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A four-dimensional screening anti-counterfeiting QR code composed of differently shaped photonic crystal (PC) dots has been fabricated that could display four images depending on different lighting conditions. By controlling the rheology of poly(dimethylsiloxane) (PDMS), three kinds of PC dots could be sequentially integrated into one pattern using the layer-by-layer printing strategy. The information can be encoded and stored in shapes and read out by the difference in optical properties. [ABSTRACT FROM AUTHOR]

Inkjet-based organ printing or 3D organ printing can be implemented using orifice-based and orifice-free approaches. Inkjetting, the most widely used orifice-based fabrication approach, has been applied to fabricate various biological constructs, such as alginate tubes. There are two main factors that may lead to failure during the fabrication of the tubular constructs with an overhang using horizontal printing: Structure instability due to the moment imbalance and structure failure due to the droplet impact-induced crash or buckling. This study aims to investigate how to theoretically construct a predicted tube printing path which can compensate for deformation in the printing process. First, we discuss the influence of stress in the printing process, subsequently we proceed to simulate the printing of the tube as a thin curved beam under droplet impact force, and obtain the unchanged shape information from the deformed shape, and then we put forward the predicted-path algorithm of the tube fabrication (PPATF). Second, we verify the method effectiveness and correctness by constructing the predicted path of a tube of 6 mm diameter and using finite element analysis (FEA) to simulate the deformation in the printing process. Lastly, we use the predicted path to print the tube. The cross section of the fabricated constructs can be nearly circular with the predictive compensation path. [ABSTRACT FROM AUTHOR]

Pen pressure is one of the important elements of handwriting and questioned document analysis which is also crucial to recognize forgery. In this paper, we present a new, non-contact, non-destructive, and relatively inexpensive technique to measure the width of the grooves made by the writing. Results demonstrate a clear difference in measured groove widths for varying pen pressure. The effect of passing a written or signed paper in different types of printers has also been studied. A clear decrease of the groove depth was noted when passing the document through a laser printer. An ink jet printer only resulted in a small decrease of the groove depth, while no effect could be detected from a dot matrix printer. [ABSTRACT FROM AUTHOR]

Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance. [ABSTRACT FROM AUTHOR]

Inkjet of conductive patterns is a topic which already attracted much interesting research. Its importance arises from the ability to deposit electrical circuits on almost any kind of substrates. Understanding the controlling parameters to obtain lines with suppressed coffee stain effect still remains an important goal. The results reported here were obtained with a commercial nanoparticle based silver ink printed with a Dimatix 2800 printer. They show the effect of the printing parameters (drop spacing, substrate temperature, ink concentration and substrate type) on the 3D shape of straight lines. In particular it is shown that flat lines can be obtained at any ink concentration on the two different substrate types tested but at specific substrate temperature and drop spacing. Dependence of line cross-section area and line width on drop spacing is also analyzed. [ABSTRACT FROM AUTHOR]

Paper properties, including the chemical or optical characteristics influence the quality and colorimetric characteristics of final printed colors. In this study, the effect of gloss, texture, and whiteness of the paper on the printed colors were investigated. The study was applied on 10 coated papers with different texture, gloss or whiteness, and the same grammage using two inkjet printers. It was found that the reproducibility of the printer can be affected with the paper brand, and this effect is statistically dependent on the brand of printer. The kind of paper significantly influences the light fastness of the final printed colors, and this effect statistically depends on the printer. Although, the paper's properties such as gloss and whiteness affect the gamut volume, it is not totally possible to model this effect. The effect of paper on the colorimetric values of the final printed colors is statistically significant. However, the influence of the brand of printer on the color changes via the paper difference is not statistically provable. Edge frequency technique was introduced as an appropriate method for computing texture properties of papers. The texture difference computed by this method shows a suitable correlation with the color differences caused by changing the paper's texture; however, it depends on the printer's brand. Furthermore, there is a good correlation between the Edge frequency difference and the gamut volume variation for papers with different texture while the other parameters such as gloss and whiteness are the same. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 284-291, 2013 [ABSTRACT FROM AUTHOR]

