ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/nj9hjk.
Texte intégralRésumé :
碩士國立虎尾科技大學
光電與材料科技研究所
99
In this investigation an optical exposure apparatus have constituted by lithography and laser-direct technique with positioning stage. By blue-ray DVD pickup head for system light source which wavelength is 405nm and numerical aperture of focus lens is 0.85, therefore the size of light spot for red-ray DVD can be reduced to 19％. The structure of this research is applying the photo diode integrated circuit in DVD pickup head and using voice coil motor to focus on the action of lock. The focus error signal reflected by the PDIC receiving the substrate which can use for testing location. And the way in auto focus controlled by programmable automation can shorten the time of system process and reduce the personal errors. With pattern substrate on Queensgate Instrument NPS-XY-100A nanopositioning stage to control the program which can bring in complicated pattern path. So it can manufacture nanostructure or micro electrodes. This research developed a blue ray laser direct write lithography system. The size of spot is 1.64 μm and time of laser control which can be 450 ns. The system can be applied in semiconductor construction and design.
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Ruizpalacios, Rodrigo. « Laser direct-write of optical components prepared using the sol-gel process ». Thesis, 2004. http://hdl.handle.net/2152/1399.
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30
Huang, Kuofeng, et 黃國峰. « The Study of Laser Direct-write Patterning Method for ITO Thin Film ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/ya9jq6.
Texte intégralRésumé :
碩士高苑科技大學
電子工程研究所
100
In this research, the laser direct-write patterning method is applied to the micromachining of ITO thin films on glass substrate. It is possible to complete the patterning process without damaging the substrate. The purpose of this study is to identify the proper processing parameters, namely the focal length, laser current and laser pulse duration. Observing the ITO insulation areas with a scanning electron microscope (SEM), we found that the patterning width was mainly determined by the laser current while the laser pulse duration had little effect. Larger laser current gave a larger patterning spot. Therefore, the laser power is an important parameter of patterning ITO films with laser direct write
31
Ruizpalacios, Rodrigo Wood Kristin L. Beaman Joseph J. « Laser direct-write of optical components prepared using the sol-gel process ». 2004. http://repositories.lib.utexas.edu/bitstream/handle/2152/1399/ruizpalaciosd18663.pdf.
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32
Fernandes, Luís. « Birefringence and Bragg grating control in femtosecond laser written optical circuits ». Tese de doutoramento, 2011. http://hdl.handle.net/10216/67867.
Texte intégral
33
Fernandes, Luís André Neves Paiva. « Birefringence and Bragg grating control in femtosecond laser written optical circuits ». Doctoral thesis, 2012. https://repositorio-aberto.up.pt/handle/10216/74049.
Texte intégral
34
Fernandes, Luís André Neves Paiva. « Birefringence and Bragg grating control in femtosecond laser written optical circuits ». Tese, 2012. https://repositorio-aberto.up.pt/handle/10216/74049.
Texte intégral
35
Chen, Shuen-Chen, et 陳順成. « Manufacturing Process Technology of Laser Direct-write Nanolithography for Localized Surface Plasmon Resonance Biosensor ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/30674711028739283733.
Texte intégralRésumé :
碩士國立臺灣海洋大學
系統工程暨造船學系
103
In recent years, in-vitro diagnostics (IVD) is widely applied in qualitative or quantitative analysis of medical diagnosis and medicine development via fast development in biomedical engineering. Immunoassay, molecular diagnostics, and point of care testing are about 50% of global IVD market, and biosensing detection is one of these main products. The main working principle of localized surface plasmon resonance (LSPR) biosensors is adoption of full-band light to excite nano-dimensional metal particles to obtain LSPR; moreover, localized electromagnetic field is affected to metal particles or structures. This paper presents a novel dual-wavelength laser direct-write nanolithography system (DLDNS) that consists of an optical pickup head system with dual-path optical design, a control system comparing a laser diode drive controller, an autofocus controller, and motor and stage controllers, and a stage system composed of a spindle motor and a linear moving stage. Heat-mode inorganic photoresist films were exposed by a blue-violet laser source in the DLDNS. Moreover, the system integration of the blue-violet laser with stable exposure output, a red laser with accurate auto focus function, and a linear moving stage with positioning servo control in nano-scale, that can make dimensional errors of the nanostructure arrays become smaller efficiently. A finite-difference time-domain (FDTD) analysis was utilized to simulate superficial characteristics of continuous gold nanoparticle arrays. Different structural model, pitch, width, and diameter size of the gold nanoparticle arrays were designed and created to investigate the influence of varied membrane thickness and the transmission spectrum on the surface layer, and chip sensitivity response. In the experimental results, the features of pitch, depth, and width of the periodic gold nanoparticle arrays are 500 nm, 43 nm, and 197 nm, respectively, and the measured transmission spectrum is 798 nm. Therefore, the LSPR biochips based on the periodic gold nanoparticle arrays have been developed, and they have advantages of functional resonant wavelength / frequency and high sensitivity to apply widely in bio-detection and biomedical fields.
