Search

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]

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]

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]

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. Both inks are commercially available and can be sintered at low temperatures, starting already at 120 °C, which allows the use of plastic substrates. In addition, a printable SU8 ink formulation cured by UV is applied as passivation layer in the sensor device. Finally, as the performance of analytical methods strongly depends on the working electrode material, is demonstrated the electrochemical feasibility of this printed DO sensor, which shows a linear response in the range between 0 and 8 mg L −1 of DO, and affords a detection limit of 0.11 mg L −1 , and a sensitivity of 0.03 μA L mg −1 . The use of flexible plastic substrates and biocompatible inks, and the rapid prototyping and low-cost of the fabricated sensors, makes that the proposed manufacturing approach opens new opportunities in the field of biological and medical sensor applications. [ABSTRACT FROM AUTHOR]

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. However, we show empirically that this is not the case and help to understand the conditions that lead to the differences. [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]

The manufacturing of three-dimensional colloidal structures on solid substrates is an important topic of applied research, aiming for photonic components especially in photovoltaic and sensor applications. Whereas conventional techniques such as wet self-assembly are based on engineering of the substrate surface energy, alternative strategies envisage the independence of the interfacial conditions. We report on inkjet printing of colloidal suspensions of monodisperse silica or polystyrene nanoparticles or both and their self-assembly to spherical colloidal photonic crystals. The formation process of the colloidal nanoparticles into stable spherical colloidal assemblies (SCAs) is achieved by a self-assembly process inside tiny droplets of a stochastic mist generated intentionally instead of a jet of individual single droplets using inkjet printing. The mist-jetted, shrinking droplets serve as confined geometries for the solidification of the nanoparticles during the evaporation; thus the particles are packed into stable ball-shaped assemblies. We show how fine-tuning of the jetting parameters allows the reliable generation and deposition of three-dimensional (3D) spherical colloidal assemblies of nanoparticles variable in size and with a high packing order. Microreflectance spectroscopy proves that the degree of order in the SCA is such that photonic stop bands occur inherent for photonic crystals. [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]

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 μm were achieved with a electrical resistivity of about 3.9·10 −3 to 5.6·10 −3 Ω·m measured by current-sensitive AFM. [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]

Wereport about a detailed comparison of the additive manufacturingmethods inkjet printing (IJP) and aerosol jet printing (AJP). Bothtechnologies are based on the direct-writing approach enabling thenon-contact deposition of various materials in flexible patterns,e.g., for printed electronic applications. The deposited pattern elementswere classified as (i) drops (IJP) or splats (AJP), (ii) lines, and(iii) squares. These elements can be considered as basic elementsof the deposition systems and also of printed electronics. The patternelements were deposited with IJP and AJP using the same silver nanoparticleink. After printing, the layers were characterized regarding theirmorphology by optical and topographical measurement methods as wellas regarding their electrical characteristics. It turned out thatdrops deposited with IJP and splats deposited with AJP can have similardimensions. However, the shapes of the deposits differ widely. Inthe case of lines, AJP enables narrower line widths and thinner linethicknesses in comparison to IJP. In IJP, the line morphology variesdepending on the direction of the deposition. Finally, the morphologyof the deposited lines determines the electrical conductivity. Forprinted squares, the IJP layers show much higher layer thickness anda different layer topography compared with AJP as result of a highervolume per area deposition of materials. [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]

The properties and applications of Ag nanowires (AgNWs) are closely related to their morphology and composition. Therefore, controlling the growth process of AgNWs is of great significance for technological applications and fundamental research. Here, silver nanowires (AgNWs) were synthesized via a typical polyol method with the synergistic effect of Cl−, Br−, and Fe3+ mediated agents. The synergistic impact of these mediated agents was investigated intensively, revealing that trace Fe3+ ions provided selective etching and hindered the strong etching effect from Cl− and Br− ions. Controlling this synergy allowed the obtainment of highly uniform AgNWs with sub-30 nm diameter and an aspect ratio of over 3000. Transparent conductive films (TCFs) based on these AgNWs without any post-treatment showed a very low sheet resistance of 4.7 Ω sq−1, a low haze of 1.08% at a high optical transmittance of 95.2% (at 550 nm), and a high figure of merit (FOM) of 1210. TCFs exhibited a robust electrical performance with almost unchanged resistance after 2500 bending cycles. These excellent high-performance characteristics demonstrate the enormous potential of our AgNWs in the field of flexible and transparent materials. [ABSTRACT FROM AUTHOR]

