Inkjet Ink Research Articles

Surface modification of cotton fabrics by gas plasmas for color strength and adhesion by inkjet ink printing

Surface properties of cotton fabric were modified by three types of gas plasma pretreatment, namely, oxygen (O2), nitrogen (N2) and sulfur hexafluoride (SF6), to improve ink absorption of water-based pigmented inkjet inks and color reproduction of the treated surfaces. Effects of gas plasma exposure parameters of power, exposure time and gas pressure on surface physical and chemical properties of the treated fabrics were investigated. XPS (X-ray photoelectron spectroscopy) was used to identify changes in functional groups on the fabric surface while AFM (atomic force microscopy) and SEM (scanning electron microscopy) were used to reveal surface topography of the fabric. Color spectroscopic technique was used to investigate changes in color strength caused by different absorptions of the printed fabrics. The O2 plasma treatments produced new functional groups, OCO/CO and OCO while N2 plasma treatments produced additionally new functional groups, CN and OCNH, onto the fabric surface which increased hydrophilic properties and surface energy of the fabric. For cotton fabric treated with SF6 plasma, the fluorine functionalization was additionally found on the surface. Color strength values (K/S) increased when compared with those of the untreated fabrics. SF6 plasma-treated fabrics were hydrophobic and caused less ink absorption. Fabric surface roughness caused by plasma etching increased fabric surface areas, captured more ink, and enhanced a larger ink color gamut and ink adhesion. Cotton fabrics exhibited higher ink adhesion and wider color gamut after the O2 plasma treatment comparing with those after N2 plasma treatment.

3D-Printed Origami Packaging With Inkjet-Printed Antennas for RF Harvesting Sensors

This paper demonstrates the combination of additive manufacturing techniques for realizing complex 3D origami structures for high frequency applications. A 3D-printed compact package for enclosing radio frequency (RF) electronics is built, that features on-package antennas for RF signal reception (for harvesting or communication) at orthogonal orientations. Conventional 3D printing technologies often require significant amounts of time and supporting material to realize certain structures, such as hollow packages. In this work, instead of fabricating the package in its final 3D form, it is 3D-printed as a planar structure with “smart” shape-memory hinges that allow origami folding to a 3D shape after heating. This significantly reduces fabrication time and effectively eliminates the need for supporting material, thus minimizing the overall manufacturing cost. Metallization on the package is performed by directly inkjet printing conductive inks on top of the 3D-printed surface with a modified inkjet-printed process without the need for surface treatment or processing. Inkjet-printed on-package conductive features are successfully fabricated, that are combined with RF energy harvesting electronics to showcase the proof-of-concept of utilizing origami techniques to build fully 3D RF systems. The methodologies presented in this paper will be enabling the manufacturing of numerous real-time shape-changing 3D complex structures for electromagnetic applications.

Formulation of Eco-Friendly Inks for Ink-Jet Printing of Polyester and Cotton Blended Fabric

The aim of this research is to discover such a strategy so that Ink-jet Printing of polyester and cotton blended fabric. This research focuses to develop inks by the combination of Reactive and disperse dyes and by using eco-friendly co-solvents. This paper covers a brief introduction of Ink jet printing technologies and types of inks. A summarized study of the evaluation amid ink jet printing as well as rotary screen printing is also given. In addition to, requirements and composition of water-based ink-jet inks focusing on methodology is given. Furthermore, shelf lives of inks, image sharpness, surface tension, color fastness to rubbing, analysis of head with some personal experiences are also discussed.

A new method of artificial latent fingerprint creation using artificial sweat and inkjet printer

In order to study fingerprinting in the field of forensic science, it is very important to have two or more latent fingerprints with identical chemical composition and intensity. However, it is impossible to obtain identical fingerprints, in reality, because fingerprinting comes out slightly differently every time. A previous research study had proposed an artificial fingerprint creation method in which inkjet ink was replaced with amino acids and sodium chloride solution: the components of human sweat. But, this method had some drawbacks: divalent cations were not added while formulating the artificial sweat solution, and diluted solutions were used for creating weakly deposited latent fingerprint. In this study, a method was developed for overcoming the drawbacks of the methods used in the previous study. Several divalent cations were added in this study because the amino acid-ninhydrin (or some of its analogues) complex is known to react with divalent cations to produce a photoluminescent product; and, similarly, the amino acid-1,2-indanedione complex is known to be catalyzed by a small amount of zinc ions to produce a highly photoluminescent product. Also, in this study, a new technique was developed which enables to adjust the intensity when printing the latent fingerprint patterns. In this method, image processing software is used to control the intensity of the master fingerprint patterns, which adjusts the printing intensity of the latent fingerprints. This new method opened the way to produce a more realistic artificial fingerprint in various strengths with one artificial sweat working solution.