Aerosol jet printing is a rather new technology for the deposition of thick film structures offering high line and space resolution. This method offers high potential for miniaturization for thick film structures. The advantages of this technology could be shown with inks carrying a single solid powder (e.g., silver, platinum, ceramic, or glass powder). One of the challenges in printing solid powder mixtures is the differences in the aerodynamic properties of different powders. Those differences result in changes of the mixing ratio within the aerosol jet and therefore poor reproducibility in the finished film. In this work, thick film resistors consisting of RuO2 with particle size <1 µm as the conducting phase and different glass powders with particle size around 1 µm as the isolating phase were investigated. One glass had a density rather close to RuO2, the other glass significantly lower. Inks were made from RuO2/glass powder mixtures, a solvent, and organic additives. After manufacturing, the inks are printed on LTCC and the microstructures of the dried and the fired films were visualized by FIB preparation and SEM. The resistances as well as the temperature coefficients of the resistors were measured and compared with resistor films with an identical solid composition manufactured by conventional screen printing. The results of the obtained resistors are presented and discussed in terms of powder properties, ink dispersion, and printing parameters. [ABSTRACT FROM AUTHOR]

This paper describes the construction of a simple inexpensive scanner which can be used in conjunction with a data logger to produce intensity plots of diffraction and interference patterns. Making use of the drive mechanism from an old inkjet-printer is the central feature. [ABSTRACT FROM AUTHOR]

The article reports on the anticipated growth in demand concerning the utilization of inkjet printing technology by the media industry in the U.S. The author provides a comparison on the benefits offered by inkjet printers with that of toner based printers and how digital media companies have engage the utilization of inkjet in carrying out digital printing processes. Among the benefits offered by inkjet printers include reduced power requirement, quality capture of color and requires less preparation. It states that at Drupa 2008, Kodak Co. will unveil its Versamark VL2000 inkjet printers and Steam Compact Press made available to customers.

The stability of inkjet printers is a major requirement for high-quality-printing. However, in piezo-driven inkjet printheads, air entrapment can lead to malfunctioning of the jet formation. The piezoactuator is employed to actively monitor the channel acoustics and to identify distortions at an early stage. Modifications of the response of the piezoactuator indicate entrapped air bubbles and these allow us to investigate them. When we employ the signal as a trigger for high-speed imaging, we can visualize the consequences of the entrained bubbles on the droplet formation. Two mechanisms are found to cause air entrapment: First, a distorted droplet formation caused by small particles, and, second, an accumulation of ink on the nozzle plate, which favors void formation once the meniscus is pulled back. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate the feasibility of using Drop-on-Demand microjet printing technology for fabricating imaging sensors by reproducibly printing an array of photopolymerizable sensing elements, containing a pH sensitive indicator, on the surface of an optical fiber image guide. The reproducibility of the microjet printing process is excellent for microdot (i.e. micrometer-sized polymer) sensor diameter (92.2±2.2μm), height (35.0±1.0μm), and roundness (0.00072±0.00023). pH sensors were evaluated in terms of pH sensing ability (≤2% sensor variation), response time, and hysteresis using a custom fluorescence imaging system. In addition, the microjet technique has distinct advantages over other fabrication methods, which are discussed in detail. [Copyright &y& Elsevier]

The emerging technology of inkjet has been used for the manufacture of tactile maps and diagrams for people with visual impairments. A design methodology was proposed by which design improvements could be made to tactile maps and the inkjet system used to produce them. The design methodology centred on balancing the primary subsystems of printhead, ink and substrate, via a triumvirate visual design tool. This was used in conjunction with a design matrix for comparing system outputs and inputs. As no rigorous standards for assessing the quality of a tactile map exist, a set of measurable output variables was argued for based on psychophysical and cartographic studies of haptics. These were compared with the input variables affecting the inkjet subsystems; printheads, inks, substrates, print algorithms, curing and motion control of a special inkjet machine. The design methodology showed how the system and the output could be improved, and, in particular, the concept was shown that knowledge of the haptic design outputs could be used to aid efficiency saving of the machine inputs without adversely affecting the output. [ABSTRACT FROM AUTHOR]

