Direct Printing Method Research Articles

COMm.PAT- Printed Antenna on a Non-Conventional Substrate for Communication

Antennas used for communication purpose have been grown recently using the direct printing methods to ensure light weight technology, ease of fabrication and simply available flexible substrates in the field of printed electronics. The use of flexible non-conventional substrates in this regard has been the current issue for the provision of same results obtained as that of using a conventional substrate. In this paper, we propose low cost printed antenna on a non-conventional substrate that provides higher read range (using ISM Band) for Real time location systems (RTLS) (for e.g. wireless sensing). This antenna makes use of the deployment techniques that involve the selection of environment friendly RF substrate thatcan be served by the localized networking companies in low cost.It further evaluates the substrate characteristics and mathematical properties using the EM Simulator Software (HFSS-High Frequency Structure Simulator) followed by the fabrication of antenna, both on a conventional PCB (FR4) substrate and on a non-conventional substrate (Kodak photo paper) having different materialistic properties using a direct write printing technology. The results include the resonant frequency and the input impedance matching for the feed on a Vector Network Analyzer.

Direct imprinting of MoS2 flakes on a patterned gate for nanosheet transistors

Nanosheet transistors based on mechanically exfoliated MoS2 and other transition metal dichalcogenide layers have already been reported demonstrating good device performances. In an approach to synthesize a large area two-dimensional (2D) sheet, chemical vapor deposition methods were reported and the transfer of those sheets onto other arbitrary substrates was also attempted, although studies on the direct imprinting of such 2D semiconductor sheets are rare. Here, we report on a direct imprinting method, the polydimethylsiloxane (PDMS)-adopting approach, that enables the fabrication of patterned bottom-gate MoS2 nanosheet field-effect transistors (FETs) on any substrate; using direct printing methods MoS2 FETs were successfully fabricated on glass. Since our FETs were also controlled to be a depletion or an enhanced mode with the modulated MoS2 thickness on a patterned bottom-gate, our imprinting approach is regarded as a meaningful advance toward 2D nanosheet electronics.

Study of the microstructure of inkjet-printed P3HT:PCBM blend for photovoltaic applications

Recently, great interest has been devoted to cost-effective alternative energy sources such as organic solar cells because of the mechanical flexibility and the versatility of chemical structure, the low cost of fabrication, and ease of processing. As regards this last point, the possibility to deposit organic materials from solutions at low temperatures makes them employable for fabricating printed solar cells by direct printing methods. In this study, we used the inkjet-printing technology to deposit P3HT blends with various fullerene acceptors ([60]PCBM, [70]PCBM and bis[60]PCBM) dissolved in single solvents, 1,2-dichlorobenzene (DCB) and chlorobenzene (CB), and their mixtures. After optimizing the printing parameters (printhead speed, drop emission frequency, and substrate temperature), the effect of the solvents on the morphology of the photoactive layers was analyzed through Raman spectroscopy and atomic force microscopy. Polymer solar cells with the structure glass/ITO/PEDOT:PSS/blend/Ca/Al were fabricated and characterized by current–voltage (I–V) measurements under 100 mW/cm2 AM 1.5G illumination. A comparative study of the performances of the devices was performed based on three different fullerene derivatives, correlating them to the microstructure of the printed blend films. The optimal devices were obtained when the blend films were deposited from a mixture of DCB:CB 4:1 by volume: this was in agreement with the most favorable morphology of these films.

Reliability of chip on glass module fabricated with direct printing method

To investigate the effect of the sintering temperature on the electrical properties of a chip on glass (COG) module, a screen-printed conductive circuit was sintered at various temperatures, viz. 150, 200, 250 and 300^oC for 30min. An anisotropic conductive film (ACF) is a suitable bonding material for the interconnection between a device and printed circuit, because of the conductive particles within it. We expected that the conductive particles in the ACF would provide a good electrical connection and reliability in our study. The electrical properties of the printed Ag circuits improved with increasing sintering temperature. The conductive particles in the ACF were well deformed in between the Au bumps and printed Ag pads after the bonding process. The resistances of the interconnections drastically decreased with increasing sintering temperature. Also, the temperature-humidity reliability of the ACF was investigated by measuring the resistance after the temperature-humidity test (THT) at 85^oC and 85% relative humidity. After the THT, the resistance shows a tendency to decrease when sintered below 200^oC, whereas it increases when sintered over 250^oC. The increase in the resistance due to the effect of surface oxidation is negligible.

