Dissertations / Theses on the topic 'Soft-lithography'
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1
Kim, Hyung-Jun. "Automation of soft lithography." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38290.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 79-82).
This dissertation is a final documentation of the project whose goal is demonstrating manufacturability of soft lithography. Specifically, our target is creating micron scale patterns of resists on a 3 square inch, relatively large area in case of soft lithography, flexible substrate using microcontact printing in order to forming electronic circuit patterns for flexible displays. At first, the general principles and characteristics of soft lithography are reviewed in order to provide the snapshot of soft lithography technologies, and the key factors that affect the productivity and quality of microcontact printing are discussed because such factors should be understood in advanced to develop current lab-based microcontact printing science into plant manufacturing technology. We proposed a prototype for automated of microcontact printing process adopting a continuous reel-to-reel design, ideal for mass production, as well as printing-side-up design in order to minimize the distortion of relief features of PDMS stamp. The machine we created not only demonstrated the manufacturability of microcontact printing, our initial project goal, but also high scalability for mass production. The machine can print micron scale patterns on a 7 square inch plastic sheet, four times bigger than initial target area, at once.
by Hyung-Jun Kim.
M.Eng.
2
Young, Richard James Hendley. "Electroluminescent devices via soft lithography." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/17139.
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This thesis provides a compendium for the use of microcontact printing in fabricating electrical devices. Work has been undertaken to examine the use of soft lithographic techniques for employment in electronic manufacture. This thesis focusses on the use of high electric field generators as a means to producing electroluminescent devices. These devices provide a quantifiable output in the form of light. Analysis of the electrical performance of electrode structures can be determined by their success at producing light. A prospective reduction in driving voltage would deem these devices more efficient, longer lasting and an improvement on current specification. The work focussed on the viability of using relatively crude print techniques to create high resolution structures. This was carried out successfully and demonstrated that lighting structures of 75 μm and 25 μm have been produced. Microcontact printing has been established as a method for patterning gold surfaces with a functionalising self-assembled monolayer using alkanethiol molecules. This layer is then utilised as an etch resist layer to expose gold tracks for use as electric field generator electrode arrays. Through careful analysis of each step of the printing process, techniques were developed and reported to create a robust and repeatable print mechanism for reliability and accuracy. These techniques were employed to optimise the print process culminating in the development of each stage and final electrode structures mounted on a rigid backplate for use as electroluminescent devices for characterisation. These devices were then modelled for their electrical characteristics and investigated for being used in low voltage application. In this case for the development of electroluminescent applications, a driving voltage of 65 V was achieved and represents a significant advance to the field of printed electronics and Electroluminescence.
3
Zheng, Zijian. "Soft lithography and nanoimprint lithography for applications in polymer electronics." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613415.
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Chen, Ying. "PATTERNING ELASTOMER, THERMOPLASTICS AND SHAPE MEMORYMATERIAL BY UVO LITHOGRAPHY AND SOFT LITHOGRAPHY." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491264216402058.
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Bhat, Rahila. "Novel routes to the fabrication oftemplates for soft lithography." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420743.
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Hassanin, Hany Salama Sayed Ali. "Fabrication of ceramic and ceramic composite microcomponents using soft lithography." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1538/.
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This PhD project is set out to develop a high precision ceramic fabrication approach suitable for mass production, and to meet the needs of microengine application. A group of new processes have been developed and the results are characterized for fabrication of high precision ceramic oxides and composite microcomponents using soft lithography and colloidal powder processing. The materials chosen in the research are alumina, yttria stabilised zirconia and their composite for their excellent properties at high temperature.
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Grothe, Julia, Florian Wissner, Benjamin Schumm, Giovanni Mondin, and Stefan Kaskel. "Precursor strategies for metallic nano- and micropatterns using soft lithography." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-189005.
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Soft lithographic methods describe a set of printing methods which are widely used for the preparation of structured surfaces. Structured surfaces are essential components in the field of (opto-)electronic devices such as organic light emitting diodes, photovoltaics or organic field effect transistors. In recent years, crucial progress has been achieved in the development of patterned metal coatings for these applications. This review focusses on new strategies for soft lithographical printing of metal structures emphasizing the subtle interplay of printing techniques, metal precursor chemistry, and surface functionalization strategiesDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Cao, Arthur Y. (Arthur Yao). "Design and prototype : a manufacturing system for the soft lithography technique." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38562.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, September 2006."August 2006."
Includes bibliographical references (leaves 155-158).
Ever since 1998 when the term "soft lithography" was first created, soft lithography techniques have drawn close attention of the academia and the industry. Micro contact printing is by far the most widely used soft lithography technique in the industry. The objective of this research project is to design and prototype a micro contact printing machine which could achieve high scalability, feature resolution and production rate. It should also fulfill quality requirements, in terms of minimizing the tool deformation and air trapping furing printing. A reel-to-reel design with wipers to create linear propagation during stamping was used in the final design. The final prototype was made of three stations, the printing station, the inking station and the rotary system, which switches the stamps between printing and inking station. The other important design novelty is that the PDMS stamp has been fixed and the Au coated PET was actually applied to the stamp to get printed. The design minimizes the deformation on the stamp and also eases the linear propagation of the printing interface. The reel-to-reel design can be easily scaled up for mass production with large volume. The prototype was tested and the printing samples were made.
by Arthur Y. Cao.
M.Eng.
9
Petrzelka, Joseph E. "Contact region fidelity, sensitivity, and control in roll-based soft lithography." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74909.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 341-349).
Soft lithography is a printing process that uses small features on an elastomeric stamp to transfer micron and sub-micron patterns to a substrate. Translating this lab scale process to a roll-based manufacturing platform allows precise control of the stamp contact region and the potential for large area, high rate surface patterning. In this manner, emerging devices can be produced economically, including flexible displays, distributed sensor networks, transparent conductors, and bio-inspired surfaces. Achieving and maintaining collapse-free contact of the soft stamp features is a necessary condition for printing. In the first part of the thesis, stamp behavior is examined at two length scales. First, microfeature collapse is examined across a range of dimensionless aspect ratios and pattern ratios to determine the collapse mode and the feature stiffness. Second, behavior of roll-mounted stamps is investigated on the macroscopic scale. The results of these analyses, simulations, and experiments show that contact is prohibitively sensitive as the feature scale shrinks to single microns or below. In the second part of the thesis, methods are developed to reduce the contact sensitivity. A compliant stamp architecture is introduced to tune the mechanical response of the stamp. Next, a new process for manufacturing cylindrical stamps is developed that removes limitations of planar stamp templates. The third part of the thesis addresses process control. A parallel kinematic stage is designed to manipulate the height and pitch of a roll over a substrate with submicron precision. A hybrid state-space / classical feedback control approach is used to achieve high bandwidth servo control in the presence of coupling and unmodeled dynamics. Using optical instrumentation, the stamp contact pattern is monitored and can be controlled using camera images as a control variable. Ultimately, a practical method of impedance control is implemented that demonstrates excellent disturbance rejection. The results of this thesis provide models for stamp behavior at the local microscale and the roll-based macroscale. These results illustrate the high sensitivity of contact to displacement disturbances in roll-based lithography, but also provide valuable design insight towards designing stamps and processing machinery that are robust to these inherent disturbances.
by Joseph Edward Petrzelka.
Ph.D.
10
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.
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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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Grothe, Julia, Florian Wissner, Benjamin Schumm, Giovanni Mondin, and Stefan Kaskel. "Precursor strategies for metallic nano- and micropatterns using soft lithography: Review." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A29056.