Wet microelectronic technologies on paper substrate for flexible electronic applications

Flexible electronics on paper is currently a challenging area of research. The use of an economical and ecological substrate, such as paper, has significant potential compared to a plastic substrate, such as PET (Polyethylene Terephthalate) or Kapton® (Polyimide). However, the roughness and tearing of paper due to moisture and temperature during operation constitute major technical challenges, considering the potential application in electronics. The use of printing techniques, such as gravure, flexographic, screen, offset, inkjet, conductive and dielectric inks, and organic polymers, all of which have different viscosities suitable for machine deposition, may allow to electronic devices on a paper substrate; example products using this technology include flexible batteries, solar cell, displays, and biomedical devices. This technology only presents a small number of disadvantages, which include poor conductivity, expensive materials, and difficulties with subtractive batch processes, such as photolithography and vacuum processes. In this article, the authors chose an unconventional way to reduce the impact of these disadvantages by adapting technological processes of microelectronics (i.e., photolithography, metal vapour deposition, electroplating, and etching) for use on a standard paper substrate.

Principal component analysis for the forensic discrimination of black inkjet inks based on the Vis–NIR fibre optics reflection spectra

Nineteen black inkjet inks of six different brands were examined by fibre optics reflection spectroscopy in Visible and Near Infrared Region (Vis–NIR FORS) directly on paper with a view to achieving good resolution between them. These different inks were tested on nineteen different inkjet printers from three brands. Samples were obtained from prints by reflection probe. Processed reflection spectra in the range 500–1000nm were used as samples in principal component analysis. Variability between spectra of the same ink obtained from different prints, as well as between spectra of square areas and lines was examined. For both spectra obtained from square areas and lines reference, Principal Component Analysis (PCA) models were created. According to these models, the inkjet inks were divided into clusters. PCA method is able to separate inks containing carbon black as main colorant from the other inks using other colorants. Some spectra were recorded from another piece of printer and used as validation samples. Spectra of validation samples were projected onto reference PCA models. According to position of validation samples in score plots it can be concluded that PCA based on Vis–NIR FORS can reliably differentiate inkjet inks which are included in the reference database. The presented method appears to be a suitable tool for forensic examination of questioned documents containing inkjet inks. Inkjet inks spectra were obtained without extraction or cutting sample with possibility to measure out of the laboratory

The chemo-rheological behavior of an acrylic based UV-curable inkjet ink: Effect of surface chemistry for hyperbranched polymers

Abstract A polyester-amid based hyperbranched polymer (HBP) with hydroxyl terminal groups is modified by the aid of saturated fatty acid groups with 7 carbon lengths. FTIR results reveal that about 85% of hydroxyl terminal groups were replaced by fatty acid chains. Having prepared and characterized the inferred modified HBP, the effect of both neat and modified forms of HBP was tested on the curing behavior of an acrylic based UV-curable inkjet ink by time-resolving photo rheo-mechanical spectroscopy (TRP-RMS). The chemo-rheological results of TRP-RMS show that the hyperbranched polymers, in both neat and modified forms affected the rheological behavior of the ink during the curing process. In this research, slope of estimated line on the chemo-rheological curves was used to measure the rate of complex viscosity growth of ink formulation during the curing process. Accordingly, slope in the blend without HBPs was 180.56 Pa and it increased to about 300 Pa on addition of HBPs even at a loading of as much as 2 wt.%. Results demonstrate that hyperbranched polymers have altering influence at the various different stages of the curing process.

Multienzyme Inkjet Printed 2D Arrays.

The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solutions as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochemical microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM.

Forensic application of laser-induced breakdown spectroscopy for the discrimination of questioned documents

Document examination is an important forensic discipline and the legal system regularly needs the knowledge and skills of the scientific expert when questioned documents are involved in criminal or civil matters. Amongst the many aspects of the scientific examination of documents, elemental analysis can provide useful results. In this study, the evaluation of the analytical performance of a commercially available laser-induced breakdown spectroscopy (LIBS) instrument was conducted on office papers, writing inks, inkjet inks and laser printer toners. The paper sample set analysed consisted of 33 Australian paper specimens originating from the same production plant but representing different brands and/or batches. In addition, a total of 131 ink or toner samples were examined that included black and blue ballpoint inks, black inkjet inks, and black laser printer toners originating from several manufacturing sources, models and/or batches. Results from the LIBS method were compared against those obtained using more established elemental profiling method such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). LIBS demonstrated detectable and significant differences between different batches of the same brand as well as between different brands of paper, ink and toner samples. The LIBS method provided comparable discrimination powers for the selected sample sets when compared to those obtained using LA-ICP-MS (discrimination from 99.8 and 100% of the sample pairs, depending on the sample subset under examination). LIBS is a suitable technique for the determination of elemental composition as part of a protocol for the examination of questioned documents.