36
Chen, Zheng-Yan, et 陳正彥. « Fabrication of embedded metal-mesh electrode by laser direct write combing with electroless plating ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/m4f77t.
Texte intégralRésumé :
碩士國立中央大學
機械工程學系
106
In this study, both techniques of laser direct writing and electroless deposition are applied to the fabrication of flexible metal-mesh transparent electrodes. Due to the Gaussian distribution of the laser beam, the intensity of laser energy decreases gradually from the middle to the periphery, resulting in transversal temperature gradient and the Marangoni effect, which makes the crosswise profile of laser-sintered metal wire with uneven height profile, lower in the middle and higher at the two ends. Thus, the first part of this study explores whether electroless deposition can repair this uneven morphology. Results show that although the surface morphology before and after electroless deposition looks similar, the cross-sectional profile measurement shows that the height difference between the middle and the two ends becomes smaller. Hence, electroless deposition is a practical solution for repairing contour defects caused by Gaussian laser beam. The second part of this study focuses on employing the electroless deposition technique to grow metal-mesh electrode from a glass substrate with an initial laser-direct-write seed pattern. The metal seeds are generated from a spin-coated composite thin film, synthesizing from silver nitrate (AgNO3) and polyvinyl alcohol (PVA) solutions, by laser direct write. PVA is capable of chelating silver ion and the silver ions are reduced to silver atoms via gaining and losing electrons as subjected to laser irradiation. In addition, the generated heat accelerates the reduction speed. The PVA/AgNO3 composite exhibits better film-formation property and the use of PVA increases the film’s linkage to substrate. Subsequently, that leads to good adhesion of the electrode to the glass substrate. The resultant metal-mesh electrode, consisting of silver and copper, has sheet resistance about 1 Ω/sq and transmittance greater than 80%. But the height of the mesh line is about 1 micron which is too high to penetrate organic thin films in an organic device, where the film thicknesses are ranging from several tens to hundreds nanometers. Thus, in the third part of this study, we embed the electroless deposited electrode into a polyimide (PI) substrate as an embedded flexible electrode. Consequently, the surface roughness of the embedded electrode is less than 10 nanometers. The reciprocating bending test shows that, even under a small bending radius of 6 mm, there is only a 20% of increase in sheet resistance after 10000 cycles of bending.
37
Ding, Chien-Fang, et 丁健芳. « Study of Compound Ultraviolet Laser Direct-Write Annealing Process on Conducting Thin Film Fabrication ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rj96pa.
Texte intégralRésumé :
博士國立臺灣大學
機械工程學研究所
107
This study investigated the photon thermal treatment by ultraviolet laser direct-write system on two promising conducting films, including ZnO:Al (AZO) and graphene. The films characteristics were systematically analyzed, using a 4-point probe instrument, an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrophotometer, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), before and after the laser annealing process. In the laser annealing process of AZO material, the experimental results indicated that varying the laser fluence and annealing speed affected the optical and electrical properties of the AZO films. After the laser annealing process, there was a slight change in the visible region with approximately 84.7 % of transmittance spectra. The maximum resistivity values of the annealed AZO films decreased from 1.15 Ω⋅cm to 1.17 × 10−2 Ω⋅cm, approximately 99 % higher than the initial value. In addition, the laser fluence not only influenced the structural properties of the films, but also improved the crystallinity of the films after the laser annealing process, with minimal changes in the thickness of the films and the concentration of the elements in the films. The root mean square surface roughness (Rrms) of the films gradually increased as the laser fluence increased. Moreover, according to the XRD pattern of the films, the intensity of the main peak corresponding to the (002) direction increased as the laser fluence increased. The average grain size (20 nm) of the annealed films, determined using the Scherrer equation, was smaller than that of the as-deposited thin film (21.7 nm) due to the low temperature effect in the laser annealing process. In the laser annealing process of graphene material, the laser fluence had a great effect on the electrical properties of the graphene thin films. The sheet resistance of printed graphene thin films decreased from 262.22 Ω/sq to 97.27Ω/sq after laser annealing, approximately 62.9 % lower than the initial value. In addition, based on the results of Raman spectrum, the ID/IG decreased from 0.75 to 0.3, showing that the structural disorder in graphene structural was reduced. Furthermore, the selective laser processing and the electrothermal response test of printed graphene thin film on a glass substrate were conducted to show the potential of multi-zone heater and further applications.
