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Fully inkjet-printed multiwall carbon nanotube (MWCNT) layers and their feasibility towards the implementation as a low cost and flexible sensing element is reported. The focus is set on the resistive behavior of the carbon nanotubes (CNTs) and the adjustability towards a defined target range. To realize the sensors on a low cost and high flexible polyethylene terephthalate (PET) foil, the intense pulsed light (IPL) sintering is introduced to achieve the required performance for both the CNT dispersion as well as the silver electrodes. The very novel topic of the simultaneous photonic sintering of a two-material layer stack and the involved challenges are demonstrated. The MWCNT dispersion was successfully printed with the inkjet printing technology and functionalized by thermal and IPL sintering methods, achieving a resistance of 100 k in the target area (1 k to 1 M) for the sensor. The dependence of the resistance on parameters like number of CNT overprints, the pattern layout as well as the post-treatment methodology is analyzed in detail. These results can be further employed for the development of CNT-based sensor elements and the change in their resistance caused by environmental conditions. In addition, such single sensors raise the opportunity of a combination to a sensor matrix to demonstrate the integration in applications such as a shoe sole (proof of concept) but primarily for medical applications e.g., in mattresses in hospitals for constant recording of bedfast or comatose patients. c 2018 Society for Imaging Science and Technology. [ABSTRACT FROM AUTHOR]

Over the past decade, inkjet technology has been well recognized for the manufacturing of products that include 'printing beyond colors.' This micrometer-scale precise technology provides a straightforward approach toward judicious deposition of electronically functional material inks on various substrates over relatively large areas, for printed/flexible electronics. The technology promotes upscalability and has become a renowned process tool for fabricating electronic devices in the field of printed/flexible electronics. Here, the fabrication of printed thin-film transistors (TFT) on cheap coated paper substrate using inkjet technology is reported. For developing the TFT layer stack conductive nanoparticle inks, a polymeric dielectric ink and a p-type organic semiconductor ink are employed. The coating on the paper provides several advantages for fabrication process of TFTs; for example, control over ink spreading. This control of ink spreading can directly influence the fabrication of interdigitated source/drain (S/D) electrodes for TFTs, when a top gate bottom contact architecture is considered. This results in better manufacturing yields and promising electrical performance, which are also the focus of this research. The all inkjet-printed TFTs on paper exhibit electrical performance with maximum S/D current ranging to 170 nA, charge carrier mobility of 0.087 cm2 V−1 s−1, and current on/off ratio of 330. [ABSTRACT FROM AUTHOR]

In this study, the application of printing technologies for the manufacturing of passive microwave components such as antennas is highlighted, and a detailed example is given. Common printing technologies such as inkjet, screen, and gravure printing become adjusted to print conductive inks for the manufacturing of printed antennas on flat substrates or even on threedimensional (3D) surfaces. Especially, printing technologies such as pad printing, micro-jetting, dispensing, and aerosol jetting are candidates for the manufacturing of microwave components onto challenging 3D surfaces, which may facilitate new designs. Depending on the substrate, one technical challenge is to choose a proper metal ink in combination with a suitable thermal treatment to reach critical requirements such as electrical conductivity above 106 S/m or proper adhesion of the printed pattern for an antenna application. This study gives an overview and comparison of the state-of-the-art materials, inks, printing processes, and options of subsequent thermal treatment. The challenges and possibilities for printed-passive microwave components are discussed with regard to microwave applications. The development of a printed radio-frequency identification antenna on a 3D surface is demonstrated, and the performance of the manufactured antenna is discussed in detail. [ABSTRACT FROM AUTHOR]