Full textAbstract:
Soft lithographic methods describe a set of printing methods which are widely used for the preparation of structured surfaces. Structured surfaces are essential components in the field of (opto-)electronic devices such as organic light emitting diodes, photovoltaics or organic field effect transistors. In recent years, crucial progress has been achieved in the development of patterned metal coatings for these applications. This review focusses on new strategies for soft lithographical printing of metal structures emphasizing the subtle interplay of printing techniques, metal precursor chemistry, and surface functionalization strategies.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Sudarsan, Arjun Penubolu. "Fabrication of masters for microfluidic devices using conventional printed circuit technology." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969/146.
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Sällström, Pär. "Fabrication of a soft magnetic toroidal core using electrodeposition and UV-lithography." Thesis, Uppsala University, Solid State Physics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-100380.
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Schwaab, Daniel. "Surface patterning by means of soft lithography for molecular and bio-electronics." Jülich : Forschungszentrum, Zentralbibliothek, 2007. http://d-nb.info/987853880/34.
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Chen, Jing. "Soft UV nanoimprint lithography : a versatile technique for the fabrication of plasmonic biosensors." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00591992.
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During the last decade, surface plasmon resonance (SPR) has become widely used to characterize a biological surface and to characterize binding events in the fields of chemistry and biochemistry. Research in this field has been favoured by the tremendous growth in nanofabrication methods among which soft lithographies are alternatively emerging. The purpose of this thesis work was to develop soft UV nanoimprint lithography, an emerging flexible technology allowing patterning on large area of subwavelength photonic nanostructures. The main advantages offered by soft UV nanoimprint lithography concern the simple patterning procedure and the low cost of the experimental setup (see state-of-art presented in chapter 1). Chapters 2 and 3 present the fabrication of master stamps, the study of nanoimprinting parameters coupled with the optimization of the etching process in order to get metallic nanostructures with limited pattern defects. The physical mechanisms of the transmission phenomenon exalted by surface plasmons were studied based on arrays of imprinted gold nanoholes (chapter 4). Extraordinary light transmission has been experimentally demonstrated. The geometrical effects on the position transmission peak were systematically analyzed. Proof-of-concept measurements performed in simple fluidic device indicate a response to small changes in refractive index in the surface vicinity. Finally, chapter 5 proposes a novel design for the optical sensor which is based on "nanocavities" exhibiting coupled localized plasmons. This LSPR sensor offers an improvement of one order of magnitude of the Figure of Merit compared to classical LSPR sensors. The resonance properties of these innovative nanocavities have been studied from numerical simulations and discussed based on their geometrical dependence. Since this system has demonstrated higher sensitivity for detection of biomolecules, it is thus fully adapted to study immunochemical binding interactions.
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Perring, Mathew Ian. "Functionalization and patterning of monolayers on silicon(111) and polydicyclopentadiene." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/722.
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The formation of a functional surfaces combines the properties of a substrate and monolayer to produce a new hybrid that can combine aspects of each. Monolayers can be made on many surfaces, and well defined functionalized monolayers were assembled on for silicon(111) and polydicyclopentadiene (PDCPD).
Acid terminated monolayers were assembled on silicon(111) and their functionalization chemistry explored. It was shown that using trifluoroacetic anhydride to generate an intermediate reactive anhydride, the surface could be functionalized with amines. It was further shown that using soft lithography these functionalized surfaces could be patterned.
Mixed monolayers of methyl and olefin terminated surfaces on silicon(111) were used to develop a new soft lithographic technique with polydimethylsiloxane (PDMS). PDMS can be controllably etched using fluoride species. The surface is first activated by the attachment of the Grubbs' 1st generation catalyst. A PDMS microfluidic device is then placed on the surface. By using a cross metathesis reaction, the exposed channel can be pacified. The next step, a fluoride etchant is used to remove PDMS, exposing an unreacted surface. Polymer brushes were then grown by ring opening metathesis polymerization (ROMP) in this region.
Functionalization of the emerging polymer PDCPD was conducted through two different routes. ROMP formed PDCPD has double bonds that can be functionalized. In the first process, the double bonds were reacted with bromine. This is a rapid reaction and proceeds to a significant depth in the material. Bromines can then be displaced with amines in a substitution reaction. This was demonstrated with a fluorinated amine that when examined by XPS were shown to be present only at the surface, further more we were able to pattern this surface too. Secondly, a process using epoxides was developed. The epoxidation reaction could not be quantified, but formation in the second step of an amine functionalized surfaces was observed by XPS. Further reaction of surface hydroxyls was also observed. This was also used to grow polyethylimine from the surface to sufficient thickness that it became observable by infrared spectroscopy.
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Supreeti, Shraddha [Verfasser], Stefan [Akademischer Betreuer] Sinzinger, Martin [Akademischer Betreuer] Hoffmann, and Steffen [Akademischer Betreuer] Strehle. "Soft nanoimprint lithography on curved surfaces / Shraddha Supreeti ; Stefan Sinzinger, Martin Hoffmann, Steffen Strehle." Ilmenau : TU Ilmenau, 2021. http://d-nb.info/1239051182/34.
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Flores, Angel Steve. "Array Waveguide Evanescent Coupler for Card-to-Backplane Optical Interconnections." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/269.
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Recent advances in computing technology have highlighted deficiencies with electrical interconnections at the motherboard and card-to-backplane levels. The CPU speeds of computing systems are drastically increasing with on-chip local clock speeds expected to approach 6 GHz by 2010. Yet, card-to-backplane communication speeds have been unable to maintain the same pace. At speeds beyond a few gigahertz the implementation of electronic interconnects gets increasingly complex, thus, alternative optical interconnection techniques are being extensively researched to relieve the expected CPU to data bus bottleneck. Despite the advantages afforded by optical interconnects there are still demands for improved packaging, enhanced signal tapping, and reduced cost expenditures. In this dissertation, we present a novel array waveguide evanescent coupling (AWEC) technology for card-to-backplane applications. The interconnection scheme is based on waveguide directional coupling between a backplane waveguide and a flexible waveguide connected to the access card or daughter board. To gain access to the shared bus media, coupling of evanescent waves is exploited to tap optical signals from the backplane waveguide to the corresponding card waveguide. The approach results in the elimination of micro-mirror out of plane deflectors and local waveguide termination obstacles present in other reported optical interconnect schemes. Most importantly, the AWEC method can yield efficient multi-drop bus architectures, not possible through free-space, fiber, or traditional guided wave approaches, that only achieve point-to-point topologies. The AWEC concept for optical interconnection was introduced through coupled mode theory, numerical simulations and BeamPROP aided CAD models. Subsequent experimental waveguide analysis was performed and shown to reasonably agree with the simulation results. Likewise, a high-resolution, cost-effective, and rapid prototyping approach for AWEC fabrication has been formulated. Significantly, when compared to other soft lithographic methods, the novel vacuum assisted microfluidic (VAM) technique results in improved waveguide structures, polymer background residue elimination and lower propagation losses. Moreover, experimental results show that our evanescent coupling approach facilitates high-speed coupling between card and backplane waveguides at speeds of 10 Gbps per channel; currently limited only by our testing electronics. In addition, satisfactory eye diagram performance comparable to that of a conventional fiber link, was also observed for the AWEC, alluding to possible aggregate speeds of 100 Gbps. Similarly, we implemented an elementary AWEC shared bus architecture and demonstrate a microprocessor-to-memory interconnect prototype through the proposed AWEC link. Notably, we expect that the AWEC scheme will be significant for high-speed optical interconnects in advanced computing systems.
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Baig, Sarfaraz Niaz Ali. "Soft Lithographic Fabrication of Micro Optics and Integrated Photonic Components." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_theses/179.
