Dissertations / Theses: 'PDMS-based'

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Vila, i. Planas Jordi. "PDMS-based opto uidic systems." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/284136.

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Al llarg de la tesis, diversos elements òptics i fluidics s’han aconseguit integrar en sistemes optofluidics completament funcionals. La integració d’aquests s’ha realitzat fent servir la tècnica de soft-lithography i el PDMS com material constituent per garantir el baix cost i la felxibilitat dels sistemes LOC. Els elements desenvolupats s’han caracteritzat individualment i els LOCs s’han testat i caracteritzat com a eines per a l’analisis bioquímic per sobrepassar problemes actuals. Es resalta el diseny, optimització, fabricació i caracterització dels elements optics individuals. Els elements òptics es divideixen en dos grups, passius i actius. Els passius són aquells que no necessiten cap font d’energia externa per funcionar. Primerament, els més simples, i.e., lents col·limadores i estructures d’autoalineament, necessàries per crear estructures més complexes. Aquests elements s’havien publicat prèviament, però l’optimització feta així com el desenvolupament d’estructures auxiliars tot fabricat utilitzant la mateixa tecnologia i sense augmentar el passos necessaris doten els elements d’una gran robustesa i ens permeten crear estructures més complexes. Miralls d’aire i lents s’han combinat per formar divisors de feix. El principal problema dels divisors de feix és la desviació entre la intensitat als canals de sortida. Aquest problema indica que pot haver-hi un desalineament en la posició de les fibres, les lents col·limadores o els miralls d’aire. Utilitzant variacions de la tecnologia MIMIC un nou element òptic passiu s’ha dissenyat, fabricat i caracteritzat. PDMS dopat amb 3 pigments diferents s’ha utilitzat per crear filtres amb stopbands al llarg de l’espectr visible. Finalment, un element actiu, un emissor integrat, s’ha redissenyat utilitzant software de simulació òptica. Els resultats suggereixen que hi ha volums morts dins l’estructura i per tant, es proposa una reducció de tamany i un canvi de forma. La integració de molts d’aquests elements més alguns de fluídics es detalla. Primerament, connectors entre mòduls es dissenyen i testegen. L’emissor redissenyat es manufactura i caracteritza. El seu comportament concorda amb les simulacions i suggereig que encara es podria rediu més el volum. Tots els mòduls es fabriquen de dues repliques de PDMS. Cada mòdul és elàstic i pot ser connectat amb els altres en qualsevol substrat, les connexions entre mòduls no són permanents i es poden fer i desfer sense cap coneixement previ sobre microfluidica o LOC. Per tant, el sistema modular té prou flexibilitat per crear LOC a la carta a investigadors sense els coneixements necessaris per crear-los des de zero. Per provar-ho diversos mòduls s’han unit i utilitzat per determinar la concentració de Cristall violeta. Les lents col·limadores ja reportades s’han integrat monolíticament en un generador de microgotes monodisperses. S’han proposat dues configuracions òptiques per possibilitar les mesures en fluorescència i absorbància de les microgotes. Ambdues s’han testejat i comparat amb el set up previ demostrant resultats equiparables. A més, les configuracions proposades poden detectar gotes no etiquetades, una fet que no era possible amb el set up previ, amb la mateixa precisió i fiabilitat. Malgrat tot, degut a les nostres lents col·limadores i els equips de lectura, la velocitat de detecció de gotes està limitada a 160 gotes/s. Finalment, la determinació del medi interior de la gota s’ha demostrat experimentalment per primer cop en un sistema optofluidic. Finalment, s’ha contruit un FCOR comapcte i integrables utilitzant tècniques de soft-lithography i utilitzant únicament PDMS i aire per assegurar baix cost i robustesa. S’han utilitzat phaseguides per crear un FCOR amb un mirall mòbil sense parts mòbils. Aquest LOC és repetitiu i té una llarga durabilitat (no s’aprecia degradació o baixada de rendiment en tot l’espectre visible durant setmanes). Per últim, FCOR s’ha integrat amb dos LOC reportats amb anterioritat per fer mesures en paral·lel de glucosa i lactat amb una única font de llum. Un cop calibrat el sistema, el FCOR permet la mesura de glucosa i lactat amb coherència amb resultats previs. Validant, per tant, el FCOR per anàlisis en paral·lel.
Along the thesis, several optics and fluidics elements are succesfully integrated in fully functional optouidic systems. Integration of these elements using soft-lithography fabrication technique and PDMS as constituent material ensures low-cost, disposable and flexible LOCs systems. Developed elements are individually characterized and LOCs are characterized and tested as (bio)chemical tools to overcome unsolved issues of the present state of the art in LOC applications. Design, optimization, fabrication and characterization of individual optical elements is outlined. Optical elements have been divided in two categories, passive and active elements. Passive elements are those which do not require an energy source to work. Firstly, the most simple elements, i.e., collimation lenses and self-alignment structures, necessary to create more complex structures. Such elements usually were published previously, but our development and optimization of elements as well as auxiliary structures, e.g., stoppers and self-alignment channels, built using a single technology with no increase of fabrication steps, provide a robust approach to create more complex structures. Air mirrors and lenses are combined to create beam splitters. The major issue of the BS is the deviation of output power between channels. This result suggests that some misalignment in the fibre position, the lens collimation or the waveguide geometry has occurred. Using developed MIMIC variations a new passive optical element are designed, fabricated and characterized. PDMS doped with three different pigments are used to create filters with stopbands along the whole visible spectrum. Finally, an active element, an integrated emitter, is redesigned using TracePro simulation software. Simulation results suggest there are dead volumes inside the emitter chamber. Then, size reduction and shape change is proposed. Integration of many of the these optical plus some fluidic elements is explained. Firstly, different connectors between modules are designed and tested. The previously redesigned integrated emitter are manufactured and characterized. Its behaviour matches with simulations results and suggest a further size reduction is not only possible but also recommendable. All the modules are fabricated from two PDMS replicas. Each module is elastic and can be assembled with other modules in any substrate, modules connections are not permanent and can be plug and unplug with no previous knowledge in microfluidics or LOC. Hence, presented modular system have enough flexibility to create LOC on demand to researchers without the background required to design and manufacture LOC systems from scratch. In order to prove it several modules are tested together in a crystal violet concentration determination. Previously reported collimation lenses are monolithically integrated in a monodisperse microdroplets generator. Two different optical configurations have been proposed in order to make possible fluorescence and absorbance measurement of droplets. Both are tested and compared to previous set up with equivalent results. In addition, proposed configurations can detect unlabelled droplets, a feature that was not possible with the previous set up, with the same precision and reliability. However, due to our collimation lenses and readout equipment, the droplet generation rate is limited to 160 drops/s. Finally, screening of droplet inner medium is experimentally proved for first time in optofluidic system. Afterwards, a compact and integrable fluidically controlled optical router (FCOR) is build using soft-lithographic techniques and made entirely of PDMS and air ensuring low-cost and robustness. Phaseguides, has been exploited to create a FCOR with a movable mirror without mobile parts. The LOC is repetitive, and has a good durability (non appreciable degradation or performance deterioration for weeks, in the whole visible spectrum). Finally, FCOR is integrated in a previously reported LOC performing parallel measurements of glucose and lactate with a single light source. After setup calibration, the FCOR allows parallel measurement of glucose and lactate showing good agreement with previous results. Validating then, the FCOR for parallel analysis.

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Ozkan, Ekrem. "PDMS-based antimicrobial surfaces for healthcare applications." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10044839/.

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This thesis describes two types of approaches for reducing the incidence of hospital-acquired infections (HAIs), which are chemical approaches that inactivate bacteria that adhere to the surface i.e. bactericidal activity and physical approaches that inhibit initial bacterial attachment to the surface i.e. anti-biofouling activity. Specifically, the antimicrobial polydimethylsiloxane (PDMS)-based systems detailed in this thesis are: (i) photosensitizer, crystal violet (CV),-coated PDMS for both medical device and hospital touch surface applications, (ii) crystal violet-coated, zinc oxide nanoparticle-encapsulated PDMS for hospital touch surface applications, (iii) superhydrophobic antibacterial copper coated PDMS films via aerosol assisted chemical vapour deposition (AACVD) for hospital touch surface applications and (iv) slippery copper-coated PDMS films to prevent biofilm formation on medical devices. The materials were characterized using techniques including: X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis absorbance spectroscopy, water-contact angle measurement and microbiology tests. Functional testing indicated that CV-coated samples were suitable for targeted applications and showed potent light-activated antimicrobial activity when tested against model Gram-positive bacteria, Staphylococcus aureus, and Gram-negative bacteria, Escherichia coli, associated with hospital-acquired infections, with > 4 log reduction in viable bacterial numbers observed. On the other hand, CVD modified samples demonstrated highly significant antibacterial activity against both bacteria (> 4 log reduction in bacterial numbers) under dark conditions. Moreover, they resulted in a significant reduction in bacterial cell adhesion compared to PDMS and glass controls. However, superhydrophobic materials accumulated biofilm of both bacteria over a 2-day period while slippery materials significantly prevented biofilm formation over the same period. The novel and highly efficacious antibacterial materials reported in this thesis show a very strong potential to be utilized in hospital environments for reducing the incidence of HAIs.

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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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Sommer, Stacy Ann. "Siloxane-Polyurethane Fouling-Release Coatings Based On PDMS Macromers." Diss., North Dakota State University, 2011. https://hdl.handle.net/10365/29313.