Azo reactive dyes: ultrafiltration and application to cotton by exhaustion and digital ink-jet printing

Three reactive dyes have been synthesized by coupling 1-amino-phenyl-4-beta hydroxyethyl sulfone sulfate ester with 1-amino-8-hydroxynaphalene-3,6-disoulphonic acid (H-acid). The dyes synthesized were then purified using ultrafiltration and water-based reactive ink jet inks were prepared for digital printing applications. The dyes were characterized by their spectrophotometrical data ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy, optical emission spectroscopy, X-ray diffraction and elemental analysis. The purity of dyes was checked by thin layer chromatography and their dyeing performance was assessed on cotton fibers by exhaustion (dyeing) and ink-jet printing. Ink-jet inks with the dyes synthesized were prepared and their physical properties were measured in order to evaluate their suitability for ink-jet printing. Color measurements and fastness properties were performed for the dyed and digitally printed samples. Coloristic values of the dyed/ printed samples were as expected, that is, K/ S values of the dyed samples were much higher than those of the printed ones, K/ S values of the samples dyed with the ultrafiltrated dyes were higher than those with the initial dyes and the rest of the coloristic co-ordinates L, a, b, C, H, were in line with strength changes of the dyes before and after ultrafiltration. The dyed samples had excellent wash fastness and medium light fastness. Ultrafiltration slightly improves the fastness properties of the dyed samples.

Diffuse reflectance infrared spectroscopic identification of dispersant/particle bonding mechanisms in functional inks.

In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated particles provide evidence for the validity of the DRIFTS measurement.

The effect of different dispersants on the physical properties of nano CoAl2O4 ceramic ink-jet ink

In this study, the prepared nano-CoAl2O4 pigments were characterized by XRD, SEM and UV spectroscopy. In addition, four different inks were formulated by distinct dispersants such as SDS, CTAB, Triton X-100 and poly acrylic acid-co-itaconic acid (AA-co-AI). The effect of disperse agents was further investigated on rheology, surface tension and dynamic light scattering of prepared inks. The dispersion stability of nanoparticles was evaluated in various formulations by turbidimetry. The ink-jet printed onto a ceramic tile was the most stable ink obtained through the use of poly (AA-co-IA). The print was set to 1, 3 and 5 runs in order to evaluate variations in the optical properties with various thicknesses of the printed film. The appearance of printed image and the morphology of the prepared nano-CoAl2O4 particles were observed by SEM. Finally, the shape and size of nano-CoAl2O4 particles in prepared ink were investigated through the employment of TEM.

Effect of BaTiO3 Nanopowder Concentration on Rheological Behaviour of Ceramic Inkjet Inks

The relationship between rheological properties of ceramic inkjet inks based on BaTiO3 nanopowder and solid phase concentration has been investigated. In the ink volume takes place the formation periodic colloidal structures (PCS). The determining factor of structure formation is powder-dispersant ratio. Structural constitution of in the system with the low pigment concentration represented as PCS2, that contains solid particles in deflocculated that stabilized by the presence of adsorption-solvate layers. Dilatant structure formation for such inks explained by constrained conditions of the interaction. Samples with high BaTiO3 concentration have been classified as PKS1. Dilatant properties of the PKS1 resulted in particles rearrangement under the influence of the flow. In the region of some values powder-dispersant ratio take place conversation PKS2 to PKS1 and ink structure transformation from monodisperse to aggregate state.

Ultra-low-cost ‘paper-and-pencil’ device for electrically controlled micromixing of analytes

We demonstrate here a frugal, printing-based fabrication methodology for paper channels, in an effort towards developing an inexpensive micromixing device. The proposed fabrication methodology utilizes the normal ink-jet cartridge ink to create the barriers for the paper channels, without involving any additional complex materials or intermediary ink modification steps. We show through experimental observations, and pertinent scaling analysis, that the electrokinetic effects, along with the capillary and viscous forces, play a significant role in enhancing the liquid transport rate through such a paper channel under an applied electrical potential, in comparison with that observed due to natural imbibition. Thereafter, we delineate the modality of active electrical control of mixing of two liquids in such a printed ‘zigzag’ ‘paper-and-pencil’ device, by exploiting the interplay between the electrohydrodynamic flows stemming from the electrokinetic phenomena and the specific channel geometry. The electrokinetically mediated flow of the liquid samples through the ‘zigzag’ paper channel can be judiciously controlled to either appreciably enhance the mixing characteristics or artificially maintain the segregation of the liquid streams by overriding the inherent wicking action-driven mixing within the paper matrix. Hence, the present endeavour will usher in a new generation of paper microfluidic platforms for micromixing, with enhanced production feasibility, controllability, functioning efficiency, and multiplexing capability.

