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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

High temperature supercapacitors

Black, Victoria J. January 2013 (has links)
The scientific objective of this research program was to determine the feasibility of manufacturing an ionic liquid-based supercapacitor that could operate at temperatures up to 220 °C. A secondary objective was to determine the compatibility of ionic liquids with other cell components (e.g. current collectors) at high temperature and, if required, consider means of mitigating any problems. The industrial motivation for the present work was to develop a supercapacitor capable of working in the harsh environment of deep offshore boreholes. If successful, this technology would allow down-hole telemetry under conditions of mechanical vibration and high temperature. The obstacles, however, were many. All supercapacitor components had to be stable against thermal decomposition up to T ≥ 220 °C. Volatile components had to be eliminated. If possible, the finished device should be able to withstand voltages greater than 4 V, in order to maximise the amount of stored energy. The internal resistance should be as low as possible. Side reactions, particularly faradaic reactions, should be eliminated or suppressed. All liquid components should be gelled to minimise leakage in the event of cell damage. Finally, any emergent problems should be identified.
52

Inks based on inorganic nanomaterials for printed electronics applications

Nelo, M. (Mikko) 24 November 2015 (has links)
Abstract In this thesis several novel inks based on dry inorganic powders enabling magnetic, piezoelectric and memory resistive (memristive) function were researched for printed electronics applications. Low curing temperature screen–printable magnetic inks for high frequency applications based on dry cobalt nanoparticles were developed in the first part of the work. Three publications were achieved. The first one concentrated on ink formulation and its process development, the second on the utilization of multifunctional surfactant, and the third on the development of the inks for plastic substrates. The magnetic inks developed were cured at 120 °C. The electrical performance, microstructure, surface quality and mechanical durability of printed and cured layers were investigated. Relative permeability values up to 3 and related loss tangents up to 0.01 were achieved at 2 GHz frequency, as well as a pull–off strength of up to 5.2 MPa. The maximum loading level of cobalt nanoparticles was 60 vol–%, after which the stability of the ink started to degrade. The developed ink enabled the miniaturization of a patch antenna. In the second part of the thesis, the formulation of inks based on piezoelectric ceramic particles in powder form with ferroelectric polymers as a matrix material is introduced. The performance and quality of the printed inks and cured layers were investigated. The measured pull off –strength was up to 3.25 MPa, relative permittivity was up to 48 at 1 kHz and piezoelectric constant d31 up to 17 pm/V. The printed piezoelectric layer can be utilized in a pressure sensor. In the third part of the thesis, the development of inks for a novel printed memory component, a memristor, is researched. A synthesis route was developed for an organometallic precursor solution, which was formulated into inkjet–printable form. The printing tests were carried out in order to find the most feasible layer thickness with memristive behaviour. The influence of substrate materials and different thermal treatments on the components’ electrical properties, durability of read/erase –cycles and overall lifetime were also investigated. The prepared memristive patterns remained functional for up to 35 days, while the precursor solution remained usable for over a year. The memristive areas withstood up to 30 read/erase cycles and by utilizing heat treatments the shift in resistance value increased by up to three orders of magnitude. / Tiivistelmä Väitöstyössä kehitettiin epäorgaanisten kuivien jauhemaisten materiaalien pohjalta magneettisia, pietsosähköisiä ja memristiivisiä musteita käytettäviksi painettavan elektroniikan sovelluksissa. Työn ensimmäisessä osassa tutkittiin korkean taajuuden sovelluksissa käytettävien magneettisten, matalassa lämpötilassa kovetettavien, jauhemaisiin kobolttinanopartikkeleihin perustuvien silkkipainomusteiden valmistamista. Tulokset on esitetty kolmessa julkaisussa, joista ensimmäinen keskittyi musteen formulointiin, toinen monifunktionaalisen surfaktantin hyödyntämiseen ja kolmas musteen kehittämiseen muovialustalle sopivaksi. Työssä kehitettiin 120 °C:ssa kovettuvia musteita, joista valmistettujen kalvojen suhteellisen permeabiliteetin maksimiarvoksi saatiin 3 ja häviöiden minimiarvoksi 0,01 kahden gigahertsin taajuudella. Pull–off –vetotestin tulokseksi saatiin jopa 5,2 MPa. Musteet säilyivät vakaina enimmillään 60 tilavuusprosentin metallipitoisuudella. Kehitettyä mustetta käytettiin tasoantennin miniatyrisoinnissa. Toisessa osassa kehitettiin pietsosähköisiä musteita, jotka pohjautuivat keraamijauheeseen ja matriisimateriaalina toimivaan ferrosähköiseen muoviin. Niistä valmistettujen kalvojen parhaaksi pull off –vetotestin tulokseksi saatiin 3,25 MPa, permittiivisyyden maksimiarvoksi 48 yhden kilohertsin taajuudella ja d31–pietsovakion maksimiarvoksi jopa 17 pm/V. Kehitettyjä painettuja rakenteita voidaan käyttää painettavissa paineantureissa. Kolmannessa osassa kehitettiin uudentyyppinen painettava muistikomponentti, memristori ja komponenttien valmistamiseksi uusi prekursoriliuoksen synteesi. Syntetisoitu liuos muokattiin mustesuihkutulostettavaksi. Painokokeiden avulla selvitettiin materiaalin paksuus, jolla saatiin aikaan muistivastukselle ominainen memristiivinen käyttäytyminen. Työssä tutkittiin substraattimateriaalien ja mahdollisten lämpökäsittelyjen vaikutusta komponenttien sähköisiin ominaisuuksiin, luku/kirjoitussyklien kestoon sekä käyttöikään. Valmistetut memristiiviset kalvot säilyivät toimivina 35 vuorokautta ja prekursoriliuos yli vuoden. Memristiiviset pinnat kestivät jopa 30 luku/kirjoitussykliä ja vastusarvon muutos saatiin lämpökäsittelyllä kolmea kertaluokkaa suuremmaksi.
53

