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In relation to conventional vacuum-based processing techniques inkjet printing enables upscaling fabrication of basic electronic elements, such as transistors and diodes. We present the fully inkjet printed flexible electronic circuits, including organic voltage inverter which can work as a NOT logic gate. For this purpose the special ink compositions were formulated to preparation of gate dielectric layer containing poly (4-vinylphenol) and of the semiconductor layer poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b]thiophene)] (DPPDTT). A printed photoxidized poly (3-hexyltiophene) semiconductor was used as the active layer of the resistors. The operation of the printed inverters and NOT logic gates was analyzed based on the DC current-voltage characteristics of the devices. The resistance of the devices to atmospheric air was also tested. Not encapsulated samples stored for three years under ambient conditions. Followed by annealing to remove moisture showed unchanged electrical parameters in comparison to freshly printed samples.

Inkjet printing is a versatile, contactless and accurate material deposition technology. The present work is focused on developing innovative strategies for inkjet printing of Catalyst-Coated Membranes (CCM) by performing Additive Manufacturing (AM) applied to Polymer Electrolyte Membrane Fuel Cells (PEMFC), without resorting to intermediate substrates. Three different approaches for AM are presented and discussed: a) inkjet-printing of the membrane ionomer layer and the top catalyst layer; b) inkjet-printing of both catalyst layers onto a membrane; c) inkjet-printing of the ionomer layer as well as the catalyst layers onto the reinforcement layer of the membrane. The produced catalyst and membrane layers were characterized and proved uniform in terms of catalyst loading (0.2-0.4 and 0.08 mgPt cm-2 for cathode and anode, respectively), ionomer distribution and thickness homogeneity (4 μm for catalyst layers). The fully inkjet-printed CCM outperformed conventionally made assemblies in electrochemical-performance testing, even reaching 15% higher power density.

We report on the development of inkjet-printed thin-film resistors using both organic and inorganic ink formulations. The passive devices were manufactured on flexible polymer substrates in ambient condition without the need for a cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. By using the same manufacturing process, the rapid electrical sintering (RES) method is demonstrated as effective for the fabrication of inkjet-printed, programmable Write-Once-Read-Many (WORM) memories. Several hundred fully inkjet-printed resistors with different parameters were fabricated and subsequently morphologically and electrically characterized with the aim of obtaining statistically significant data. From a manufacturing process viewpoint, the procedures based on inkjet printing herein described are highly attractive: they do not require high temperatures, low pressures, special atmospheric conditions, and any masks, therefore providing a versatile low-cost approach to fabricate passive electrical components and simple circuits useful for the electronic industry. Printing can be carried out at a sufficiently low temperature to avoid damage to the fabric substrate and these devices can be used in a range of applications requiring flexible and conformal devices from embedded passive filters in PCBs to wearable electronics.

Herein, the inkjet printing of bioresorbable materials tuned to function as electrode, dielectric, and semiconductor layers is reported, thereby developing multilayered microelectronic devices such as capacitors and thin‐film transistors, potentially applicable to address specific medical needs. Polymers and natural materials, e.g., poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate), shellac, and v‐carotene, indigo inks are implemented using jettable formulations, that are either commercially procured or self‐formulated, designed explicitly to deposit fundamental layers for capacitors and transistors. Several parameters are evaluated and adjusted to precisely define a layer's thickness, topology, and geometry, matching with the properties of a fully biodegradable Ormocere substrate, explicitly developed for the specific biological applications. Furthermore, these parameters support in acquiring the intended electrical properties of layers, i.e., conductivity, insulation, semiconductivity, capacitance, and current versus voltage characteristics. The entire manufacturing process of devices is accomplished on the Ormocere substrate under ambient conditions and below 60 °C. The results exhibit that the electrical characteristics of the printed functional layers and devices show direct influence to the physical geometry of the printed features. A fully printed capacitor demonstrates capacitance of 1 nF cm−2, whereas transistors show p‐type and n‐type characteristics with current 0.18-5 mA and mobility 6 × 10−4-7 × 10−2 cm2 V−1 s−1.