Due to its high image quality and moderate computational complexity, error diffusion is a popular halftoning algorithm for use with inkjet printers. However, error diffusion is an inherently serial algorithm that requires buffering a full row of accumulated diffused error (ADE) samples. For the best performance when the algorithm is implemented in hardware, the ADE data should be stored on the chip on which the error diffusion algorithm is implemented. However, this may result in an unacceptable hardware cost. In this paper, we examine the use of quantization of the ADE to reduce the amount of data that must be stored. We consider both uniform and nonuniform quantizers. For the nonuniform quantizers, we build on the concept of tone-dependency in error diffusion, by proposing several novel feature-dependent quantizers that yield improved image quality at a given bit rate, compared to memoryless quantizers. The optimal design of these quantizers is coupled with the design of the tone-dependent parameters associated with error diffusion. This is done via a combination of the classical Lloyd-Max algorithm and the training framework for tone-dependent error diffusion. Our results show that 4-bit uniform quantization of the ADE yields the same halftone quality as error diffusion without quantization of the ADE. At rates that vary from 2 to 3 bits per pixel, depending on the selectivity of the feature on which the quantizer depends, the feature-dependent quantizers achieve essentially the same quality as 4-bit uniform quantization. [ABSTRACT FROM AUTHOR]

In this paper, we present the design, fabrication, and experimental results of 4-bit digital microinjectors, whose ejected droplet volumes are adjusted by the digital operation of a 4-bit microheater array. We design the reference microinjectors as well as its comparative test structures. In the fabrication process, we use a five-mask micromachining process and the total chip size of the fabricated microinjector is 7640 μm × 5260 μm. We observe the microbubble generation and collapse on the microheater array. The microhubbles initiate and grow individually on top of each operating microheater, however the microbubbles merge together before collapse. We measure the ejected droplet volumes and velocities, which are adjusted from 12.1 - 55.6 pl and 2.3 - 15.7 m/s, respectively, depending on the 15 possible combinations of 4-bit microheater array. We also experimentally characterize the effect of geometric variation including the microheater size, intermicroheater gap, microchannel width and sequential operation of microheater array on the ejected droplet volume and velocity. Thus, the present microinjector has a potential for application to the high-resolution inkjet printers with multiple gray levels or high- precision fluid injectors with variable volume control. [ABSTRACT FROM AUTHOR]

Abstract: A simple experimental arrangement was used to study the trajectories of droplets ejected by an ink-jet printer. Droplets with an average diameter of were ejected from a nozzle with an orifice of . The recorded flight path was used to find the drag force, deceleration and hence the loss of height when the droplets were ejected horizontally. Using various approaches for semi-turbulent flow, good fits for trajectory were obtained. A model was developed to include the effect of the change in droplet shape from cylinder to sphere during flight but this did not improve trajectory fit. Methods for calculation of exit velocity produced deviations of 4–15% from the value measured by high-speed photography. [Copyright &y& Elsevier]

Abstract: This paper presents a low-cost and direct-writing silver metallization process based on drop-on-demand inkjet printing technique. Silver nitrate dissolved in the mixture of water and dimethyl sulfoxide (DMSO) was used as a metal precursor for metallization. The fabricated silver films on polyimide substrate were characterized by means of scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and electrical measurements. The experimental results show that the inkjet-printed silver tracks have well-defined shapes. The resistivity of the printed silver tracks is around 1.5×10−5 Ω·cm, one order of magnitude larger than that of bulk silver, which is attributed to the porosities as well as the residual impurities. Two conducting polymers (CP), sulfonated polyaniline (SPANi) and poly(ethylene dioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS), were inkjet-printed on the surface of the silver tracks to study electrical properties of the Ag–polymer contacts. The current–voltage measurement results show that the printed Ag–PEDOT/PSS and Ag–SPANi contacts exhibit ‘ohmic’ behavior. [Copyright &y& Elsevier]

An aqueous suspension of clay was delivered through an electromagnetic ink-jet printer head onto partially dried clay tile to produce patterns in relief. The patterns formed Braille symbols intended for tactile recognition by visually impaired persons (VIP). This solid freeforming procedure means that conventional clay products such as wall tile, although mass-produced, can acquire individuation so that tactile information can be delivered to VIPs to assist, for example, in navigation in the built environment. [ABSTRACT FROM AUTHOR]

Inkjet printing has been used as a solid freeform technique to fabricate a wider rage of miniature ceramic components with structures difficult to obtain using traditional ceramic fabrication techniques. Quality control of fabricated components is crucial to avoid macroscopic and microscopic defects. Macroscopic defects are those due to lack of accuracy of deposition, which affect both the precision of size and shape definitions. Microscopic defects are internal voids or flaws due to deposition or subsequent treatments. This paper reports the work in the identification of different types of defects, their causes and prevention in terms of ink properties and printing conditions. [Copyright &y& Elsevier]