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Marine biofouling is the accumulation of organisms onto surfaces immersed in sea water. Fouling of ships causes an increase in hydrodynamic drag which leads to performance issues such as increased fuel consumption and a reduced top operating speed. Fouling-release (FR) coatings are one way that paints have been used in combating biofouling by allowing for the easy removal of settled organisms. Traditional FR coatings are silicone elastomers which are soft, easily damaged, and require a tie coat for adhesion to marine primers. Siloxanepolyurethane FR coatings have shown promise as FR coatings, providing enhanced durability and toughness, better adhesion to marine primers, and comparable FR performance to commercial coatings. Preliminary studies were conducted to explore the use of PDMS macromers in the preparation of siloxane-polyurethane FR coatings. Attachment and removal of fouling organisms on the siloxane-polyurethane coatings based on PDMS macromers was comparable to commercial FR coatings. Extended water aging was also carried out to determine effects of extended water immersion on the fouling-release performance of the coatings. At up to four weeks of aging, the FR performance of the coatings was not affected. Static immersion marine field testing was performed to determine the fouling-release performance of siloxane-polyurethane coatings prepared with PDMS macromers. The performance was found to be comparable to commercial FR coatings for up to one year, including water jet removal of slimes, barnacle push-off removal, and soft sponging. The coatings showed good fouling-release performance until extremely heavy fouling was allowed to settle. Underwater hull cleaning was conducted for one siloxane-polyurethane composition identified as a top performer from static field testing. The coating was easily cleaned of fouling with rotating brushes for six months. The cleaning capability of the coating was reduced when large barnacles and other extremely heavy fouling was present. A commercial FR coating became heavily damaged with brush cleaning while the siloxane-polyurethane coating remained mostly undamaged. With more frequent cleaning, it is suspected that siloxanepolyurethane coatings would show cleaning capability for longer periods of time. Pigmentation of siloxane-polyurethane coatings based on difunctional PDMS and PDMS macromers was explored to investigate the effect on FR performance. Pigmentation with titanium dioxide caused a slight decrease in FR performance in some cases, but this was easily overcome by the addition of slightly more PDMS in the coating binder, thus illustrating the feasibility of siloxane-polyurethane coatings as effective, pigmented FR coatings. Finally, the exploration of unique PDMS polymer architectures has been explored for the development of additional, novel, fouling-release coatings. The incorporation of end-functional PDMS homopolymer molecular brushes and branched PDMS macromers into siloxane-polyurethane fouling-release coatings shows promise for the development of unique coatings where improved FR performance may be obtained.
Office of Naval Research (U.S.)

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Gong, Xiuqing. "PDMS based microfluidic chips and their application in material synthesis /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?NSNT%202009%20GONG.

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Samel, Björn. "Novel Microfluidic Devices Based on a Thermally Responsive PDMS Composite." Doctoral thesis, KTH, Mikrosystemteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4470.

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The field of micro total analysis systems (μTAS) aims at developments toward miniaturized and fully integrated lab-on-a-chip systems for applications, such as drug screening, drug delivery, cellular assays, protein analysis, genomic analysis and handheld point-of-care diagnostics. Such systems offer to dramatically reduce liquid sample and reagent quantities, increase sensitivity as well as speed of analysis and facilitate portable systems via the integration of components such as pumps, valves, mixers, separation units, reactors and detectors. Precise microfluidic control for such systems has long been considered one of the most difficult technical barriers due to integration of on-chip fluidic handling components and complicated off-chip liquid control as well as fluidic interconnections. Actuation principles and materials with the advantages of low cost, easy fabrication, easy integration, high reliability, and compact size are required to promote the development of such systems. Within this thesis, liquid displacement in microfluidic applications, by means of expandable microspheres, is presented as an innovative approach addressing some of the previously mentioned issues. Furthermore, these expandable microspheres are embedded into a PDMS matrix, which composes a novel thermally responsive silicone elastomer composite actuator for liquid handling. Due to the merits of PDMS and expandable microspheres, the composite actuator's main characteristic to expand irreversibly upon generated heat makes it possible to locally alter its surface topography. The composite actuator concept, along with a novel adhesive PDMS bonding technique, is used to design and fabricate liquid handling components such as pumps and valves, which operate at work-ranges from nanoliters to microliters. The integration of several such microfluidic components promotes the development of disposable lab-on-a-chip platforms for precise sample volume control addressing, e.g. active dosing, transportation, merging and mixing of nanoliter liquid volumes. Moreover, microfluidic pumps based on the composite actuator have been incorporated with sharp and hollow microneedles to realize a microneedle-based transdermal patch which exhibits on-board liquid storage and active dispensing functionality. Such a system represents a first step toward painless, minimally invasive and transdermal administration of macromolecular drugs such as insulin or vaccines. The presented on-chip liquid handling concept does not require external actuators for pumping and valving, uses low-cost materials and wafer-level processes only, is highly integrable and potentially enables controlled and cost-effective transdermal microfluidic applications, as well as large-scale integrated fluidic networks for point-of care diagnostics, disposable biochips or lab-on-a-chip applications. This thesis discusses several design concepts for a large variety of microfluidic components, which are promoted by the use of the novel composite actuator. Results on the successful fabrication and evaluation of prototype devices are reported herein along with comprehensive process parameters on a novel full-wafer adhesive bonding technique for the fabrication of PDMS based microfluidic devices.
QC 20100817

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Samel, Björn. "Novel microfluidic devices based on a thermally responsive PDMS composite /." Stockholm : Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4470.

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Tabarizadeh, Elham. "PDMS-based membranes for dehydration of Triethylene glycol using pervaporation technology." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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This thesis is relying on membrane separation technology and it seeks to find an appropriate membrane to use in pervaporation setup for the subsea regeneration of triethylene glycol (TEG) in natural gas dehydration. Although some effort have been spent on membrane absorption for gas dehydration with glycols, there is still a lack of information about TEG dehydration using pervaporation technology with different membranes, therefore experimental data is needed to assess the feasibility of using membrane pervaporation for regeneration of TEG for subsea condition. In the present work, an experimental study of dehydration of TEG with pervaporation technology has been carried out using a composite membrane with the porous support of polysulfone (PSF) coated with a dense layer of Polydimethylsiloxane (PDMS). The membrane was characterized in terms of compatibility to TEG, chemical analysis identification using Fourier Transform Infrared (FTIR) spectroscopy, morphology and surface properties with scanning electron microscopy (SEM), and contact angle measurements. Furthermore, a method for analyzing low concentrations of TEG in aqueous solutions was used with gas chromatography (GC) as this was vital to the pervaporation study. The criteria for choosing PDMS polymer was the minimum TEG uptake, high flux, and lower price.

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Forster, Simon. "Surface modification of PDMS-based microfluidic devices through plasma polymerisation : production and application." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531221.

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Abraham, Berhane Teclesenbet. "Degradation and recovery of polydimethylsiloxane (PDMS) based composites used as high voltage insulators." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49902.

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Thesis (MSc)--Stellenbosch University, 2004.
ENGLISH ABSTRACT: Polydimethylsiloxane (PDMS) compounds are utilized in outdoor high voltage insulation due to their low weight, vandalism resistance, better anti-contamination performance and their superior hydrophobic nature. Under severe environmental conditions and over prolonged service time, however, the hydrophobic surface can gradually become hydrophilic and then recover with adequate resting period. In this study, room temperature vulcanized (RTV) PDMS samples were prepared with different formulations and then exposed to corona discharge to evaluate its effect. The influence of different additives, such as different types and amount of fillers and additionally added low molar mass silicone oils, on the hydrophobicity recovery of the material was investigated. The effects of two types of corona treatment were also evaluated. Hydrophobicity recovery of corona and UV-C aged PDMS samples was evaluated by means of static contact angle measurements. Positron annihilation spectroscopy (PAS) gave important information on the micro structural change after corona treatment of RTV PDMS as well as naturally aged high temperature vulcanized (HTV) PDMS samples. The different formulations of the RTV PDMS samples and the effect of the additives were studied with this technique. The formation of a thin, highly crosslinked inorganic silica-like (SiOx) layer was confirmed even at the early stage of degradation. It was also possible to estimate the thickness of the silica-like layer formed during corona exposure that is responsible for the loss and recovery of hydrophobicity. The surface hardness and hydrophilicity change of PDMS samples due to corona treatment were studied simultaneously with force distance measurements by atomic force microscopy (AFM). The adhesive force calculated from the pull-off force-distance curves showed that the adhesive force between the probe and the sample decreased with increasing corona treatment time, indicating hydrophobicity recovery. In addition to this, the increase in hardness after corona exposure provides indirect evidence of the formation of a silica-like layer. In all cases the hydrophilicity and the surface hardness of the PDMS samples increased directly after corona treatment and recovered with time. Two types of FTIR spectroscopy were used to analyse the surface of the polymer.
AFRIKAANSE OPSOMMINGS: Polidimetielsiloksaan (PDMS) word in buitelug hoogspanninginsulasie gebruik as gevolg van sy lae massa, weerstand teen vandalisme, verbeterde anti-kontaminasie werkverrigting en superieure hidrofobiese karakter. Die hidrofobiese oppervlakte kan egter gelydelik hidrofillies word onder uiterste omgewingsomstandighede en oor langdurige dienstyd. PDMS materiaal herstel egter nadat dit genoeg rustyd toegelaat is. Kamertemperatuur-gevulkaniseerde (KTV) PDMS met verskillende formulasies is in hierdie studie voorberei, aan korona ontlading blootgestel, geëvalueer en vergelyk. Die invloed van bymiddels soos verskillende tipes en hoeveelhede vuiler, asook addisionele lae molekulêre massa silikoonolie, op die herstel van hidrofobisiteit van die materiaal is ondersoek. Twee verskillende metodes van korona behandeling is ook geëvalueer. Die herstel van hidrofobisiteit van korona en UV-C verouderde PDMS monsters is met statiese kontakhoekmeting geëvalueer. Positronvernietigingspektroskopie (PVS) is 'n kragtige tegniek wat belangrike inligting oor die mikrostrukturele verandering van korona behandelde van KTV PDMS sowel as natuurlik-verouderde hoë temperatuur gevulkaniseerde (HTV) PDMS monsters gee. Die verskillende formulasies van die KTV PDMS monsters, sowel as die effek van die vullers, is met behulp van hierdie tegniek ondersoek. Die vorming van 'n dun, hoogskruisgebinde, anorganiese silika-agtige (SiOx) laag op die PDMS oppervlak, selfs tydens die vroeë stadium van degradasie, is bevestig. Dit was ook moontlik om die dikte van die silika-agtige laag wat gedurende die korona blootstelling gevorm het, en wat verantwoordelik is vir die verlies aan hidrofobisiteit, te bepaal. Die oppervlakhardheid en hidrofilisiteit verandering van PDMS monsters as gevolg van korona behandeling, was gelyktydig met krag-afstand metings deur middel van atoomkragmikroskopie (AKM) bestudeer. Die kleefkrag, soos bereken van aftrek kragafstandkurwes, dui daarop dat kleefkragte tussen die taster en die monster afneem met toenemende korona behandelingstyd, wat beduidend is op die herstel van hidrofobisiteit. Daarbenewens is die toename van oppervlakhardheid na korona blootstelling "n indirekte bewys van die formasie van 'n silika-agtige laag. In alle gevalle het die hidrofilisiteit en die oppervlakhardheid van die PDMS monsters toegeneem direk na afloop van korona behandeling en gevolglik herstel met tyd. Twee tipes IR spektroskopie metodes is gebruik vir die chemiese-oppervlak analises

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To, Josiah. "Developing a novel heterogeneous three electrode system for a PDMS-based microfluidic electrochemical sensor." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/56174.

