112 research outputs found

    Suitability of Paper-Based Substrates for Printed Electronics

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    Flexible plastic substrates are widely used in printed electronics; however, they cause major climate impacts and pose sustainability challenges. In recent years, paper-based electronics has been studied to increase the recyclability and sustainability of printed electronics. The aim of this paper is to analyze the printability and performance of metal conductor layers on different paper-based substrates using both flexography and screen printing and to compare the achieved performance with that of plastic foils. In addition, the re-pulpability potential of the used paper-based substrates is evaluated. As compared to the common polyethylene terephthalate (PET) substrate, the layer conductivity on paper-based substrates was found to be improved with both the printing methods without having a large influence on the detail rendering. This means that a certain surface roughness and porosity is needed for the improved ink transfer and optimum ink behavior on the surface of the substrate. In the case of uncoated paper-based substrates, the conductivity and print quality decreased by preventing the formation of the proper and intimate ink-substrate contact during the ink transfer. Finally, the re-pulpability trials together with layer quality analysis detected very good, coated substrate candidates for paper-based printed electronics competing with or even outperforming the print quality on the reference PET foil

    Flexo-printed piezoelectric PVDF pressure sensors

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    The main focus in this thesis was to study the suitability of flexographic printing and new electrode materials in the manufacture of flexible piezoelectric pressure sensors. There are numerous application where flexible and economical pressure sensors can be used. Such are process controll in industry and measurement of vital functions and pressure stress in health care. Flexography would enable economical and efficient mass-production of such sensors. Function of the pressure sensors fabricated in this work is based on piezoelectricity of the uniaxially stretched and poled polyvinylidene fluoride (PVDF) that is used as substrate in sensors. When piezoelectric PVDF is exposed to mechanical stress, electric charges of opposite signs (voltage difference) form on opposite sides of the substrate. If conducting electrodes are fabricated on surface of the substrate, formed charges can be conducted to measuring unit that analyses the magnitude of the charge. Because formed charge is proportional to the force applied on PVDF, force or pressure applied on sensor can be solved. Because piezoelectric PVDF cannot resist high temperatures, no inks that require high sintering temperatures can be used as electrode materials. Manufacture of metal electrodes by sputtering or evaporation is slow and expensive. In this work carbon nanotubes and conducting poly(3,4-ethylenedioxythiophene) polymer are studied as alternative electrode materials. Electrodes are fabricated by using RK Flexiproof 100 flexo-printer or CX202 Motorized bar coater. For lower price and better availability also non-piezoelectric substrates were used to evaluate printing process and electrode materials. Fabricated samples were electrically characterized. Main focus was in sheet resistance of the electrodes and sensitivity of the sensor elements. Obtained sheet resistance values varied a lot. Highest values were up to over four orders of magnitude larger than those of metal electrodes. Despite the high sheet resistance, fabricated samples showed sensitivities comparable to reference samples. According to the results of this work, studied new electrode materials are most likely suitable to be used in flexible pressure sensors

    Flexo-printed piezoelectric PVDF pressure sensors

    Get PDF
    The main focus in this thesis was to study the suitability of flexographic printing and new electrode materials in the manufacture of flexible piezoelectric pressure sensors. There are numerous application where flexible and economical pressure sensors can be used. Such are process controll in industry and measurement of vital functions and pressure stress in health care. Flexography would enable economical and efficient mass-production of such sensors. Function of the pressure sensors fabricated in this work is based on piezoelectricity of the uniaxially stretched and poled polyvinylidene fluoride (PVDF) that is used as substrate in sensors. When piezoelectric PVDF is exposed to mechanical stress, electric charges of opposite signs (voltage difference) form on opposite sides of the substrate. If conducting electrodes are fabricated on surface of the substrate, formed charges can be conducted to measuring unit that analyses the magnitude of the charge. Because formed charge is proportional to the force applied on PVDF, force or pressure applied on sensor can be solved. Because piezoelectric PVDF cannot resist high temperatures, no inks that require high sintering temperatures can be used as electrode materials. Manufacture of metal electrodes by sputtering or evaporation is slow and expensive. In this work carbon nanotubes and conducting poly(3,4-ethylenedioxythiophene) polymer are studied as alternative electrode materials. Electrodes are fabricated by using RK Flexiproof 100 flexo-printer or CX202 Motorized bar coater. For lower price and better availability also non-piezoelectric substrates were used to evaluate printing process and electrode materials. Fabricated samples were electrically characterized. Main focus was in sheet resistance of the electrodes and sensitivity of the sensor elements. Obtained sheet resistance values varied a lot. Highest values were up to over four orders of magnitude larger than those of metal electrodes. Despite the high sheet resistance, fabricated samples showed sensitivities comparable to reference samples. According to the results of this work, studied new electrode materials are most likely suitable to be used in flexible pressure sensors

