Printing Substrate Research Articles

Study on the process of infiltration for ink droplets in the inkjet printing substrate

The printing pressure of ink droplets in inkjet printing comes from the droplets kinetic energy after jetting, the energy of the ink droplets infiltrating and diffusing in the substrate is derived from the conversion of ink droplets kinetic energy, this is one of the main factors of producing the dot gain phenomenon in the inkjet printing. The mathematical model of ink droplets infiltrating in the substrate was researched in this paper, we analyzed the different structures of paper coatings at first, proved that the paper substrate was the porous medium, so the process of inkjet imaging was the process of droplets infiltrating the porous substrate and drying. But traditional model is no easy to use in practice, we studied this problem based on the energy dissipation and conversion view and obtained the new mathematical model. At the same time, the imaging results of the ink droplets in the paper coating were analyzed in this paper by QEA image analysis instrumentation, the experimental results showed that the imaging process of ink droplets in the substrate could be represented by the mathematical model of the discrete-phase fluid flowing in the porous media, these results described the causes of the inkjet imaging dot gain and provided a scientific theory in order to solve the dot gain problem in the inkjet imaging printing system.

Direct Cell Printing With Microfabricated Quill-Pen Cantilevers

AbstractA novel direct cell printing technique has been developed to control and manipulate the position of cells on solid surfaces. The method utilizes microfabricated polymeric “quill-pen” cantilevers to transfer living cells onto a wide variety of surfaces. In contrast with existing cell deposition methods, such as ink jet or laser ablation methods, the quill-pen approach imparts minimal thermal and shear stress to cells, preserving cell viability and biological functionality. Deposition of both bacterial and mammalian cells into defined patterns has been demonstrated using this method. The size of printed, cell-containing droplets could be controlled by varying the geometry of the quill-pen stylus and by varying printing conditions such as contact time, relative humidity, and surface hydrophobicity. Initial experiments using 10 μm diameter polymer beads demonstrated that the number of beads per droplet could be controlled by varying spot size and particle concentration in the printing solution. Spots could be printed ranging from 20 μm and 100 μm in diameter with approximate volumes ranging from 1-250 pL. We demonstrated deposition of both cells and beads onto a variety of solid surfaces including agarose gel, polystyrene, polyethylene, and glass. Printed cells have also been immobilized on glass and polymer surfaces using biocompatible hydrogel materials (both alginic acid and hyaluronic acid-based matrices) as well as poly-L-lysine. Similar to polymer beads, the number of cells in printed droplets was shown to be dependent upon the size of the droplet, and could be varied by adjusting the concentration of cells present in the printing fluid. As few as one cell per spot could be achieved by adjusting these parameters. The viability and proliferation of printed cells has been evaluated using live optical imaging to observe cell growth and division. Both bacterial cells (Escherichia coli) and mammalian cells were able to divide and proliferate for at least 96 hr post-printing (experiments were discontinued after 96 hr). Live/dead staining was also used to confirm the viability of printed cells. Rat mammary adenocarcinoma MTLn3 cells and mouse embryonic stem cells were also shown to survive the printing process for at least 24 - 96 hr post-printing. These results demonstrate the feasibility of the printing method and its compatibility with a wide range of cell types. It is especially noteworthy that embryonic stem cells could survive the printing process (and proliferate on the printing substrate). This novel printing method has applications for tissue engineering, cell-to-cell signaling studies, and for directly interfacing cells with nanodevices and biosensors.

Large Scale Laser Microstructuring in the Printing Industry

AbstractApplying lasers in gravure print form fabrication is getting more and more important due to a high machining rate, high spatial resolution and the ability of digital modulation. Direct laser engraving into the metallic surface is the fastest and most versatile process for gravure cylinder imaging (ablation rate up to 1 cm3/min). High power Q‐switch Nd:YAG and fiber lasers up to repetition rates of 100 kHz are used, tuned for high reproducibility and stability. A fast modulation of the laser beam profile for each single pulse allows for optimization of the cell shape to get the best ink transfer interaction on a specific print substrate. Highest screen resolutions are made with single mode cw fiber lasers > 100 W.