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Biosensors have seen an increased use in recent years as an in situ testing device for various industries such as agriculture, environmental sustainability, food, health, etc. On-site testing devices have an advantage over traditional testing system because they can be used for real-time monitoring and improving the accuracy of time-sensitive detection results. Out of all the industries, the health industry benefits most from in situ devices as point-of-care diagnostic devices. Point-of-care devices are useful tools to quickly diagnose diseases and direct patients’ course of treatment in low-income countries with few resources. In 2014 there were approximately 9.6 million global cases of tuberculosis (TB) and 1.5 million deaths due to TB (caused by the infection of Mycobacterium Tuberculosis [MTB]). Globally, this made TB the second most common cause of death by an infection disease in 2014. With a rising incidence of multi drug-resistant and extensive drug-resistant TB, TB is again becoming a global issue that wealthy countries will likely be unable to ignore. Since transmission is commonly through airborne particulates, early diagnosis and correct treatment of TB are fundamental to not only preventing the spread of the disease, but also eradicating it. Currently, the screening and detection tools that lower resource countries have are limited. Although the MTB genome has been sequenced since 1998, cost-effective, point-of-care, gene-based detection technology has had limited development. Since the integration of MEMS technology to biologically relevant needs in the late 90s there has been much development in creating small, portable detection systems for point-of-care use. Furthermore, this work details the development of a novel heterogeneous 3-material 3-electrode electrochemical sensor in a PDMS based bonded device. This sensor was developed with the intention of integration into a biosensor system. The final 3-electrode system was composed of 3 different materials: Au counter electrode, carbon working electrode, and Ag/AgCl reference electrode. The 3 material 3-electrode system was tested as an electrochemical system by detection of aqueous 5 μM carminic acid in room temperature and post 65◦C heating conditions. Parallel work was done to develop a robust, leak-free bonding method that survived 65◦C heating conditions and preserved electrochemical functionality.
Applied Science, Faculty of
Graduate

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Yang, Cheng Wei Tony. "Adsorption of a carboxylated silane on gold : characterization and application to PDMS-based electrochemical cells." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58832.

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Integrated sensing and biosensing microfluidic systems often require sealing between polydimethylsiloxane (PDMS), glass, and gold interfaces. Studying substances that can self-organize onto glass and gold surfaces may achieve these goals and pave the way for new technological advances. Work presented in this thesis focuses on characterizing the adsorption of N-[(3-trimethoxysilyl)propyl]ethylene-diamine triacetic acid (or TMS-EDTA) on Au and applying this knowledge to construct leak-free PDMS-based electrochemical cells. First, surface analysis of TMS-EDTA-modified Au surfaces was conducted using various techniques. Water contact angle measurements and X-ray photoelectron spectroscopy confirm that the carboxylated silane can chemically modify Au surfaces. Atomic force microscopy studies indicate that a uniform surface coverage with monolayer thickness is formed. Infrared spectroscopy studies indicate that there is little evidence of siloxane cross-linking. Surface plasmon resonance results suggest that the carboxylates on TMS-EDTA-modified Au are available for streptavidin immobilization. Second, electrochemistry was used to determine the Gibbs free energies of adsorption of TMS-EDTA on Au under aqueous conditions. Electrochemical differential capacitance measurements reveal that the potential-dependent free energies of adsorption are ∼ - 20 to - 30 kJ/mol (for potentials between - 0.5 and 0.2 V) in the complex electrolyte solution used. Furthermore, at highly negative potentials ( ∼ - 1.1 V), TMS-EDTA adsorbs minimally onto the Au surface. Third, PDMS surfaces were functionalized to present primary amino groups, and glass or gold slides were functionalized to present carboxyl groups. Strong bonding was achieved by bringing the two surfaces in contact and reacting at room temperature. Shear tests reveal that the novel carboxyl-amine bonding strategy achieved a comparable bond strength as the conventional methods. Subsequently, TMS-EDTA was applied to construct leak-free PDMS-based electrochemical cells. Pressure leak tests were conducted to provide a more realistic measure of the bond strengths under aqueous conditions. A method to electrochemically remove the adsorbed TMS-EDTA layer off of the Au electrode, while maintaining the sealed cell chamber, was also developed. The characterization studies and fabrication strategy presented have led to the development of leak-free PDMS-based electrochemical devices that are suitable for sensing and biosensing applications.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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Ana, U. J. "The attainment of controlled adhesion by incorporation of low level additives in a PDMS-based adhesive." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7764.

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Stearates are commonly used in polymer technology as slip additives and lubricants. The release properties of stearic acid and its metallic derivatives are extensively manipulated in rubber processing industries where they are used as mold release agents. Previous unrelated studies have shown that increased additions of stearic acid consistently reduced mold sticking. Despite their widespread usage, however, few studies have been directed to study their mechanism of action. In a preliminary study conducted by AWE and Loughborough University, the attainment of low levels of adhesion was studied and in particular the use of stearic acid as an adhesion modifier was studied. It was found that adding minute amounts of stearic acid resulted in dramatic reductions to the strength of aluminium bonded with a PDMS-based adhesive. The cause of this fall-off in adhesion (as measured by T-peel test) was initially attributed to the migration of stearic acid to the surface forming a weak boundary layer. The possibility that stearic acid acts as an inhibitor for the cure reaction was also considered. Surface analysis predominantly with static secondary ion mass spectrometry (SSIMS) and X-ray photoelectron spectroscopy (XPS) was carried out to ascertain locus of failure and the likelihood of stearic acid at the interface. Failure was identified as having taken place in a cohesive, and potentially interphasial, layer near the interface of the joint. No evidence was given to support the WBL theory proposed by most researchers, thus findings from the present study contradicted existing literature. Fourier Transform infrared (FT-IR) spectroscopy in collaboration with differential scanning calorimetry (DSC) was used to investigate the effect of stearic acid on the cure reaction. These studies disclosed a catalytic effect on the curing process of the adhesivp... It was suggested that the resultant increase in modulus of the stearic acid modified material in the region of failurew as the cause of prematurejo int failure at low level loads.

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Wang, Zhengmu. "Design, fabrication and characterization of a double-network alginate-pHEMA hydrogel coating for PDMS-based biomedical implants." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61102.

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Traditional silicone biomedical implants, such as urinary catheters, often suffer from high surface friction, high stiffness, and a lack of hydrophilicity, which can cause discomfort or discomfort. To tackle these challenges, we developed a double-network alginate-pHEMA hydrogel “cushion” coating for polydimethylsiloxane (PDMS) biomedical implants. The double-network hydrogel presented here consists of two distinct networks made of alginate and pHEMA, respectively. The alginate network is covalently bonded to PDMS substrates as scaffolding, and the denser pHEMA network fills the free space within the alginate network. In this proof of concept study, the double-network hydrogel achieved a compressive fracture stress of 502.04±14.41 kPa, which is 5.8-fold stronger than the alginate hydrogel, while its elasticity is still comparable to soft tissues. The proposed double-network hydrogel has a negligible amount of swelling in biological fluids and exhibits no cytotoxicity, which are desirable qualities for biomedical and coating applications. Both chemical modification using APTES and micropillar anchors have been used to improve the coating stability. We found that the adhesion strength of the hydrogel coating on micropillar PDMS substrates is 55% stronger than on bare PDMS substrates when both substrates are grafted with APTES. In comparison to native PDMS and K-Y Jelly-lubricated PDMS, the double-network alginate-pHEMA hydrogel-coated PDMS demonstrated significantly less friction and superior hydrophilicity.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

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15

Cao, Hong Ha. "The fabrication process of microfluidic devices integrating microcoils for trapping magnetic nano particles for biological applications." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112150/document.

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Le but de cette étude est de concevoir, fabriquer et caractériser une puce microfluidique afin de mettre en oeuve la capture de nanoparticules magnétiques fonctionnalisées en vue de la reconnaissance d’anticorps spécifiques (couplage d’une très grande spécificité et sensibilité). Après avoir modélisé et simulé les performances de la microbobine intégrée dans le canal de la puce microfluidique en prenant soin de limiter la température du fluide à 37°C, la capture devant être effective, le microsystème est fabriqué en salle blanche en utilisant des procédés de fabrication collective. La fabrication du microdispositif en PDMS a aussi donné lieu à l’optimisation de procédés de modification de surface afin d’assurer la ré-utilisation du microdispositif (packaging réversible) et la limitation de l’adsorption non spécifique. L’immobilisation des anticorps su les billes (300 nm) a été menée à l’intérieur du canal en utilisant un protocole de type ELISA éprouvé. Le procédé a montré qu’il était également efficient pour cet environnement puisque nous avons pu mettre ne évidence la capture de nanoparticules
In this study, a concept of microfluidic chip with embedded planar coils is designed and fabricated for the aim of trapping effectively functionalized magnetic nanobeads and immobilizing antibody (IgG type). The planar coils as a heart of microfluidic chip is designed with criterion parameters which are optimized from simulation parameters of the maximum magnetic field, low power consumption and high power efficiency by FE method. The characterization of microcoils such as effectively nanobeads (300 nm) at low temperature (<37oC) is performed and confirmed. The channel network in PDMS material is designed for matching with entire process (including mixing and trapping beads) in microfluidic chip. A process of PDMS’s surface modification is also carried out in the assemble step of chip in order to limit the non-specific adsorption of many bio substances on PDMS surface. The microfluidic chip assemble is performed by using some developed techniques of reversible packaging PDMS microfluidic chip (such as stamping technique, using non-adhesive layer, oxygen plasma combining with solvent treatment). These packaging methods are important to reused microchip (specially the bottom substrate) in many times. The immobilization of antibody IgG-type is performed inside microfluidic chip following the standard protocol of bead-based ELISA in micro test tube. The result showed that IgG antibodies are well grafted on the surface of carboxyl-beads (comparing to result of standard protocol); these grafted antibodies are confirmed by coupling them with labeled second antibody (Fab-FITC conjugation)

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Chan, Yau-kei, and 陳佑祺. "Reducing the complications associated with emulsification in the use of polydimethylsiloxane (PDMS) based silicone oil in vitreous surgery by engineering approaches." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196728.