Conception d'un dispositif de pesage innovant pour véhicule en mouvement et fabrication de transducteurs en couches épaisses / Designing of an innovative wheigh-in-motion device and manufacturing of thick-film transducers

Coudouel, Denis 24 October 2013 (has links)
Cette thèse de doctorat porte sur l'étude et la réalisation d'une plateforme de pesage dynamique pour véhicule roulant basée sur un concept d'intégration de la charge. Ce concept est mis en œuvre en vue de pouvoir minimiser la taille et l'encombrement de ce type de dispositif tout en effectuant des pesées présentant des caractéristiques métrologiques acceptables. Nous démontrons tout d'abord au travers de la réalisation d'un prototype et de plusieurs campagnes d'essais, la faisabilité de la méthode utilisée. Nous évaluons dans un deuxième temps les performances présentées par le prototype lors du pesage de véhicules légers roulant jusqu'à des vitesses de 35km/h. Une étude est ensuite menée sur les jauges de déformation piézorésistives et les jauges piézoélectriques réalisées en couches épaisses grâce à des techniques de sérigraphie. Nous caractérisons ces transducteurs avec pour objectif leur utilisation dans des dispositifs de pesage en remplacement des jauges de déformation classiques à filaments métalliques. / This PhD thesis is devoted to the study and implementation of a weigh-in-motion platform for vehicle based on a concept of integration of load. This concept is used to minimize the size of this kind of device while performing weighings with acceptable results. First, we show thanks to a protoype and several test campagns, the feasability of the method used. In a second time, we evaluate the performances of the prototype in terms of precision and repeatability with the dynamic weighing of vehicles at speeds up to 35km/h. A study is finally conducted on thick-film piezoresitive strain gauges and piezoelectric gauges manufacturing by a screen-printing process with cermet and polymer pastes. We characterize these tranducers with the goal of used them as an alternative of conventional foil strain gauges.
54

Studium vlivu dielektrika na optoelektronické vlastnosti elektroluminiscenčních zařízení / Study of the influence of the dielectrics on the optoelectronic properties of electroluminescent devices