Some applications in miniaturized fabrication like valves or force sensors require self‐supporting structures. These may be generated on top of a solid substrate and separated from it afterwards, but this separation is an additional manufacturing step and may stress the structure. Therefore, it may be of advantage to create the desired objects directly on top of a liquid. Here, it is shown that self‐supporting and self‐contained structures including lines of defined width, full tone squares and delicate structures with non‐uniform line width, edges and openings can be prepared by inkjet printing of a photo‐curable ink onto a water surface followed by irradiation with ultraviolet light and lift‐off. To make this feasible, convection, spreading, and dewetting of the ink from the water surface has to be suppressed by controlling the timing of the irradiation, the mobility of the water surface and the long and short range interactions between the printed ink and the water substrate. These tasks may be achieved via addition of soluble amphiphiles or via spreading of water insoluble amphiphiles or hydrophobized particles onto the water surface prior to printing. Best results are obtained by printing the desired structures onto a water surface that bears a monolayer of hydrophobized particles.

The electronic properties of a printed layer are influenced by a number of factors, including the nature of the ink (nanoparticle- or solution-based), ink composition (solvents, additives, concentration), and post-treatment technologies, especially sintering. One of the major challenges in the field of printed electronics is achieving the desired performance, for example, in terms of conductivity, resistivity, or work function (WF). This work investigates the dependence of sheet resistance and WF on various sintering methodologies. Four different silver nanoparticle inks were inkjet-printed on a flexible polymeric foil and post-treated by thermal sintering (in an oven) or novel sintering processes using infrared or intense pulsed light. The surfaces of the printed and sintered layers were investigated optically, and various inhomogeneities in the layer surface were observed, varying from a smooth to a highly rough appearance with ring-shaped drying structures. An analysis of the sheet resistance revealed notable variation among the various inks and sintering methodologies used. Here, for the very first time, WF is measured and evaluated as a function of sintering methodology and silver ink, and the respective layer formation characteristics realized with the inkjet printing technology. The WF values obtained by ultraviolet photoemission show a similar spread and allow unambiguous trends to be tracked with respect to the type of ink and sintering method used. The values of the WF obtained range from 3.7 eV to 4.3 eV, approaching the reported bulk values of 4.3-4.7 eV. The various silver inks resulted in different WFs when the same sintering method was used, while the same silver ink resulted in different WFs when various sintering methods were applied. Therefore, it is believed that the WF can be tuned over a broad range in a controlled manner to satisfy electronic device requirements.

Herein we demonstrated, for the first time, the possibility to use the paper employed in printed electronics (i.e. p_e:smart) as substrate to develop a paper-based sensor. To improve the electrochemical performances of the inkjet-printed sensor, a dispersion based on carbon black nanoparticles was used to modify the working electrode, allowing for a highly performant nanomodified electrochemical sensor platform. This disposable sensor was characterized both electrochemically and morphologically, and it has been successively challenged towards a model analyte namely ascorbic acid. It has been evidenced that the presence of carbon black as nanomodifier decreased the overpotential for ascorbic acid oxidation (from 0.47 V to 0.28 V) with respect to the unmodified sensor and boosted the sensitivity (ca. 3-times). The applicability of this printed electrochemical sensor was demonstrated for the detection of ascorbic acid in a dietary supplement, quantifying 999 ± 130 mg with respect to the 1000 mg reported on the label.

