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In the last decades, the demand for electronics and, therefore, electronic waste, has increased. To reduce this electronic waste and the impact of this sector on the environment, it is necessary to develop biodegradable systems using naturally produced materials with low impact on the environment or systems that can degrade in a certain period. One way to manufacture these types of systems is by using printed electronics because the inks and the substrates used are sustainable. Printed electronics involve different methods of deposition, such as screen printing or inkjet printing. Depending on the method of deposition selected, the developed inks should have different properties, such as viscosity or solid content. To produce sustainable inks, it is necessary to ensure that most of the materials used in the formulation are biobased, biodegradable, or not considered critical raw materials. In this review, different inks for inkjet printing or screen printing that are considered sustainable, and the materials that can be used to formulate them, are collected. Printed electronics need inks with different functionalities, which can be mainly classified into three groups: conductive, dielectric, or piezoelectric inks. Materials need to be selected depending on the ink’s final purpose. For example, functional materials such as carbon or biobased silver should be used to secure the conductivity of an ink, a material with dielectric properties could be used to develop a dielectric ink, or materials that present piezoelectric properties could be mixed with different binders to develop a piezoelectric ink. A good combination of all the components selected must be achieved to ensure the proper features of each ink.

Electronic waste carries energetic costs and an environmental burden rivaling that of plastic waste due to the rarity and toxicity of the heavy-metal components. Recyclable conductive composites are introduced for printed circuits formulated with polycaprolactone (PCL), conductive fillers, and enzyme/protectant nanoclusters. Circuits can be printed with flexibility (breaking strain ≈80%) and conductivity (≈2.1 × 104 S m-1 ). These composites are degraded at the end of life by immersion in warm water with programmable latency. Approximately 94% of the functional fillers can be recycled and reused with similar device performance. The printed circuits remain functional and degradable after shelf storage for at least 7 months at room temperature and one month of continuous operation under electrical voltage. The present studies provide composite design toward recyclable and easily disposable printed electronics for applications such as wearable electronics, biosensors, and soft robotics.

Self-sinterable gallium-based liquid metal (LM) ink for a handy drop-casting coating method is developed. The fabricated LM electrode is coffee-ring-free and bilayer-free, which guarantees high electrical conductivity, wettability, flexibility, and stretchability. The ink consists of Galinstan, ethanol-water mixture, hydrochloric acid, and polyvinylpyrrolidone. The binary mixture provides excellent wetting conditions and suppresses a coffee-ring stain from Marangoni mixing. The acid removes an oxide layer on the LM interface. The colloidal interaction forces by self-assembled polyvinylpyrrolidone induce avalanche coalescences of the particles at the end of evaporation, which produces a thin and uniform dried conductive layer. The acid and polymer provide a bilayer-free structure and electrification without any post sintering. The drop-casted self-transformed LM electrode showed excellent electrical resistance of O (0.1-1 omega) on folding and stretching conditions. It is believed that this method can serve as flexible and stretchable electrodes, on various substances for soft robots and wearable devices, without any complicated post-process.

El present document presenta el procediment de desenvolupament, disseny i muntatge per construir sensors flexibles impresos sobre un substrat flexible per construir un guant terapèutic intel·ligent. Els elements de mesura que caracteritzen el guant són els sensors de pressió i flexió i els sensors de mesura inercial. El projecte pretén proposar un disseny que integri correctament aquests elements mitjançant una tècnica d’impressió additiva: la serigrafia., El presente documento presenta el procedimiento de desarrollo, diseño y montaje para construir sensores flexibles impresos sobre un sustrato flexible para construir un guante terapéutico inteligente. Los elementos de medición que caracterizan al guante son sensores de presión y flexión y sensores de medición inercial. El proyecto pretende proponer un diseño que integre correctamente estos elementos utilizando una técnica de impresión aditiva: la serigrafía., The present document presents the development, design, and assembly procedure for constructing printed flexible sensors onto a flexible substrate to build a wearable smart therapeutic glove. The measurement elements that characterize the glove are pressure and flexural sensors and inertial measurement sensors. The project intends to propose a design that correctly integrates these elements utilizing an additive printing technique: screen printing.

