Inkjet 3D Research Articles

On the quantitative assessment of the effect of multiple process parameters on the printed layer height in 3D inkjet printing

ABSTRACT 3D inkjet (3D-IJ) printing is recognised for its potential in high-value applications, including printed electronics, tissue engineering and bio-inspired structures, given its precision and ability to deposit multiple materials. The quality of 3D-IJ printed parts is contingent upon meticulous control of the process governing parameters. This study experimentally investigates the influence of various parameters within the 3D-IJ process, i.e., printing resolution, coverage percentage, droplet volume, printing speed and UV-Power and their interaction effects on the printed layer height. The results were analysed statistically using ANOVA and a quadratic regression model was developed to quantitatively identify the relationship between the process response and parameters. Except UV-Power, all parameters, and their interactions with each other had noticeable effects on the printed layer height, with a distinct trend observed for each, affecting the height that ranged from 4.73 µm to 98.58 µm. Increasing printing resolution, coverage percentage and droplet volume resulted in an increase in layer height as all three parameters contribute to a larger volume of dispensed material per layer. Printing resolution was found to be the most influential parameter, evidenced by a significant p-value. Finally, the optimal printing parameters for two scenarios, highest printed layer and cost-effective printing were individually identified.

Customizing ultraviolet curable polymer‐ink properties via reactive diluent modification and viscosity control

AbstractIn inkjet 3D printing, material selection plays a crucial role in shaping both printing performance and material characteristics. Achieving the desired properties relies on precisely formulated compositions. In this context, ultraviolet (UV) curable polymers require specific viscosities, typically ranging from 3700 to 5700 mPa·s, to function effectively in 3D printing's material jetting technique, preventing complications during material dispensing. This study formulates UV‐curable polymers by blending four distinct monomers: Genomer 4247 Aliphatic Urethane Dimethacrylate, 1,10‐Decanediol Dimethacrylate, Isobornyl Acrylate, and Methyl Acrylate, within a controlled dark room environment at room temperature to prevent undesired crosslinking reactions during mixing. The selection of these monomers and their compositions is meticulous, considering their capacity to achieve specified viscosities and enhance overall material performance. This formulation process yields a wide range of UV‐curable polymer viscosities. The study employs comprehensive methodologies, including rheometry, Fourier transform infrared analysis, Soxhlet extraction, thermal analysis, and tensile testing, for rigorous evaluation of viscosity, curing efficiency, thermal characteristics, and mechanical performance. Notably, mechanical and chemical performance exhibits marginal differences within the viscosity range, attributed to UV‐curable polymer crosslinking, consistently exceeding 99% for all samples. However, the polymer composed of 98% v/v oligomer and methyl acrylate (MA) demonstrates notably better thermal and mechanical properties due to its 99.91% gel content crosslinking. Remarkable polymer fabrication thus occurs within the desired viscosity range.

Investigation of the profilogram structure of microstrip microwave modules manufactured using additive 3D-printing technology

Objectives. The aim of the work is to study the surface roughness of the current-carrying topology and dielectric of the upper (Top Layer) and lower (Bottom Layer) sides of microwave modules manufactured using additive three-dimensional printing technology when prototyping prototypes of microwave modules on a 3D printer of DragonFly 2020 LDM multilayer printed circuit boards.Methods. Methods of metallographic analysis in bright and dark fields, surface roughness profiling, and computer modeling were used.Results. Experimental samples of microstrip microwave elements of modules of multilayer boards of a given configuration, telemetry sensors, printed circuit board (PCB) antennas were obtained. The topological and radiophysical features of the additively formed upper and lower surface layers of experimental samples of boards of strip modules were studied. Optical profilogram measurements of the roughness of the outer sides of the board were carried out at 10 points, amounting to 2 µm for the upper layer of the topology and 0.3 µm for the lower layer; the average grain size of the dielectric base was determined at 0.007 mm2. The roughness of the conductive topology and upper side dielectric was shown to correspond to an accuracy class of 6–7, while the roughness of the microstrip conductive topology and the dielectric of the lower side of the board corresponds to an accuracy class of 10–12.Conclusions. It is established that an uneven formation of the lower and upper strip layers of the printed module can affect the inhomogeneity of the distribution of radiophysical parameters (dielectric permittivity, surface conductivity, etc.), as well as the instability of the structural (adhesion ability, thermal conductivity, etc.) characteristics of the strip module, which must be taken into account when prototyping devices using inkjet 3D printing technology, including when adapting Gerber projects of PCB modules created for classical board production technology.