Inkjet and screen printing technologies are well known in the graphic arts industry for the reproduction of texts, images, and graphics. During the last decades, these printing technologies have been attracting increasing interest for the deposition of functional materials, e.g., in the field of printed electronics and for biological applications. However, their usage is mainly limited to 2D applications, i.e., rather flat deposits ranging from nanometers to several tens of micrometers in thickness. For 3D applications, sophisticated additive manufacturing technologies are developed to manufacture structures with high shape complexities. Herein, the potential of standard inkjet and screen printing technology as tools for the development of functional 3D objects is demonstrated. 3D functional structures printed by inkjet and screen printing technology combining conductive and nonconductive materials to a multi‐material structure are shown. A metal nanoparticle ink formulation is applied to inkjet‐print conductive metal pillars with a high aspect ratio (in the range of 50) used as vertical interconnects. The interconnects are encapsulated with an inkjet‐printed polymeric ink formulation and finally used as conductive tracks to light up a solid‐state light‐emitting diode (LED). Screen printing is applied to print primary batteries used as the power source for the LED. [ABSTRACT FROM AUTHOR]

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: URL10.1039/c5tc02291f/URL. [ABSTRACT FROM AUTHOR]

In this contribution we discuss the sintering of an inkjet-printed copper nanoparticle ink based on electrical performance and microstructure analysis. Laser and intense pulsed light (IPL) sintering are employed in order to compare the different techniques and their feasibility for electronics manufacturing. A conductivity of more than 20% of that of bulk copper material has been obtained with both sintering methods. Laser and IPL sintering techniques are considered to be complementary techniques and are highly suitable in different application fields. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The properties and applications of Ag nanowires (AgNWs) are closely related to their morphology and composition. Therefore, controlling the growth process of AgNWs is of great significance for technological applications and fundamental research. Here, silver nanowires (AgNWs) were synthesized via a typical polyol method with the synergistic effect of Cl - , Br - , and Fe 3+ mediated agents. The synergistic impact of these mediated agents was investigated intensively, revealing that trace Fe 3+ ions provided selective etching and hindered the strong etching effect from Cl - and Br - ions. Controlling this synergy allowed the obtainment of highly uniform AgNWs with sub-30 nm diameter and an aspect ratio of over 3000. Transparent conductive films (TCFs) based on these AgNWs without any post-treatment showed a very low sheet resistance of 4.7 Ω sq -1 , a low haze of 1.08% at a high optical transmittance of 95.2% (at 550 nm), and a high figure of merit (FOM) of 1210. TCFs exhibited a robust electrical performance with almost unchanged resistance after 2500 bending cycles. These excellent high-performance characteristics demonstrate the enormous potential of our AgNWs in the field of flexible and transparent materials., Competing Interests: The authors declare no conflict of interest.

Organic photodetectors (PDs) based on printing technologies will allow to expand the current field of PD applications toward large-area and flexible applications in areas such as medical imaging, security, and quality control, among others. Inkjet printing is a powerful digital tool for the deposition of smart and functional materials on various substrates, allowing the development of electronic devices such as PDs on various substrates. In this work, inkjet-printed PD arrays, based on the organic thin-film transistor architecture, have been developed and applied for the indirect detection of X-ray radiation using a scintillator ink as an X-ray absorber. The >90% increase of the photocurrent of the PDs under X-ray radiation, from about 53 nA without the scintillator film to about 102 nA with the scintillator located on top of the PD, proves the suitability of the developed printed device for X-ray detection applications.

During the last years, intense pulsed light (IPL) processing has been employed and studied intensively for the drying and sintering of metal nanoparticle layers deposited by means of printing methods on flexible polymer substrates. IPL was found to be a very fast and substrate-gentle approach qualified for the field of flexible and large-area printed electronics, i.e. manufactured via roll-to-roll processing. In this contribution, IPL is used for the fine-patterning of printed silver nanoparticle layers. The patterning is obtained by induced and controlled crack formation in the thin silver layer due to the intense exposure of IPL. The crack formation is controlled by selection of the substrate material, the fine-tuning of the morphology of the silver layer and an application of a dielectric layer on top of the silver layer that acts as a stress concentrator. Careful optimization of the IPL parameters allowed to adjust the lateral width of the crack. This novel approach turned out to be a fast and reproducible high-resolution patterning process for multiple applications, e.g. to pattern the source-drain electrodes for all-inkjet-printed thin-film transistors.

Printed flexible electronics have been widely studied for their potential use in various applications. In this paper, a simple, low-cost method of fabricating flexible electronic circuits with high conductivity of 4.0 × 10 7 S·m -1 (about 70% of the conductivity of bulk copper) is demonstrated. Teslin paper substrate is treated with stannous chloride (SnCl 2 ) colloidal solution to reduce the high ink absorption rate, and then the catalyst ink is inkjet-printed on its surface, followed by electroless deposition of copper at low temperature. In spite of the decrease in conductance to some extent, electronic circuits fabricated by this method can maintain function even under various folding angles or after repeated folding. This developed technology has great potential in a variety of applications, such as three-dimensional devices and disposable RFID tags.

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.

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 Ω·□(-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 nΩ·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.

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 OTS molecules adsorbed to the surface, representing at least a fragmented, inhomogeneous self-assembled OTS monolayer (OTS-SAM).