Printed sensors have been explored for more than two decades and have now gained significant interest in real-world applications due to low cost, simple and scalable fabrication processes. These sensors must satisfy the requirement of long-term usage as wearable devices, especially for health monitoring and rehabilitation purposes. However, when such devices are continuously worn on the body or implanted within the body, they may cause unexpected risk to the patient’s health. To avoid potential health risks, transition to ‘green’ strategies has already begun in the research, design and manufacturing of these sensors. This review is dedicated to offering a snapshot of current realization and future prospects of printed sensors through green strategies. The utilization of eco-friendly and cost-effective materials for sensor components and the adoption of various printing methods are summarized. The reusability and multi-detection capability of printed sensors that are within the scope of green analytical chemistry are discussed. © 2020, © 2020 Taylor & Francis Group, LLC.

The electrical conductivity of the black commercial ink was modified by introducing multi-walled carbon nanotubes (CNTs) in percentages of 0.5 to 1.5% by weight. The carboxylic groups, present on the surface of the CNTs, were sufficient for the dispersion of the nanostructures to be adequate in the ink. In addition, no incompatibility was distinguished between the CNTs and the ink components. In fact, a synergy between the black pigment and CNT could be observed. The application of the ink using the modified corrector pen made it possible to obtain uniform lines on ordinary paper based on cellulose fibres and on photographic paper. The patterns drawn by hand with the best conductivity were those made on ordinary paper and whose CNT content was equal to or greater than 1% by weight., La conductividad eléctrica de la tinta comercial de color negro fue modificada al introducir nanotubos de carbono (NTC) multipared en porcentajes de 0,5 hasta 1,5% en peso. Los grupos carboxílicos, presentes en la superficie de los NTC, fueron suficientes para que la dispersión de las nanoestructuras fuera adecuada en la tinta. Además, no se distinguió incompatibilidad entre los NTC y los componentes de la tinta. De hecho, se pudo constatar una sinergia entre el pigmento negro y los NTC. La aplicación de la tinta utilizando el bolígrafo corrector modificado permitió obtener líneas uniformes sobre papel ordinario a base de fibras de celulosa y sobre papel fotográfico. Los patrones dibujados a mano que mejor conductividad presentaron fueron aquellos realizados sobre papel ordinario y cuyo contenido de NTC fue igual o superior al 1% en peso.

This thesis presents a detailed discussion on designing the system architecture to control the piezoelectric micro dispensing system from Microdrop Technologies equipped with a 70 µm nozzle diameter MD-K-140 dispenser head via a host computer. The system architecture is designed to control the two main modules of the inkjet printing system. They are, (i) the motor positioning control electronics to control the movement of micro dispenser head to print the structure and (ii) The micro-dispenser control electronics to control the dispensing parameters required to dispense the ink drops. An interactive user interface is designed create a structure, parse it and transmit the command to interact with these modules. The structures were printed on a glass substrate using micro dispensing system from Microdrop Technologies. The printing was done at room temperature. A UTDAgIJ conductive silver nano inks was used for printing structures. The glass substrates were thoroughly cleaned by washing subsequently with DI water, acetone and isopropanol and kept for few hours before printing. Two types of thermal sintering process were used for this work. They were, (i) An oven sintering, and (ii) A 500 W 120 V tungsten halogen lamp sintering. The sintering results were compared using these methods. Oven sintering process was done at different temperatures and time. Incandescent lamp sintering was done varying the distance of the printed structures from the lamp and the time. It was observed that, the conductivity of the printed structure using an incandescent lamp sintering at 1cm from the lamp for 2 minutes yielded almost the same value as obtained using oven sintering at 250 ᵒC for 15 minutes. Maximum conductivity of around 2.64E+05 S/cm was obtained using oven sintering at 250 ºC for 30 min.