The development of novel manufacturing methods for flexible, light weight and cost-efficient electronics has attracted great interest in recent years. The inkjet printing technology is an attractive fabrication process due to its additive, high precision and up-scalable deposition process. One of the key components of printed electronic devices is the conductive track. A major requirement is a desired and device dependent electrical performance induced by an appropriate post treatment process. Here, the novel method of using intense pulsed light (IPL) to convert printed liquid films into solid and functionalized metallic layers has great potential when it comes to fabrication of electronics on thin, flexible and even stretchable polymeric foils. Within this research, the IPL sintering and its dependence on the spectral absorption and reflection of various materials is investigated. A nanoparticle silver ink is inkjet printed on a transparent PET foil. Afterwards, the printed samples are placed at a defined distance from the background inside the photonic sintering equipment and flashed on one hand with various flashing parameters and on the other with changing background materials and colors. Changing the background color influences the reflection and absorption properties of the flashlight; the electrical performance of the IPL processed conductive layers can be drastically changed when such a phenomenon occurs. Highly conductive silver tracks or electrodes can be manufactured on thin and flexible polymeric substrates without damage. [ABSTRACT FROM AUTHOR]

A simple and low-cost process for fabricating conductive copper patterns on flexible polyimide substrates was demonstrated. Copper catalyst patterns were first produced on polyimide substrates using reactive inkjet printing of Cu (II)-bearing ink and reducing ink, and then the conductive copper patterns were generated after a two-step electroless plating procedure. The copper layers were characterized by optical microscope, SEM, XRD and EDS. Homogeneously distributed copper nanoclusters were found in the catalyst patterns. A thin copper layer with uniform particle size was formed after first-step electroless plating, and a thick copper layer of about 14.3 μm with closely packed structure and fine crystallinity was produced after second-step electroless plating. This resulting copper layer had good solderability, reliable adhesion strength and a low resistivity of 5.68 μΩ cm without any sintering process. [ABSTRACT FROM AUTHOR]

All-inkjet-printed thin-film transistors (TFTs) have been demonstrated in literature using mainly laboratory inkjet equipment, simple one-channel layout and only a low number of manufactured TFT devices. We report on the development and the up-scaling of the manufacturing of all-inkjet-printed TFT arrays using industrial inkjet equipment. The manufacturing of the TFTs was carried out in ambient condition without the need for cleanroom environments or inert atmospheres and at a maximum temperature of 150 °C enabling the use of flexible polymer films as substrate. Arrays of 924 TFTs were manufactured on an area of about DIN A4 (297 × 420 mm 2 ). This allows the consideration of statistics, e.g. to determine the process yield as a function of device design and layout. We present process yields for all-inkjet-printed TTFs up to 82% demonstrating the potential of the developed all-inkjet-printing process. [ABSTRACT FROM AUTHOR]

Inkjet printing is employed to apply a mechanically stablereinforcing pattern to polymeric microsieves prepared by float casting,where particles are used as molds for the pores. A mixture of silicaparticles and nonvolatile monomers is cast onto a water surface andsubsequently photopolymerized to produce membranes consisting of apolymer film with embedded particles. These composite membranes aretransferred onto an aluminum foil. Subsequently, a UV-curable inkis directly inkjet-printed onto the membranes in line patterns ofgrids or honeycombs and cured by UV radiation to create a mechanicallyreinforcing pattern. Afterwards, the particles and the aluminum foilare removed by chemical etching. The reinforcing pattern overcasts40% of the previously manufactured membrane, is mechanically stable,and gives the microsieves such a robustness that they can be handledin further manufacturing processes. [ABSTRACT FROM AUTHOR]

Abstract: The use of silver(I)-2-[2-(2-methoxyethoxy)ethoxy]acetate, [AgO2C(CH2OCH2)3H], and its application as an aqueous metal-organic decomposition (MOD) inkjet ink is reported. The chemical and physical properties of the silver carboxylate and the ink formulated thereof are discussed. The ink meets all requirements of piezo driven inkjet printing. The printed features were converted into electrically conducting silver patterns by thermal or photo-thermal treatment. The conversion of [AgO2C(CH2OCH2)3H] to elemental silver follows a two-step decomposition as demonstrated by thermogravimetry–mass spectrometry (TG–MS) measurements. The measured conductivities of the printed features on glass and polyethylene-terephthalate (PET) are 2.7×107 Sm− 1 and 1.1×107 Sm− 1, respectively, which correspond to 43% (glass) and 18% (PET) of the bulk silver conductivity. [Copyright &y& Elsevier]