The current upscaling of large area electronics is pushing the technological and cost limits of conventional processing and materials. Introduction of new materials, sophisticated device architectures and advanced deposition techniques has made organic photo detector (OPD) attractive for many applications. Spin coated Titanium Oxide (TiOx) has been successfully established as an electron transport layer (ETL) in many optoelectronic devices, including OPDs. In this paper, on one hand OPDs are fabricated with TiOx as ETL deposited by sputtering and electron beam techniques, where the dark current density is reduced by two orders of magnitude up to 10-7 A/cm2 while retaining high photo responsivity. On the other hand, inkjet printing is demonstrated as an alternative additive and digital manufacturing route for the vacuum-free deposition of TiOx and active layer composition of poly(3-hexylthiophene) and [6,6]-phenyl-C60-butyric acid methyl ester (P3HT:PC60BM). OPDs fabricated with inkjet printed TiOx layers showed comparable performance as the state of the art devices fabricated by spin coated TiOx. In addition, OPDs were manufactured using inkjet technology for both the active and ETL layers. Our research proves that there is a significant influence of the deposition technique to the corresponding device performance. The results obtained in terms of figure of merit for OPDs (dark current density of 2.7×10−5 A/cm2, signal to noise ratio of 320, external quantum efficiency of 45% and fabrication yield of 30%-60%) from the developed inkjet printing process shows that further investigation on the ink formulation and optimizations can result into better performing OPDs.

Various applications of functional devices need a tailored and reliable supply of electrical energy. Batteries are electrochemical systems that deliver energy for functional devices and applications. Due to the common use, several rigid types of batteries have been standardized. To fully integrate the battery into a product that is bendable, free in geometry and less than 1mm thick, printing of power adaptable batteries is a challenging area of research. Therefore, the well-known zinc-manganese system, which is very promising due to its environmental sustainability and its simplicity, has been used to manufacture battery solutions on a new kind of substrate: technical textiles. Another challenge is the deposition of conductive patterns. At present, embroidery with metallic yarn is the only possibility to provide conducting paths on technical textiles, a time-consuming and elaborate process. Screen printed conductive pathways will generate a new momentum in the manufacturing of conductivity on textiles.

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 mm 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 mO cm without any sintering process.

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.

Inkjet printing is a promising alternative manufacturing method to conventional standard microfabrication techniques for the development of flexible and low-cost devices. Although the use of inkjet printing for the deposition of selected materials for the development of sensor devices has been reported many times in literature, it is still a challenge and a potential route towards commercialization to completely manufacture sensor devices with inkjet technology. In this work is demonstrated the fabrication of a functional low-cost dissolved oxygen (DO) amperometric sensor with feature sizes in the micrometer range using inkjet printing. All the required technological steps for the fabrication of a complete electrochemical three electrodes system are discussed in detail. The working and counter electrodes have been printed using a gold nanoparticle ink, whereas a silver nanoparticle ink was used to print a pseudo-reference electrode.

We report about the inkjet printing of multi-walled carbon nanotubes (MWCNTs) for conductive tracks. The MWCNTs were grown by chemical vapor deposition allowing a defined length and diameter. An inkjet-printable ink formulation was prepared by dispersing the MWCNTs in water. Inkjet-printed high resolution patterns were obtained by printing the prepared ink formulation on silicon wafers utilizing evaporation-driven self-assembly processes. After the deposition of the ink, the solvent evaporation induces material flows within the liquid moving the MWCNTs preferably to the edges of the printed patterns as well as to the print starting position where they assemble. Atomic force microscopy (AFM) reveals a preferential orientation of the deposited MWCNTs. The resulting deposit pattern is well-known as coffee-ring effect which is used here to enable high resolution printing and self-ordering of the MWCNTs. Depending on different print parameters such as drop spacing or substrate temperature, conductive track widths in the range of 5-15 mm were achieved with a electrical resistivity of about 3.9·10−3 to 5.6·10−3 O·m measured by current-sensitive AFM.

We present a morphological and electrical analysis of inkjet-printed two-dimensional films of silver nanoparticle inks arranged at different orientation to the raster-scan-based printing process. Different parameters causing morphological and functional irregularities in the inkjet-deposited films as a function of their orientation to the printing process are introduced in detail and the relevance for the field of printed electronics is discussed. Researchers have demonstrated the manufacturing of various microelectronic devices using inkjet printing. Nearly all of the devices are based on simple rectilinear geometries. Usually, these geometries have a preferential orientation that is exactly (i) along the deposition process or exactly (ii) perpendicular to the deposition process. So far, it was assumed that the geometrical and functional characteristics are identically for the both cases.