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Silicone oil (SO) is widely used as the long-term intraocular tamponade in treating various eye diseases such as complicated retinal detachment, proliferative vitreoretinopathy, proliferative diabetic retinopathy, giant retinal tear and ocular trauma. However, its propensity to emulsify is an inherent problem of its long-term use in-vivo. Dispersal of SO into many tiny oil droplets causes numerous complications such as inflammation, glaucoma and reproliferation. It may also be responsible for possible toxicity to both retina and optic nerve. Emulsification is one of the problems associated to the use of SO as a long-term intraocular tamponade. This study focused on the understanding on the physical nature and formation of in-vivo SO emulsion and the development of methods to reduce the complications associated with emulsification of SO by engineering approaches. A stepper motor driven mechanical platform was built to study the fluid flow of SO within an eye model chamber during eye-like movements and a quantitative method was established to study SO emulsification, both in-vivo and in-vitro. This method was used to compare the relative resistance of different SO against emulsification. In the last part of the thesis a novel rinse was proposed which aimed at removing the emulsified SO droplets in-vivo in an effective way. In the dynamic eye model experiment, both the increase in shear viscosity of SO and the extent of SO fill had an effect in reducing the shear. These effects were small compared to the effect of indents at reducing shear rate during eye-like movements. When SO emulsions from patients were analyzed it was found that over 90% of the emulsified droplets were outside the observable range under slit-lamp biomicroscopy. When the emulsification resistance of SO was tested using the quantitative method the result confirmed that SO with high-molecular-weight component (HMWC) was more emulsification resistant than SO with the same shear viscosity. The addition of HMWC increases the elasticity and thus increasing its resistance against emulsification. A novel rinse was also proposed to remove the emulsified droplets using physical phenomenon of double emulsification. To conclude, this study improved the understanding of the formation of SO emulsification. The clinical observable emulsified droplets are probably in all cases that was just the tip of the iceberg. Three practical suggestions were made: Firstly, the use of SO and encircling scleral buckling procedure in combination might reduce the shear rate. Secondly, the use of HMWC can reduce emulsification. Lastly, there may be a role in rinsing out the emulsified droplets using the proposed novel solution. The novel solution is going to fully developed and commercialized in the near future.
published_or_final_version
Ophthalmology
Doctoral
Doctor of Philosophy

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17

Sang, Shengbo [Verfasser], Hartmut [Akademischer Betreuer] Witte, Klaus [Akademischer Betreuer] Liefeith, and Theodor [Akademischer Betreuer] Doll. "An approach to the design of surface stress-based PDMS micro-membrane biosensors - concept, numerical simulations and prototypes / Shengbo Sang. Gutachter: Klaus Liefeith ; Theodor Doll. Betreuer: Hartmut Witte." Ilmenau : Universitätsbibliothek Ilmenau, 2010. http://d-nb.info/1010814516/34.

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Kukhta, Dziyana. "Metody přípravy buněčných transplantátů v kardiologii." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400529.

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Tato diplomová práce se zabývá tkáňovým inženýrstvím, zejména tvorbou homogenní, izotropní a planární vrstvy buněk srdečního svalu pomocí dvou technologii:”scaffold-based” a ”scaffold-free”. Nejprve popsaný histologie srdeční stěny, buňky srdečního svalu a buněčné kultury. Následuje popis tkáňového inženýrství, který zahrnuje technologii “cell sheet” a tkáňové inženýrství na bázi scaffoldů. Na konci teoretické části je popsána aplikace tkáňového inženýrství a buněčná vizualizace. Praktická část věnovaná tvorbě planární buněčné vrstvy z kardiomyocytů a fibroblastů s využitím informací z teoretické části.

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Kwong, Brian. "Poly-dimethyl-siloxane based responsive structures." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53018.

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This thesis focuses on the design, fabrication and characterization of polymeric smart structures that are able to alter their geometry and thus their properties upon the application of external stimuli in a reversible and controllable manner. Two different responsive structures are studied that both contain poly dimethyl-siloxane (PDMS) and differ in the design, geometry, and actuation mechanism. The first structure is a surface decorated by a square array of posts (cilia) made of PDMS reinforced with magnetic particles and is actuated magnetically. The structures are meant to mimic cilia, a hair-like structure found in nature. The physical parameters necessary for the magnetic response of the cilia including physical dimensions and filler concentration are investigated. In addition, the elastic modulus of the composites is measured and the microstructure is examined in order to determine the dispersion and homogeneity of the composites. The second structure is a planar hetero-structure consisting of a PDMS substrate and a nanoporous (NP) metal foam film which is actuated thermally or chemically by tuning the generation and release of residual stresses at the NP metal foam/PDMS interface. The effect of strain, applied to the PDMS substrate prior to the deposition of the NP metal foam and the effect of the PDMS and NP metal foam thicknesses on the shape/size of the planer hetero-structure after the actuation is investigated.

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Mier, Alexandro Castellanos. "Poly(N-Isopropylacrylamide) based BioMEMS/NEMS for cell manipulation." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001814.

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21

Mukhtar, Husneni. "Development of compensated immersion 3D optical profiler based on interferometry." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD017/document.

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La CSI (Coherence Scanning Interferometry) ou la WLSI (White Light Scanning Interferometry) est une technique d'imagerie optique bien établie pour mesurer la rugosité de surface et la forme des surfaces microscopiques. Les avantages sont la sensibilité axiale nanométrique, un large champ de vision (des centaines de μm à plusieurs mm) et la vitesse de mesure (quelques secondes à quelques minutes). La technique est basée sur l'interférométrie optique avec une configuration de Linnik très difficile à ajuster mais elle présente plusieurs avantages: des objectifs d'ouverture numérique plus élevés pour améliorer la résolution spatiale; longue distance de travail, car il n'y a aucun besoin de l'un des composants devant l'objectif; une configuration de mode de lumière polarisée; franges contrastées en raison de la possibilité de modifier les voies optiques et les intensités des deux bras indépendamment. Alors que l'utilisation d'un objectif d'immersion dans l'eau présente les avantages suivants: éviter les problèmes liés à l'ajustement entre la formation des franges et le plan de formation de l'image; et pour minimiser la différence de dispersion entre les bras de l'interféromètre. Afin de pouvoir mesurer en mode eau et d'obtenir des échantillons à haute résolution latérale de types chimiques et biologiques, plusieurs défis doivent être surmontés tels que l'équilibrage de l'OPD sur les deux bras; trouver et ajuster les bonnes franges de contraste; trouver et adapter une compensation adéquate de l'eau dans le bras de référence horizontal pour faire fonctionner un système dans l'eau
Coherence Scanning Interferometry (CSI) or White Light Scanning Interferometry (WLSI) is a well-established optical imaging technique for measuring the surface roughness and the shape of microscopic surfaces. The advantages are the nanometric axial sensitivity, a wide field of view (hundreds of μm to several mm) and the measurement speed (a few seconds to a few minutes). The technique is based on optical interferometry with a Linnik configuration which very difficult to adjust but it offers several advantages: higher numerical aperture objectives to improve spatial resolution; long working distance, because there is no need for any of the components in front of the lens; a polarized light mode configuration; contrasting fringes because of the possibility of modifying the optical pathways and the intensities of the two arms independently. While the use of a water-immersion objective gives the following advantages: to avoid the problems related to the adjustment between the formation of the fringes and the plane of formation of the image; and to minimize the difference in dispersion between the arms of the interferometer. In order to be able to measure in water mode and to obtain high lateral resolution samples of chemical and biological types, several challenges must be overcome such as balancing the OPD on both arms; finding and adjusting the good contrast fringes; finding and adapting a suitable water compensation of water in horizontal reference arm to operate a system in water

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22

McClain, Maxine Alice. "Elastomer-based microcable electrodes for electrophysiological applications." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39606.

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Compliant microelectrodes have been designed in a microcable geometry that can be used individually or in an array and either as a shank-style electrode or as a string-like electrode that can be threaded around features such as the peripheral nerve. The fabrication process, using spin-cast micromolding (SCuM), is simple and adaptable to different patterns. The microcables were fabricated using polydimethyl siloxane (PDMS) for the insulating substrate and thin-film gold for the conductive element. The thin, metal film and the low tensile modulus of the PDMS substrate created an electrode with a composite tensile modulus lower than other compliant electrodes described in the literature. The gold film increased the composite modulus approximately three-fold compared to the unaltered PDMS. The durability of the electrodes and tolerance for stretch was also tested. The microcables were found to be conductive up to 6% strain and to regain conductivity after release from multiple applications of 200% strain. The tolerance for high-strain shows that the electrodes can be deployed for use and stretched or pulled into place as needed without damaging the conductivity. The microcable electrode recording sites were electrically characterized using frequency-based impedance modeling and were tested for electrophysiological recording using a peripheral nerve preparation. A suitable insertion mechanism was designed to use the microcables as shank-style cortical electrodes. The microcables were coated on one side with fibrin, which, when dry, stiffens the microcables for insertion into cortical tissue. A 28-day implant study testing the inflammatory response to fibrin coated PDMS microcable electrodes showed a positive, but relatively low inflammatory response, as measured by glial fibrillary astrocytic protein (GFAP; indicating activated astrocytes) immediately at the tissue edge of the implant site. The response of the control, silicon shank-style electrodes, was varied, but also trended toward low levels of GFAP expression. The GFAP staining was possibly due to the clearance of the fibrin from the implant site in addition to the presence of the PDMS-based electrode. Implant studies extending beyond 28 days are necessary to determine whether and to what degree the inflammation persists at the implant site of PDMS-based electrodes.