Preparation of SiO2/PSSS dispersion for formulation of white inkjet ink

SiO2 particles were prepared by sol–gel method and further modified with γ-methacryloxypropyltrimethoxysilane (KH570). A SiO2/PSSS composite was prepared with a core–shell structure, by the in situ polymerization of p-styrene sulfonate sodium (SSS) and the reaction with the KH570-modified SiO2. The SiO2/PSSS composite was optimized by adjusting the mass ratios of KH570 to SiO2, SSS to SiO2 and APS to SSS for control of the particle size and polymer layer thickness. Fourier transform infrared spectrum, contact angle and thermogravimetric analysis indicated that PSSS was successfully coated onto SiO2 particle surface. Transmission electron microscopy images showed that the prepared SiO2/PSSS dispersion had small particles and narrow particle size distribution. The white inkjet ink prepared from the SiO2/PSSS dispersion exhibited excellent thermal and centrifugal stabilities. The white inkjet ink was applied for pretreatment of fabric before colored printing which resulted in a significant enhancement of pattern brightness.

Study of Inks Used in Biomedical Optics Phantoms: Stability and Ageing

Inks are the most common absorbers added in phantoms for biomedical optics experiments. Due to the small quantities required, it is usual to prepare dilutions in distilled water and to store them for future use. However, they may degrade with time. This work investigates the stability, over a 60-day period, of various types of ink dilutions as a component used in tissue-mimicking phantoms. For this purpose, the optical properties, particularly the absorption coefficient, of a diffusive phantom fabricated with various pre-diluted inks have been determined using time-resolved experiments, for the period of time under investigation. Two commercial India inks were studied, namely Rotring® and Higgins®, as well as a third type, a black ink-jet printer ink (Powertec®). Results suggest that all ink dilutions suffer from ageing, affecting the reproducibility of the optical properties of the phantoms. For the investigated period, this effect was more noticeable for the India inks, but almost negligible for the ink-jet printer ink.

Advanced LED UV inks for industrial applications

The technology of inkjet is used not only in house but also in commercial and industrial area. To expand business area, it is one of the main issues that ink is necessary to be used with nonabsorbent substrates such as plastic films. One of solution of this issue is UV ink. The market of UV curable inkjet have shown rapid growth in industrial area, especially in decoration market. We developed UV curable inkjet ink cured by LED lamp, which is able to be used in decoration with inkjet technology. The newly developed ink is superior in stretch to former UV inkjet ink for decoration, and it will be able to be used in forming process with higher curvature. Moreover, the newly developed ink also overcomes the difficulties that the hardness of former UV inkjet ink for stretch forming process is low, and curing coating film is broken off during punching process.

Flow characteristics of ink-jet inks used for functional printing

The rheology-related effects of nozzle clogging in inkjet printing can seriously affect ink ejection rate and result in irregular droplet trajectory, resulting in poor printing results. In this study three different inkjet inks, used for functional printing with a Dimatix materials inkjet printer, are investigated rheologically. In connection with rheological observation a novel method of inkjet trajectory image analysis gives insight into the irregularity of directional deviation due to clogging of nozzles of the printer It is found that the type of solvent used in the ink formulation has an important influence on the rheological behaviour in the printing regime, which directly has an effect on ink-droplet trajectory and contact characteristic with the substrate.

Rheology and Stability of Functionalized Particle Loaded Inkjet Inks

In this study, we investigate the rheological properties as well as the stability and the electrical properties of inkjet inks based on silane-functionalized TiO2-particles. At first, we describe the preparation of the surface modified TiO2-particles, the formulation of the inks and the measurement procedures. The results of the measurements are presented and mechanisms, which could explain the observed characteristics, are discussed. Based on these findings, we discuss the limits of application of the surface modified nanoparticle inks for functional inkjet printing. Furthermore, we show the successful application of a surface modified nanoparticle ink for inkjet printing of photo electrodes for photo assisted water splitting.

A Review of Silver Nanoparticles: Synthesis Methods, Properties and Applications

In recent years, nanoparticles of noble metals such as gold, silver and palladium have drawn immense attention due to the wide range of new applications in various fields of industry. Particularly, silver nanoparticles have significant interest in medical applications such as very effective antibacterial agents without the toxic effects, and industry application such as inkjet inks containing well uniform dispersions of nano-sized silver particles that are useful for producing electronic circuits. It is important that the silver nanoparticles require not only the particles to be of nano-size, but also synthesis of the nanoparticles to be produced easily and at low cost. Over the past few decades, many synthetic methods of silver nanoparticles have been studied. This paper aims to review different synthesis routes of silver nanoparticles and their applications. In particular, we mainly present several chemical approaches to preparing silver nanoparticles and their properties as well as applications based on our recent studies. The focus is on effective and efficient synthesis of pure colloidal silver nanoparticles with high electrical conductivity and their potential application.