We report on inkjet printing of aqueous colloidal suspensions containing monodisperse silica and/or polystyrene nanosphere particles and a systematic study of the morphology of the deposits as a function of different parameters during inkjet printing and solvent evaporation. The colloidal suspensions act as a model ink for an understanding of layer formation processes and resulting morphologies in inkjet printing in general. We investigated the influence of the surface energy and the temperature of the substrate, the formulation of the suspensions, and the multi-pass printing aiming for layer stacks on the morphology of the deposits. We explain our findings with models of evaporation-driven self-assembly of the nanosphere particles in a liquid droplet and derive methods to direct the self-assembly processes into distinct one- and two-dimensional deposit morphologies. Electronic supplementary material The online version of this article (doi:10.1186/s11671-015-1065-2) contains supplementary material, which is available to authorized users.

Drying and sintering of conductive nanoparticle inks for printed electronics attracts more and more interest. Sintering can be performed not only by conventional thermal heating (e.g. using a hot plate or an oven), but also by alternative sintering methods such as microwave, laser, intense pulsed light (IPL) sintering and others. It was recognized that most of the sintering processes limit the feasibility of roll-to-roll (R2R) processing due to the long time duration required for the sintering. In this contribution, we report about R2R IR drying and sintering of inkjet-printed silver (Ag) layers on a non-absorbent polyethylene naphthalate (PEN) substrate. A tailored IR module was developed and installed in a R2R printing system. We demonstrated the high potential of the IR post-treatment technology resulting in a conductivity of up to 15% of that of bulk Ag. In comparison to a conventional hot plate drying and sintering the conductivity achieved using the IR approach was more than doubled. By optimization of the presented IR parameters, drying and sintering was achieved at high web velocities up to 1 m s−1 with an exposure time of less than 0.5 s.

The electrical conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was enhanced by dipping the thin films prepared by spin coating technique in an aqueous DMSO solution. The low concentration range of DMSO in water between 0-5 vol % was studied in comparison with pure water and pure DMSO. It was found that the electrical conductivity dramatically increased as increasing the concentration of DMSO and reached the constant value of 350 S cm-1 at 2 vol % of aqueous DMSO solution. This could be explained by the conformational change of PEDOT chains from the coil structure to the linear or expanded coil structure as confirmed by Raman spectra. Further, white patches were obviously noticed on the surface of the films dipped in pure DMSO, indicating the phase separation of conductive PEDOT grains and associated PSS. The sulfur element of the dipped film surface was investigated by XPS. The XPS S2p core-level spectra displayed that the unassociated PSS was considerably removed from the surface of PEDOT:PSS films dipped in pure water and 2 vol % of aqueous DMSO solution, indicating that the presence of water in the solvents is important to prominently promote the washing effect. Finally, UV-Vis spectra revealed the improved transparency of the films probably owing to the decreased film thickness.

We report about a detailed comparison of the additive manufacturing methods inkjet printing (IJP) and aerosol jet printing (AJP). Both technologies are based on the direct-writing approach enabling the non-contact deposition of various materials in flexible patterns, e.g., for printed electronic applications. The deposited pattern elements were classified as (i) drops (IJP) or splats (AJP), (ii) lines, and (iii) squares. These elements can be considered as basic elements of the deposition systems and also of printed electronics. The pattern elements were deposited with IJP and AJP using the same silver nanoparticle ink. After printing, the layers were characterized regarding their morphology by optical and topographical measurement methods as well as regarding their electrical characteristics. It turned out that drops deposited with IJP and splats deposited with AJP can have similar dimensions. However, the shapes of the deposits differ widely. In the case of lines, AJP enables narrower line widths and thinner line thicknesses in comparison to IJP. In IJP, the line morphology varies depending on the direction of the deposition. Finally, the morphology of the deposited lines determines the electrical conductivity. For printed squares, the IJP layers show much higher layer thickness and a different layer topography compared with AJP as result of a higher volume per area deposition of materials.