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WHITLOCK, PATRICK W. "SILICON-BASED MATERIALS IN BIOLOGICAL ENVIRONMENTS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1116264213.

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24

Pussadee, Nirut. "Poly(dimethylsiloxane) Based Micro- and Nanofluidic Device Fabrication for Electrophoresis Applications." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268179904.

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25

Mohan, Greeshma. "Silicone Elastomer-Based Combinatorial Biomaterial Gradients for High Throughput Screening of Cell-Substrate Interactions." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5857.

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Biomaterials have evolved over the years from the passive role of mere biocompatibility to an increasingly active role of presenting instructive cues to elicit precise responses at the molecular and cellular levels. Various characteristics common to synthetic biomaterials in vitro and extracellular matrices in vivo, such as immobilized functional or peptide groups, mechanical stiffness, bulk physical properties and topographical features, are key players that regulate cell response. The dynamics in the cell microenvironment and at the cell adhesive interface trigger a web of cell-material and cell-cell information exchanges that have a profound impact in directing the ultimate cell fate decision. Therefore, comprehension of cell substrate interactions is crucial to propel forward the evolution of new instructive biomaterials. Combinatorial biomaterials that encompass a wide range of properties can help to recapitulate the complexity of a cell microenvironment. The objective of this research was to fabricate combinatorial biomaterials with properties that span wide ranges in both surface chemistries and mechanical moduli. These materials were based on polydimethyl siloxane (PDMS), an elastomeric silicone biomaterial with physiologically relevant stiffness. After developing these mechano-chemical gradient biomaterials, we conducted high throughput screening of cell responses on them to elucidate cell substrate interactions and material directed behaviors. Our central hypothesis was that materials encompassing monotonic gradients in mechanical elastic modulus and orthogonal surface chemistry gradients could be engineered using the soft biomaterial, polydimethyl siloxane (PDMS) and that these gradient biomaterials would evoke a varied cell response. Furthermore, we expected high throughput screening of cell-material interactions using these materials would elucidate patterns and thresholds of synergy or antagonism in the overall cell response to the increased complexity presented by combinatorial materials. First, reproducible gradients in surface chemistry were generated on PDMS through surface modification techniques. Cell response to PDMS surface chemistry gradients was then screened in a rapid high throughput manner. Additionally, characteristics of the adhesive interface were probed to understand its role in cell response. Finally, a 2D combinatorial gradient with a gradient in mechanical elastic modulus and an orthogonal gradient in surface chemistry was fabricated with PDMS. High throughput screening of the synergistic influence of the varied mechanical and biochemical extracellular signals presented by the combinatorial biomaterial on cell response was conducted in a systematic manner. This research demonstrates the fabrication of combinatorial biomaterials with a wide range of mechanochemical properties for rapid screening of cell response; a technique that will facilitate the development of biomaterial design criteria for numerous biomedical engineering applications including in vitro cell culture platforms and tissue engineering.

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Jo, Myeong Chan. "An Acoustic-based Microfluidic Platform for Active Separation and Mixing." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4697.

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Particle separation is of great interest to many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In addition, current gold standard active separation techniques are only capable of separation based on particle size; hence, separation cannot be achieved for same-size particles with different densities. In this dissertation, a sheathless acoustic-based microfluidic platform using surface acoustic wave for not only size-dependent but also density-dependent particle separation has been investigated. In this platform, two different functions were incorporated within a single microfluidic channel with varying the number of pressure node and position. The first function was to align particles on the center of the microfluidic channel without adding any external sheath flow. The second function was to separate particles according to their size or density. Two different size-pairs of polystyrene particles with different diameters (3 µm and 10 µm for general size-resolution, 3 µm and 5 µm for higher size-resolution) were successfully separated. Also, the separation of two 10 µm diameter, different-density particle streams (polystyrene: 1.05 g/cm3, melamine: 1.71 g/cm3) was successfully demonstrated. The effects of the input power, the flow rate, and particle concentration on the separation efficiency were investigated. A range of high separation efficiencies with 94.8-100 % for size-based separation and 87.2 - 98.9 % for density-based separation were accomplished. In this dissertation, an acoustic-based microfluidic platform using dual acoustic streaming for active mixing has also been investigated. The rapid and high efficiency mixing of a fluorescent dye solution and deionized water in a microfluidic channel was demonstrated with single acoustic excitation by one interdigital transducer (IDT) as well as dual excitation by two IDTs. The mixing efficiencies were investigated as a function of applied voltage and flow rates. The results indicate that with the same operation parameters, the mixing efficiency with dual-IDT design increased to 96.7 % from 69.8 % achievable with the traditional single-IDT design. The effect of aperture length of the IDT on mixing efficiency was also investigated. Additionally, the effects of the polydimethylsiloxane (PDMS) channel wall thickness on the insertion loss and the particle migration to the pressure node due to acoustic radiation forces induced by SAW have been investigated. The results indicate that as the PDMS channel wall thickness decreased, the SAW insertion loss is reduced as well as the velocity of the particle migration due to acoustic forces increased significantly. As an example, reducing the side wall thickness of the PDMS channel from 8 mm to 2 mm in the design results in 31.2 % decrease in the insertion loss at the resonant frequency of 13.3 MHz and 186 % increase the particle migration velocity at the resonant frequency of 13.3 MHz with input power of 27 dBm. Lastly, a novel acoustic-based method of manipulating the particles using phase-shift has been proposed and demonstrated. The location of the pressure node was adjusted simply by modulating the relative phase difference (phase-shift) between two IDTs. As a result, polystyrene particles of 5 µm diameter trapped in the pressure node were manipulated laterally across the microfluidic channel. The lateral displacements of the particles from -72.5 µm to 73.1 µm along the x-direction were accomplished by varying the phase-shift with a range of -180° to 180°. The relationship between the particle displacement and the phase-shift of SAW was obtained experimentally and shown to agree with theoretical prediction of the particle position.

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27

Wang, Qian. "Elastomer-based Cellular Micromechanical Stimulators for Mechanobiological Study." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397610258.

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28

Cashman, Mark Francis. "Siloxane-Based Reinforcement of Polysiloxanes: from Supramolecular Interactions to Nanoparticles." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/100134.

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Polysiloxanes represent a unique class of synthetic polymers, employing a completely inorganic backbone structure comprised of repeating –(Si–O)n– 'siloxane' main chain linkages. This results in an assortment of diverse properties exclusive to the siloxane bond that clearly distinguish them from the –(C–C)n– backbone of purely organic polymers. Previous work has elucidated a methodology for fabricating flexible and elastic crosslinked poly(dimethyl siloxane) (PDMS) constructs with high Mc through a simultaneous crosslinking and chain-extension methodology. However, these constructs suffer the poor mechanical properties typical of lower molecular weight crosslinked siloxanes (e.g. modulus, tear strength, and strain at break). Filled PDMS networks represent another important class of elastomers in which fillers, namely silica and siloxane-based fillers, impart improved mechanical properties to otherwise weak PDMS networks. This work demonstrates that proper silicon-based reinforcing agent selection (e.g. siloxane-based MQ copolymer nanoparticles) and incorporation provides a synergistic enhancement to mechanical properties, whilst maintaining a low viscosity liquid composition, at high loading content, without the use of co-solvents or heating. Rheological analysis evaluates the viscosity while photorheology and photocalorimetry measurements evaluate rate and extent of curing of the various MQ-loaded formulations, demonstrating theoretical printability up to 40 wt% MQ copolymer nanoparticle incorporation. Dynamic mechanical analysis (DMA) and tensile testing evaluated thermomechanical and mechanical properties of the cured nanocomposites as a function of MQ loading content, demonstrating a 3-fold increase in ultimate stress at 50 wt% MQ copolymer nanoparticle incorporation. VP AM of the 40 wt% MQ-loaded, photo-active PDMS formulation demonstrates facile amenability of photo-active PDMS formulations with high MQ-loading content to 3D printing processes with promising results. PDMS polyureas represent an important class of elastomers with unique properties derived from the synergy between the nonpolar nature, unusual flexibility, and low glass transition temperature (Tg) afforded by the backbone siloxane linkages (-Si-O)n- of PDMS and the exceptional hydrogen bond ordering and strength evoked by the bidentate hydrogen bonding of urea. The work herein presents an improved melt polycondensation synthetic methodology, which strategically harnesses the spontaneous pyrolytic degradation of urea to afford a series of PDMS polyureas via reactions at high temperatures in the presence of telechelic amine-terminated oligomeric poly(dimethyl siloxane) (PDMS1.6k-NH2) and optional 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BATS) chain extender. This melt polycondensation approach uniquely circumvents the accustomed prerequisite of isocyanate monomer, solvent, and metal catalysts to afford isocyanate-free PDMS polyureas using bio-derived urea with the only reaction byproduct being ammonia, a fundamental raw ingredient for agricultural and industrial products. As professed above, reinforcement of polysiloxane materials is ascertained via the incorporation of reinforcing fillers or nanoparticles (typically fumed silica) or blocky or segmented development of polymer chains eliciting microphase separation, in order to cajole the elongation potential of polysiloxanes. Herein, a facile approach is detailed towards the synergistic fortification of PDMS-based materials through a collaborative effort between both primary methods of polysiloxane reinforcement. A novel one-pot methodology towards the facile, in situ incorporation of siloxane-based MQ copolymer nanoparticles into segmented PDMS polyureas to afford MQ-loaded thermoplastic and thermoplastic elastomer PDMS polyureas is detailed. The isocyanate-free melt polycondensation achieves visible melt dispersibility of MQ copolymer nanoparticles (good optical clarity) and affords segmented PDMS polyureas while in the presence of MQ nanoparticles, up to 40 wt% MQ, avoiding post-polymerization solvent based mixing, the only other reported alternative. Incorporation of MQ copolymer nanoparticles into segmented PDMS polyureas provides significant enhancements to modulus and ultimate stress properties: results resemble traditional filler effects and are contrary to previous studies and works discussed in Chapter 2 implementing MQ copolymer nanoparticles into chemically-crosslinked PDMS networks. In situ MQ-loaded, isocyanate-free, segmented PDMS polyureas remain compression moldable, affording transparent, free-standing films.
Master of Science
Polysiloxanes, also referred to as 'silicones' encompass a unique and important class of polymers harboring an inorganic backbone. Polysiloxanes, especially poly(dimethyl siloxane) (PDMS) the flagship polymer of the family, observe widespread utilization throughout industry and academia thanks to a plethora of desirable properties such as their incredible elongation potential, stability to irradiation, and facile chemical tunability. A major complication with the utilization of polysiloxanes for mechanical purposes is their poor resistance to defect propagation and material failure. As a result polysiloxane materials ubiquitously observe reinforcement in some fashion: reinforcement is achieved either through the physical or chemical incorporation of a reinforcing agent, such as fumed silica, or through the implementation of a chemical functionality that facilitates reinforcement via phase separation and strong associative properties, such as hydrogen bonding. This research tackles polysiloxane reinforcement via both of these strategies. Facile chemical modification permits the construction PDMS polymer chains that incorporate hydrogen bonding motifs, which phase separate to afford hydrogen bond-reinforced phases that instill vast improvements to elastic behavior, mechanical and elongation properties, and upper-use temperature. Novel nanocomposite formulation through the incorporation of MQ nanoparticles (which observe widespread usage in cosmetics) facilitate further routes toward improved mechanical and elongation properties. Furthermore, with growing interest in additive manufacturing strategies, which permit the construction of complex geometries via an additive approach (as opposed to conventional manufacturing processes, which require subtractive approaches and are limited in geometric complexity), great interest lies in the capability to additively manufacture polysiloxane-based materials. This work also illustrates the development of an MQ-reinforced polysiloxane system that is amenable to conventional vat photopolymerization additive manufacturing: chemical modification of PDMS polymer chains permits the installation of UV-activatable crosslinking motifs, allowing solid geometries to be constructed from a liquid precursor formulation.