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Lin, Ding-Zheng, et 林鼎晸. « Simulation and Fabrication of Sub-wavelength Structures for a Nanometer Feature Enabled Lensless Laser Writers ». Thesis, 2003. http://ndltd.ncl.edu.tw/handle/23988118186412761751.
Texte intégralRésumé :
碩士國立臺灣大學
應用力學研究所
91
This dissertation concentrated its focus on the extraordinary optical transmission phenomena investigated by many leading research groups worldwide. Many of such results were still published in Science and Nature Journal in year 2003. Taking some of the understanding generated by all previous studies, this dissertation proposed a setup to propagate sub-micrometer light beams without resorting to the conventional approach of using a lens. The main target is to locate a way to either by pass or circumvent the diffraction limit and then evolve this newly developed optical head to the integration of a Laser Writer system. This dissertation includes using surface plasma theory to explain the mechanism of extraordinary transmission phenomena, fabrication process of freestanding metal film, measurements of transmission spectrum and observation of transmission light beam in far field. Both RCWA (Rigorous Coupled Wave Analysis method) and FDTD (Finite Difference Time Domain method) were adopted to simulate the transmission spectrum and electromagnetic field distribution of transmission light beams from near field to far field. The experimental results confirmed that surface structures on the incident side of the incoming light beams can excite surface plasma and enhance the throughput energy of the transmission light beam. In addition, it was also identified that surface structures on the exit side can suppress diffraction effect and make transmission light beam directional. Good agreements were found between the experimental and the simulation results. Finally, this dissertation takes both the simple fabrication process and the general operating condition into considerations, which led to an invention that is related to substrate-based optical head design concepts for sub-wavelength light beam projections.
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Huang, Guo Jang, et 黃國彰. « A study of recording materials for write-once optical disc with red or blue laser ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/63580313699597468725.
Texte intégralRésumé :
碩士元智大學
光電研究所
93
In this study, we focused our interests on the recording materials for inorganic write-once optical disc. For choosing the recording materials, we adopted CrOx and Zn/Ge bilayer thin film. For CrOx thin film, we found that the gas could be released from the layer as the heating temperature over 400 ℃. This outgoing gas can destroy the substrate and remain a hole on the substrate so that the optical properties of the film were changed. Therefore, CrOx thin film was firstly used in DVD-R disc as the recording material illuminated by red ray (its wavelength is 650 nm) and then analyzed. Through a series of optimization for the layer structures, the carries noise ratio (CNR) obtained from the dynamic tester had been improved clearly. By using DSC technique, the phase transition temperature of Zn/Ge bilayer thin film is 385 ℃. The optical contrast of this film was more than 73.57% as the phase transition occurred. Then, we had this material as the recording layer used in HD-DVD disc illuminated by blue ray (its wavelength is 405 nm) and then analyzed. Through a series of optimization for the layer structures, we found that the optical contrast of the disc was still remained over 56.27%. Thus, the Zn/Ge bilayer thin film is a very potential for replacing the conventional recording layer material used in blue-ray disc.
40
Chen, Ping-Chun, et 陳柄均. « The Silver Wire Process System Made of Blu-ray Laser Direct-write Welded Silver Nanoparticle ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/74750445672465285394.
Texte intégralRésumé :
碩士國立中興大學
機械工程學系所
102
This research applies laser direct-write technique to implant silver wire on glass substrates. Different from the CO2 laser and Nd: YAG which are widely used domestically, we use blue-ray optical pickup as light source. In preparation for the sample, we firstly clean up glass substrates, sputtered coating the surfactant layer, and then coat nano-silver solution on the surface, and use laser light source to sinter into bulk. While sintering, the photo diode integrated circuit (PDIC) of blu-ray optical pickup can receive the focus error signal (FES) reflected from glass substrates to distinguish whether the laser spot is on the positive focus. With the use of piezoelectric crystal and LabVIEW program to control vertical displacement to easily achieve automatic focusing, it can reduce production time and human focus errors. The sintered pattern of glass substrates moves through triaxial precision nanometer movable platform to write silver wire on glass substrates. The automatic focusing technique alone with laser variables, the written silver wire width can be sintered under 2.94μm.