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Optical waveguides, quantum dot emitters, and flat top beam shapers were designed and fabricated by two soft lithographic techniques; micro transfer molding (microTM) and vacuum assisted microfluidics (VAM). Optical waveguides were fabricated through a microTM technique that utilizes a poly dimethylsiloxane (PDMS) stamp. Generation of the flexible stamp required development of a channel waveguide pattern mask, defined by maskless lithography, and followed by construction of a three dimensional channel waveguide master, acquired through contact lithography on a glass substrate coated with SU-8 photoresist. Creation of a positive imprint replicating mold was accomplished through prepolymer PDMS solution settling and curing around the master. Waveguide fabrication was achieved through PDMS conformal contact on, and subsequent curing of, ultraviolet (UV) polymer resins on a silicon substrate. A slight modification of the microTM PDMS stamp, whereby inlet and outlet tunnels were incorporated, resulted in a novel VAM structure and correspondingly waveguides. Waveguide propagation losses were determined to be 1.14 dB/cm and 0.68 dB/cm for the microTM and VAM fabricated waveguides, respectively. A lithographic approach employing quantum dots doped in SU-8 photoresist has led to the realization of a new quantum dot emitter. Uniform coating of a doped material on a silver coated substrate was followed by contact mask lithography. Evaporation of a thin silver layer, upon development of the resultant quantum dot doped channel waveguide structure, facilitates confined emission. Successful edge emitting was demonstrated with blue laser pumping. The lithographic fabrication of such quantum dot emitter is successfully replaced by soft lithographic VAM technique. A flat top beam shaper, whose profile was developed on cured UV polymer resins, was fabricated by microTM technique. The master used for the development of the PDMS stamp was produced through an iterative wet etching process capable of achieving etching depths as small as a few nanometers. Comparisons between the reference wet etched beam shaper and the microTM based beam shaper produced near identical output flat top beams from incident Gaussian beams. Through this research work, successful soft lithographic fabrication of optical waveguides, quantum dot emitters, and flat top beam shapers were demonstrated. The vast potential exhibited by these and other related technologies show great promise for cost-effective mass production of various micro optics and integrated photonic components.
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Hwang, Pey-Hua B. (Pey-Hua Betty) 1982. "The use of soft lithography to reproduce snail-like movement by creating pressure gradients in thin films." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32806.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 18-20).
By imitating nature, man finds ways to expand his capacities. To achieve this aim, he often takes natures designs, simplifies them to their most basic principles and then works in a retrograde fashion to add back the complexity originally stripped away to make the first discoveries. This thesis is based on previous work done on modeling snail movement on a macroscopic scale using a motor driven wave propagation machine. This project scaled down the mechanism to a size more commonly found in nature. This downscaling required a new method for producing waves. Peristaltic pumping achieved through the use of soft-lithography and pneumatics was the method chosen. This combination of ideas proved challenging for several reasons. First, the pumping method had previously only been used with one channel per pneumatic input, whereas the snail required each input to feed a multitude of branching channels creating a more complicated fluid dynamics problem. Second, the snail waves were downscaled from a continuous sinusoid to the three phase stepping mechanism of the peristaltic pump. Each three-phase cycle was considered equivalent to one wavelength. Thus, after creating a design that could move, the ratio between the traveling wavelength speed and subsequent net movement were compared to the aforementioned mathematical model. The model's ratio was 0.56 net/wave velocity. The actual ratio was .05 net/wave velocity. The difference by an order of magnitude could be attributed to the discontinuity of the pumping mechanism as opposed to the continuous nature of an actual traveling wave.
by Pey-Hua B. Hwang.
S.B.
21
Yang, Sheng-Chieh, Ji-Ling Hou, Andreas Finn, Amit Kumar, Yang Ge, and Wolf-Joachim Fischer. "Synthesis of multifunctional plasmonic nanopillar array using soft thermal nanoimprint lithography for highly sensitive refractive index sensing." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36330.
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A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated.
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Guan, Jingjiao. "Microfabricated particulate devices for drug delivery." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118247862.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxiii, 163 p.; also includes graphics. Includes bibliographical references (p. 118-123). Available online via OhioLINK's ETD Center
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Overbuschmann, Johannes [Verfasser]. "Fabrication of Fresnel Zone Plates for Soft X-Ray and EUV Microscopy by Ion Beam Lithography / Johannes Overbuschmann." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/107728926X/34.
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DiBartolomeo, Franklin. "HIGH SPEED CONTINUOUS THERMAL CURING MICROFABRICATION SYSTEM." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/105.
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Rapid creation of devices with microscale features is a vital step in the commercialization of a wide variety of technologies, such as microfluidics, fuel cells and self-healing materials. The current standard for creating many of these microstructured devices utilizes the inexpensive, flexible material poly-dimethylsiloxane (PDMS) to replicate microstructured molds. This process is inexpensive and fast for small batches of devices, but lacks scalability and the ability to produce large surface-area materials. The novel fabrication process presented in this paper uses a cylindrical mold with microscale surface patterns to cure liquid PDMS prepolymer into continuous microstructured films. Results show that this process can create continuous sheets of micropatterned devices at a rate of 1.9 in2/sec (~1200 mm2/sec), almost an order of magnitude faster than soft lithography, while still retaining submicron patterning accuracy.
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Kumar, Girish. "Cell Engineering: Regulating Cell Behaviors Using Micropatterned Biomaterials." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1225816129.
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Schwaab, Daniel [Verfasser]. "Surface patterning by means of soft lithography for molecular and bio-electronics / vorgelegt von Daniel Christian Johannes Wendelin Schwaab." Jülich : Forschungszentrum, Zentralbibliothek, 2007. http://d-nb.info/1001759729/34.
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Filipponi, Luisa, and n/a. "New micropatterning techniques for the spatial addressable immobilization of proteins." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20060905.113858.
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Bio-microdevices are miniaturised devices based on biologically derived components
(e.g., DNA, proteins, and cells) combined or integrated with microfabricated substrates.
These devices are of interest for numerous applications, ranging from drug discovery, to
environmental monitoring, to tissue engineering. Before a bio-microdevice can be fully
developed, specific fabrication issues need to be addressed. One of the most important
is the spatial immobilization of selected biomolecules in specific micro-areas of the
device. Among the biomolecules of interest, the controlled immobilization of proteins to
surfaces is particularly challenging due to the complexity of these macromolecules and
their tendency to lose bioactivity during the immobilization step. The present Thesis
reports on three novel micropatterning techniques for the spatial immobilization of
proteins with bioactivity retention and improved read-out of the resulting micropatterns.
The technologies developed are based on three different micropatterning approaches,
namely 1) direct-writing UV laser microablation (proLAB), 2) a novel microcontact
printing method (�CPTA) and 3) a replica molding method combined with bead selfassembly
(BeadMicroArray). The first two technologies, proLAB and �CPTA, are an
implementation of existing techniques (laser ablation and �CP, respectively), whereas
the third, i.e., the BeadMicroArray, is a totally new technique and type of patterning
platform.
'ProLAB' is a technology that uses a micro-dissection tool equipped with a UV laser
(the LaserScissors�) for ablating a substrate made of a layer of ablatable material, gold,
deposited over a thin polymer layer. The latter layer is transparent to the laser but
favours protein adsorption. In the present work microchannels were chosen as the
structure of interest with the aim of arranging them in 'bar-codes', so to create an
'information-addressable' microarray. This platform was fabricated and its application
to specific antigen binding demonstrated.