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Martinez, Rivas Adrian. "Wafer scale integration of coulomb blockade-based nanobiosensors with microfluidic channels for label-free detection of cancer biomarkers." Toulouse, INSA, 2009. http://eprint.insa-toulouse.fr/archive/00000344/.

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In this thesis we propose and implement the fabrication on 4 inch wafer of a novel type of nanobiosensor capable of high sensitivity detection. The principle of the nanobiosensor is based on the variation of electrical tunnelling conductivity through metal nanoislands due to the quantum phenomenon called “Coulomb blockade”. Nickel nanoislands (~5nm diameter), are placed between interdigitated nanoelectrodes devices (IND) (width~45nm). Hence, the conductivity of these Multiple-Tunnel-Junction (MTJ) devices is modified by the adsorption of biomarkers involved in tumourigenesis. Oncologists have recently isolated and characterised a new conformational single chain variable fragment (scFv) which selectively recognises the active form of RhoA. This potential biomarker has been found overexpressed in various tumours. Antibodies fragments (scFv) are adsorbed through coordinative bonds onto nickel nanoislands. Hence the scFv are capable of recognising specifically the active RhoA conformation. We have investigated this biomarker and validated the nickel nanoilands based chemical construction for label-free biodetection using a quartz crystal microbalance (QCM) before implementing the methodology to our devices. An innovative methodology to realise photoPDMS-based microchannels was also developed. Encapsulation with an etched PDMS-nanocomposite finalised the integration of the devices. The final electrical characterisation of the integrated device was tested in real time and continuous biological flow. The active form of RhoA was discriminated against its inactive conformation. In annexe, I present my epistemological and ethical opinions in nanotechnology
Dans cette thèse, nous proposons et démontrons un nouveau type de nanobiocapteur pour la détection de biomolécules à haute sensibilité et leur intégration à grande échelle (plaquette de 4 pouces). Le principe du nouveau nanobiocapteur électrique est basé sur la variation de conductivité électrique à travers des nano-îlots grâce au phénomène quantique appelé « blocage de Coulomb ». Les nano-îlots de nickel (~5nm de diamètre) sont placés entre les nano-électrodes interdigitées (IND) (~45nm de largeur). La conductivité de ces dispositifs à Jonctions Tunnel Multiples (MTJ) est modifiée par l’adsorption de biomarqueurs impliqués dans la tumorogènese. Les oncologues ont récemment isolé et caractérisé un nouveau fragment d’anticorps à chaîne simple (scFv) qui reconnaît sélectivement la forme active de RhoA. Ce biomarqueur potentiel a été trouvé surexprimé dans diverses tumeurs. Les fragments d’anticorps ont été adsorbés, par des liaisons de coordination, sur les nano-îlots de nickel. Ces fragments sont capables de reconnaître spécifiquement la forme active de RhoA. Nous avons étudié ce biomarqueur et validé la chimie de surface à base de nano-’îlots de nickel pour la détection sans marquage, en utilisant une microbalance à quartz (QCM). Puis, nous avons mis au point et adapté à notre dispositif une méthodologie innovatrice pour réaliser, à l’échelle d’une plaquette, des microcanaux basés sur du photoPDMS. La caractérisation électrique finale des dispositifs intégrés a été testée en temps réel et à flux biologique continu. La forme active de RhoA a été détectée en discriminant la forme inactive. En annexe, je présente mon opinion épistémologique et éthique sur la nanotechnologie

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Terp, Megan Cavanaugh. "Improved Nanoparticle Preparation and Delivery Technology for DOTAP and Oligonucleotide Based Lipoplexes." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338301430.

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Kim, Tae-Young. "Novel sol-gel titania-based hybrid organic-inorganic coatings for on-line capillary microextraction coupled to high-performance liquid chromatography." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001833.

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Wei-Ching, Fang, and 方韋清. "Development of PDMS-based rotational Micropump." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/84543439694566930608.

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碩士
國立屏東科技大學
材料工程研究所
102
This experiment used CO2 laser as the primary source of method to process the PMMA. The traditional Photolithography process was not applied, because the CO2 laser saves a significant amount of time and budget for manufacturing. PMMA (Polymethyl-Methacrylate) is processed to be used as a base for the peristaltic micropump. Next, the PDMS (Poly-di-methyl-siloxane) is poured onto the PMMA where it creates a seal for the micropump when it has been solidified. This experiment uses a motor reduction model and a cross rotor to control the flow of fluid inside micropump. The relationship of the voltage range and the rotation speed of the motor has been monitored. When the range of the motor is set from 0.5 V to 5.5 V, the rotation speed is directly proportional to the voltage, and will increase accordingly before the micropump has been installed. But after it has been installed into the system, the rotation speed decreased by an average of 50 rpm. The fluidic design of the micropump uses a cross rotor, and has the input and output on the right and left side respectively. When the input is on, the cross rotor closes the output, allowing fluid to flow in. As the rotor rotates, it pushes the fluid until the output is on and input is off, thus letting the fluid flows out. This experiment uses de-ionized water as the tester, before the micropump has been installed, 1 V allows the motor produces 60 rpm, while at 5 V, the motor produces 285 rpm. After the micropump has been installed, the rotation was too low to calculate when the voltage was set to 1 V, thus this experiment started at 2 V. At 2 V, the motor produced 65 rpm with the flow rate of 0.51 ml/min, and at 5 V, the motor produces 232 rpm with the flow rate of 1.22 ml/min. To test out the functionality of the micropump, this experiment used 95% ethanol, salad oil and 15W40 motor oil as testers. When the motor reaches the speed of 65 rpm, the flow rate of ethanol is 0.367 ml/min, salad oil is 0.116 ml/min and motor oil is 0.048 ml/min. When the speed of the motor is increased to 232 rpm, the flow rate of ethanol is 0.901 ml/min, salad oil is 0.724 ml and motor oil is 0.336 ml/min.

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Su, Yu-Ren, and 蘇昱仁. "High-Performance Magnetic Sensor Based on Microstructured PDMS." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/58839484594955681576.

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碩士
國立臺灣大學
物理學研究所
105
Resistive magnetic sensors measure different resistance values at different magnetic fields, in which the magnitude of the magnetic field can be monitored. However, the magnetic field will decline quickly when the distance increases, so that the sensitivity of the sensor for the measurement of the change of magnetic field is greatly desirable. In this thesis, we propose a new approach by the integration of microstructured PDMS embedded with FeNi50 particles and to form a highly sensitive magnetic sensor. Several key factors combined together makes the performance possible. First, FeNi50 nanoparticles possess a very high magnetic susceptibility. Second, the microstructured PDMS has unique features of low viscoelasticity and low elastic resistance. Third, AgNWs have the characteristics of excellent conductivity, enabling to be very sensitive with the change of magnetic field. Fourth, this newly designed device can be operated under a very low operational voltage. Therefore, the magnetic sensor can be integrated with solar cells, and it even can work under room light illumination, which is very useful for the development of wearable devices. In addition, we have demonstrated that our magnetic sensor can be integrated with light emitting diodes and can be used to create touchless panel.

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Lin, Min-Han. "PDMS (polydimethylsiloxane) Based Polymerase Chain Reaction Component Design." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2707200515463700.

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Lin, Min-Han, and 林旻翰. "PDMS (polydimethylsiloxane) Based Polymerase Chain Reaction Component Design." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/63011026529983047608.