    Flexo-printed piezoelectric PVDF pressure sensors

    Get PDF
    The main focus in this thesis was to study the suitability of flexographic printing and new electrode materials in the manufacture of flexible piezoelectric pressure sensors. There are numerous application where flexible and economical pressure sensors can be used. Such are process controll in industry and measurement of vital functions and pressure stress in health care. Flexography would enable economical and efficient mass-production of such sensors. Function of the pressure sensors fabricated in this work is based on piezoelectricity of the uniaxially stretched and poled polyvinylidene fluoride (PVDF) that is used as substrate in sensors. When piezoelectric PVDF is exposed to mechanical stress, electric charges of opposite signs (voltage difference) form on opposite sides of the substrate. If conducting electrodes are fabricated on surface of the substrate, formed charges can be conducted to measuring unit that analyses the magnitude of the charge. Because formed charge is proportional to the force applied on PVDF, force or pressure applied on sensor can be solved. Because piezoelectric PVDF cannot resist high temperatures, no inks that require high sintering temperatures can be used as electrode materials. Manufacture of metal electrodes by sputtering or evaporation is slow and expensive. In this work carbon nanotubes and conducting poly(3,4-ethylenedioxythiophene) polymer are studied as alternative electrode materials. Electrodes are fabricated by using RK Flexiproof 100 flexo-printer or CX202 Motorized bar coater. For lower price and better availability also non-piezoelectric substrates were used to evaluate printing process and electrode materials. Fabricated samples were electrically characterized. Main focus was in sheet resistance of the electrodes and sensitivity of the sensor elements. Obtained sheet resistance values varied a lot. Highest values were up to over four orders of magnitude larger than those of metal electrodes. Despite the high sheet resistance, fabricated samples showed sensitivities comparable to reference samples. According to the results of this work, studied new electrode materials are most likely suitable to be used in flexible pressure sensors

    Flexo-printed piezoelectric PVDF pressure sensors

    Get PDF
    The main focus in this thesis was to study the suitability of flexographic printing and new electrode materials in the manufacture of flexible piezoelectric pressure sensors. There are numerous application where flexible and economical pressure sensors can be used. Such are process controll in industry and measurement of vital functions and pressure stress in health care. Flexography would enable economical and efficient mass-production of such sensors. Function of the pressure sensors fabricated in this work is based on piezoelectricity of the uniaxially stretched and poled polyvinylidene fluoride (PVDF) that is used as substrate in sensors. When piezoelectric PVDF is exposed to mechanical stress, electric charges of opposite signs (voltage difference) form on opposite sides of the substrate. If conducting electrodes are fabricated on surface of the substrate, formed charges can be conducted to measuring unit that analyses the magnitude of the charge. Because formed charge is proportional to the force applied on PVDF, force or pressure applied on sensor can be solved. Because piezoelectric PVDF cannot resist high temperatures, no inks that require high sintering temperatures can be used as electrode materials. Manufacture of metal electrodes by sputtering or evaporation is slow and expensive. In this work carbon nanotubes and conducting poly(3,4-ethylenedioxythiophene) polymer are studied as alternative electrode materials. Electrodes are fabricated by using RK Flexiproof 100 flexo-printer or CX202 Motorized bar coater. For lower price and better availability also non-piezoelectric substrates were used to evaluate printing process and electrode materials. Fabricated samples were electrically characterized. Main focus was in sheet resistance of the electrodes and sensitivity of the sensor elements. Obtained sheet resistance values varied a lot. Highest values were up to over four orders of magnitude larger than those of metal electrodes. Despite the high sheet resistance, fabricated samples showed sensitivities comparable to reference samples. According to the results of this work, studied new electrode materials are most likely suitable to be used in flexible pressure sensors

