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Spherical colloidal photonic supraparticle systems or assemblies (SCAs) are investigated as a model system for confined optical and photonic components. Simulations of the reflection spectrum to calculate their photonic and optical properties for different parameter constellations are compared with experimental studies by microreflectance spectroscopy (μRS) on SCAs fabricated by inkjet in‐flight deposition, proving the existence of a dual‐band reflection spectrum originating from the supraparticle system. Finite‐difference time‐domain (FDTD) calculations are employed to verify these findings as a function of structural parameters. Both, theory and experiment, show a double reflection peak for the SCAs and agree well in the variation of position and shape, scaling clearly with the packing density of the SCAs. Reducing this parameter from 0.6 to 0.3, the higher‐wavelength reflection maximum decreases in intensity and increases in width but keeps its spectral position. The lower‐wavelength reflection maximum decreases in intensity, increases in width and shows a red shift. The results clearly indicate that aspects of disorder decisively contribute to the particular spectral photonic properties of the supraparticle system which are usually related to order in photonic crystals. This finding can stipulate novel, tailor‐made nanostructured optical components such as low‐dimensional micro resonators and waveguides. [ABSTRACT FROM AUTHOR]

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 β‐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 μA and mobility 6 × 10−4–7 × 10−2 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

All-inkjet-printing of transistors has received much attention for low cost and flexible integrated circuits. However, most flexible field-effect transistors (FETs) based on the emerging two-dimensional materials suffer from the high cost of substrate and electrode materials. The requirements for high-temperature synthesis and precise control in processing add another layer of complexity. To overcome these issues, low-cost flexible paper-based MoS2 FETs were fabricated by inkjet printing of MoS2 channel materials on paper. Additionally, we proposed and achieved the mask-less and low-temperature formation of source and drain electrodes on paper using in-situ selective-area copper reduction. A low sub-threshold swing of 80 mV/dec, high on/off ratio of 105, and very high turn-on current (Ion) of 200 μA of the paper-based flexible MoS2 FETs were demonstrated using the proposed low-cost and facile all-inkjet-printing technique. The all-inkjet-printing technique assisted by in-situ copper reduction opens new opportunities for low-cost and batch fabrication of paper-based electronic devices in ambient conditions. [ABSTRACT FROM AUTHOR]

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]

The technological advancement in the field of printed electronics over roll-to-roll (R2R) platform has become very attractive, because of the several advantages such as mass production, large area application, cost-saving and high-speed capabilities. The inkjet technology, on the other hand, among other printing technologies promotes individualization and contact-less deposition process qualities. In this article, the authors demonstrate the state of the art R2R setup for printing silver (Ag) conductive patterns on PEN substrate using inkjet and infra-red technologies. The deposition of the conductive patterns was accomplished using a nanoparticle-based Ag ink and industrial printheads from Fujifilm Dimatix. The novelty of the research work is realization of a print setup, consisting of an industry relevant flexible printhead assembly and drop evaluation station, which are mounted over a R2R printing system. The entire setup allows the user to first evaluate the ejection of the droplets and then stabilize the print parameters without involving the web substrate, followed by re-positioning of the inkjet assembly back to the R2R printing system. The capability of the print setup is exhibited by varying the printing resolution for the defined digital patterns. In addition, the post-treatment of the conductive patterns was tailored with the implementation of an infra-red based sintering module from Heraeus Noblelight GmbH. The power density of the filaments from the sintering module was varied to achieve the maximum conductivity and to ensure no physical damage to the patterns and substrate. The results indicate that such a print setup is very flexible and can offer several benefits to the printing process of conductive patterns, e.g., obtaining line width below 80 µm and sheet resistance of about 0.5 =, with the advantage of sintering the patterns within 20 s. c 2018 Society for Imaging Science and Technology. [ABSTRACT FROM AUTHOR]

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\times 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. [ABSTRACT FROM PUBLISHER]

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]

Inkjet technology is commonly used as a nonimpact, versatile, and additive digital manufacturing/printing technology. The flexibility offered by this technology toward deposition accuracy, usage, industrial upscaling relevance, and even testing of various solution processable functional materials, e.g., conductors and insulators, makes it very attractive for printed electronic applications. The focus of this paper is improving the curing time durations for inkjet-printed polymeric dielectric layers. In this paper, enhancement with regard to curing time durations is performed and they were found to be reduced dramatically down to less than 1 min using Infrared (IR) emitters, whereas the state-of-the-art curing demands a minimum of 60 min. Here in the experiments, inkjet printing was done using conductive and dielectric inks for developing fundamental devices like a capacitor. The sintering of silver electrodes was done using a conventional oven, and curing of the polymeric dielectric was done using a conventional oven as well as IR radiation. Observations are made on the basis of the dielectric insulation between the top and bottom electrodes for the capacitors containing dielectrics cured in conventional oven and those which are cured using IR radiation under two different manufacturing platforms, i.e., sheet to sheet and roll to roll. [ABSTRACT FROM PUBLISHER]

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]

This paper demonstrates the manufacturing of inductor coils, capacitors, and rectifying diodes solely using the inkjet printing technology. Industrially relevant printheads from Fujifilm Dimatix were employed to prove the process scalability of the inkjet printing technology by manufacturing hundreds of devices. Organic and inorganic conductors and different organic dielectrics were applied for the manufacturing of electrical devices as well as a p-type organic semiconductor. The manufacturing yield effects of varying printing parameters, such as print resolution (drop spacing) and the size of the printed area on the layer morphology and electrical characteristics, were investigated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42108. [ABSTRACT FROM AUTHOR]

A novel wearable electronic nose for armpit odor analysis is proposed by using a low-cost chemical sensor array integrated in a ZigBee wireless communication system. We report the development of a carbon nanotubes (CNTs)/polymer sensor array based on inkjet printing technology. With this technique both composite-like layer and actual composite film of CNTs/polymer were prepared as sensing layers for the chemical sensor array. The sensor array can response to a variety of complex odors and is installed in a prototype of wearable e-nose for monitoring the axillary odor released from human body. The wearable e-nose allows the classification of different armpit odors and the amount of the volatiles released as a function of level of skin hygiene upon different activities. [ABSTRACT FROM AUTHOR]