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碩士
國立臺灣大學
應用力學研究所
93
This thesis presents a new device to perform polymerase chain reaction (PCR) using polydimethylsiloxane (PDMS) polymer as disposable PCR channel. Particular feature in the device include gravity-fed, circularly reciprocating action to ensure the PCR reagent is in contact with a specific temperature region during the PCR cycle of three temperatures – 94oC, 55oC, 72oC. The PCR channel (3.5 mm width by 1 mm height) is fabricated by molding PDMS against a laser scriber engraved PMMA master, with a 4 µm thick parylene film coated on the PCR channel inner and outer surfaces to alleviate bubble formation at high temperature. Simulation, using ANSYS, of heat transfer of the device is also undertaken to aid the design of the device. Results from temperature measurement, using resistive temperature detectors (RTD) sensors, show that the reagent can be cooled down to 55oC (from 94oC ) in 30 sec, or heated up to 72oC and 94oC in 15 sec, in agreement with ANSYS predictions. PCR is demonstrated by a 773 bps DNA template, which is incubated at 94oC for 30 sec, 55oC for 1 min., and 72oC for 1 min. to perform DNA denaturation, primer annealing, and extension of DNA template, respectively. Using the present first-generation device, DNA amplification is clearly proven, however, the efficiency is not as good as commercial PCR machine. Evaporation in the reagent is believed to be the key problem that needs to be improved.

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Li, Wei. "Dual function magnetic PDMS microsphere-based microfluidic valve and mixer." 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=370102&T=F.

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Gu, Wei-guo, and 古偉國. "Fabrication and properties of PDMS-based flow-through PCR device." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/5zzz4a.

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碩士
大同大學
生物工程學系(所)
95
Polymerase chain reaction (PCR) utilizes DNA polymerase to amplify specific DNA fragment. The reaction is carried out under three different reaction temperatures, and the amplified DNA product can be used in subsequent analysis and research. In this thesis, a PDMS-based flow-though PCR device was fabricated using micro-fabrication techniques. The flow channel (50 μm deep) plate and a 1 mm-thick flat back plate were fabricated using PDMS, then the two plates were bonded after oxygen plasma treatment. A thin-film chromium resistive heater was manufactured on Corning 1737 glass substrate. The PCR device was assembled simply by placing the PDMS flow channel on the top of the glass heating chip. The cDNA of D-amino acid oxidase (from Trigonopsis variabilis) was used as the DNA template. The effects of flow rate and cross contamination on the efficiency of the PCR device were studied. In addition, the effects of surface modification by BSA, Pluronic® F-68, Pluronic® F-127, and neat silane were discussed.

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Yang, Han-Yu, and 楊翰宇. "PDMS-based cylindrical hybrid lens for fluorescence enhancement used in microfluidics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/91557050927847378187.

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碩士
國立交通大學
影像與生醫光電研究所
100
Microfluidic systems have recently been developed and applied for many biological and chemical applications based on fluorescence detections. Because of the tiny amount of sample in the system, the induced fluorescence can be weak. Therefore, most of microfluidic systems require many optical components, such as filters, lens, or micro structure, to enhance the efficiency of fluorescence detection. However, these components encounter the common issues of complex manufacturing processes and expensive costs. In this study, a miniature, cylindrical, and hybrid lens made of polydimethylsiloxane (PDMS) is proposed to focus the excitation light and simultaneously improve the efficiency of collecting fluorescence in the microfluidic device. The hybrid lens integrated a laser focusing lens and a fluorescence collecting lens to achieve the dual functions and simplify the optical setups. Moreover, PDMS has advantages of low-cost and easy fabrication compared with conventional optical components. For the efficiency of focusing excitation light, the proposed hybrid lens can provide an 81.7% reduction of spot size and 93.39% efficiency enhancement of the excitation light. For the integrated efficiency of collecting fluorescence, the proposed hybrid lens can provide 85.00% and 108.42% fluorescence enhancements for Rhodamine 6G and Nile Red respectively.

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Peng, Rong-Gui, and 彭榮貴. "Design and Performance Analyses of Si and PDMS-based Micro PEMFC." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26598371384470373619.

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博士
國立交通大學
機械工程學系
99
The dissertation consists of two parts. Part one utilizes Micro- electromechanical Systems (MEMS) technology to fabricate micro Si-based proton exchange membrane fuel cell (PEMFC) and followed by carrying out a series experiments. It designs masks firstly, then, uses MEMS technology to fabricate the flow field plate. The processes include physical vapor deposition (PVD) and chemical vapor deposition (CVD), coating photo resist (PR), exposure, development, dry and wet etching. Finally, assemble the components, such as acrylic end plates, flow field plates, collector plates, gaskets and gas diffusion layer (GDL) into a cell. The active area of the membrane-electrode-assembly (MEA) is 2cm×2cm. The parameters include open ratio of flow field plates, conducting area of current collector, material of current collector and different cathode gases, respectively. The experimental results show that both the conducting area and material of current collector slices have great influence on the performance of micro PEMFC, especially the former one. The performance is better for open ratio 75% compared with those of 50 and 67%. The concentration polarization is improved by increasing the air flow rate at high current densities. Furthermore, the performance at difference operating voltages can maintain a stable power output for a long time use up to 10 hours. Part two uses dry etching process of MEMS to fabricate micro PDMS-based (Polydimethyl Siloxane) PEMFC. A series of performance experiments on a single micro PDMS PEMFC was carried out firstly. The experimental parameters included current collector shape, convection type and clamping force, respectively. Secondly, a planar PDMS-based PEMFC stack was designed and assembled to test the performance. In this test, the parameters consisted of clamping force and fuel supply condition. In addition, both the single cell and stack were tested for durability. The experimental results showed that both the performances of the air-breathing and forced convection cells increase with an increase of the circle number on the current collector under the same current collector open ratio; The forced convection cell is a better choice for long-time high current-density output, whereas the air-breathing cell is more suitable for lower current density output; An appropriate clamping torque should be considered carefully to enhance the performance but without narrowing down the fuel flow channels; The increase of flow rate is not a best way to improve the concentration loss in this air-breathing stack experiment because of the limiting air supply. Experiments also employed the thermal imager to observe the cell temperature. It was found that each cell in the same stack has different performance under series arrangement; Both the single micro PDMS fuel cell and the cell stack can maintain a stable power output for a long time use up to 14 hours. Finally, a comparison between PDMS-based PEMFC and Si-based one was made. The PDMS-based PEMFC has a better performance than that of the Si-based one under both the forced oxygen supply and air-breathing ways, because PDMS substrate with high thermal insulation can quickly evaporate the liquid water.

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Yeh, Yi-hsing, and 葉怡杏. "Novel silicon hydrogel based on PDMS-polyurethane-HEMA for contact lens application." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/38194141679201755736.

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碩士
國立臺灣科技大學
高分子系
97
A novel hydrogel based on the block copolymer of polydimethylsiloxane-polyurethane (PDMS-PU) and 2-hydroxyethyl methacrylate (HEMA) was synthesized. This novel hydrogel was consisting of soft segment of poly(dimethylsiloxane) dialkanol with hydroxyethyl propoxy end groups and hard segment of isophorone diisocyanate (IPDI). Poly(ethylene glycol) methacrylate (PEGMA) was added as the chain-extender. Finally, by reacting silicone macromer (PDMS-PU) with HEMA under UV-photopolymerization, the copolymer was resulted (PDMS-PU-HEMA). The results showed that the water content of the hydrogel increased with the HEMA content. The Young’s modulus and tensile strength of the dry hydrogel also increased with HEMA content. At a HEMA content of 40%, the oxygen permeability (Dk) would remain 77% of that of the PDMS-PU. The optical transmittance of the PDMS-PU-HEMA hydrogel remained 94% of that of PDMS-PU. Furthermore, these hydrogels were non-cytotoxic through in vitro L929 fibroblasts assay. Overall results demonstrated that the PDMS-PU-HEMA hydrogel exhibited relatively high oxygen permeability, hydrophilicity, and optical transparency, therefore would be applicable as an ophthalmic material.

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Chen, Wei-Hao, and 陳偉豪. "Novel Stretchable Ambipolar Electrochromic Devices Based on Highly Transparent Silver Nanowire/PDMS Hybrid Electrodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/up97qr.

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碩士
國立臺灣大學
高分子科學與工程學研究所
106
This study has been separated into four chapters. Chapter 1 is the general introduction. Chapter 2 includes the synthesis of silver nanowire (AgNW) with high aspect ratio, preparation of highly transparent AgNW/PDMS hybrid electrodes and the fabrication of the stretchable ambipolar electrochromic devices (ECDs) with five different EC color performance. Chapter 3 describes the stabilities studies of the AgNW/PDMS stretchable ECDs and the ways for improvement. Chapter 4 is conclusions. The synthesis of AgNW, basic characterization, fabrication parameters, optical and electrical properties, electrochemical and spectroelectrochemical properties of the novel stretchable ambipolar ECDs were investigated and improved. The AgNW/PDMS hybrid electrodes were prepared by a simple preparation process. Owning to the carefully controlled experimental conditions, the obtained stretchable electrodes showed great performance on both optical and electrical properties. Moreover, we applied these AgNW/PDMS electrode to fabricate the stretchable ECDs with five different triphenylamine (TPA) EC materials and heptyl viologen. The obtained stretchable ECDs all showed transparent at neutral state and switched to various colors according to the different redox pair under applied potential. In another part, we firstly examined the electrochemical stabilities of the above ambipolar ECDs. There were an improvement on their electrochemical stability while utilizing the ambipolar EC pair with lower redox potential. Besides, we also find out another approach for improvement by covering the exposed AgNW with electroactive EC films. By this sensible combination, we can not only increase the stability of AgNW/PDMS electrode but also get the EC behavior on these stretchable electrode.

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Yu-ChiehHsiao and 蕭宇傑. "Cleavable Peptide Synthesis on Polydimethylsiloxane (PDMS)-based Microarrays and Its Application for PKA Kinase Assay." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/45885866078939904334.

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碩士
國立成功大學
化學系
102
Solid state synthesis of cleavable peptides on the surface of gold nanoparticle-coated poly(dimethylsiloxane) (PDMS) substrate was demonstrated as an array format using a 5-mer molecule of poly-Trp5 as an example and heterobifunctional crosslinkers as the anchoring layer, t-Boc chemistry/ trifluoroacetic acid (TFA) for protection and de-protection, and reducing agents for peptide cleavage. The method was judiciously designed to use reagents and solvents that are compatible with the PDMS polymer substrate and the formation of the covalent binding during the synthesis steps were monitored by Infrared spectroscopy (IR), Atomic Force Microscopy (AFM) and Fluorescence spectroscopy. The products of each step were characterized by mass spectrometry and the final production yield of the 5-mers was estimated to be near 43%. Due to flexible molding techniques for PDMS fabrication, such peptide synthesis can be implemented inside a traditional 96-well ELISA plate or on a patterned PDMS substrate for assay developments using either the light or MS detection. We applied the method to fabricate kemptide peptide microarrays on PDMS and demonstrated that protein kinase A (PKA) could phosphorylate the serine residue by chemiluminescence detection.