The thesis deals with the conductive priting of RF electronic components like antennas and transmission lines. The thesis shows conductive printing with commercial ink jet printers which use AgIc conductive ink. Conductive printing with commercial printers is cheaper and faster as silkscreen therefore we can use the AgIc for printing prototypes of electronic circuits.

The thesis deals with the conductive priting of RF electronic components like antennas and transmission lines. The thesis shows conductive printing with commercial ink jet printers which use AgIc conductive ink. Conductive printing with commercial printers is cheaper and faster as silkscreen therefore we can use the AgIc for printing prototypes of electronic circuits.

The thesis deals with the conductive priting of RF electronic components like antennas and transmission lines. The thesis shows conductive printing with commercial ink jet printers which use AgIc conductive ink. Conductive printing with commercial printers is cheaper and faster as silkscreen therefore we can use the AgIc for printing prototypes of electronic circuits.

The thesis deals with the conductive priting of RF electronic components like antennas and transmission lines. The thesis shows conductive printing with commercial ink jet printers which use AgIc conductive ink. Conductive printing with commercial printers is cheaper and faster as silkscreen therefore we can use the AgIc for printing prototypes of electronic circuits.

A systematic procedure that provides an efficient workflow for formulating conductive inks is developed. Qualitative product attributes of the inkjet ink are first identified and transformed into quantitative product specifications. Ingredients are then selected based on heuristics, mechanistic, and empirical models to meet the product specifications. Printability checks based on theoretical criteria are used to ensure that stable droplets can in principle be formed and coalesced properly to form a printed line of ink. Then, the conductive ink is prepared and printed to evaluate the performance of the inkjet ink experimentally. An example of preparing a copper ink for inkjet printing is used to illustrate the systematic procedure. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2740–2753, 2016. © 2016 American Institute of Chemical Engineers

In this paper, electrical properties of inkjet printed graphene patterns on a PET-based (Novele (TM) IJ-220) substrate are presented. Water-soluble graphene conductive ink (Phene plus I3015) was used. Tested samples were printed with up to 12 layers. Desktop inkjet printer with 2000 dpi resolution was used for printing. After that, structures were sintered at 100 degrees C for 30 minutes. Printed patterns surface topography and profiles were observed using atomic force microscope (AFM) NTEGRA prima (NT-MDT). According to the results of AFM characterization, the thickness of 12 printed layers is similar to 750 nm. Measurements of electrical properties were performed with Hall effect measurement system at 0.37 T. Carrier mobility is 2330 cm(2)/Vs, while the conductivity is 389.11 1/Omega cm. All patterns are printed successfully with uniform structure and they are showing excellent compatibility with flexible PET-based substrate.

Ink-jet printing (IJP) using conductive inks, has gained the attention of scientistsand researchers during the past decades. Solar Cells (SCs), Radio FrequencyIdentication (RFID), E-papers and antennas are only some of the applicationsfor which IJP is being applied. IJP facilitates printing complex antenna structureswith a good resolution. The use of the IJP process is compatible with devicefabrication on unusual substrates such as paper, polymer lms (Polyethylenenaphthalate (PEN), Polyethylene terephthalate (PET), Polyimide (PI)), textiles,etc at low temperature. The aim of this study is to design and fabricate antennason paper substrates capable of operating at 2.4 GHz via printing technique.Simulation and experimental studies have been presented for microstrip patchantenna and dipole antenna using Itoh's balun.

