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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.
31

Droplet Deposition in Solid Ink Printing

Li, Ri 20 January 2009 (has links)
Introduced in 1991, solid ink color printing technology is widely used in the office printing, prepress proofing, and wide format color printing markets. Ink droplets are first deposited on a rotating drum and then transferred to paper to reproduce images with high print quality. The objective of this thesis is to develop scientific knowledge of ink droplet deposition, which is needed for precise image buildup on the drum surface. The first problem studied in the thesis is droplet formation from the printhead with varied working voltages and jetting frequencies. Attention is paid to the formation of satellite droplets, the contraction of ligaments and the startup of high frequency jetting. The jetting conditions for obtaining consistent droplet generation with satellites are determined. A theoretical model is developed to predict the lifetime of ligaments. The second problem we studied is the deposition of single droplets on solid surfaces. The surface texture and final shape of deposited droplets are correlated with impact conditions, which include printhead temperature, substrate temperature, distance from printhead to substrate, and the type of substrate surface. An analytical model is developed to evaluate the interaction of oscillation and viscous damping in the droplet during impact. The third problem covered in the thesis is the deposition of multiple ink droplets on the drum surface. Interaction between droplets causes drawback effect, which degrades print quality. We define a parameter to quantify the drawback effect with varied deposition conditions. A simple model is provided to predict conditions for making continuous lines based on the results of two ink droplets deposition. To understand the hydrodynamics in causing drawback effect, a series of experiments using large liquid droplets are carried out. Focus is put on the evolution of spread length and dynamics of contact line. Correlations for maximum and minimum spread lengths are developed, which are used to reveal the cause of drawback effect in the deposition of ink droplets.
32

Microstructuring inkjet-printed deposits from silver nanoparticules coalescence to the fabrication of interconnections for electronic devices.

Cauchois, Romain 07 February 2012 (has links) (PDF)
Several challenges are still holding back the technological transfer of printed electronics to industry in spite of recent progresses. In this thesis work, the printing method of inks based on silver nanoparticles (<Ø>=25 nm) was optimized according to its rheology and to the fluid/substrate interactions for the fabrication of electrical interconnections with a thickness of 500 nm. These lines were printed on silicon or flexible substrates and annealed either by conventional (oven or infrared) or selective methods (microwave) at temperatures comprised between 100 and 300 °C.A better understanding of the relationship between process and microstructure of these printed thin films, based on several crystallographic equipments (XRD, EBSD and EDX), led to the optimization of nanocrystallites growth with an activation energy of about 3 to 5 kJ*mol-1. In addition to the low residual stress (70 MPa), this optimization is used to achieve low electrical resistivity (3.4 μOhm*cm) associated with a greater coherence of the crystal lattices at grain boundaries. The probability of electron scattering at such interfaces can be further reduced using an innovative approach of oriented crystallite growth by atomic interdiffusion from the substrate.The low mechanical stiffness (E<50 GPa) of these porous lines requires a reinforcement step either by crystalline texturation or by electroless growth to withstand the assembly and wire-bonding steps. The fabrication of a functional demonstrator thus validated the printing technology for the manufacture of electronic components.
33