Inkjet printing of various nanoparticle inks, made from silver or copper nanoparticles, and its transformation into solid functional patterns is of high interest in the field of printed electronics. Liquid materials can be deposited as defined patterns in selected areas with micrometer precision. To convert these printed liquid films, consisting of solvents, additives and nanoparticles, into solid functional patterns a post-treatment is required. To this date, many investigations report on various sintering techniques to achieve e.g. high conductivity from the printed conductive materials. Direct thermal sintering (via furnace or hotplate) requires high temperatures, which makes it not suitable for sensitive polymeric substrates. The novel method of intense pulsed light (IPL) sintering opens the window of opportunity to convert liquid or dried metal layers into solid functional layers within milliseconds without damaging the thermally fragile polymeric substrate. In this work we present and analyze the application of the IPL sintering on inkjet printed silver patterns on various flexible substrates, like Poly(ethylene naphthalate) (PEN), Poly(ethylene terephthalate) (PET), Polyimide (PI) foils and paper. A high dependency of the electrical and structural performance of the printed silver layers on the base substrate was observed when flashing with the IPL technique. Flashing parameters were varied and the resulting sheet resistance is presented. With the analytical comparison of optical and electrical results, the flashing settings could be adapted to achieve highly conductive inkjet printed silver patterns on flexible substrates, when compared to other thermal sintering techniques. Furthermore the first integration of this post treatment methodology into semi-industrial roll-2-roll processing was successfully performed and will be demonstrated.

Correction for 'Roll-to-roll infrared (IR) drying and sintering of an inkjet-printed silver nanoparticle ink within 1 second' by Enrico Sowade et al., J. Mater. Chem. C, 2015, DOI: 10.1039/c5tc02291f. © The Royal Society of Chemistry.

The Inkjet printing technology is a direct patterning technique to deposit functional materials with high precision and accuracy. This deposition technology is often used to manufacture conductive electrodes for different active and passive electronic devices on flexible foils. It is an up-scalable process in terms of printing devices from low (via. Sheet-to-Sheet, S2S platform) to high (via. Roll-to-Roll platform) quantities. For manufacturing of these conductive electrodes and hence electronic devices through the R2R platform, a suitable post-treatment/curing methodology is very much desired. In this work, the focus is concentrated on the curing methodology using the Infra-red radiation for both the inkjet-printed conductive electrodes and insulator layer, for completing a ""proof of concept"" Metal-Insulator-Metal (MIM) electronic device structure over the R2R platform. A conductive silver nano-particle and a polymeric dielectric ink are used to print the top and bottom conductive electrodes, with a middle insulator layer for the MIM structure respectively. It is observed that not only the printed silver electrode layers (both top and bottom) can be cured with the help of the Infra-red radiation, but also the insulator layer. Additionally, the layers constituting the MIM device structure is cured with the conventional curing methodology which in this case is thermal curing using a convection oven. This curing procedure for the printed functional layers is generally performed for the S2S manufacturing process. The conductive electrodes are then electrically characterized by measuring the sheet resistance (on the foil and dielectric layer) as a function of the un-conventional Infra-red radiation and conventional oven curing methodologies. The cured layers for both the conductive electrodes and insulator layers are morphologically analyzed for the layer thickness and homogeneity. The electrical performance of the cured insulator in form of the obtained capacitance from the MIM passive device is compared for the two mentioned curing methodologies.

In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a primer layer approach. The primer layer is based on a UV-curable ink formulation and deposited as well as the silver ink with inkjet printing technology. Industrial relevant printheads were chosen for the deposition of the materials. The usage of inkjet printing allows highest flexibility in terms of pattern design. The primer layer was proven to optimize the surface characteristics of the substrate, mainly reducing the surface roughness and water absorptiveness. Thanks to the primer layer approach, ultra-high-frequency (UHF) radio-frequency identification (RFID) antennas were deposited by inkjet printing on the corrugated cardboards. Along with the characterization and interpretation of electrical properties of the established conductive antenna patterns, the performance of the printed antennas were analyzed in detail by measuring the scattering parameter S-11 and the antenna gain.