Misregistration sensitivity in clustered-dot color halftones

Halftoned separations of individual colorants, typically cyan, magenta, yellow, and black, are overlaid on a print substrate in typical color printing systems. Displacements between these separations, commonly referred to as interseparation misregistra- tion, can cause objectionable color shifts in the prints. We study this misregistration-induced color shift for periodic clustered-dot half- tones using a spatiospectral model for the printed output that com- bines the Neugebauer model with a periodic lattice representation for the individual halftones. Using Fourier analysis in the framework of this model, we obtain an analytic characterization for the condi- tions for misregistration invariance in terms of colorant spectra, pe- riodicity of the individual separation halftones, dot shapes, and mis- registration displacements. We further exploit the framework in a hybrid analytical-numerical simulation that allows us to obtain quan- titative estimates of the color shifts due to misregistration, thereby providing a characterization for these shifts as a function of the op- tical dot gain, halftone periodicities, spot shapes, and intersepara- tion misregistration amounts. We present simulation results that demonstrate the impact of each of these parameters on the color shift and demonstrate qualitative agreement between our approxi- mation and experimental data. © 2008 SPIE and IS&T.

Printing of Patterned Copper on Pliable, Microtextured PDMS/Ceramic Composites

AbstractIn this work, we present a novel printing technique that enables the usage of PDMS and ceramic powder mixed PDMS composites (we refer as “PDMS-ceramic composites” in this context), as a substrate for printing of copper conduction layers. This technique is based on microtransfer molding (μTM) and lift-off for pattern formation [4]. Another key feature is the usage of microtextured PDMS and PDMS-ceramic composites before any copper film deposition. Our microtextured surface is composed of pyramid shaped wells (100 μm depth and 150 μm sides on PDMS surface). The poor adhesion between PDMS and copper is overcome by oxygen plasma application and titanium deposition before copper layer.In order to demonstrate the convenience of this technique in RF applications, copper conduction lines (5 mm wide, different lengths) were printed on microtextured PDMS substrates. These transmission lines successfully maintained a low resistance during large strain. The printed lines have the DC resistance of 0.5 Ω and conductivity of 1.3e6 S/m, and the transmission analysis of these lines show good results especially in the MHz range when compared to copper tape measurements.Apart from the conduction lines, the substrates can have ranging dielectric constants from 3 (no powder) to 23 (50% D270 powder, provided by TransTech) by volume mixing rule. Dielectric constant is important for RF applications, especially antenna designs. Therefore, provided with a range of dielectric constants, these composite substrates are a great promise in RF field for pliable antenna fabrication [5]. For experiment purposes, some of the transmission lines are printed on these composite substrates as well as pure PDMS.In this study, apart from the fabrication of transmission lines, this novel technique will be applied in a GPS antenna design for demonstration purposes. This antenna design is a single-fed circularly-polarized stacked antenna for tri-band GPS (L1, L2 and L5) applications [6]. For the fabrication of the antenna, polymer-ceramic materials of ε1=16 and ε2=30 will be utilized as the substrates [6].

Ultra-high-resolution monolithic thermal bubble inkjet print head

A monolithic inkjet print head, fabricated with silicon micromachining technology and capable of generating microscale liquid droplets, is developed and shown to function successfully. The print head uses a dense array of thermal bubble inkjet devices, made on a single silicon wafer. Each device is made of a Pt heater stack, a small, shallow fluid chamber, and a refilling channel formed by a Ge-sacrificial etching process, a deep-etched through-wafer feeding hole, and a micron-scale nozzle opened in a thin nitride membrane by plasma etching. Experimental results with a high resolution video imaging system show that this print head is capable of generating water droplets as small as 3 µm in diameter (0.014 pL), about 1/70th the volume of the droplets produced by existing inkjet systems. The printing process is also found to be stable, uniform in droplet size and velocity, and free of satellite droplets at optimum operation conditions. At small distances between the print head and substrate, droplet spreading is also small. This print head is then a capable tool for ultra-high-resolution inkjet printing and can be used in research areas where delivery of micron-scale fluid droplets is desired.

Security Printing Deterrents: A Comparison of TIJ, DEP and LEP Printing

Security printing is the use of variable data printing (VDP) to add readable information to printed regions. This is used for brand identification, track and trace, product authentication and if applicable for investigation and evidentiary purposes. Wellcrafted, multi-region deterrents can be powerful means to simultaneously provide readable information and deter would-be counterfeiters through the crafting of difficult-to-reproduce printing effects. This allows the brand owner to select the best printing technology for the deterrents (or for different aspects of a multi-region deterrent), and to gain insight into how the counterfeiter may attempt to reproduce their deterrent with a different printing approach. In this paper, we consider repeated line patterns (to test print quality), 2D bar code reading, and authentication of a color deterrent (color tile). We print these features using thermal inkjet (TIJ), dry electrophotography (DEP) and liquid electrophotography (LEP) digital printers. Color tiles demonstrate the printer's color fidelity and are used to show authentication accuracy on multiple printers. 2D barcodes demonstrate the printer's binary print quality, and also test different capture settings and substrates for printing. In this way, we test different printers, different inks, different substrates different reading devices and settings along with different security printing deterrent characteristics. Finally, we introduce and discuss meaningful metrics for comparison, including security payload density, deterrent reproducibility, color and spatial frequency fidelity, deterrent pre-compensation and the sensitivity of deterrent authentication to image capture settings and devices.