41
Tong, Steven. « Development of Non-planar Interconnects for Flexible Substrates using Laser-assisted Maskless Microdeposition ». Thesis, 2012. http://hdl.handle.net/10012/6992.
Texte intégralRésumé :
With the industry striving for smaller devices, new technologies are developed to further miniaturize electronics devices. To this end, realization of 3D/non-planar interconnects, which aim at miniaturizing the interconnects formed between components on the same device, has attracted many researchers. This thesis focuses on a feasibility analysis for developing non-planar interconnects on various flexible substrates using laser assisted maskless microdeposition (LAMM), which is a pressure-less process. There are two types of flexible substrates that are used: double-sided copper substrates separated by a layer of polyethylene terephthalate (PET) as well as a polyethylene terephthalate flexible substrate with surface-mounted resistors. For both substrates, multiple types of experiments were conducted to discover procedures which result in the highest rate of success for forming conductive interconnects. Optimal process parameters and deposition techniques were determined after multiple experiments. After experiments were completed, the resultant substrates were subject to various characterization methodologies including optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and profilometery. The results of these methodologies are documented in this thesis.
After many types of experiments involving substrate manipulation of the double-sided copper substrates, it was shown that the silver nano-particles were more likely to form a conductive interconnect when a polished slant was fabricated on the substrate.
Many deposition patterns were used for the flexible substrates with surface-mounted resistors. Of these patterns, the two patterns, the ‘zigzag’ and ‘dot solder’ patterns, proved to have a much higher success rate for creating conductive interconnects compared to the other patterns.
During this study, the results of the experiments using the LAMM process show that this technology has great potential for creating non-planar interconnects on flexible substrates. The experiments however suggest that the process is very sensitive to the material composition and process parameters. As such, with a small change in parameters, the 3D interconnects can fail to be produced. It was also observed that the possibility of silver interconnect fractures is higher where dissimilar materials with different thermal expansion rates are used for the underlying substrates.
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Yin, Chong Poh, et 張寶瑩. « Fabrication and Characterization of Microstructures Initiated Using Femtosecond Laser Direct Write from SU8 and Its Composites ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/y7kpq5.
Texte intégralRésumé :
碩士國立中央大學
光機電工程研究所
106
Two-photon absorption is a nonlinear optical phenomenon which can be realized with a tightly focused beam with high peak intensity. The interaction region is limited to an extremely localized focal volume. In this study, two-photon polymerization of negative tone photoresist, SU8 is investigated. Titanium sapphire femtosecond laser at 740 nm is used as energy source to induce two-photon absorption which in turn leads to polymerization of SU8. Two-photon polymerization of SU8 is accumulative in nature, as bigger voxel is obtained with increased exposure time. Line width of SU8 structures demonstrate logarithmic dependence on scanning speed and laser power. Resolution is determined by laser power and scanning speed, which is greatly dependent on efficiency of photoinitiator. A minimum line width of 80 nm is achieved in this study. Adhesion of structures is influenced by pattern design. Without sufficient mechanical support, these structures are unable to withstand rinsing forces during development stage. Composite material is developed using SU8 and copper precursors, particularly copper (II) nitrate tyihydrate and copper (II) chloride dihydrate. Copper is selected as filler material due to excellent electrical conductivity and cost effectiveness. Blue, homogenous composite solution is synthesized, which can be spin coated on substrate to create a uniform thin film. Irradiation of femtosecond laser induces two-photon absorption that leads to polymerization of SU8, reduction of copper ions and sintering of copper particles. Surface morphology is affected by scanning speed, as low scanning speed subsequently leads to accumulation of heat energy and ablation. Line width of composite structure is determined by laser power. Electrical resistance of the composite structures decreases with scanning speed until optimum scanning speed is achieved. On the other hand, as laser power increases, line width increases while resistance decrease. Electrical conductivity of 365.50 S/m is achieved, which is a leap of advancement as compared to pure SU8 with conductivity of 10-14 S/m.
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Tsai, Jeng Shiuan, et 蔡政軒. « A study of Zn/Ge bilayer as a recording medium for write-once disc with blue laser ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23722014358066577457.