Foldynová, Klára January 2019 (has links)
This diploma thesis is studing the possibilities of influencing the optoelectric properties of printed light emitting panels, which work on the principle of electroluminescence excited by alternating electric field. The aim of this worrk is to monitor the influence od dielectric properties of electroluminescent phosphor binder on the targeted electroluminescence. In the theoretical part of this thesis, there are described principles of electroluminescence, suitable materials methods of characterization and preparation of panels using printing techniques. Experiment part contains electrical characterization of selected binders to determine their dielectric constants. Subsequently, printing pastes were formulated in different weight ratios of binder electroluminescent phosphor and model light-emitting panels were prepared. Optoelectric characterization was used to determine the change in irradiance. It was found that the dielectric properties of the binder significantly affect the resulting irradinace. It has same irradiance for a smaller amount od phosphor than with the binder with a low dielectric constant. The finding of this work can be used to improve the luminosity at the electroluminescent panels.
55

Printed Biosensor Based on Organic Electrochemical Transistor / Printed Biosensor Based on Organic Electrochemical Transistor

Omasta, Lukáš January 2019 (has links)
Organické elektronické zariadenia sú vyvíjané ako vhodné riešenia senzorov pre bioelektroniku, a to najmä kvôli dobrej biokompatibilite organických polovodičov v nich použitých. Takzvané biosenzory dokážu premeniť elektrochemické procesy na elektronický signál. Matrica takýchto biosenzorov môže simultánne skenovať množstvo biologických vzoriek, alebo rôznych tkanív v živých systémoch. Aktívnou súčasťou zariadenia je organický elektrochemický tranzistor (OECT). V tejto práci je diskutovaný teoretický rámec fungovania takéhoto zariadenia, jeho elektrická charakterizácia, aplikácia v biosenzoroch na báze buniek, spôsoby výroby a aktuálnym stavom techniky v oblasti organickej elektroniky. Experimentálna časť obsahuje konkrétne výrobné postupy vývoja OECT zariadení, ktoré boli použité v našom laboratóriu. Hlavný dôraz sa kladie na schopnosť vyrobených zariadení detekovať reakciu a monitorovať stimuláciu elektrogenných buniek. Za týmto účelom boli vyvinuté matice mikroelektródových OECT zariadení založených na polovodivom polyméri PEDOT:PSS. Tieto boli vyrobené s využitím bežnými tlačiarenských techník (atramentová tlač a sieťotlač) spolu so štandardnými litografickými postupmi. Najnovšie nami vyvinuté zariadenia dosahujú najväčšieho zosílením signálu, g = 2,5 mS a časovú konštantu t = 0,15 s. Tieto zariadenia sú porovnateľné, často dokonca lepšie ako niektoré iné najmodernejšie a plne litograficky pripravené senzory.
56

Návrh a realizace struktur s vnořenými komponenty / Design and Realization of Structures with Embeded Components

Němec, Tomáš January 2011 (has links)
The master thesis deals with multilayer structures and thick film technology. The main goal of this work is measure basic electric features of structures realized with thick film technology. The results will make possible more accurate design of these structures.
57

Développement d'immunoessais associés aux électrodes sérigraphiées: des particules superparamagnétiques aux nanobodies