Inkjet and Screen Printed Electrochemical Organic Electronics

Mannerbro, Richard, Ranlöf, Martin January 2007 (has links)
Linköpings Universitet och Acreo AB i Norrköping bedriver ett forskningssamarbete rörande organisk elektrokemisk elektronik och det man kallar papperselektronik. Målet på Acreo är att kunna trycka denna typ av elektronik med snabba trycktekniker så som offset- eller flexotryck. Idag görs de flesta demonstratorer och prototyper, baserade på denna typ av elektrokemisk elektronik, med manuella och subtraktiva mönstringsmetoder. Det skulle vara intressant att hitta fler verktyg och automatiserade tekniker som kan underlätta detta arbete. Målet med detta examensarbete har varit att utvärdera vilken potential bläckstråleteknik respektive screentryck har som tillverkningsmetoder för organiska elektrokemiska elektroniksystem samt att jämföra de båda teknikernas för- och nackdelar. Vad gäller bläckstråletekniken, så ingick även i uppgiften att modifiera en bläckstråleskrivare avsedd för kontor/hemmabruk för att möjliggöra tryckning av de två grundläggande materialen inom organisk elektrokemisk elektronik - den konjugerade polymeren PEDOT och en elektrolyt. I denna uppsats rapporteras om hur en procedur för produktion av elektrokemisk elektronik har utvecklats. Världens första elektrokemiska transistor som producerats helt med bläckstråleteknik presenteras tillsammans med fullt fungerande implementeringar i logiska kretsar. Karaktärisering av filmer, komponenter och kretsar som producerats med bläckstråle- och screentrycksteknik har legat till grund för den utvärdering och jämförelse som har gjorts av teknikerna. Resultaten ser lovande ut och kan motivera vidare utveckling av bläckstrålesystem för produktion av prototyper och mindre serier. En kombination av de båda nämnda teknikerna är också ett tänkbart alternativ för småskalig tillverkning. / Linköping University and the research institute Acreo AB in Norrköping are in collaboration conducting research on organic electrochemical electronic devices. Acreo is pushing the development of high-speed reel-to-reel printing of this type of electronics. Today, most demonstrators and prototypes are made using manual, subtractive patterning methods. More tools, simplifying this work, are of interest. The purpose of this thesis work was to evaluate the potential of both inkjet and screen printing as manufacturing tools of electrochemical devices and to conduct a comparative study of these two additive patterning technologies. The work on inkjet printing included the modification of a commercially available desktop inkjet printer in order to print the conjugated polymer PEDOT and an electrolyte solution - these are the two basic components of organic electrochemical devices. For screen printing, existing equipment at Acreo AB was employed for device production. In this report the successful development of a simple system and procedure for the inkjet printing of organic electrochemical devices is described. The first all-inkjet printed electrochemical transistor (ECT) and fully functional implementations of these ECTs in printed electrochemical logical circuits are presented. The characterization of inkjet and screen printed devices has, along with an evaluation of how suitable the two printing procedures are for prototype production, been the foundation of the comparison of the two printing technologies. The results are promising and should encourage further effort to develop a more complete and easily controlled inkjet system for this application. At this stage of development, a combination of the two technologies seems like an efficient approach.
34

High-gain millimeter-wave antenna design and fabrication using multilayer inkjet printing processes

Tehrani, Bijan K. 08 June 2015 (has links)
The research provided in this thesis focuses on the development of high-gain multilayer millimeter-wave (mm-Wave) antenna structures through additive inkjet printing fabrication processes. This work outlines the printing processes of thick dielectric films for use as printed radio frequency (RF) substrates and provides a proof-of-concept demonstration of the first fully-printed RF structures. Using the outlined processes, demonstrations of high-gain mm-Wave proximity-coupled patch array and Yagi-Uda array antennas are presented, achieving the highest realized gain within the 24.5 GHz ISM band for inkjet-printed antennas in literature.
35

Inkjet-assisted printing of encapsulated polymer/biopolymer arrays

Suntivich, Rattanon 27 August 2014 (has links)
The goal of the proposed study is to understand the morphology, physical, and responsive properties of synthetic polymer and biopolymer layer-by-layer (LbL) arrays using the inkjet printing and stamping technique, in order to develop patterned encapsulated thin films for controlled release and biosensor applications. In this study, we propose facile fabrication processes of hydrogen-bonded and electrostatic LbL microscopic dot arrays with encapsulated target organic and cell compounds. We study encapsulation with the controllable release and diffusion properties ofpoly(vinylpyrrolidone) (PVPON), poly(methacrylic acid) (PMAA), silk-polylysine, silk-polyglutamic acid, pure silk films, and E-coli cells from the multi-printing process. Specifically, we investigate the effect of thickness, the number of bilayers, and the hydrophobicity of substrates on the properties of inkjet/stamping multilayer films such as structural stability, responsiveness, encapsulation efficiency, and biosensing properties. We suggest that a more thorough understanding of the LbL assembly using inkjet printing and stamping techniques can lead to the development of encapsulation technology with no limitations on either the concentration of loading, or the chemical and physical properties of the encapsulated materials. In addition, this study offers new encapsulation concepts with simple, cost effective, highly scalable, living cell-friendly, and controllable patterning properties.
36