Texte intégralRésumé :
碩士元智大學
光電工程研究所
95
In this study, we focused our interests on inorganic recording materials for write-once optical disc. We adopted Zn/Ge bilayer as the recording material for the disc. For our previous work in this laboratory, we found that the phase-transition temperature of Zn/Ge bilayer is 385 ℃. According to the results obtain from TEM and XRD, we found that Zn/Ge recording media has distinct changed. To optimize layer structure to obtain better performance, the carry to noise ratio (CNR) obtained by dynamic tester need to be over 45 dB. Through a series of optimization for layer structure, we found that the optical contrast of the disc was over 68.44% with blue laser illuminating. By viewing the surface of the substrate, we found that the substrate could not be destroyed through blue laser illumination. In this thesis, the experimental results showed that the Zn/Ge bilayer is very potential for write-once disc under blue laser illumination.
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Lin, Bo-Jyun, et 林柏均. « Synthesis of Silver Oxalate Complex Ink for Fabricating Ag-metal-mesh Transparent Electrode by Laser-Direct-Write Method ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/t2cy8e.
Texte intégralRésumé :
碩士國立中央大學
能源工程研究所
107
Indium tin oxide (ITO) is an excellent transparent electrode material, but it has some disadvantages, such as it is rare in nature, its fabrication process is material wasting and poor in flexibility, and it is not applicable to wearable electronics. Recently, many studies have shown that metal mesh electrodes are quite excellent in light transmittance and conductivity, and are fairly potential ITO replacement electrodes. The main purpose of this research is to develop a new approach for rapidly fabricating metal mesh transparent electrodes using the technique of laser direct writing in the ambient environment. In this study, we first synthesize a new type of metal ink based on silver oxalate and propylenediamine. It is then subjected to the method of laser direct write to fabricate into a silver-based metal mesh electrode. Finally, the conductivity, transparency and mechanical properties of the electrode are examined. For metal ink configurations, the advantage of using silver oxalate as a precursor is its high silver content and which can be directly thermally decomposed into metallic silver and carbon dioxide without other by-products. In this study, we combine both ethanol and water as the solvent to synthesize inks, and the effects of the weight ratios between water and ethanol on the surface morphology and electrical properties of the resulting mesh were studied. The proposed ink has good stability and is stable in colorless and transparent state after being left in the ambient for 7 days. By a fixing set of laser writing parameters, the results indicate that the higher the content of ethanol in the solvent, the better surface morphology as well as higher conductivity on the resulting silver metal mesh. As the average thickness of the written meshes is of 800 nm and the transmittance of the electrode is up to 86% (@550 nm), the electrode’s resistivity is only 1.8 times that of the block silver. The second part of this study is to examine the electrode’s flexibility. The originally fabricated silver electrode on a glass substrate is embedded into a flexible PI (liquid polyimide) thin film to make the electrode flexible. Its flexibility is examined by a cyclely bending test which is executed 5000 cycles with a radius of bending curvature of 5 mm. The increase of relative resistance (ΔR/R0) was less than 40% of its original one and that was still within the allowable range.
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Huang, C. Y., et 黃兆義. « Near-field optical recording on cyanine dye layer of a commercial write-once compact disk ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/41350996631551749237.
Texte intégral
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Lin, Kai-Hsiang, et 林楷翔. « KVSSD : Close Integration of LSM trees and Flash Translation Layer for Write-Efficient KV Store ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6r2wdw.
Texte intégralRésumé :
碩士國立交通大學
資訊科學與工程研究所
106
Log-Structured-Merge (LSM) trees are a write-optimized data structure for lightweight, high-performance Key-Value (KV) store. Solid State Disks (SSDs) provide acceleration of KV operations of LSM trees. However, this hierarchical design involves multiple software layers, including the LSM tree, host file system, and Flash Translation Layer (FTL) inside of SSDs, causing cascading write amplifications. We propose KVSSD, a close integration of LSM trees and the FTL, to manage write amplifications from different layers. It exploits the FTL mapping to implement copy-free compaction of LSM trees, and it enables direct data allocation in flash memory for efficient garbage collection. In our experiments, compared to the hierarchical design, our KVSSD reduced the write amplification by 80% and improved the throughput by 290%.
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CHANG, CHIAO-PO, et 張喬博. « Fabrication of Oxidation Resistant, Cu-Ni Alloy Metal-mesh Transparent Electrode by Laser Direct Write from Self-Reduction Metal Complex Inks ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/33mn5k.