The layer-by-layer nature of additive manufacturing (AM) allows for access to the entire build volume of a component during manufacture including the internal structure. Voids are accessible during the build process and allow for components to be embedded and sealed with subsequently printed layers. This process, in conjunction with direct write (DW) of conductive materials, enables the direct manufacture of parts featuring embedded electronics, including interconnects and sensors. The scope of previous works in which DW and AM processes are combined has been limited to single material AM processes. The PolyJet process is assessed for hybridization with DW because of its multi-material capabilities. The PolyJet process is capable of simultaneously depositing different materials, including rigid and elastomeric photopolymers, which enables the design of flexible features such as membranes and joints. In this work, extrusion-based DW is integrated with PolyJet AM technology to explore opportunities for embedding conductive materials on rigid and elastomeric polymer substrates. Experiments are conducted to broaden the understanding of how silver-loaded conductive inks behave on PolyJet material surfaces. Traces of DuPont 5021 conductive ink as small as 750?m wide and 28?m tall are deposited on VeroWhite+ and TangoBlack+ PolyJet material using a Nordson EFD high-precision fluid dispenser. Heated drying at 55°C is found to accelerate material drying with no significant effect on the conductor's geometry or conductivity. Contact angles of the conductive ink on PolyJet substrates are measured and exhibit a hydrophilic interaction, indicating good adhesion. Encapsulation is found to negatively impact conductivity of directly written conductors when compared to traces deposited on the surface. Strain sensing components are designed to demonstrate potential and future applications.

Processes for using a MakerBot Computer Numerical Control (CNC) machine and Fujifilm Dimatix Materials Printer (DMP) were developed to facilitate future research in integrating electronics into structural features. In this project, the concept of structural electronics, or structronics, was investigated. Structronics seek to build wiring and electrical interconnects directly into component structures to diminish the need for structural fasteners. A MakerBot Cupcake CNC was used to investigate the fabrication of plastic structures by printing, and a Fujifilm DMP was used to create flexible Printed Circuit Boards (PCBs). After developing processes to make these machines easier to use, others in the lab will be able to utilize them to develop structures with integrated electronics., The original document contains color images.

Different types of the commercial surface treatment InkAid have been evaluated as a surface treatment to enhance print quality of silver nano-particle ink structures printed on polyimide and polyethene substrate. Originally these coatings have been specified to be applied on substrates for graphical ink jet printing. On the coated polyimide and polyethene substrates lines of different widths have been printed using a Dimatix materials printer together with silver nano-particle ink manufactured by Advanced Nano Products. The prints have then been evaluated in terms of print quality and resistivity before and after sintering. The results show that the application of these coatings can improve the print quality considerably, making it possible to print lines with a good definition, which is not otherwise possible with this type of ink on this substrate types. It has been found that the coating Semi Gloss provides the best results, both in terms of print quality as well as the lowest resistivity. The resistivity on polyethene is 3.5*10-7Ωm at best when sintered at 150°C and for polyimide 8.9*10-8Ωm sintered at 200°C. This corresponds to a conductivity of about 4.5% and 18%of bulk silver, respectively. It can be concluded that applying such PVP based coatings to polyethene and polyimide will increase the print quality quite substantially, making it possible to print patterns with requirements of smaller line widths and more details than what is possible without coating.

Radio frequency identification (RFID) tags with printed antennas are lower in cost but have lower performance than those with metal antennas. Printed antennas can replace metal ones if the performance is increased without raising cost. The performance of printed antennas can be increased if the series resistance in the antennas is lowered. The resistance is dependent on the line thickness and the resistivity of the conductive ink. Printed antennas with different line thicknesses were fabricated to investigate the effect of compaction and thickness on the resistance. The resistance of the printed antenna coils decreased by more than 40\% after compaction, while the inductance and the parasitic capacitance were unchanged. RFIDs with compacted printed antennas were found to have significantly increased read range. RFIDs with thick printed antennas were fabricated and tested. These RFIDs were shown to have read ranges comparable to the RFIDs with copper wire antennas. Moreover, a geometry-independent plateau for the read range was found. The presence of a plateau is valuable for thick-line printed antenna since the plateau will enable the usage of low precision printing techniques to lower tag fabrication cost.