We demonstrate intense pulsed light (IPL) sintering of inkjet-printed CuO layers on a primer-coated porous PET substrate to convert the electrically insulating CuO into conductive Cu. With this approach, conductive layers are obtained in less than 1 s after the printing process. The IPL sintering was performed for high productivity with minimum duration and repetition of IPL irradiation to evaluate the effect of pulse number and energy output on the conductivity and morphology of the sintered Cu layers. Depending on the energy output, sheet resistances were measured as 0.355, 0.131, and 0.121 ·-1 by exposure energy of 5.48 (single pulse), 7.03 (double pulse), and 7.48 J·cm-2 (triple pulse), respectively. In contrast, an excessive energy with relatively short pulse duration causes a delamination of the Cu layer. The lowest resistivity of about 55.4 n·m (corresponds to about 30% conductivity of bulk Cu) was obtained by an IPL sintering process of 0.26 s after the printing , which was composed of 2 ms triple pulses with 10 Hz frequency.

Roll-to-roll (R2R) solution printing method has been attracting as a promising technology for a mass production of flexible functionalities, such as radio-frequency identification (RFID), photovoltaic, flexible batteries, etc. High resolution of register control is mandatory to prevent electrical leakages, and short circuitries in the multilayered flexible printed circuitries through R2R mass production. In this paper, a mathematical modeling of the register was derived for the hybrid printing systems, which consisted of contact printing and non-contact printing such as gravure and inkjet printing. Parameter sensitivity analysis was carried out in various operation conditions. And linear quadratic (LQ) regulator was proposed to control both the tension and register. The performance of the LQ regulation of the register was trade-off considering the permitted variation of tension and resolution of register. The proposed mathematical model will be used for the development of hybrid register controller.

The research is focused on the development of a customized inkjet printed WLAN antenna for the application, e. g., in smartphones. Therefore a new three dimensional antenna for communication devices was designed. This antenna is facing requirements such as high functionality (high communication quality) by being manufactured in a cost efficient digital printing process (inkjet printing). In order to manufacture such an antenna, the processes of contactless inkjet printing, thermal sintering and substrate folding need to be applied-always in direct relation to the antenna performance (antenna parameter). The three dimensional shape of the antenna allows an optimized antenna performance and a decreased antenna size. For the development of printed three dimensional WLAN antennas, we are focusing on advanced antenna design engineering, antenna parameter simulation (to speed up the development process), inkjet printing on flexible polymer substrates and antenna parameter measurements for validation. Our research results proof the suitability of printing as a beneficial manufacturing method for highly integrated smartphone antennas. We could also show the dependency of inkjet printing parameters (such as drop space) and the antenna performance afterwards.

In this work results obtained on the marking of thermoplastics (polyethylene terepthalate, polyethylene napthalate and polyimide) using an ytterbium Q-switch pulsed laser are presented. In these experiments the fiber laser beam was directed onto the substrate by a laser scanner. A test form has been created to study the influence of variable laser parameters such as power level, repetition frequency and mark speed in microstructuring.

We present a case study about inkjet printing as a tool for molecular patterning of silicon oxide surfaces with hydrophobic functionality, mediated by n-octadecyltrichlorosilane (OTS) molecules. In contrast to state-of-the-art techniques such as micro contact printing or chemical immersion with subsequent lithography processes, piezo drop-on-demand inkjet printing does not depend on physical masters, which allows an effective direct-write patterning of rigid or flexible substrates and enables short run-lengths of the individual pattern. In this paper, we used mesithylene-based OTS inks, jetted them in droplets of 10 pL on a silicon oxide surface, evaluated the water contact angle of the patterned areas and fitted the results with Cassie's law. For inks of 2.0 mM OTS concentration, we found that effective area coverages of 38% can be obtained. Our results hence show that contact times of the order of hundred milliseconds are sufficient to form a pattern of regions with O TS molecules adsorbed to the surface, representing at least a fragmented, inhomogeneous self-assembled OTS monolayer (OTS-SAM).