Texte intégralRésumé :
碩士國立中央大學
機械工程學系
106
Indium tin oxide, ITO, has good performance in both transmittance and conductivity. Thus, it has been playing an important role in transparent conducting electrodes. However, ITO is brittle that restricts its applications in the blooming flexible electrotrincs. Many research reports reveal that metal-mesh-based electrodes by varios metal materials such as gold, silver, and copper, have demonstrated high potential as alternative transparent electrodes. However, gold and silver are too expensive and copper is easy to get oxidated either at the duration of fabricating process or in the course of operations. Thus, this study is committing to develop a low-cost alloy electrode that is with high oxidation resistance. We aim to develop a copper-nickel-alloy-based metal mesh electrode fabricated by the technique of laser direct write. The resulting capability in oxidation resistance is tested in an elevated temperature environment. Copper formate and nickel formate are all metal organic thermal decomposition (MOD) compounds that take the advantages in both reducing to metal ions without the need of any reducing agents and obtaining the resulting various compound solutions by mixing both inks at different molar ratios. The mixed MOD solution is then spin-coated on a glass substrate and dried in vacuum at 100 °C to form a uniform MOD thin film. It is then heated by a focused 532 nm laser beam to induce thermal decompositons of both copper formate and nickel formate and sintered reduced copper and nickel particles. The pattern of the resulting metal-mesh can be accomplished by laser direct wirte, a maskless process and executable in the ambient. Results show that the fabricated copper-nickel alloy electrode exhibit good characterisitics: sheet resistance less than 70 Ω/□, transmittance over 80% and the average thickness about 500 nm. Copper is very easy to get oxided, expecially at high temperatures. The excellent ability in oxidation resistance of our copper-nickel mesh elelctrode is examined in an oven maintaining at temperature up to 250 °C for 48 hours. The resistance increasement is only 3 folds, which is much more smaller than that of a copper mesh electrode that shows 106 times in resistance enhancement.
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Lin, Wu Chang, et 吳昌霖. « A Study of the Dual Layer a-Si/Cu Inorganic Recording Thin Film for Blue-ray Write-once Disk ». Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09065071762239255602.
Texte intégralRésumé :
碩士國立中興大學
材料工程學研究所
91
Organic dyes have been used as the recording materials for most of the write-once（W/O）disks. However, the absorption spectrum of the organic dye is strongly wavelength dependent and is very weak at the range of blue wavelengths. It is very difficult to synthesize a suitable organic recording material for the write-once blue-ray disk. Therefore, inorganic recording materials exhibiting adequate optical properties at blue wavelength become possible candidates for the write-once blue-ray disks. In this study, an a-Si/Cu dual layer prepared by an Ion Beam Assisted Deposition system（IBAD）was adopted as the recording layer for the write-once blu-ray disk. The results of thermal analysis showed that there were two reflectivity changes occurring at 175℃ and 495℃ at the heating rate of 100℃/min. The results of TEM and AES analyses confirmed that the first change corresponded to the formation of Cu3Si through the diffusion of Cu into the amorphous Si layer, while the second change corresponded to the crystallization of amorphous Si where poly-crystalline Si grew from the existing Cu3Si nuclei. At the blue wavelength of 405nm, the as-deposited a-Si/Cu recording film exhibited an absorptance of 47.3％ and a reflectivity of 43.9％. After being annealed at 500℃, the reflectivity of c-Si/Cu3Si film increased to 59.9％, and an optical contrast of 36.4％ was obtained. It is obvious that the a-Si/Cu dual layer with optical properties fulfilling the requirements for the write-once blu-ray disk is one of the promising recording materials. The results of the static testing demonstrated that the copper layer could effectively enhanced the crystallization of amorphous silicon layer. As the laser powers of 6mW、8mW and 10mW were applied the minimum durations of writing pulse were found to be 100ns、50ns and 10ns, respectively, which corresponded to the maximum linear velocities of 3m/s、6m/s and 29m/s, and data transfer rates of 18.1Mbps、36.2Mbps and 181.2Mbps, respectively.
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Chen, Zhuo. « Panel econometric evidence of Chinese agricultural household behavior in the later 1990s : production efficiency, size effects and human mobility / ». 2004. http://www.gbv.de/dms/zbw/546596630.pdf.
Texte intégral
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Čepková, Ivana. « Vývoj vypravování u dětí staršího školního věku ». Doctoral thesis, 2020. http://www.nusl.cz/ntk/nusl-435265.
Texte intégralRésumé :
The suggested project is patterned on the need to learn more about the development of narration skills in children of later school age. The goal of this project is to research written narration in formal school environments so as to lead towards a more efficient, purposeful development of communication competence in children, and to contribute to other research in the field of language development.