    N-colour separation methods for accurate reproduction of spot colours

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    In packaging, spot colours are used to print key information like brand logos and elements for which the colour accuracy is critical. The present study investigates methods to aid the accurate reproduction of these spot colours with the n-colour printing process. Typical n-colour printing systems consist of supplementary inks in addition to the usual CMYK inks. Adding these inks to the traditional CMYK set increases the attainable colour gamut, but the added complexity creates several challenges in generating suitable colour separations for rendering colour images. In this project, the n-colour separation is achieved by the use of additional sectors for intermediate inks. Each sector contains four inks with the achromatic ink (black) common to all sectors. This allows the extension of the principles of the CMYK printing process to these additional sectors. The methods developed in this study can be generalised to any number of inks. The project explores various aspects of the n-colour printing process including the forward characterisation methods, gamut prediction of the n-colour process and the inverse characterisation to calculate the n-colour separation for target spot colours. The scope of the study covers different printing technologies including lithographic offset, flexographic, thermal sublimation and inkjet printing. A new method is proposed to characterise the printing devices. This method, the spot colour overprint (SCOP) model, was evaluated for the n-colour printing process with different printing technologies. In addition, a set of real-world spot colours were converted to n-colour separations and printed with the 7-colour printing process to evaluate against the original spot colours. The results show that the proposed methods can be effectively used to replace the spot coloured inks with the n-colour printing process. This can save significant material, time and costs in the packaging industry

    Manufacturing conductive patterns on polymeric substrates : development of a microcontact printing process

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 215-233).The focus of this research was to develop a process suitable for creating very high resolution conductive patterns on polymer substrates, in a way that can be scaled to high volume manufacturing. The original motivation for this work came from the problem of manufacturing electrodes on microfluidic devices (which in volume production are commonly formed from polymers), but the findings of this work also have applications in flexible electronics, optics, surface patterning, organic micromanufacturing, and photovoltaics. After an initial exploration of various micromanufacturing processes, microcontact printing (μCP) was chosen as the most promising technique for further study. By using μCP to directly pattern conductive inks, this work has demonstrated previously unachievable printing: feature sizes down to 5μm, using liquid inks on polymer substrates, with a process that can be scaled to high-volume production. An understanding of the mechanisms of direct liquid ink transfer was used to identify relevant process input and output factors, and then the process sensitivities of those factors were investigated with a careful design of experiments. From the empirical data, a process model was built with generalized variables. This model was then used to successfully predict behavior of other inks and other substrates, thus validating the model and showing that it is extendable for future work. By developing an empirically verified model of ink transfer at the micron scale, this work has enabled a process for low cost, high volume microfeature patterning over large areas on polymer substrates.by Melinda Hale.Ph.D

    Inkjet printing of functional materials for optical and photonic applications

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    Inkjet printing, traditionally used in graphics, has been widely investigated as a valuable tool in the preparation of functional surfaces and devices. This review focuses on the use of inkjet printing technology for the manufacturing of different optical elements and photonic devices. The presented overview mainly surveys work done in the fabrication of micro-optical components such as microlenses, waveguides and integrated lasers; the manufacturing of large area light emitting diodes displays, liquid crystal displays and solar cells; as well as the preparation of liquid crystal and colloidal crystal based photonic devices working as lasers or optical sensors. Special emphasis is placed on reviewing the materials employed as well as in the relevance of inkjet in the manufacturing of the different devices showing in each of the revised technologies, main achievements, applications and challenges

    Analysis of Linoprint distribution channels, development of marketing concepts and tools

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    PFC del programa Erasmus EPS elaborat a Fachhochschule Kiel University of Applied SciencesTreball desenvolupat dins el marc del programa 'European Project Semester'.The objective of this report is to analyze the effectiveness of current Linoprint distributors and potential new distributors, to analyze Linoprint’s company strengths compared to its competitors in the digital printing market, to develop Microsoft Excel based marketing tools, and to propose marketing concepts to Linoprint by analyzing Linoprint’s current marketing material and the package printing industry, which is the market that Linoprint is active in. The results of the project are used to develop tools and recommendations to improve Linoprint’s marketing and current company positioning, and to recommend strategies for Linoprint to consider as it enters the market
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