Application of 3D Bioprinting in Liver Diseases.

Liver diseases are the primary reason for morbidity and mortality in the world. Owing to a shortage of organ donors and postoperative immune rejection, patients routinely suffer from liver failure. Unlike 2D cell models, animal models, and organoids, 3D bioprinting can be successfully employed to print living tissues and organs that contain blood vessels, bone, and kidney, heart, and liver tissues and so on. 3D bioprinting is mainly classified into four types: inkjet 3D bioprinting, extrusion-based 3D bioprinting, laser-assisted bioprinting (LAB), and vat photopolymerization. Bioinks for 3D bioprinting are composed of hydrogels and cells. For liver 3D bioprinting, hepatic parenchymal cells (hepatocytes) and liver nonparenchymal cells (hepatic stellate cells, hepatic sinusoidal endothelial cells, and Kupffer cells) are commonly used. Compared to conventional scaffold-based approaches, marked by limited functionality and complexity, 3D bioprinting can achieve accurate cell settlement, a high resolution, and more efficient usage of biomaterials, better mimicking the complex microstructures of native tissues. This method will make contributions to disease modeling, drug discovery, and even regenerative medicine. However, the limitations and challenges of this method cannot be ignored. Limitation include the requirement of diverse fabrication technologies, observation of drug dynamic response under perfusion culture, the resolution to reproduce complex hepatic microenvironment, and so on. Despite this, 3D bioprinting is still a promising and innovative biofabrication strategy for the creation of artificial multi-cellular tissues/organs.

Fabrication of carbon nanotube components using 3D printing: Review

One of the most recognizable innovations in nanotechnology is the Carbon Nanotube (CNT). Due to their promising applications, CNTs have been the focus of many studies during the last two decades. CNTs are nano-sized, very flexible, resistant to corrosion, electrically and thermally conductive, biocompatible, and can be customized and functionalized. By building up materials layer by layer, Additive Manufacturing (AM) is a useful method for fabricating nanocomposites in complicated geometries. It has recently come to light that AM techniques are promising contenders for synthesizing CNT applications with varied functions. Extrusion-based 3D printing techniques (such as Fused Deposition Modeling (FDM), inkjet printing, and Direct Ink Writing (DIW)) show great potential for fabricating CNT applications such as sensors, batteries, electrodes, supercapacitors, and scaffolds. This article provides an overview of the latest literature on 3D-printed CNT applications using various AM processes.

Preliminary study on the design of superhydrophobic surface by 3D inkjet printing of a sol-gel solution

Preliminary study on the design of superhydrophobic surface by 3D inkjet printing of a sol-gel solution

Dynamics of drop formation and characterization of additive manufactured CS/AgNP/PVA composite membranes

AbstractThis study investigated the dynamics of drop formation and the printability of chitosan/silver nanoparticles composite fluid (CS/AgNP) modified with polyvinyl alcohol (PVA) using an inkjet 3D printer. It specifically investigated the relationship between rheological properties and fluid mechanical properties in determining the minimum drop velocity for 3D printing of modified CS ink. Proper matching of modified CS fluid rheological properties to the established physical parameters generated adequate droplets on glass substrates and formed membrane composites. The dynamic viscosity of the CS ink decreased with an increase in the concentration of PVA, which resulted in the disruption of existing molecular forces within the CS/AgNP polymer chains, suggesting that the solvent (PVA) was responsible for reducing the shear stress, surface tension, and viscosity of the composite membranes and subsequently improving the flow rates of the CS matrix at the nozzle orifice. Optimized drop velocity of 1.77 m/s yielded adequate formation of the CS/AgNP/PVA membrane composite with enhanced surface morphology, while an increase in drop velocity to 2.5 m/s brought about the formation of satellite droplets with irregular surface structures in printed CS composites. Therefore, adherence to minimum fluid drop velocity is fundamental to effective inkjet printing of composite membranes.