Inkjet-printed RF modules for sensing and communication applications

Lee, Hoseon 13 January 2014 (has links)
The objective of the proposed research is to integrate nanotechnology, applied electromagnetics, and inkjet printing fabrication methods to develop a series of novel inkjet-printed RF modules for sensing and communication applications: wireless gas sensor, wearable RFID tag, and RF inductor. Passive, wireless sensors have various applications in a wide range of fields including military, industry, and medicine. However, there are issues such as cost, sensitivity of sensors, manufacturing complexities, and feasibility of further miniaturization of these RF modules. One aspect of this research investigates the feasibility of addressing these issues by integrating nanotechnology and applied electromagnetics. The underlying common theme for the three designs is inkjet-printing silver nanoparticles on organic paper substrate. The research will investigate the characterization of thin film carbon nanotubes and the optimization of inkjet-printing the CNT material on paper substrate followed by the design of a patch antenna based gas sensor. Measurement results from a closed measurement system will be shown. Secondly, an inkjet-printed, conformal, wearable RFID tag on an artificial magnetic conductor is designed and tested using an RFID Reader. Lastly an inkjet-printed high Q RF inductor is designed and integrated with magnetic nanomaterial to evaluate the feasibility of increasing inductance using high permeability nanomaterial. Through the design and testing of the aforementioned three designs, it will be shown that through a multidisciplinary design process, novel, low-cost RF modules can be designed for sensing and communication applications.
37

Inkjet-printed sensors and via-enabled structures for low-cost autonomous wireless platforms

Kim, Sangkil 12 January 2015 (has links)
Fundamental research to implement the printed autonomous wireless sensor platform is studied in three aspects: fabrication method, material selection, and novel applications for autonomous sensing/communication. Additive fabrication processes, such as inkjet printing technology and electroless electroplating, are discussed and the additively created metal layers are characterized. Fundamentals for material characterization utilizing resonators are presented and electrical properties of flexible low-cost substrates like synthetic Teslin paper and Poly(methyl methacrylate) (PMMA) are characterized. Widely used flexible substrates for printing, such as Liquid Crystal Polymer (LCP) and Kapton (polyimide), are summarized and tabulated as well. Novel antenna-based applications for efficient and autonomous operation of wireless sensor system, such as an antenna on Artificial Magnetic Conductor (AMC) for wearable applications, an active beacon oscillator for Wireless Power Transfer (WPT), and a multiband RF energy harvester, are designed and their performances are experimentally verified. The printed RFID-enabled sensor topologies with/without RFID chip are discussed as a new sensor platform for autonomous wireless operation. Fully inkjet-printed via topology for system miniaturization and integration is proposed for the first time. Challenges, circuit modeling and experimental data are presented. Future and remaining work to implement the novel low-cost autonomous wireless sensor platform are also discussed.
38

Printable Biosensors based on Organic Electrochemical Transistors with a Platinized Gate Electrode / Tryckbara biosensorer baserade på organiska elektrokemiska transistorer med en platinerad gate-elektrod

Broman, Eva January 2012 (has links)
There is a great demand for low-cost disposable sensors in a variety of markets, such as the food chainand health care. No assay is performed more than that of glucose and approximately 85 % of the entirebiosensor market accounts for glucose biosensors. Each year, 6 billion glucose assays are performed andthe majority of them are based on electrochemical detection. Organic electrochemical transistors(OECTs) have favorable properties in terms of low operating voltages and have previously been used asbase for electrochemical detection of glucose. A low-cost disposable biosensor can be achieved by theuse of high throughput printing techniques. Up until now, no printable biosensors based on organic electrochemicaltransistors have been developed. In this thesis a printable miniaturized prototype for a glucose biosensor based on an OECT with a platinizedgate electrode has been designed, developed and evaluated. The biosensor has been functionalizedwith the enzyme glucose oxidase. Different platinum deposition techniques have been used to depositplatinum onto the printed carbon gate electrode: electrodeposition, platinum nanoparticle solutiondeposited either by inkjet printing or pipetting and thermal evaporation. The gate electrodes were characterized with cyclic voltammetry in hydrogen peroxide, ferricyanide andglucose. The characterizations revealed no significant differences between the different deposition techniques.However, with gate electrodes produced by printed carbon followed by electrodeposition ofplatinum it was possible to sense glucose in a concentration in the range of the values for diabetic persons.Thus, the electrodes are a promising option as gate electrodes in a glucose biosensor based on anOECT. The characteristics of the OECT revealed that the responses resembled a transistor.
39