Abstract: The paper investigates the competing and morphology-dependent wetting and imbibition behaviours of ‘sodium-alginate/urea’ films that are currently used as thickeners in inkjet printing processes, dealing specifically with the structural changes of the coating within the swelled spot of the contacting (wetting) liquid drop. Depending on the initial morphology of the coating, the re-drying of the swelled wetting spot was found to lead to re-crystallization morphologies that are qualitatively different in both their texture and physicochemical properties. Well beyond the investigated ‘alginate/urea’ mixture, these results well highlight the critical influence that swelling-induced morphological re-constructions might have on interface phenomena in general, and in particular, on the wetting, impregnation and adhesion of solvent-processed polymeric assemblies. [Copyright &y& Elsevier]

A novel thermal inkjet printhead with monolithically fabricated nickel nozzle plate on SOI wafer has been proposed for the first time. A chamber and a restrictor are implemented on the 40 μm thick top silicon layer, and a nozzle plate covering heater layers is monolithically fabricated on them. Unlike the general back-shooters, the inkjet printhead reported here is a kind of back-shooter, which has a chamber and a restrictor with arbitrary shape by utilizing the silicon dioxide etch-stop layers in the bottom and sidewalls of chamber. Moreover, the electroplating process for nozzle, followed by placing the chamber underneath the heater layer, is performed on a planar surface, resulting in more uniform and reliable control of nozzle size.The new design was applied for monochrome inkjet printhead, which has 56 nozzles in two columns with real 600 NPI (nozzle per inch), and showed good performances such as a drop velocity of 12 m/s, a drop volume of 30 pl, and a maximum firing frequency of 12 kHz for single nozzle ejection. From nozzle by nozzle inspection, we observed the uniformity variation of less than 4% in drop speed as well as drop volume. The monolithic fabrication process resulted in a good uniformity and is expected to have superior manufacturing yield to the nozzle assembly process. [Copyright &y& Elsevier]

This paper presents design modifications of a backshooter type inkjet printhead, DomeJet, to enhance the firing frequency. DomeJet is a thermally driven monolithic inkjet printhead that consists of dome-shaped ink chambers and omega-shaped heaters over the chambers. Since it is monolithic, the manufacturing is very cost effective. As the firing frequency increases, the residual heat accumulated in heater layer may cause unstable droplet ejection. Thus, an efficient heat passage is necessary to increase the firing frequency. Contrary to a roofshooter architecture printhead, a backshooter type printhead has disadvantage in heat release since the heater is confined to a thin film which has low thermal conductivity. In this study, four models are proposed and studied. Compared to the basic model of DomeJet, all the proposed models are found to improve heat dissipation capability. The best performing model is found to operate at a frequency of 40 kHz, a much higher frequency than 15 kHz of the basic model. [Copyright &y& Elsevier]

Deals with a study which demonstrated that advances in printing technology make it possible to produce grids with lower pitches. List of full-field measurement techniques that have become popular in experimental mechanics; Steps in obtaining grids with low-frequency grids; Details of the grid transfer method; Application of the method to tensile tests.

The author in this article says that in CTP, Drupa turned out to be less a battle of technologies than an expected evolution of platesetters that vendors are accustomed to manufacturing and distributing. Esko-Graphics Espresson platesetter for UV-sensitive contact plate did not establish a new trend because by the time it becomes available next year, Espresso will be trailing the more than 500 UV-platesetters that basysPrint already has on the market. Nor did Jetplate break any new ground with its inkjet platesetter using Epson Stylus Pro inkjet printer. They are limited by the resolution of inkjet printers, which already have higher resolution than they need for color prints in photographic quality. That limits the expectation of a better quality for inkjet platesetters in the future. Quality offset printers so far have not decided in large numbers that the present quality is good enough for them.