Effect of Sintering Temperature on Electrical Properties of Chip on Glass Module with Direct Printing Method

In order to apply the direct printing method to the fabrication of chip on glass (COG) modules, we examined that the effect of the sintering temperature on the electrical properties of a COG module with direct printing method. Firstly, we fabricated an Ag conductive circuit on a glass substrate by the screen-printing method. To investigate its the effect on the electrical properties of the circuit, it was sintered at various temperatures, such as 150, 200, 250, and 300 °C for 30 min. Subsequently, we conducted Au electro-plating for the fabrication of a Si dummy chip. Finally, the flip-chip bonding process was conducted using anisotropic conductive film (ACF). The printed Ag circuits were well formed on the quartz substrate without any shorts or remarkable changes compared with the initial design. The electrical properties of the printed Ag circuits improved with increasing sintering temperature. The conductive particles in the ACF were well deformed in between the Au bumps and printed Ag pads after the bonding process. The four-point probe method was employed to measure the connection resistance of the joints constructed with the Au bumps on the Si chip and printed Ag circuit on the quartz substrate. The resistances of the interconnections drastically decreased with increasing sintering temperature, i.e., subsequently converged from 11.8 Ω to 7.36 mΩ.

Effect of Sintering Temperature on Electrical Properties of Chip on Glass Module with Direct Printing Method

Effect of Sintering Temperature on Electrical Properties of Chip on Glass Module with Direct Printing Method

Ink-jet printing of micro-emulsion TiO2 nano-particles ink on the surface of glass

Abstract A self-cleaning ceramic ink that contains nano-titanium dioxide was formulated. The nano-titanium dioxide was generated through the micro-emulsion process. The physical properties such as surface tension and viscosity of the prepared ink were evaluated. The ink-jet printing was carried out with an Epson Stylus Photo P50 printer on microscope glass slides. The print was set to 1, 3 and 5 runs in order to evaluate variations in wettability and resulting self-cleaning properties with varying thicknesses of the printed film. Following initial drying of the printed self-cleaning microscope glass slides; they were heat-treated at 400 °C. The SEM analysis and contact angle measurements of the printed microscope glass slides were carried out. The thicknesses of the raw printed self-cleaning ceramic inks were increased linearly with the number of printing runs. Ultimately, the results demonstrated that the direct ceramic ink-jet printing method can be used to produce a self-cleaning film on the glass.

Potentials of the “Direct inkjet printing” method for manufacturing 3Y-TZP based dental restorations

Abstract The potentials of the direct inkjet printing (DIP) method for manufacturing 3Y-TZP dental restorations were investigated. Aqueous inks of 3Y-TZP and carbon were developed and characterised for the DIP method. A sample 3Y-TZP framework of a dental bridge was produced by DIP. The stress distribution on this framework under realistic clenching conditions was simulated using finite element analysis. Four-point bending specimens produced by DIP and a slip cast reference sample were tested to characterise the flexural strength of the DIP produced components.

High-Resolution Patterning of Silver Thin Films with a Water-Mediated Metal Transfer Printing

We report a direct printing method, water-mediated metal transfer printing (mTP), for generating Ag patterns with a wide range of feature sizes. Water-mediated mTP is based on the direct transfer of a metal thin film from a stamp to a substrate via a water-mediated surface bonding. An Ag thin film is used as a solid "ink" in the mTP, which can be used for the formation of micro- and nanoscale Ag structures. To demonstrate its usefulness, we used the water-mediated mTP to fabricate low voltage ZnO thin-film transistors.