The second technique that was developed is a microstamping method which exploits the
instability of a high-aspect ratio rubber stamp fabricated via soft-lithography. The
technique is denominated microcontact printing trapping air (�CPTA) since the collapsing of a rubber stamp made of an array of micro-pillars over a plane glass surface
resulted in the formation of a large air gap around the entire array. The method can be
successfully employed for printing micro-arrays of proteins, maintaining biological
activity. The technique was compared with robotic spotting and found that microarrays
obtained with the �CPTA method were more homogeneous and had a higher signal-tonoise
ratio.
The third technique developed, the BeadMicroArray, introduces a totally new platform
for the spatial addressable immobilization of proteins. It combines replica molding with
microbead self-assembling, resulting in a platform where diagnostic beads are entrapped
at the tip of micropillars arranged in a microarray format. The fabrication of the
BeadMicroArray involves depositing functional microbeads in an array of V-shaped
wells using spin coating. The deposition is totally random, and conditions were
optimised to fill about half the array during spin coating. After replica molding, the
resulting polymer mold contains pyramid-shaped posts with beads entrapped at the very
tip of the post. Thanks to the fabrication mode involved, every BeadMicroArray
fabricated contains a unique geometric code, therefore assigning a specific code to each
microarray. In the present work it was demonstrated that the functionality of the beads
after replica molding remains intact, and that proteins can be selectively immobilized on
the beads, for instance via biorecognition. The platform showed a remarkable level of
selectively which, together with an efficient blocking towards protein non-specific
adsorption, lead to a read-out characterized by a very good signal-to-noise. Also, after
recognition, a code was clearly visible, therefore showing the encoding capacity of this
unique microarray.
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Lopez, Marcano Ana Graciela. "Surface Modification of Multimaterial Multifunctional Fibers Enabling Biosensing Applications." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/96145.
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During the last decades, the continuing need for faster and smaller sensors has indeed triggered the rapid growth of more sophisticated technologies. This has led to the development of new optical-based sensors, able to detect and measure different phenomena using light. Furthermore, material processing technologies and micro fabrication methods have exponentially advanced, allowing engineers and scientists to develop new and more complex sensors on optical fibers platforms; specifically attractive for life science and biomedical research. All these substantial developments have brought biosensors to a point where multifunctionality is needed, this has led to envision the "Lab-on-Fiber" concept. Which promotes the integration of different sensing components into a single platform, an optical fiber.
In this work, an integrated system with non-conventional polymer optical fibers and their further surface modification has been developed. With these different approaches, electrodes, hollow channels and plasmonic nanostructures can be incorporated into a single optical fiber-based sensor, allowing for both electrical and optical sensing with the capabilities of tuning and signal enhancement thanks to the metallic nanostructures. Different fiber substrates can be designed and modified in order to satisfy multiple requirements for a wide variety of applications.MS
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Kim, Eun Jung. "Surface Microtopography Modulation of Biomaterials for Bone Tissue Engineering Applications." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1273557062.
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Quintero, Pinzón Carlos Mario. "Luminescent spin crossover nanomaterials : physical properties and applications." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1899/.
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L'objectif principal de cette thèse est de fournir un nouveau protocole qui permet la détection de la transition de spin (TS) dans un nano-objet unique. Dans ce but, nous proposons d'utiliser la luminescence comme sonde très sensible qui peut être employée à des échelles où d'autres méthodes conventionnelles ne sont plus efficaces. Nous avons cherché à développer des nano-matériaux à TS avec des propriétés de luminescence dans le but d'isoler ces objets et ensuite sonder leurs propriétés via la détection luminescente. Sur la base de techniques de lithographie douce, plusieurs méthodes allant de l'assemblage aléatoire jusqu'à l'assemblage capillaire dirigé de nanoparticules à TS et également la synthèse in situ d'objets isolés luminescents à TS (ca. 150 nm) ont été explorées. Dans le même temps, leur étude en microscopie de fluorescence est présentée et les défis expérimentaux que cette tâche a imposée sont discutés. En outre, l'application potentielle de ces matériaux hybrides en microthermométrie est étudiée. Comme preuve de concept, des films minces de systèmes luminescents à TS ont été déposés sus des micro / nanofils chauffés par effet Joule afin de cartographier leur températureThe main objective of this thesis is to provide a new protocol that permits the detection of the spin crossover (SCO) phenomenon in a single nano-object. To accomplish this, we propose luminescence as a highly sensitive technique that may be employed at scales where other conventional methods are no longer effective. We aimed to develop SCO nano-materials with luminescence properties in order to isolate these objects, address them and then probe their properties via luminescent detection. Methods ranging from random to directed microcappilary assembly of SCO nanoparticles and also in situ synthesis of isolated luminescent SCO objects (ca. 150 nm) based on soft lithographic techniques were explored. At the same time, their investigation in fluorescence microscopy is shown and the experimental challenges that this task imposed are discussed. Also, the potential application of these hybrid materials in microthermometry is studied. As a proof of concept, thin films of luminescent SCO systems were employed to obtain thermal cartographies of gold micro - nanowires heated by Joule effect
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Rajabasadi, Fatemeh, Lukas Schwarz, Mariana Medina-Sánchez, and Oliver G. Schmidt. "3D and 4D lithography of untethered microrobots." Elsevier, 2021. https://slub.qucosa.de/id/qucosa%3A75414.
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In the last decades, additive manufacturing (AM), also called three-dimensional (3D) printing, has advanced micro/nano-fabrication technologies, especially in applications like lightweight engineering, optics, energy, and biomedicine. Among these 3D printing technologies, two-photon polymerization (TPP) offers the highest resolution (even at the nanometric scale), reproducibility and the possibility to create monolithically 3D complex structures with a variety of materials (e.g. organic and inorganic, passive and active). Such active materials change their shape upon an applied stimulus or degrade over time at certain conditions making them dynamic and reconfigurable (also called 4D printing). This is particularly interesting in the field of medical microrobotics as complex functions such as gentle interactions with biological samples, adaptability when moving in small capillaries, controlled cargo-release profiles, and protection of the encapsulated cargoes, are required. Here we review the physics, chemistry and engineering principles of TPP, with some innovations that include the use of micromolding and microfluidics, and explain how this fabrication schemes provide the microrobots with additional features and application opportunities. The possibility to create microrobots using smart materials, nano- and biomaterials, for in situ chemical reactions, biofunctionalization, or imaging is also put into perspective. We categorize the microrobots based on their motility mechanisms, function, and architecture, and finally discuss the future directions of this field of research.
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Königsmarková, Kristýna. "Mikrofluidický enzymatický reaktor pro testování léčiv." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401925.
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This master thesis deals with the use of microfluidics for the purpose of microfluidic enzymatic reactor for drug screening. At first it considers the issue from a theoretical point of view – describes microfluidics as a newly developing and promising field of production of microfluidic devices, materials, biomedical applications and advantages and disadvantages of microfluidics overall. Furthermore, it focuses on an area of analytical utilization of enzymes within enzyme reactors. In the first part of the experimental section, conditions for the testing of enzymes of xenobiotics metabolism in the liver were optimized, namely the model of coumarin metabolism via the spectrofluorimetry method. The second part of the experimental work dealt with optimization of the fabrication conditions of microfluidic chips from OSTE (off-stoichiometry Thiol Ene) via the soft lithography method. Subsequently, the functionality of the produced chips was tested. Based on the results of both parts of the experimental work, an evaluation was carried out to assess the suitability of their interconnection for future research – screening of microsomal enzyme activity and model biotransformation of drugs within the channels of the fabricated devices.