Inkjet printed indicators

Inkjet is an exceptionally versatile printing technology, which application areas vary from inexpensive desktop printers for home printing to photo-quality wide format printers for graphic arts applications and ultra-high-speed digital printing machines for transactional and book printing. Because inkjet is a digital method – where liquid drops are generated from a print head driven by computer controlled electronic signals – very small amounts of material can be added and aligned precisely. Inkjet is also the only non-contact printing method, because there is no interaction between the print head and printing substrate during printing. This means that topography of printing substrate or shape of a printed object isn't as critical as it is in other printing methods, which often require relatively planar, smooth and durable printing surfaces. These two features make the inkjet technology especially appealing also for manufacturing applications. VTT has worked with inkjet technology more than a decade in the areas of publication and packaging production. In the end of last decade, we got interested in developing manufacturing methods based on inkjet. One of our goals has been the development of inkjet printed quality indicators.Optical indicators are based on active compounds, which undergo a definite colour chance depending on changes in exposure conditions. Indicators are used to monitor, for example, food product quality in real time and also remaining shelf-life can this way be better estimated. VTT has developed and patented special ultra-low-cost ink jet printable indicator systems for example in checking the freshness of food supplies. VTT has also developed indicator monitoring systems based on emerging camera phone technology. In this paper, the technologies and the operational environment, in which the new camera phone based indicator applications are developed, are described.

Customizing Paper-Based Substrates for Digital Fabrication Printing

Paper is generally not considered as a suitable printing medium for digital fabrication processes. However, several techniques and measures are available to overcome the intrinsic disadvantages of plain paper. The most important is extrusion coating with a thermoplastic resin, giving, beside other advantages, a mechanical smooth and chemical inert surface.

Modelling the role of paper microstructure in electrophotography

We study how paper microstructure heterogeneity affects the electrostatic field acting on toner particles during xerographic printing. We use an efficient multigrid Poisson solver to simulate electrostatic fields. The dielectric distribution of paper is obtained either analytically or input numerically using a recently developed 3D fibre network model of paper. Simulations are used to elucidate the relative importance of paper surface, filler and porosity variations in establishing spatial variations of the electrostatic field. It is found that only long wavelength variations of surface height, bulk filler or porosity variations affect variations in electrostatic transfer forces to any relevant degree. Furthermore, we show that the effect of these long wavelength perturbations can be modelled using a new 1D effective capacitor model. When surface variations and surface filler are mixed together, we found the interesting result that mode mixing can decrease the spatial fluctuations of the electric field. Finally, using simulated 3D paper webs, which mimic the properties of laboratory handsheets, we find that to lowest order surface roughness and not formation is responsible in controlling variations of the electrostatic transfer field, a result of importance in digital printing onto stochastic printing substrates, such as commercial paper.

Covalent Microcontact Printing of Proteins for Cell Patterning

We describe a straightforward approach to the covalent immobilization of cytophilic proteins by microcontact printing, which can be used to pattern cells on substrates. Cytophilic proteins are printed in micropatterns on reactive self-assembled monolayers by using imine chemistry. An aldehyde-terminated monolayer on glass or on gold was obtained by the reaction between an amino-terminated monolayer and terephthaldialdehyde. The aldehyde monolayer was employed as a substrate for the direct microcontact printing of bioengineered, collagen-like proteins by using an oxidized poly(dimethylsiloxane) (PDMS) stamp. After immobilization of the proteins into adhesive "islands", the remaining areas were blocked with amino-poly(ethylene glycol), which forms a layer that is resistant to cell adhesion. Human malignant carcinoma (HeLa) cells were seeded and incubated onto the patterned substrate. It was found that these cells adhere to and spread selectively on the protein islands, and avoid the poly(ethylene glycol) (PEG) zones. These findings illustrate the importance of microcontact printing as a method for positioning proteins at surfaces and demonstrate the scope of controlled surface chemistry to direct cell adhesion.