Inorganic and Organic Photovoltaic Materials for Powering Electrochromic Systems

January 2018 (has links)
abstract: ABSTRACT Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. Here, we describe the processing and performance of two classes of visibly-transparent photovoltaic materials, namely inorganic (ZnO thin film) and fully organic (PCDTBT:PC70BM), for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on ITO, with transparency in the visible range, were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor (MIS), and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fitted against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0×1011 eV−1cm−2) and neutral level (Eo ≈ -5.2 eV). These devices exhibited photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors exhibited responsivity (R) and photoconductive gain (G) of 1.93×10−4 A/W and 6.57×10−4, respectively. Confirmed via matched-pair analysis, post-metallization, oxygen plasma treatment of Ag and Ti/Ag electrodes resulted in increased Schottky barrier heights, which maximized with a 2 nm SiO2 electron blocking layer (EBL), coupled with the suppression of recombination at the metal/semiconductor interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm2. A fully organic bulk heterojunction photovoltaic device, composed of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyli2’,1’,3’-benzothiadiazole)]:phenyl-C71-butyric-acidmethyl (PCDTBT:PC70BM), with corresponding electron and hole transport layers, i.e., LiF with Al contact and conducting/non-conducting (nc) PEDOT:PSS (with ITO/PET or Ag nanowire/PDMS contacts; the illuminating side), respectively, was developed. The PCDTBT/PC70BM/PEDOT:PSS(nc)/ITO/PET stack exhibited the highest performance: power conversion efficiency (PCE) ≈ 3%, Voc = 0.9V, and Jsc ≈ 10-15 mA/cm2. These stacks exhibited high visible range transparency, and provided the requisite power for a switchable electrochromic stack having an inkjet-printed, optically-active layer of tungsten trioxide (WO3), peroxo-tungstic acid dihydrate, and titania (TiO2) nano-particle-based blend. The electrochromic stacks (i.e., PET/ITO/LiClO4/WO3 on ITO/PET and Ag nanowire/PDMS substrates) exhibited optical switching under external bias from the PV stack (or an electrical outlet), with 7 s coloration time, 8 s bleaching time, and 0.36-0.75 optical modulation at λ = 525 nm. The devices were paired using an Internet of Things controller that enabled wireless switching. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018
40

Estudo de supercapacitores orgânicos impressos em papel à base de PEDOT:PSS / Study of organic supercapacitors printed onto paper based on PEDOT:PSS