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Koucky, Michael Harten. "PIEZOELECTRIC POLYMER MICROSTRUCTURES FOR BIOMEDICAL APPLICATIONS." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1238080858.
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Bello, Carlos A. "Microsphere-aided characterization of stimuli-responsive polymer networks." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002788.
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Zhao, Yue. "Self-Assembled Lipid Tubules: Structures, Mechanical Properties, and Applications." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2204.
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Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules are systematically studied in terms of persistence length, bending rigidity, strain energy, axial and radial elastic moduli, and critical force for collapse. Mechanisms of recovery and surface stiffening are discussed. Due to the high aspect ratio of lipid tubules, the hierarchical assembly of lipid tubules into ordered arrays and desired architectures is critical in developing their applications. Two efficient methods for fabricating ordered arrays of lipid tubules on solid substrates have been developed. Ordered arrays of hybrid silica-lipid tubes are synthesized by tubule array-templated sol-gel reactions. Ordered arrays of optical anisotropic fibers with tunable shapes and refractive indexes are fabricated. This thesis work provides a paradigm for molecularly engineered structures.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr PhD
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Vargová, Alžběta. "Pokročilé membránové systémy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316229.
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The diploma thesis deals with cellular membrane model preparation on microfluidic devices. It summarizes means of microfluidic device fabrication, phospholipid bilayer formation mechanisms, optimization techniques and characterization methods of those systems. It focuses on free-standing planar lipid bilayers which are easily accessible by a number of different characterization methods and at the same time exhibit good stability and variability. The aim of this work is to design and prepare a microfluidic chip on which a planar lipid bilayer can be prepared. It therefore presents microfluidic device prepared by soft lithography of PDMS adapted for model membrane formation by self-assembly of phospholipids at the interface of aqueous and organic phases created by the architecture of the microfluidic device. Formation of the model membrane was visualized by optical microscopy and fluorescence-lifetime imaging microscopy.
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Magnusson, Karin. "DNA chips with conjugated polyelectrolytes as fluorophore in fluorescence amplification mode." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11559.
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The aim of this diploma work is to improve selectivity and sensitivity in DNA-chips by utilizing fluorescence resonance energy transfer (FRET) between conjugated polyelectrolytes (CPEs) and fluorophores.
Leclerc and co-workers have presented successful results from studies of super FRET between fluorophore tagged DNA and a CPE during hybridisation of the double strand. Orwar and co-workers have constructed a DNA-chip using standard photo lithography creating a pattern of the hydrophobic photoresist SU-8 and cholesterol tagged DNA (chol-DNA). This diploma work will combine and modify these two ideas to fabricate a improved DNA-chip.
Immobilizing of DNA onto surface has been done by using soft lithography. Hydrophobic pattern arises from the poly(dimethylsiloxane) (PDMS) stamp. The hydrophobic pattern will attract chol-DNA that is adsorbed to the chip. Different sets of fluorophores are covalently bound to the DNA and adding CPEs to the complex will make FRET occur between CPE and bound fluorophore.
We will here show that the specificity in DNA hybridization by using PDMS patterning was high. FRET clearly occurred, especially with the CPEs as donor to the fluorophore Cy5. The intensity of FRET was higher when the fluorophore and the CPE were conjugated to the same DNA strand. The largest difference in FRET intensity between double stranded and single stranded complexes was observed with the CPE tPOMT. Super FRET has been observed but not yet fully proved. The FRET efficiency was lower with the fluorophore Alexa350 as donor compared to the Cy5/CPE complex. Most of the energy transferred from Alexa350 was extinguished by quenching.
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Adeyemi, Adefemi Habib. "Microfluidic Devices for the Characterization and Manipulation of Encapsulated Cells in Agarose Microcapsules Using Dielectrophoresis and Electrophoresis." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37102.
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Cell encapsulation is a promising concept in regenerative medicine and stem cell treatment of diseases. Cells encapsulated in hydrogels have shown to yield better therapeutic outcome over cells in suspension. Microfluidic platforms have facilitated the process of cell encapsulation through the controlled mixing of aqueous cell solution and hydrogel with an immiscible liquid to yield a monodispersed population of microcapsules at a high throughput. However, given that the microfluidic process of placing cells in microcapsules is completely random, yielded samples are often riddled with empty microcapsules, raising the need for a post-encapsulation purification step to sort empty microcapsules from cell-laden ones. Sorting of microcapsules can be achieved through several techniques, most desirable of which are electrokinetic such as dielectrophoresis (DEP) and electrophoresis (EP). The advantages of DEP and EP techniques are that they support label-free sorting and yield a high throughput. However to achieve true effective DEP or EP sorting, there is a need to understand how empty microcapsules react to these electrokinetic forces versus occupied microcapsules. This study developed microfluidic devices for characterising the electrokinetic effects on microcapsules using DEP and EP. Results of both characterization techniques showed notable differences in the response of empty microcapsules versus cell-laden ones, reinforcing their potentials for sorting. Furthermore, this study proposed designs for microcapsules sorting devices that leverage EP and DEP.
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Zhang, Yue Zhang. "Phase Separation of Polymer-grafted Nanoparticle blend Thin Films." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494885057468539.
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Cates, Ryan S. "Influence of Crosslink Density on Swelling and Conformation of Surface-Constrained Poly(N-Isopropylacrylamide) Hydrogels." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1592.
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A stimuli-responsive microgel is a three-dimensional polymer network that is able to absorb and expel a solvent (commonly water). These materials are unique in the fact that their sponge-like behavior can be actuated by environmental cues, like temperature, ion concentration, pH, and light. Because of the dynamic properties of these materials they have found applications in drug-delivery systems, micro-assays, selective filtration, artificial muscle, and non-fouling surfaces. The most well-known stimuli-responsive polymer is Poly(N-isopropylacrylamide) or PNIPAAm and it experiences a switchable swelling or deswelling over a critical temperature ( Tc=~32°C). Below the critical temperature, the gel begins mixing with the surrounding solvent and swells; above this temperature, the opposite is true. The unconstrained hydrogel will continue to swell in all directions until equilibrium is established between its propensity for mixing with the surrounding solvent and the elastic restoring forces of the gel matrix. The strength of the elastic restoring forces is dependent on the interconnectedness of the polymer network and is therefore a function of crosslink density. An increase in crosslink density results in a decreased swelling and vice versa. If the hydrogel is mechanically constrained to a surface, it can experience various wrinkling and buckling conformations upon swelling, as the stresses associated with its confinement are relieved. These conformation characteristics are a strong function of geometry (aspect ratio) and extent of swelling (i.e. crosslink density). In order to capitalize on the utility of this material, it is imperative that its volume transition is well characterized and understood.
Toward this end, pNIPAAm gels have been created with 1x10-7 to 2x10-³ mol/cm³ crosslink density and characterized. This was done by first examining its bulk, unattached swelling ability and then by evaluating its microscale properties as a surfaceconfined monolithe. The latter was achieved through the use of confocal microscopy and copolymerization with a fluorescent monomer. This method allows for a detail analysis of the deformations experienced (bulk-structural bending and surface undulating) and will ultimately lend itself to the correlation between crosslink density and the onset of mechanical phenomena.
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Si, Shuhao [Verfasser], Martin [Akademischer Betreuer] Hoffmann, Stefan [Gutachter] Sinzinger, and Hartmut [Gutachter] Hillmer. "Soft UV nanoimprint lithography : concept, development, and fabrication of nanostructures with tunable feature sizes at constant pitch / Shuhao Si ; Gutachter: Stefan Sinzinger, Hartmut Hillmer ; Betreuer: Martin Hoffmann." Ilmenau : TU Ilmenau, 2018. http://d-nb.info/1178128717/34.