Patris, Stéphanie 19 November 2014 (has links)
Cette thèse a pour vocation de contribuer au développement de différents immunocapteurs ampérométriques associés aux électrodes sérigraphiées (SPE). Les immunocapteurs sont des dispositifs simples associant un anticorps ou un antigène qui assurent la sélectivité à un transducteur (ici une SPE) ;ce dernier transforme la liaison anticorps/antigène en un signal mesurable (ici ampérométrique).<p>Le travail est divisé en deux volets principaux.<p>Le premier est consacré à la mise en œuvre de différents modèles d’immunocapteurs ampérométriques pour le dosage d’anticorps anti-tetani. La vaccination contre le tétanos est généralisée, toutefois pour maintenir un taux d’anticorps suffisant, il est indispensable d’administrer un rappel tous les 10 ans. Ce schéma vaccinal n’est pas toujours respecté, ce qui a pour conséquence qu’une partie de la population n’est plus protégée. Afin de déterminer le statut immunitaire du patient, il est indispensable de pouvoir déterminer le taux d’anticorps. Les immunocapteurs ampérométriques répondent à cet objectif. Plusieurs stratégies d’immobilisation de l’anatoxine tétanique (antigène) sur une SPE ont été mises en œuvre et comparées. L’une d’elles repose sur l’utilisation de microparticules superparamagnétiques pour la réaction immunologique et d’une SPE rendue magnétique par un support aimanté pour la mesure. D’autres reposent sur l’immobilisation de l’antigène et les réactions immunologiques directement à la surface de la SPE. L’utilisation de plans d’expérience, pour l’optimisation des immunoessais sur SPE est également exploitée dans ce travail. Les immunocapteurs développés ont permis de doser les anticorps anti-tetani dans le sérum de cobaye en dessous des valeurs considérées comme protectrices.<p>Dans le second volet, un immunocapteur basé sur l’utilisation de nanobodies® (NB) a été mis au point. Nous avons qualifié ce type d’immunocapteur original de nanoimmunocapteur. Le récepteur de facteur de croissance épidermique humain (HER2) a été utilisé comme cible. La protéine HER2 est considérée comme un biomarqueur important car sa surexpression provoque un type agressif de cancer du sein. Les NB sont des fragments à domaine unique dérivés d'anticorps à chaînes lourdes de camélidés. La stratégie de dosage immunologique en sandwich développée a tiré profit de la petite taille des NB pour la détection du marqueur électroactif d’oxydoréduction. La stabilité élevée des NB immobilisés a permis une durée de stockage des SPE modifiées supérieure à 3 semaines. De très courtes durées d'incubation étaient suffisantes pour obtenir une réponse satisfaisante. Le nanoimmunoessai a permis de déterminer le taux d’HER2 dopé dans des lysats cellulaires.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished
58

Reveal

Simmons, Kathryn Elizabeth 17 June 2021 (has links)
No description available.
59

Entwicklung und Charakterisierung piezokeramischer Dickschichten mit hohem aktorischen Potenzial für aktive Mikrosysteme

Ernst, Dörthe 04 December 2023 (has links)
Siebgedruckte piezokeramische Dickschichten eignen sich für Sensoren, Aktoren oder Ultraschallwandler. Zur Auslegung von Dickschicht-Aktoren werden grundlegende Kenntnisse über die elektromechanischen Eigenschaften benötigt. Diese Arbeit beschreibt die elektromechanischen Eigenschaften piezokeramischer Dickschichten unter Klein- und Großsignalbedingungen. Durch gezielte Variationen der Biegerlänge und Materialien werden Einflüsse auf die Gefügeentwicklung, das Arbeitsvermögen und weitere elektromechanische Kennwerte beschrieben und optimale Herstellungsparameter identifiziert. Interdigitalelektroden (IDE) ermöglichen die Polarisation und Ansteuerung der piezokeramischen Schicht in der Ebene (in-plane). Aufgrund des d 33 -Effektes kommt es zur Dehnung in der Ebene, woraus eine Verdopplung der Biegung in entgegengesetzter Richtung zu through-thickness-Aktoren resultiert. In der Arbeit wird das Arbeitsvermögen siebgedruckter in-plane-Biegeaktoren in Abhängigkeit vom Substratmaterial, von der Biegerlänge und vom piezokeramischen Material beschrieben und diskutiert. An zwei Mikropositioniersystemen wird die Eignung piezokeramischer Dickschichtaktoren für adaptive optische Systeme gezeigt.
60

Thin Indium Tin Oxide Layer Development for Crystalline Silicon/Perovskite Two Terminal Tandem Solar Cell