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Cheng, Yu-Hung, and 鄭有宏. "Study of flexible organic light emitting diodes for functional lighting by using PDMS-based substrate." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/36297185883545356471.

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博士
國立清華大學
電機工程學系
96
The requirement for flexible electronics and functional lighting has made the design of low-cost flexible optical devices increasingly important. This study proposes a novel technology for preparing a flexible substrate for OLEDs (organic light emitting diodes), based on mechanical, electrical and optical considerations. PDMS (polydimethylsiloxane) was used as the substrate of OLEDs. Meanwhile, it can be used for a light-emitting-enhancement layer and a package layer for OLEDs. This work can be organized into three main parts. First, the substrate suitable for device fabrication was developed by mixing the PDMS substrate with various nanoparticles, to optimize the CTE (coefficient of thermal expansion) and hardness. Embedding the Al2O3 nanocomposite layer nearer the PDMS surface showed the best improvement on surface hardness. Second, a mesh structure on the emitting surface to enhance the external quantum efficiency and its fabrication process that can be applied for a large-area device with low production cost were developed. This mesh structure can be integrated with the Al2O3-embedded PDMS substrate and the electroluminance of the OLED under mechanical strain was examined. The experimental results indicate that the PDMS-based substrate with the optical structures can be successfully realized for FOLEDs (flexible organic light emitting diodes). However, such FOLEDs still suffer from short lifetime and bending instability due to relatively large CTE. Possible solutions are proposed to make this system more robust in FOLEDs applications.

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Cheng, Wei-Chih, and 鄭偉志. "Analysis of the Optical Characteristic of Photonic Crystal based on Silicon Substrate with PDMS Pillars." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/y3zwsk.

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碩士
國立虎尾科技大學
光電與材料科技研究所
103
In this thesis, the photonic crystal design software Crystal Wave ver. 3.2 is used to simulate the silicon-based substrate with etched periodically arranged holes, filled with PDMS material. Plane Wave Expansion method is used to calculate the photonic band gap, then the photonic crystal waveguide and resonant cavity is formed by crystal defects. Simulate the propagation behaviors of light using finite-difference time-domain method. Design the structure of waveguides and to compare the filter characteristics in different structures. By the simulation results, we can find out some filter structure could be suitable in optical communication devices.

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Hsu, Pei-ning, and 徐佩寧. "Fiber-optic Fabry-Pérot Interferometer Based on a PDMS Microlens on a Fiber Tip for Sensing Applications." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/g9fan5.

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碩士
國立中山大學
光電工程學系研究所
103
Fiber-optic Fabry-Pérot interferometers (FFPIs) have been widely utilized in many areas due to their advantages of compact size and high sensitivity. FFPIs have two reflective interfaces. As light propagates to the two interfaces, we can get two reflective light beams with different optical paths to form the interference spectrum. The optical path difference will be influenced by the surrounding environment. As a result, we can use the FFPIs for sensing applications. In previous studies, the FFPIs are fabricated by etching, femtosecond lasers or splicing different types of fibers. However, those fabrication processes are complicated or expensive. In this thesis, we fabricate a FFPI which is based on a Polydimethylsiloxane (PDMS) microlens on a fiber tip. It has simple and low-cost fabrication process. The PDMS microlens can function as the Fabry-Pérot cavity which is flexible and recoverable. We use the PDMS-microlens-based FFPI for sensing applications of temperature, refractive index, displacement, and tilt angle. The temperature sensitivity of the FFPI with the radius of curvature R = 130μm is 631pm/°C between 30°C~65°C. When we vary the surrounding refractive index, the intensity of interference peak will be changed. The refractive index sensitivity of the FFPI with R = 93μm is -59.61dB/RIU in the refractive index range of 1.333~1.3997. The sensitivity of displacement is -50.98nm/μm for the FFPI with R = 103μm, which is better than other displacement sensors. In the tilt angle measurement, when the tilt angle is increased, the extinction ratio is decreased. We have also found that the FFPI with smaller R has a larger critical angle. In addition, the appearances of the PDMS microlens have no change after measurement, which demonstrates that the PDMS microlens has the good recoverable property.

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Chen, Yung-Ming, and 陳永明. "A novel CNT-PDMS-based pressure and temperature sensor with resistivity retaining and recovering by using dielectrophoresis effect." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/87021663804433081257.

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碩士
國立臺灣大學
機械工程學研究所
99
In this work, we present novel resistive pressure and temperature sensors with reversible signal tracking capabilities. The sensing material was prepared by dispersing multi-walled carbon nanotubes (CNTs) and silver nano-particles through polydimethylsiloxane (PDMS) polymer with the assistance of the dielectrophoresis (DEP) technique. When the sensing element is pressed, a number of conductive CNT networks within the polymer are broken, thereby increasing the resistivity of the element. The polymer retains resistivity following the removal of the external force, and resistivity can be recovered to the original value using DEP to reform the conductive CNT networks. Similar resistivity behaviors induced by temperature elevation and DEP were also observed. This study demonstrates the performance and repeatability of the proposed sensing elements and investigates the characteristics of devices with various electrode gaps. We also fabricated flexible tactile sensor array and demonstrated image retaining and erasing capabilities. The potential applications of the sensor include reusable footstep tracking carpets, inertia switches, temperature switches, and other applications.

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Wang, Chih-Ming, and 汪志銘. "Low-cost and Flexible Atmospheric-pressure Microplasma Generation Devices as a Microreactor of CO2 Decomposition and Integrated with PDMS-based Microchannels." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/94550348891955820317.

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Pai, Jeng Yung, and 鄭永湃. "The Emulsion Polymerization and Physical Properties of EO-ended PDMS-based PUs and their Application of Water Vapor Permeability and Waterproof on Nylon Fabrics." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/69951564735087172272.

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"Study on Buckling of Stiff Thin Films on Soft Substrates as Functional Materials." Doctoral diss., 2014. http://hdl.handle.net/2286/R.I.24814.

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abstract: In engineering, buckling is mechanical instability of walls or columns under compression and usually is a problem that engineers try to prevent. In everyday life buckles (wrinkles) on different substrates are ubiquitous -- from human skin to a rotten apple they are a commonly observed phenomenon. It seems that buckles with macroscopic wavelengths are not technologically useful; over the past decade or so, however, thanks to the widespread availability of soft polymers and silicone materials micro-buckles with wavelengths in submicron to micron scale have received increasing attention because it is useful for generating well-ordered periodic microstructures spontaneously without conventional lithographic techniques. This thesis investigates the buckling behavior of thin stiff films on soft polymeric substrates and explores a variety of applications, ranging from optical gratings, optical masks, energy harvest to energy storage. A laser scanning technique is proposed to detect micro-strain induced by thermomechanical loads and a periodic buckling microstructure is employed as a diffraction grating with broad wavelength tunability, which is spontaneously generated from a metallic thin film on polymer substrates. A mechanical strategy is also presented for quantitatively buckling nanoribbons of piezoelectric material on polymer substrates involving the combined use of lithographically patterning surface adhesion sites and transfer printing technique. The precisely engineered buckling configurations provide a route to energy harvesters with extremely high levels of stretchability. This stiff-thin-film/polymer hybrid structure is further employed into electrochemical field to circumvent the electrochemically-driven stress issue in silicon-anode-based lithium ion batteries. It shows that the initial flat silicon-nanoribbon-anode on a polymer substrate tends to buckle to mitigate the lithiation-induced stress so as to avoid the pulverization of silicon anode. Spontaneously generated submicron buckles of film/polymer are also used as an optical mask to produce submicron periodic patterns with large filling ratio in contrast to generating only ~100 nm edge submicron patterns in conventional near-field soft contact photolithography. This thesis aims to deepen understanding of buckling behavior of thin films on compliant substrates and, in turn, to harness the fundamental properties of such instability for diverse applications.
Dissertation/Thesis
Ph.D. Mechanical Engineering 2014

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Wells, Elizabeth Christine. "Fluidic Tuning of a Four-Arm Spiral-Based Frequency Selective Surface." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9403.

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Abstract:

Frequency selective surfaces (FSSs) provide a variety of spatial filtering functions, such as band-pass or band-stop properties in a radome or other multilayer structure. This filtering is typically achieved through closely-spaced periodic arrangements of metallic shapes on top of a dielectric substrate (or within a stack of dielectric materials). In most cases, the unit cell size, its shape, the substrate parameters, and the inter-element spacing collectively impact the response of the FSS. Expanding this design space to include reconfigurable FSSs provides opportunities for applications requiring frequency agility and/or other properties. Tuning can also enable operation over a potentially wider range of frequencies and can in some cases be used as a loading mechanism or quasi-ground plane. Many technologies have been considered for this type of agility (RF MEMS, PIN diodes, etc.). This includes the recent use of microfluidics and dispersions of nanoparticles, or fluids with controllable dielectrics, which have entered the design space of numerous other EM applications including stub-tuners, antennas, and filters. In this work they provide a material based approach to reconfiguring an FSS. An FSS based on a four-arm spiral with tunable band-stop characteristics is presented in this work. A thin colloidal dispersion above each element provides this tuning capability. The radial expansion and contraction of this dispersion, as well as the variable permittivity of the dispersion, are used to load each element individually. This design incorporates thin fluidic channels within a PDMS layer below the substrate leading to individual unit cells that provide a closed pressure-driven subsystem that contains the dispersion. With the capability to individually control each cell, groups of cells can be locally altered (individually or in groups) to create gratings and other electromagnetically agile features across the surface or within the volume of a radome or other covering. Simulations and measurements of an S-band tunable design using colloidal Barium Strontium Titanate dispersed Silicone oil are provided to demonstrate the capability to adjust the stop-band characteristics of the FSS across the S-band.

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Dissertations / Theses on the topic 'PDMS-based'

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