The application of liquid [AuO2CCH2(OCH2CH2)2OCH3(nBu3P)] (1) as a metal-organic decomposition ink containing 34.2 wt.% of gold is reported. Chemical and physical properties of 1 are discussed. The ink formulated of 20 wt.% of 1 in toluene (gold concentration 6.9 wt.%) exhibits rheological properties well-suited for piezo inkjet printing. Conversion into electrically conductive gold was accomplished by thermal treatment optimized to provide best possible conductivity, contour accuracy, and layer homogeneity. The thermal decomposition of 1 was studied by thermogravimetry-mass spectrometry coupling experiments. It was found that at first decarboxylation takes place forming [AuCH2(OCH2CH2)2OCH3(PnBu3)], further heating cleaves the Ausingle bondP bond and releases PnBu3. This resulting compound decomposes via Ausingle bondC, Csingle bondC and Csingle bondO bond cleavage processes giving gold and appropriate organics (CxHyOz (x > 3)). The printed features exhibit conductivities of up to 1.9 × 107 S·m− 1 on glass which corresponds to 43% of bulk gold conductivity.

Vehicle tracking systems based on ultra high frequency (UHF) radio frequency identification (RFID) technology are already introduced to control the access to car parks and corporate premises. For this field of application so-called Windshield RFID transponder labels are used, which are applied to the inside of the windshield. State of the art for manufacturing these transponder antennas is the traditional lithography/etching approach. Furthermore the performance of these transponders is limited to a reading distance of approximately 5 m which results in car speed limit of 5 km/h for identification. However, to achieve improved performance compared to existing all-purpose transponders and a dramatic cost reduction, an optimized antenna design is needed which takes into account the special dielectric and in particular metallic car environment of the tag and an roll-to-roll (R2R) printing manufacturing process. In this paper we focus on the development of a customized UHF RFID transponder antenna design, which is adopted for vehicle geometry as well as R2R screen printing manufacturing processes.

In this paper we report about combining inkjet printing technology and self-assembly as a scalable manufacturing tool for spherical, well-ordered aggregates. The aggregates consist of a high number of ordered colloidal nanospheres arranged as ball-shaped structures. Applying inkjet printing based on the principle of droplet ejection the spherical aggregates can be deposited on various surfaces in dry environment and under ambient conditions. The aggregation of the nanospheres is independent of the surface energy of the substrate leading to the assumption that the main part of the assembly and aggregation process takes place in-flight. By applying inkjet printing with an adapted control signal, small droplets of a water-based ink formulation containing monodisperse polystyrene nanoparticles are ejected out of the inkjet nozzles. The ejected droplets serve as a confined geometry for the nanospheres in the carrier liquid during evaporation. As a result, the particles form stable ball-shaped aggregates with hexagonal order. Due to the in-flight self-assembly of the nanospheres, our approach is suitable for any solid surface in dry environment and allows the deposition of the ball-shaped aggregates in appropriate patterns.

Inkjet printing is employed to apply a mechanically stable reinforcing pattern to polymeric microsieves prepared by float casting, where particles are used as molds for the pores. A mixture of silica particles and nonvolatile monomers is cast onto a water surface and subsequently photopolymerized to produce membranes consisting of a polymer film with embedded particles. These composite membranes are transferred onto an aluminum foil. Subsequently, a UV-curable ink is directly inkjet-printed onto the membranes in line patterns of grids or honeycombs and cured by UV radiation to create a mechanically reinforcing pattern. Afterwards, the particles and the aluminum foil are removed by chemical etching. The reinforcing pattern overcasts 40% of the previously manufactured membrane, is mechanically stable, and gives the microsieves such a robustness that they can be handled in further manufacturing processes.