Antennas in RFID tags have often been designed in a single layer with copper as conductor and plastic foils as substrate. There is currently a large interest in roll to roll production of RFID tags and silver based inks have been developed for use in printed RFID antennas. Silver ink based single layer antennas works well and is providing 70% to 80% of the reading range compared to copper solutions. However, more advanced antennas are needed to provide less sensitivity to the environment of RFID tags .i.e. need for placing tags on metal or near water. In this work we present a study of multilayered antennas so called patch antennas, for 2.45 GHz RFID tags. The advantage of the patch antenna is that it can be applied to any kind of material, reflecting or lossy material, and still provide good antenna function. However, the patch antenna efficiency is strongly dependent on the material used. For low cost RFID tags in logistics there is a need to manufacture the antenna as a part of the packaging process. In the current work we have investigated the possibility to manufacture printed patch antennas of common packaging materials., VR, STC - Sensible Things that Communicate

One of the complex tasks in mass production of RF electronics is printing the communication antenna using electrically conductive ink. For example, this is very common for radio- frequency identification (RFID) tags. Electrical properties of the ink are mostly determined by conductive (e.g. silver) particles mixed into the ink solution and the way they `connect' in the cured ink. It is also desirable to minimise the amount of ink used per antenna, because high-conducting metals like silver used in the ink are rather expensive. Metal-based inks have limited conductivity, so the thicker the cured ink layer will be the better the antenna radiation efficiency can be achieved, but also the higher will be the costs. In the paper, the authors report on the investigations of the possibility of minimising the amount of ink used per antenna. This can be achieved by printing thicker ink layers, where antenna structures are known to have high current density. Two common antenna structures and a dedicated antenna for passive RFID are used in the investigation. The main result of the paper is that radiation efficiency depends primarily on the total amount of ink used for printing the antenna, rather than on the variations of the layer thickness within the antenna structure, VR, STC - Sensible Things that Communicate

The production of electronic circuits and devices is limited by current manufacturing methods that limit both the form and potentially the performance of these systems. Additive Manufacturing (AM) is a technology that has been shown to provide cross sectoral manufacturing industries with significant geometrical freedom. A research domain known as Multi-Functional Additive Manufacturing (MFAM) in its infancy looks to couple the positive attributes of AM with application in the electronics sector could have a significant impact on the development of new products, however there are significant hurdles to overcome. This paper reports on the single step MFAM of three dimensional (3D) electronic circuitry within a polymeric structure using a combination of conductive and non-conductive materials within a single material jetting based AM system. The basis of this breakthrough is a study of the optical absorption regions of a silver nanoparticle (AgNP) conductive ink which lead to a novel method to rapidly process and sinter silver nanoparticle inks in ambient conditions using simple UV radiation contemporaneously with UV-curing of deposited polymeric structures.

The production of electronic circuits and devices is limited by current manufacturing methods that limit both the form and potentially the performance of these systems. Additive Manufacturing (AM) is a technology that has been shown to provide cross sectoral manufacturing industries with significant geometrical freedom. A research domain known as Multi-Functional Additive Manufacturing (MFAM) in its infancy looks to couple the positive attributes of AM with application in the electronics sector could have a significant impact on the development of new products, however there are significant hurdles to overcome. This paper reports on the single step MFAM of three dimensional (3D) electronic circuitry within a polymeric structure using a combination of conductive and non-conductive materials within a single material jetting based AM system. The basis of this breakthrough is a study of the optical absorption regions of a silver nanoparticle (AgNP) conductive ink which lead to a novel method to rapidly process and sinter silver nanoparticle inks in ambient conditions using simple UV radiation contemporaneously with UV-curing of deposited polymeric structures.

The production of electronic circuits and devices is limited by current manufacturing methods that limit both the form and potentially the performance of these systems. Additive Manufacturing (AM) is a technology that has been shown to provide cross sectoral manufacturing industries with significant geometrical freedom. A research domain known as Multi-Functional Additive Manufacturing (MFAM) in its infancy looks to couple the positive attributes of AM with application in the electronics sector could have a significant impact on the development of new products, however there are significant hurdles to overcome. This paper reports on the single step MFAM of three dimensional (3D) electronic circuitry within a polymeric structure using a combination of conductive and non-conductive materials within a single material jetting based AM system. The basis of this breakthrough is a study of the optical absorption regions of a silver nanoparticle (AgNP) conductive ink which lead to a novel method to rapidly process and sinter silver nanoparticle inks in ambient conditions using simple UV radiation contemporaneously with UV-curing of deposited polymeric structures.