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Bhaswara, Adhitya. "Fabrication of suspended plate MEMS resonator by micro-masonry." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30325/document.
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L'impression par transfert, une technique utilisée pour transférer divers matériaux tels que des molécules d'ADN, de la résine photosensible ou des nanofils semi-conducteurs, s'est dernièrement révélée utile pour la réalisation de structures de silicium statiques sous le nom de micro-maçonnerie. L'étude présentée ici explore le potentiel de la technique de micro-maçonnerie pour la fabrication de résonateurs MEMS. Dans ce but, des microplaques de silicium ont été transférées sur des couches d'oxyde avec cavités intégrées à l'aide de timbres de polymère afin de créer des structures de type plaques suspendues. Le comportement dynamique de ces structures passives a été étudié sous pression atmosphérique et sous vide en utilisant une excitation externe par pastille piézo-électrique mais aussi le bruit thermomécanique. Par la suite, des résonateurs MEMS actifs, à actionnement électrostatique et détection capacitive intégrés, ont été fabriqués en utilisant des étapes supplémentaires de fabrication après impression. Ces dispositifs ont été caractérisés sous pression atmosphérique. Les facteurs de qualité intrinsèques des dispositifs fabriqués ont été évalués à 3000, ce qui est suffisant pour les applications de mesure à pression atmosphérique et en milieu liquide. Nous avons démontré que, puisque l'adhérence entre la plaque et l'oxyde est suffisamment forte pour empêcher une diaphonie mécanique entre les différentes cavités d'une même base, plusieurs résonateurs peuvent être facilement réalisés en une seule étape d'impression. Ce travail de thèse montre que la micro-maçonnerie est une technique simple et efficace pour la réalisation de résonateurs MEMS actifs de type plaque à cavité scelléeLately, transfer printing, a technique that is used to transfer diverse materials such as DNA molecules, photoresist, or semiconductor nanowires, has been proven useful for the fabrication of various static silicon structures under the name micro-masonry. The present study explores the suitability of the micro-masonry technique to fabricate MEMS resonators. To this aim, silicon microplates were transfer-printed by microtip polymer stamps onto dedicated oxide bases with integrated cavities in order to create suspended plate structures. The dynamic behavior of fabricated passive structures was studied under atmospheric pressure and vacuum using both external piezo-actuation and thermomechanical noise. Then, active MEMS resonators with integrated electrostatic actuation and capacitive sensing were fabricated using additional post-processing steps. These devices were fully characterized under atmospheric pressure. The intrinsic Q factor of fabricated devices is in the range of 3000, which is sufficient for practical sensing applications in atmospheric pressure and liquid. We have demonstrated that since the bonding between the plate and the device is rigid enough to prevent mechanical crosstalk between different cavities in the same base, multiple resonators can be conveniently realized in a single printing step. This thesis work shows that micro-masonry is a powerful technique for the simple fabrication of sealed MEMS plate resonators
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Ferraro, Davide. "Microdroplets: fabrication of microdevices for interfacial phenomena studies." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422999.
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When fluids are confined on the length scales of microfluidic channels, typically in the range of tens and hundreds microns, their behavior may results significantly different with respect to the so called “bulk” proprieties. This is mainly due to the fact that the miniaturization is always characterized by a large surface to volume ratio, where the body forces can be normally neglected in favor of the surface forces. Notable example of this kind of systems is observable when two immiscible fluids are mixed to form droplets of emulsions. In the last ten years, the idea to use droplets in microfluidics has been inspired mainly because it allows to further scale down the typical size involved in these systems, bringing to a huge number of applications in chemistry, biology and physics. However, despite a large notoriety, microfluidic systems using droplets are not yet fully understood for the complexity of the interfacial phenomena that are involved. Aim of this thesis is to characterize the droplet systems commonly used in microfluidic devices. In detail, we worked with droplets in both open and closed microfluidic systems, focusing with the problem of their generation, control and manipulation with suitable microdevices, in presence of defects having different geometry and wettability.
Regarding the open microfluidics, in Chapter 3,we first compared the shape of water droplets confined on posts having circular and square cross sections, observing that the pinning of the contact line is strongly influenced by the post shape. In particular, in the case of a circular profile, the contact line is pinned to the whole edge, confirming the Gibbs criteria, while on the square post, the contact line can spill along the vertical walls, because it is sustained by the corners.
Then, in Chapter 4,we moved to investigate the change of morphological configuration from filament to bulge state, typical of liquid droplets confined on posts with rectangular cross section. This effect was already know in literature, but it was not quantify in term of post geometry and volume of the water droplets. Therefore, we realized rectangular posts with different aspect ratio ("l"), between length (L) and width (W). Changing the water volume on the posts, we observed that the morphological transition occurs for all the aspect ratios "l" and that, for "l">16, there is a bistability of the two states at the same volume. Furthermore, we started to investigate the dynamic of the transition, induced by oscillations, founding that, for posts with "l">16, it is possible to induce the transition by the oscillation, without change the volume.
Next, in order to control the droplets motion, in Chapter 5, we studied the different behavior of sliding droplets on homogeneous and on chemically patterned surfaces. To do that we realized surfaces with hydrophilic and hydrophobic stripes by microcontact printing. On these surfaces, droplets show stick-slip motion, which causes the deformation of their shapes and introduces an extra friction imputable to the dissipation of energy at the contact line.
With the aim to study generation and control of droplets in closed microfluidic channels, in Chapter 6, we focused our attention to define a reliable protocol for the production of droplets by T-junctions. Moreover, we investigated the swelling problem, which occurs using organic solvent into PDMS microchannels. We noticed that the swelling deformation is strongly connected with the geometry of the devices, being more evident when the aspect ratio (high to width) of the channel cross section is higher.