Srinivasachari, Aravind January 2023 (has links)
ITO is widely regarded as the optimal TCO for serving as front window layer in PSK/c-Si tandem solar cells. It is known to effectively mitigate several stability issues present in perovskite solar cells while demonstrating excellent lateral conductivities and optical transparency across the entire solar spectrum. However, due to the damaging effects of traditional magnetron sputtering methods on the underlying cell precursor and the limited range of annealing temperatures viable for maintaining the stability of Perovskite Solar cells, realizing the full capability of ITO layer is constrained. This investigation focuses on developing and optimizing the front Indium Tin Oxide (ITO) layer properties for high-efficiency monolithic Perovskite/PERC tandem solarcells. The study employs two widely employed industrial techniques, Magnetron Sputtering and Screen Printing for the deposition of ITO thin-films and subsequent metallization of Ag front contacts. The sputtering process parameters, namely the carrier speed, O2 : Ar ratio, and the sputter power were varied to obtain an optimized ITO layer, which exhibited a thickness of 53nm, Rsheet of 107 ohm/□, mobility of 37 cm2/V s, and 90 % average optical transparency between 400−1200nm. A low contact resistivity of 5.4mΩ·cm2 was achieved between the ITO and metal contacts which is the lowest reported value for ITO annealed at low temperature (140 °C). Champion cells, featuring Perovskite on Ohmic substrate and 2T perovskite/PERC tandem cells, exhibited high VOC values of 1.116 V and 1.75 V on 0.97 cm2 cell aperture areas and cell efficiencies of 17.2 % and 23.85 %. Additionally, a large area (158.7 cm2) tandem cell was also fabricated which demonstrated an excellent VOC of 1.75 V . The results of this investigation demonstrates the versatility of ITO layer properties achievable at low-temperatures through Magnetron sputtering and underscores the potential of existing commercialized technologies for the fabrication of high-efficiency tandem solar cells. / ITO anses allmänt vara den optimala TCO för användning som frontfönsterskikt i PSK/c-Si tandemsolceller. Den är känd för att effektivt mildra flera stabilitetsproblem som finns i perovskitsolceller samtidigt som den uppvisar utmärkt lateral konduktivitet och optisk transparens över hela solspektrumet. På grund av de skadliga effekterna av traditionella magnetronförstoftningsmetoder på den underliggande cellprekursorn och det begränsade intervallet av glödgningstemperaturer som är användbara för att upprätthålla stabiliteten hos perovskitsolceller, begränsas dock ITO-skiktens fulla kapacitet. Denna undersökning fokuserar på att utveckla och optimera egenskaperna hos det främre Indium Tin Oxide (ITO)-skiktet för högeffektiva monolitiska Perovskite/PERC tandemsolceller. I studien används två allmänt använda industriella tekniker, magnetronförstoftning och screentryckning, fördeponering av ITO-tunnfilmer och efterföljande metallisering av Ag-frontkontakter. Parametrarna för sputteringsprocessen, nämligen bärarhastigheten, förhållandet O2 : Ar och sputterkraften varierades för att få ett optimerat ITO-lager, som uppvisade en tjocklek på 53nm, Rsheet på 107 ohm/□, rörlighet på 37 cm2/V s och 90 % genomsnittlig optisk transparens mellan 400 − 1200 nm. En låg kontaktresistivitet på 5.4mΩ.cm2 uppnåddes mellan ITO och metallkontakterna, vilket är de lägstarapporterade värdena för ITO glödgat vid låg temperatur (140 °C). Champion-cellerna, med perovskit på ohmskt substrat och 2T perovskit/PERC tandemkonfigurationer, uppvisade höga VOC-värden på 1.116 V och 1.75 V på 0.97 cm2 cellaperturområden och cellverkningsgrader på 17.2 % och 23.85 %. Dessutom tillverkades en tandemcell med stor area (158.7 cm2) som uppvisade en utmärkt VOC på 1.75 V . Resultaten av denna undersökning visar mångsidigheten hos ITO-skiktets egenskaper som kan uppnås vid låga temperaturer genom magnetronförstoftning och understryker potentialen hos befintliga kommersialiserade tekniker för tillverkning av högeffektiva tandemsolceller.

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