Recent progress in inkjet printing of parts of biosensors are highlighted, with particular reference to the printing of biologically active molecules. We describe a system constituted by a thermal inkjet printer, adapted to layering a bidimensional array of dots [701 × 701 dots per inch] on solid supports. The printer was used to depose a β-galactosidase (GAL)-containing ink on a polyester sheet, with dots obtained from 10 pL drops, each drop containing in turn 6 pg of enzyme. The activity of GAL after the preparation was determined using a colorimetric probe (Brilliant Blue FCF). The activity loss of the microdeposed enzymes was found to be around 15%, showing that the 2 µsec-lasting thermal shock experienced by the biomolecule into the printhead nozzle affects to a lesser extent the activity of the thermal inkjet deposited enzyme. In conclusion, the most recent findings of our group in this line are depicted, and a view of possible future developments of the “biopolytronics” field is outlined. [ABSTRACT FROM AUTHOR]

As we look around Drupa 2004, we can anticipate what may change and what we may see at Drupa 2008. The direction of change is clear, but the pace is not. The ink-jet area is highly uncertain. How quickly the ink-jet suppliers will develop their imaging heads to provide greater speed, higher quality and lower cost is the question. In the xerographic area, we are dealing with a more mature technology. Changes will happen, but they will mostly be predictable enhancements and they will come slowly. What we can expect is the improvement of light production designs to challenge in the midrange production area. Cost reduction, now happening rapidly in low-end and office markets as xerographic suppliers try to match the success of ink-jet vendors.

The analysis of oscillatory fluid flow in a piezoelectric drop-on-demand cylindrical inkjet print head has traditionally been implemented by computationally expensive numerical methods although the print head itself consists of simple shaped components such as a cylindrical tube surrounded by a piezoelectric actuator, and a conical tube for the nozzle part. In a preliminary design stage, it is strongly desirable to save time and effort when simulating the impact of the design on the drop generation. For this purpose, approximate analytic solutions, which describe the fluid motion in an inkjet print head, are developed. Axial velocity history is fed back to a further drop formation simulation with a simplified 1D FDM model. The strengths and weaknesses of the 1D approach are identified. Despite the compactness of the present approach, the results show encouraging agreement of mass transport rate with experimental data. [Copyright &y& Elsevier]

The article presents excerpts from various articles in the September 1975 issue of the magazine. One article discusses the drawbacks of nonimpact printers that keep them from replacing impact printers on the market. Another reports on an optical mark reader system by National Computer Systems that checks and grades test papers. A third article reports on the development of a computerized pen that can recognize if a forger is using it.

The article discusses the existence of VersaDropT, considered to be a new inkjet technology breakthrough introduced by Dimatix Inc. Accordingly, the presence of the new technology will enhance the company's drop-on-demand Shaped Piezo SiliconT Micro electro mechanical system head technology. It could allegedly vary the size of the drop fired rather than just the number of drops fired or the number of passes by the print-head to create each pixel. Because of its features, it is claimed that the existence of the new inkjet technology is another significant growth both in the development and application of inkjet technology.

The article talks about the new Xerox motorcycle called NuNess which will be designed by California-based custom bike designer Arlene Ness. The new bike is based on the Xerox Nuvera monochrome high-speed digital printer and will feature a color scheme that is monochromatic but not bland. Other details on the new bike such as its color scheme that would be full of highlights are given. Xerox plans to tour the country with the bike once it is finished, as well as go to Xerox customer events and select bike events.

In this article, the author examines large-format, flatbed inkjet printers, a market that did not exist four years ago, and discusses the suppliers who emerged at the conference in 2004. The flatbed market, where large sheets of board or other solid materials for markets, such as point of sale and displays, are printed began on Easter 2001, when Inca Digital launched its Eagle printer. The emphasis now is on speed, as quality is sufficient for the purpose, and newer machines, such as Inca's Columbia, have accelerated the speed of imaging.

This article presents information on biologists experiment with cheap inkjet printers. Don't throw away that out-of-date inkjet printer. Older versions from the mid-1990s, which tend to have wider nozzles than newer ones, are particularly good at spitting out molecules and cells. For example, tissue engineers interested in studying cell interactions or creating artificial skin, blood vessels, and whole organs, are using inkjets to deposit precisely ordered layers of different cell types, complete with growth factors and extra-cellular matrices. In a prototype experiment published recently in the January 2005 issue of Biomaterials, bioengineer Thomas Boland of Clemson University in South Carolina and his colleagues have used a modified Hewlett-Packard inkjet to apply viable mammalian cells to a variety of "papers," including collagen gel.