Finally, in Chapter 7, we introduced a new method to change the wettability proprieties of thiolen resins, which are commonly used in microfluidics. In particular we worked with NOA, a commercial available resin, which shows a contact angle of 70°. Using chlorosilane chemistry, we changed its wettability to a more hydrophilic and to hydrophobic contact angles, showing that this technique can be used both to open and closed microfluidic devicesQuando i fluidi vengono confinati in canali microfluidici, di dimensioni caratteristiche dell’ordine della decina o centinaia di micron, le loro proprietà possono risultare significativamente diverse da quelle tipicamente osservate negli stessi fluidi, ma nella cosiddetta condizione massiva. Ciò è dovuto principalmente al fatto che la miniaturizzazione di qualsiasi sistema porta a un rapporto superficie/volume grande, in cui tipicamente le forze volumetriche sono trascurabili rispetto a quelle superficiali. Questo effetto si verifica ad esempio quando due fluidi immiscibili vengono mescolati per formare emulsioni di gocce. Negli ultimi dieci anni, l'idea di utilizzare gocce in dispositivi microfluidici si è diffusa soprattutto perché permette di ridurre le tipiche dimensioni coinvolte in questi sistemi, comportando un notevole numero di applicazioni in chimica, in biologia ed in fisica. Tuttavia, nonostante la loro grande notorietà, per la complessità dei fenomeni interfacciali coinvolti, i sistemi microfluidici che utilizzano gocce non sono stati ancora pienamente compresi. Lo scopo di questa tesi è, quindi, quello di caratterizzare i sistemi di gocce comunemente utilizzati in dispositivi microfluidici. In particolare, abbiamo lavorato con gocce confinate sia in sistemi aperti che in sistemi chiusi, focalizzandoci sulla loro produzione, il loro controllo e la loro manipolazione. Per fare ciò abbiamo realizzato vari tipi di micro-dispositivi che presentano diverse caratteristiche geometriche e di bagnabilità. Per quanto riguarda i sistemi aperti, nel Capitolo 3, abbiamo paragonato la forma di gocce d’acqua confinate su strutture aventi sezioni circolari e quadrate, osservando che la condizione di “pinning” della linea di contatto è fortemente influenzata dalla geometria della struttura. In particolare, nel caso del profilo circolare, la linea di contatto è bloccata lungo tutto il bordo della struttura, confermando il criterio di Gibbs, mentre nel caso del profilo quadrato, la linea di contatto può scendere lungo le pareti verticali, perché sostenuta dagli angoli. Nel capitolo 4, siamo passati ad indagare la transizione morfologica tipica di gocce confinate su strutture allungate: da uno stato di “filamento”, dove il liquido è distribuito uniformemente sulla struttura, a un stato “gonfiato”, dove esso forma una protuberanza al centro della struttura stessa. Questo effetto era già noto in letteratura, ma non era mai stato quantificato in termini di geometria della struttura e del volume delle gocce. Abbiamo quindi considerato strutture con profilo rettangolare, aventi diversi rapporti di aspetto "l" (rapporto tra lunghezza (L) e larghezza (W). Aumentando e diminuendo progressivamente il volume dell'acqua sulla superficie delle strutture, abbiamo osservato che la transizione morfologica si verifica per tutti i rapporti di aspetto "l", ma che soltanto per "l">16, vi è una bistabilità dei due stati allo stesso volume. Inoltre, abbiamo iniziato a studiare la transizione sotto l’aspetto dinamico, cercando di indurla mediante delle oscillazioni, osservando che questo è possibile solo per strutture con "l">16. Inoltre, al fine di controllare il movimento delle gocce, nel capitolo 5, abbiamo studiato il loro diverso comportamento di scorrimento su superfici omogenee e strutturate chimicamente. Per fare questo abbiamo realizzato superfici con microstrisce idrofile e idrofobe, mediante la tecnica del “microcontact printing”. Osservando lo scivolamento di gocce d’acqua su queste superfici, abbiamo riscontrato che esse presentano un moto denominato “stick-slip”, che provoca la loro deformazione e introduce un nuovo attrito al sistema goccia-superficie, imputabile alla dissipazione di energia alla linea di contatto. Con lo scopo di studiare la produzione e il controllo di gocce in canali microfluidici chiusi, nel Capitolo 6, abbiamo focalizzato la nostra attenzione per definire un protocollo affidabile per la produzione di gocce mediante giunzioni a T. Inoltre, abbiamo studiato il tipico problema del rigonfiamento del PDMS, che si verifica quando esso si trova a contatto con solventi organici. Confrontando microcanali con diversa sezione, abbiamo notato che le deformazioni dovute al rigonfiamento sono fortemente connesse con la geometria dei dispositivi. In particolare esse risultano più evidenti quando il rapporto di aspetto (altezza/larghezza) della sezione trasversale del canale è maggiore. Infine, nel capitolo 7, abbiamo introdotto un nuovo metodo per modificare le proprietà di bagnabilità di resine tioleniche, che vengono comunemente usate in microfluidica. In particolare abbiamo lavorato con il NOA, una resina disponibile in commercio, che mostra un angolo di contatto statico di 70 °. Utilizzando la chimica tipica dei clorosilani, abbiamo cambiato la bagnabilità della resina, portandola ad angoli di contatto più idrofili ed idrofobi. Inoltre abbiamo anche dimostrato che questa tecnica può essere utilizzata sia con sistemi microfluidici chiusi, sia con sistemi aperti
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Lamperti, Emanuele. "PDMS based microfluidics membrane contactors for CO2 removal applications." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15261/.
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This work proposes a gas-liquid contactor study in microfluidics field, using dense membrane working with a concentration gradient; a microfluidic gas-liquid contactor was developed for CO2 removal and the general idea is to transport CO2 through a polymer dense membrane, followed by its capture by a liquid solvent with chemical absorption. Like recent studies demonstrate, this kind of devices could solve problems related to extracorporeal lung oxygenation (Garofalo, C. Quintavalle, G. Romano, C.M. Croce, 2013) for critical surgical support and critical care medicine, it can work like a real lung because can mimic the architecture of the human vasculature better than the existing technologies. Applications in this fields are related for example to the separation of Xenon from CO2 in anaesthesia. Xe is a very expensive element perfect for anaesthesia, is hemodynamically stable, low soluble in liquid and produces high regional blood flow reducing the risk of hypoxia (Malankowska et al., 2018). The major advantage of using microfluidics devices is that they could be reach a high surface to volume ratio and thanks to miniaturization can be tested reducing the time as well as the production of waste, thus increasing the number of experimental tests can be achieved.
In the present thesis in particular one alveolar design channel based of literature results (Malankowska et al., 2018) was realized with soft lithography and tested in different experimental conditions. In particular, for the present geometry the transport of CO2 through the membrane was monitored, calculating the overall mass transfer coefficient and the molar flow of the gas through the membrane in different operating conditions.
In additions, the production of other two microfluidics device with different channels configurations was attempted by using a 3-D printing technique that allows the generations of complex structures with high surface to volume ratio.
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Vastesson, Alexander. "Micro-Structuring of New Materials Combined with Electronic Polymers for Interfaces with Cells." Thesis, Linköpings universitet, Biomolekylär och Organisk Elektronik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-78766.
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Materials based on novel Off-Stoichiometry Thiol-Ene polymers, abbreviated OSTE, show promising properties as materials forlow cost and scalable manufacturing of micro- and nanosystems such as lab-on-chip devices. The OSTE materials have tunablemechanical properties, offer possibility for low temperature bonding to many surfaces via tunable surface chemistry, and can beused in soft lithography. Unlike the commonly used elastomer poly(dimethylsiloxane), PDMS, the OSTE materials have lowpermeability for gasses, are resistant to common solvents and can be more permanently surface modified.In this master’s thesis project, the OSTE materials have been evaluated with focus on compatibility with cells, possibility fornanostructuring using soft lithography and the use of OSTE as a flexible support for conducting polymers.Results from cell seeding studies with HEP G2 cells suggest that cells can proliferate on a low thiol off-stoichiometry OSTEmaterial for at least five days. The biocompatibility for this type of OSTE material may be similar to poly(styrene). However, highlevels of free thiol monomers in the material decrease cell viability considerably.By using soft lithography techniques it is possible to fabricate OSTE nanochannels with at least the dimensions of 400 nm x 15nm. Combined with the advantages of using the OSTE materials, such as low temperature bonding and possibility for stablesurface modifications, a candidate construction material for future development of systems for DNA analysis is at hand.OSTE can serve as a flexible support for an adsorbed film of a conducting polymer with the possibility for future applicationssuch as electronic interfaces in microsystems. In this project, a film of PEDOT:PSS with the electrical resistance of ~5 kΩ wascreated by adsorption to an flexible OSTE material. Furthermore, results suggest that it is possible to further optimize theconductivity and water resistance of PEDOT:PSS films on OSTE.
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Varagnolo, Silvia. "Study and control of drop motion on inclined surfaces." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424346.
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This PhD thesis collects different experimental studies in the field of wetting phenomena and open microfluidics, which analyze the behavior of liquid drops on free open surfaces. The main goal of such a research is to develop smart coatings featuring useful wetting properties (e. g. water repellent, antifogging and antireflection materials) or techniques aimed at manipulating droplets for chemical or biological applications.