Polycaprolactone Scaffolds Fabricated with an Advanced Electrohydrodynamic Direct-Printing Method for Bone Tissue Regeneration

Electrohydrodynamic (EHD) direct writing has been used in diverse microelectromechanical systems and various supplemental methods for biotechnology and electronics. In this work, we expanded the use of EHD-induced direct writing to fabricate 3D biomedical scaffolds designed as porous structures for bone tissue engineering. To prepare the scaffolds, we modified a grounded target used in conventional EHD direct printing using a poly(ethylene oxide) solution bath, elastically cushioning the plotted struts to prevent crumbling. The fabricated scaffolds were assessed for not only physical properties including surface roughness and water uptake ability but also biological capabilities by culturing osteoblast-like cells (MG63) for the EHD-plotted polycaprolactone (PCL) scaffold. The EHD-scaffolds showed significantly roughened surface and enhanced water-absorption ability (400% increase) compared with the pure rapid-prototyped PCL. The results of cell viability, alkaline phosphatase activity, and mineralization analyses showed significantly enhanced biological properties of the scaffold (20 times the cell viability and 6 times the mineralization) compared with the scaffolds fabricated using RP technology. Because of the results, the modified EHD direct-writing process can be a promising method for fabricating 3D biomedical scaffolds in tissue engineering.

Thermoresponsive gelling behavior of concentrated alumina suspensions containing poly(acrylic acid) and PEO–PPO–PEO copolymer

Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO101–PPO56–PEO101, Pluronic F127) was investigated as a function of PAA concentration (0.4–1.2mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel [1]. In this study, the concentrated alumina aqueous suspensions (φ=35vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ∼0.6mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as “solid” inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.

Synthesis and Ferromagnetic Properties of Magnetic Ink for Direct Printing

Magnetic nanoparticles with a core/shell structure were fabricated by a sol-gel method and following hydrogen reduction process. The reduction process changed the crystal structure of synthesized nanoparticles from iron-oxide single phase to iron phase covered with an iron-aluminum oxide shell layer. These nanoparticles were dispersed by homogenizing and ultrasonication in order to form ferromagnetic ink. Using synthesized ink, patterns with soft magnetic properties were successfully printed on Si substrates by a direct printing method.

Direct Metal Transfer Lithography for Fabricating Wire-Grid Polarizer on Flexible Plastic Substrate

This paper reports on the fabrication of polymer-based metallic wire-grid polarizers using a direct metal contact printing method. The proposed method can directly transfer a metal pattern from a silicon mold to a soft plastic substrate simply by roller pressing and infrared (IR) heating. With properly chosen loading contact pressure and heating temperature, metallic linear grating structures with a linewidth of 60 nm, a period of 170 nm, and an area size of 2.5 ×2.5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> are successfully formed on the surface of a polyethylene terephtalate (PET) substrate. The optical performance of the fabricated flexible polarizers is experimentally measured and numerically analyzed in the near-IR spectrum with wavelength from 800 to 1500 nm. Inspired by the numerical simulation results, the optical characteristics of the flexibe polarizers are further enhanced by reactive ion etching on the PET substrate. Good agreements between experiments and theoretical simulation are obtained. Future developments and potential applications of this metal contact transfer lithography method will be addressed.

High-Performance Pentacene Thin-Film Transistors Fabricated by Organic Vapor-Jet Printing

Organic vapor-jet printing, a maskless direct printing method, is used to fabricate high-performance pentacene thin-film transistors. By combining the optimal carrier gas temperature and the surface treatment of gate dielectrics, a mobility of 0.46 (±0.03) cm2 V-1 s-1 and an on-off ratio greater than 107 are achieved. Morphological analyses indicate that the relatively high carrier gas temperature and low surface energy of the dielectric surface are the keys in achieving the level of performance comparable to that of devices based on conventional technologies.

Characteristics of Printed Thin Films Using Indium Tin Oxide (ITO) Ink

Characteristics of the indium tin oxide (ITO) thin films fabricated by a direct printing method were investigated. For the direct printing, 30 mass% ITO ink was formulated by dispersing ITO nanoparticles of less than 10 nm in diameter into alcohol based solvent with additives. Then, the ITO ink was printed onto a glass substrate, which was followed by the heat treatment at 350, 400, 500 and 600°C to fabricate the sintered films. Then, cross-section of sintered film was observed. As a result, the ITO thin film showed porous nanostructure. Also, sheet resistance of the ITO thin film decreased with increasing heating temperature. The decrease of the resistance was attributed to the improvement of carrier concentration in the ITO thin film. In the meanwhile, the optical transmittance increased in proportional to the heating temperature. In case of the ITO thin film heated at 600°C, the improved characteristics of the electrical resistance and the optical transmittance were achieved as 2.19 × 10 3 Ω/sq and 78.6%, respectively.