Klem, Maykel dos Santos [UNESP] 27 September 2017 (has links)
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49804b0b4c75b954b2c9c7e4aa93265e (MD5) / Submitted by Maykel dos Santos Klem null (maykel_klem@hotmail.com) on 2017-11-28T12:13:07Z No. of bitstreams: 1 Dissertação_mestrado_Maykel.pdf: 4072759 bytes, checksum: 49804b0b4c75b954b2c9c7e4aa93265e (MD5) / Submitted by Maykel dos Santos Klem null (maykel_klem@hotmail.com) on 2017-11-28T14:22:46Z No. of bitstreams: 1 Dissertação_mestrado_Maykel.pdf: 4072759 bytes, checksum: 49804b0b4c75b954b2c9c7e4aa93265e (MD5) / Submitted by Maykel dos Santos Klem null (maykel_klem@hotmail.com) on 2017-11-28T14:31:56Z No. of bitstreams: 1 Dissertação_mestrado_Maykel.pdf: 4072759 bytes, checksum: 49804b0b4c75b954b2c9c7e4aa93265e (MD5) / Submitted by Maykel dos Santos Klem null (maykel_klem@hotmail.com) on 2017-11-28T14:37:45Z No. of bitstreams: 1 Dissertação_mestrado_Maykel.pdf: 4072759 bytes, checksum: 49804b0b4c75b954b2c9c7e4aa93265e (MD5) / Approved for entry into archive by Minervina Teixeira Lopes null (vina_lopes@bauru.unesp.br) on 2017-11-28T15:54:43Z (GMT) No. of bitstreams: 1 klem_ms_me_bauru.pdf: 4012228 bytes, checksum: f1af56b8b0b9f5e19934e197b4755874 (MD5) / Made available in DSpace on 2017-11-28T15:54:43Z (GMT). No. of bitstreams: 1 klem_ms_me_bauru.pdf: 4012228 bytes, checksum: f1af56b8b0b9f5e19934e197b4755874 (MD5) Previous issue date: 2017-09-27 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Realizou-se primeiramente neste trabalho o estudo de um supercapacitor padrão utilizando coletores de aço inox e eletrodos de grafite Aquadag®. Este dispositivo apresentou uma capacitância máxima de 22 F/g, e seu espectro de impedância foi modelado por um circuito do tipo R(C(RW))(RC)(RC). Com este dispositivo foi possível testar os métodos de produção dos supercapacitores, e identificar as características desejáveis no supercapacitor impresso. Foram testadas duas técnicas de impressão distintas visando o preparo de eletrodos e coletores de corrente impressos em papel para aplicação em supercapacitores. O material ativo utilizado nos eletrodos foi basicamente o PEDOT:PSS, com a adição de óxido de grafeno, grafite aquadag® e nanotubos de carbono de paredes múltiplas (MWNT) para a formação compósitos condutores. Foram realizadas caracterizações morfológicas e elétricas nas superfícies dos eletrodos impressos em papel filtro, vegetal e sulfite. Os eletrodos produzidos por serigrafia utilizando o compósito de PEDOT:PSS com MWNT impressos em papel filtro apresentaram os menores resultados de resistência de folha (17 Ω/sqr), sendo assim utilizados na produção dos supercapacitores. O supercapacitor impresso em papel apresentou um bom comportamento capacitivo através de medidas de espectroscopia de impedância e voltametria cíclica. A curva de impedância foi modelada através de um circuito do tipo R(RC)(C(RQ))(RC), evidenciando uma alta capacitância de dupla camada. Foi encontrada uma capacitância específica máxima de 20,3 F/g.para uma corrente de carga/descarga de 1 mA, e uma resistência equivalente em série de 60 Ω. Estes valores levaram a densidades de energia e potência de 3,1 Wh/kg e 420 W/kg, respectivamente. Realizaram-se também simulações e ajustes a partir das análises em corrente contínua, usando um circuito equivalente RC paralelo com uma resistência em série. Através destes ajustes foi possível extrair parâmetros de grande importância na utilização prática dos supercapacitores. / In this study, we first produced a standard supercapacitor using stainless steel collectors and Aquadag® graphite electrodes. The device exhibited a maximum capacitance of 22 F/g, and an R(C(RW))(RC)(RC) circuit modeled its impedance spectrum. With this device was possible to test the production methods of supercapacitors, and identify its desirable characteristics. Two different printing techniques were tested to produce electrodes/current collectors. The active material used in the electrodes was PEDOT: PSS, with addition of graphene oxide, Aquadag® graphite and multi-walled carbon nanotubes (MWNT), in order to obtain conductive composites. Morphological and electrical characterizations were performed over the surfaces of printed electrodes onto filter, vegetable and bond paper. The electrode produced by screen-printing using the PEDOT: PSS/MWNT composite printed onto filter paper exhibited low sheet resistance (17 Ω /sqr), being used in the production of supercapacitors. Printed supercapacitor showed good capacitive behavior through impedance spectroscopy and cyclic voltammetry measurements. An R(RC)(C(RQ)(RC) circuit modeled the impedance spectrum, evidencing a high double layer capacitance. A maximum specific capacitance of 20.3 F / g was found for a charge/discharge current of 1 mA, and an equivalent series resistance of 60 Ω. These values led to energy and power densities of 3.1 Wh / kg and 420 W / kg, respectively. Simulations and curve fitting were also performed from DC analyzes, using a parallel RC circuit coupled with a series resistance, obtaining important parameters for the practical use of supercapacitors. / FAPESP: 2015/18091-8

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