Laser Precision Micro Fabrication in the Printing Industry

The printing industry is a growing market for laser applications with a wide spectrum of different kinds of lasers having been established. This paper focuses on the precise micro structuring of gravure, flexo, and embossing print forms by direct laser ablation. The principle of gravure printing is the direct ink transfer from an ink source to the print substrate by small 3-dimensional cells engraved into the surface of a cylinder. Direct laser engraving into metallic cylinders is performed with a high power Q-switched Nd:YAG laser system tuned for high reproducibility and stability of the mean pulse energy (σ 2 < 1%). An exact modulation technique allows fast variation and precise calibration of the energy of each single laser pulse as well as active modulation of the intensity profile of the beam. This method permits to set diameter and depth of each cell independently from pulse to pulse at a rate of 70 kHz. The aspect ratio and the shape of each single cell can therefore be defined freely for each laser pulse controlled by digital image data. Thus the cell shape can be optimized for the best ink transfer characteristic on different print substrates. e

Direct ink-jet printing and low temperature conversion of conductive silver patterns

A drop-on-demand ink-jet printer has been used in the production of conductive silver tracks onto glass, polyimide, polytetrafluoroethylene, carbon and glass fibre reinforced epoxy substrates. Silver patterns were obtained from an organometallic solution by heat treatment at 150°C in air and were found to have resistivity values of 1.3 to 2 times the theoretical resisitivity of bulk silver. Printed track lateral resolution is a function of the ink/substrate wetting behaviour and a simple model is presented that relates track width to equilibrium contact angle. The influence of printing parameters and substrate surface properties on line quality is discussed.

Patterned Protein Films on Poly(lipid) Bilayers by Microcontact Printing

The use of polymerized lipid bilayers as substrates for microcontact printing (muCP) of protein films was investigated. We have previously shown that vesicle fusion of bis-SorbPC, a dienoate lipid, on glass and silica substrates, followed by redox-initiated radical polymerization, produces a planar supported lipid bilayer (PSLB) that is ultrastable(1a) [Ross, E. E.; Rozanski, L. J.; Spratt, T.; Liu, S.; O'Brien, D. F.; Saavedra, S. S. Langmuir 2003, 19, 1752] and highly resistant to nonspecific adsorption of dissolved proteins [Ross, E. E.; Spratt, T.; Liu, S.; Rozanski, L. J.; O'Brien, D. F.; Saavedra, S. S. Langmuir 2003, 19, 1766].(1b) Here we demonstrate that muCP of bovine serum albumin (BSA) onto a dried poly(bis-SorbPC) PSLB from a poly(dimethylsiloxane) (PDMS) stamp produces a layer of strongly adsorbed protein, comparable in surface coverage to films printed on glass surfaces. Immobilization of proteins on poly(PSLB)s has potential applications in biosensing, and this work shows that direct muCP of proteins is a technically simple approach to create immobilized monolayers, as well as multilayers of different proteins.

Permanence and durability of digital prints on paper

The paper used as a printing substrate in electro photographical techniques should achieve appropriate structure, surface and optical properties as well as thermal stability. Printing products are often exposed to negative influence from external climate conditions. Surface treatment with varnishing and lamination is a common solution for protecting the final products against light, higher temperatures and elevated relative humidity. In the context of the applied research done in cooperation with the printing industry we studied permanence and durability of paper, image of prints and final printed product. We were also examining the influence of accelerated artificial ageing of paper and colour prints in electro photographic printing technique (Xeikon), with two types of surface treatment on the quality of the printed products. Determination of basic physical, chemical and surface characteristics (mechanical strength, optical and colorimetric characteristics of paper) as well as the evaluation of permanence according to EN ISO 9706 (∞) have shown unsuitable optical and colorimetric properties of paper. The evaluation of durability of paper and prints after accelerated artificial ageing according to the EN ISO 5630-3 standard indicates unsuitable optical and colorimetric properties, which consequently cause low optical and colorimetric stability. Colour prints with a surface protection of polymer varnish or foil protection are very unstable, causing deterioration of colour, contrasts and colour balance. The results of research work are very useful for the evaluation of durable printing paper used for various new digital printing systems and for evaluation of printing material of permanent quality.