In particular this work considers both passive and active methods to control the statics and dynamics of drops deposited on an inclined plane and consequently subject to an external constant force, the gravity force. Among the passive techniques based on surface patterning, we investigated the adhesion properties of multiscale nano- and microstructured hairy surfaces made of polymers having different elasticity. Also, chemically patterned surfaces, formed by hydrophilic and hydrophobic regions of different shape (stripes, squares and triangles), have found to be an effective tool to passively tune drop sliding velocity. Chemically heterogeneous surfaces can affect not only sliding velocity, but also drop trajectory. To further investigate the deviation of a drop by means of a chemical pattern we considered a sample formed by only two regions featuring different wettability, i. e. a chemical step characterized by a linear interface. On the other hand, an active manipulation implies the application of an external field, as, for instance, electric, magnetic or acoustic. As active technique we considered asymmetric vibrations of the substrate, able to induce interesting and surprising dynamical behaviors: small droplets placed on a vertically oscillating inclined plane can stay pinned, slide down, but even climb up the surface against gravity.
Even if the vast majority of our experiments involves ordinary liquids, in particular water and aqueous solutions, our research about sliding includes also the study of complex fluids, more precisely polymer solutions, exhibiting rheological properties (e. g. viscosity and elastic behaviors) depending on the applied stress.Questa tesi raccoglie una serie di lavori sperimentali che si collocano nell'ambito della microfluidica aperta e dei fenomeni interfacciali di bagnamento e fondamentalmente studiano il comportamento di gocce depositate su superfici. Lo scopo principale di questo tipo di ricerca è lo sviluppo di superfici che presentino proprietà particolari, come ad esempio superfici autopulenti, antinebbia o antiriflesso, o di tecniche di manipolazione di gocce finalizzate ad applicazioni nel campo biologico o chimico. In particolare questo lavoro considera metodi attivi e passivi atti a controllare sia la statica che la dinamica di gocce poste su superfici inclinate e quindi soggette ad una forza esterna costante, la forza di gravità. Tra le tecniche passive basate sull'utilizzo di superfici strutturate sono state studiate le proprietà di adesione di superfici polimeriche geometricamente nano/microstrutturate. Inoltre, campioni chimicamente eterogenei formati da regioni idrofiliche e idrofobiche di geometria diversa (strisce, quadrati, triangoli) si sono dimostrati uno strumento efficace per la regolazione passiva della velocità di scivolamento delle gocce. Questo tipo di superfici può influire non solo sulla velocità, ma anche sulla traiettoria della goccia. Per analizzare più nel dettaglio come si può deviare una goccia è stato studiato lo scivolamento su una superficie formata da due sole regioni di diversa bagnabilità, cioè una sorta di gradino chimico. D'altra parte, un controllo attivo implica l'applicazione di un campo esterno, ad esempio elettrico, magnetico o acustico. Come tecnica attiva in questa tesi è stata considerata l'applicazione di vibrazioni asimmetriche del substrato, capaci di indurre comportamenti dinamici interessanti e sorprendenti: piccole goccioline poste su un piano inclinato che oscilla verticalmente possono non solo rimanere ferme o scivolare, ma addirittura risalire contro la forza di gravità. Anche se la maggioranza di questi esperimenti riguarda liquidi ordinari, in particolare acqua e soluzioni acquose, una parte della ricerca è stata dedicata allo scivolamento di fluidi complessi, più precisamente soluzioni polimeriche, caratterizzati da proprietà reologiche (ad esempio viscosità o effetti elastici) che dipendono dallo sforzo applicato sul fluido.
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Schwaab, Daniel [Verfasser]. "Surface patterning by means of soft lithography for molecular and bio-electronics / Forschungszentrum Jülich in der Helmholtz-Gemeinschaft, Institute of Bio- and Nanosystems (IBN), Bioelectronics (IBN-2). Daniel Schwaab." Jülich : Forschungszentrum, Zentralbibliothek, 2007. http://d-nb.info/987853880/34.
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Riordon, Jason A. "Developing Microfluidic Volume Sensors for Cell Sorting and Cell Growth Monitoring." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30955.
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Microfluidics has seen an explosion in growth in the past few years, providing researchers with new and exciting lab-on-chip platforms with which to perform a wide variety of biological and biochemical experiments. In this work, a volume quantification tool is developed, demonstrating the ability to measure the volume of individual cells at high resolution and while enabling microfluidic sample manipulations. Care is taken to maximise measurement sensitivity, range and accuracy, though novel use of buoyancy and dynamically tunable microchannels. This first demonstration of a microfluidic tunable volume sensor meant volume sensing over a much wider range, enabling the detection of ̴ 1 µm3 E.coli that would otherwise go undetected. Software was written that enables pressure-driven flow control on the scale of individual cells, which is used to great success in (a) sorting cells based on size measurement and (b) monitoring the growth of cells. While there are a number of macroscopic techniques capable of sorting cells, microscopic lab-on-chip equivalents have only recently started to emerge. In this work, a label-free, volume sensor operating at high resolution is used in conjunction with pressure-driven flow control to actively extract particle/cell subpopulations. Next, a microfluidic growth monitoring device is demonstrated, whereby a cell is flowed back and forth through a volume sensor. The integration of sieve valves allows cell media to be quickly exchanged. The combination of dynamic trapping and rapid media exchange is an important technological contribution to the field, one that opens the door to studies focusing on cell volumetric response to drugs and environmental stimuli. This technology was designed and fabricated in-house using soft lithography techniques readily available in most biotechnology labs. The main thesis body contains four scientific articles that detail this work (Chapters 2-5), all published in peer-reviewed scientific journals. These are preceded by an introductory chapter which provides an overview to the theory underlying this work, in particular the non-intuitive physics at the microscale and the Coulter principle.
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Sarkar, Saheli. "Combined Experimental and Mathematical Approach for Development of a Microfabrication-Based Model to Investigate Cell-Cell Interaction during Migration." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1301420667.
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Zhang, Shuyu. "Directional organic light-emitting diodes using photonic microstructure." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6356.
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This thesis describes investigations into the optical and device design of organic light-emitting diodes (OLEDs) with the aim of exploring the factors controlling the spatial emission pattern of OLEDs and developing novel OLEDs with directional emission by applying wavelength-scale photonic microstructure. The development of directional OLEDs was broken down into two steps: the development of efficient narrow linewidth OLEDs and the integration of wavelength-scale photonic microstructures into narrow linewidth OLEDs. The narrow linewidth OLEDs were developed using europium (Eu) complexes. The electrical optimisation of solution-processed Eu-based OLEDs using commercially available materials was investigated. The optimised Eu-based OLEDs gave an external quantum efficiency of 4.3% at a display brightness of 100 cd/m². To our knowledge, this is the highest efficiency reported for solution-processed Eu-based OLED devices, and the efficiency roll-off has been reduced compared with other reported references. Photonic microstructures were applied to develop directional OLEDs using the efficient Eu-based OLEDs. Two contrasting strategies were used. One was to embed photonic microstructures into Eu-based OLEDs, the other was to couple photonic microstructures externally onto the devices. The microstructured devices developed by the former strategy boosted the emitted power in desired angles in both s- and p-polarisations and doubled the fraction of emission in an angle range of 4⁰. The devices developed by the external coupling strategy achieved even higher directionality and the out-coupled emission was a confined beam with easy control of beam steering. Around 90% of the emitted power was confined in an angular range of 20⁰ in the detection plane. The optical properties can be optimised independently without compromising the electrical properties of devices, which gives major advantages in terms of effectiveness and versatility. Optical models were also developed to investigate the out-coupling mechanism of various trapped modes and develop OLEDs with stronger directionality.