P‐185L: Late‐News Poster: Direct Patterning of Metal Electrodes for TFT‐LCD Fabrication

AbstractWe have analyzed a metal direct printing method using roll printing technology for the low cost process in TFT‐LCD fabrication. The silver metal electrodes patterned down to 3 μm in space width between lines were directly printed by this method. Very low line resistivity of 4.5 μΩ⋅cm was obtained, which is comparable to that of the AlNd metal alloy for the gate electrode of TFT‐LCD. Furthermore, we evaluated the transfer characteristics of an a‐Si:H TFT using directly printed silver material as a gate line.

Direct printing of aligned carbon nanotube patterns for high-performance thin film devices

The aligned assembly of carbon nanotubes (CNTs) on substrate presents a significant bottleneck in the fabrication of high-performance thin film devices. Here, we report a direct printing method to prepare laterally aligned thick CNT patterns over large surface regions. In this method, CNT forests were grown selectively on specific regions of one substrate, and the forest patterns were transferred on another SiO2 substrate in a laterally aligned formation while keeping their original shapes. The degree of alignment was characterized via electrical measurement and polarized Raman spectroscopy. Furthermore, we demonstrated high-performance field-effect transistors and gas sensors using our method.

Massive integration of inorganic nanowire-based structures on solid substrates for device applications

Inorganic nanowire-based devices have recently drawn extensive attention as one of the next-generation device architectures. Nevertheless, a lack of mass-production methods has been one of the major hurdles holding back the practical applications of such devices. Herein, we review three promising strategies for the massive assembly of inorganic nanowires for their device applications, which are topically selected: selective growth, selective assembly, and direct printing methods. The advantages and disadvantages of these methods are also discussed.

Immobilization strategies for single‐chain antibody microarrays

Sandwich ELISA microarrays have great potential for validating disease biomarkers. Each ELISA relies on robust-affinity reagents that retain activity when immobilized on a solid surface or when labeled for detection. Single-chain antibodies (scFv) are affinity reagents that have greater potential for high-throughput production than traditional IgG. Unfortunately, scFv are typically less active than IgG following immobilization on a solid surface and not always suitable for use in sandwich ELISAs. We therefore investigated different immobilization strategies and scFv constructs to determine a more robust strategy for using scFv as ELISA reagents. Two promising strategies emerged from these studies: (i) the precapture of epitope-tagged scFv using an antiepitope antibody and (ii) the direct printing of a thioredoxin (TRX)/scFv fusion protein on glass slides. Both strategies improved the stability of immobilized scFv and increased the sensitivity of the scFv ELISA microarray assays, although the antiepitope precapture method introduced a risk of reagent transfer. Using the direct printing method, we show that scFv against prostate-specific antigen (PSA) are highly specific when tested against 21 different IgG-based assays. In addition, the scFv microarray PSA assay gave comparable quantitative results (R(2) = 0.95) to a commercial 96-well ELISA when tested using human serum samples. In addition, we find that TRX-scFv fusions against epidermal growth factor and toxin X have good LOD. Overall, these results suggest that minor modifications of the scFv construct are sufficient to produce reagents that are suitable for use in multiplex assay systems.

LCD Colorfilter용(用) Millbase의 분산특성과 레올로지 거동

LCD color filters have been manufactured in a process called photolithography to date, but various printing methods have been studied currently in response to the trend of low-end LCD panels. Direct Printing Process is a suitable fabrication technique to develope pigment components whose dimensions are in nano. The success of this process depends on the systematic preparation of pigment millbase. Conventional millbase dispersions are constituted of the organic pigments, monomer, dispersant and solvents. An experimental study on the rheology of millbase dispersions is presented. Subsequently, this thesis attempts to find out the dispersive characteristics as well as the selection of pigments, monomers and dispersants in the part of millbase among the stages of manufacturing LCD color filters using the direct printing methods. The dispersive characteristics were shown through analytic devices such as PSA, Rheometer, etc.