Nondestructive Microscopic and Spectroscopic Methods for Depth Profiling of Ink Jet Prints

The binding process of printing inks on the printing substrate is one of the final phases in the creative chain of a new product formation-the print. It is not only the expected mechanism of ink drying that influences the ink distribution on the substrate surface, but also the properties of the substrate itself. Many factors, like hydrophobicity, roughness, and porosity influence the ink distribution on both coated and uncoated papers. The aim of this study was to evaluate the applicability of several nondestructive methods in the analysis of vertical and radial ink distribution on diverse ink jet prints. What are the limits and the extent of confocal Raman, ultraviolet (UV) Raman, CLSM and Fourier-transform infrared (FTIR) PAS in the analysis of ink jet ink distribution in the z direction of the print? In the experiment, both dye- and pigment-based ink jet inks were printed on different types of coated and uncoated papers. The results show a correlation between the confocal Raman and CLSM methods for depth profiling. UV Raman proved useful in the surface analysis of prints while FTIR PAS was useful for measurements at low depth in the z direction. The applied microscopic and spectroscopic methods provide a precise distinction between the upper homogeneous and the inside nonhomogeneous ink layers. Sporadic streams of deeply penetrated ink jet ink were also detected.

Continuous Pattern Transfer and Arbitrable Piping Process for Ink-Jet Fabrication

As a bright star of manufacture process development, the inkjet fabrication has penetrated into the field of display and semiconductor, for example, the fabrication of color filter, the forming of metal circuit, the dispensing of liquid crystal, and further continuous manufacture of flexible display etc. Would it be ideal and expectable? The obstacle lies across is the throughput rate, or the data transfer speed compromises of printing speed. Prior researches suggested to equipping multiple ink-jet heads to speed up printing and patterning, however, it was unfavorable for some applications need high class environment, because of its huge platform occupied and high cost expense. This article designed an electrical system with twin memory arbiter to swing the image data while printing and substrate delivery. It was realized by piping the image data in a multiplexer, and then transferring the data follow with printing process and substrate delivery synchronously. In thus design, the printing head is always kept on its maximum firing speed and the jetting quality can be maintainable. Estimation of the performance improving, the save of waiting time would be 40% or above, and is also accessible for mass production needs.

Quality Analysis of Spot Color Reproduction with an Inkjet Printer

Spot color is widely used in commercial, product or packaging printing to obtain a colorful appearance. With the combination of the right software, inks and media, an inkjet printer can be treated as a digital proofer for spot color printing, providing significant time and cost savings compared to conventional procedures for jobs approval. An Epson Stylus Pro 4000 digital printer combined with two commercially available RIPs were tested and compared. ICC profiles were generated for the Epson Stylus Pro 4000 printer, using the actual production printing substrate and manufacturer recommended proofing paper. Color gamuts of different output combinations were compared and the quality of spot color reproduction was evaluated in terms of the &#x394;E in L*a*b* color space for selected spot colors.

The Pore Structure of Direct Methanol Fuel Cell Electrodes

The pore structure and morphology of direct methanol fuel cell electrodes are characterized using mercury intrusion porosimetry and scanning electron microscopy. It is found that the pore size distributions of printed primer and catalyst layers are largely dictated by the powders used to make the printing ink. The extent to which the pore structure is modified by changing several parameters in the membrane electrode assembly (MEA) manufacturing process is discussed. The pore structure of the printed layers is found to be invariant with respect to changes in powder loading or in choice of printing substrate, and is relatively undisturbed by MEA hot-pressing. Changing the source of the primer powder and adding a pore-forming agent to the catalyst ink are found to be successful methods of creating a more open pore structure in the printed layers.

Kerr gated resonance Raman spectroscopy in light fastness studies of ink jet prints

Resonance Raman spectroscopy offers several advantages in the studies of ink jet prints stemming from its inherent selectivity and sensitivity. These include the possibility to obtain direct information on the chemical interactions between the paper and ink that play a major role in long-term print fastness. However, resonance Raman techniques can suffer from obtrusive fluorescence from colorants or printing substrate and this severely complicates the Raman measurements. The aim of this investigation was to evaluate the applicability of resonance Raman spectroscopy combined with a Kerr gate fluorescence rejection system to gain information on the light fastness of ink jet prints. This was studied using a set of experimental coatings and inks with known compositions. The results indicate that Kerr gated resonance Raman spectroscopy is applicable to the light fastness studies of ink jet prints owing to the effective suppression of the sample-related fluorescence. Moreover, detailed molecular information can be obtained by tuning the laser to get selective resonance enhancement. This enables specific analyses of chemical paper–ink interactions, which generally contribute decisively to the light fastness of ink jet prints.