An Anode-Supported Solid Oxide Fuel Cell (SOFC) Half-Cell Fabricated by Hybrid 3D Inkjet Printing and Laser Treatment

A NiO-10YSZ/10YSZ half-cell for anode-supported solid oxide fuel cells (SOFCs) was fabricated using 3D inkjet printing and layer-by-layer laser treatment of printing compositions followed by thermal sintering by a co-firing method. The optimal granulometric composition and rheological characteristics of the printing compositions to fabricate the NiO-10YSZ (60:40 wt.%) anode support, NiO-10YSZ (40:60 wt.%) anode functional layer (AFL), and 10YSZ electrolyte were determined. Effects of the pore former and laser post-treatment on the morphology of the as-prepared anodes for the manufacture of SOFC anode supports were studied, and the optimum laser exposure for hybrid 3D printing was determined. A mechanism of influence of the exposure of laser post-treatment on the morphology of the NiO-10YSZ anode supports has been proposed. The mass content of 10YSZ and the number of layers were shown to affect the surface microstructure and the thickness of the thin-film electrolytes deposited on the surface of the anode supports. The hybrid inkjet 3D printing offers great opportunities as it allows a one-pot procedure to fabricate a NiO-10YSZ/10YSZ SOFC half-cell for SOFC anode supports.

Prediction model and compensation method for curing shrinkage of inkjet 3D printing parts

Inkjet 3D printing has huge potential for applications in electronics printing, ceramic printing, and other fields, primarily due to the excellent dimensional accuracy of printed products, which is particularly important for device performance. However, in inkjet 3D printing, the fusion and solidification of droplets can cause the samples to shrink in various directions, resulting in a deviation from the designed target size, and subsequently affecting the performance of the part. In this study, the curing shrinkage behavior of parts in inkjet 3D printing is examined. First, a shrinkage model of the droplet element is established using the finite element method in accordance with the material parameters, and the linear shrinkage rates of different droplet groups are obtained. A curing shrinkage prediction model of the printed parts is then established, and the size and shape of the cured parts are predicted accordingly. A height calculation model of the printed parts is established according to the concept of volume conservation, and the height prediction of the printed parts is realized according to the number of printed layers and their resolution. An approach for compensation of the print model graphic layers is developed using the established prediction model. Experiments using two printing materials with different degrees of shrinkage are conducted to verify the feasibility of this method. The results indicate that the proposed curing shrinkage prediction model can seamlessly capture the curing shrinkage behavior of printed parts for materials with different shrinkages. Furthermore, after shrinkage, the model-based print compensation method achieves the measured sizes that are closer to the target size than that without compensation. The dimensions of inkjet 3D printed parts can be accurately controlled using this method.

Three-Dimensional Scaffolds for Bone Tissue Engineering.

Immobilization using external or internal splints is a standard and effective procedure to treat minor skeletal fractures. In the case of major skeletal defects caused by extreme trauma, infectious diseases or tumors, the surgical implantation of a bone graft from external sources is required for a complete cure. Practical disadvantages, such as the risk of immune rejection and infection at the implant site, are high in xenografts and allografts. Currently, an autograft from the iliac crest of a patient is considered the "gold standard" method for treating large-scale skeletal defects. However, this method is not an ideal solution due to its limited availability and significant reports of morbidity in the harvest site (30%) as well as the implanted site (5-35%). Tissue-engineered bone grafts aim to create a mechanically strong, biologically viable and degradable bone graft by combining a three-dimensional porous scaffold with osteoblast or progenitor cells. The materials used for such tissue-engineered bone grafts can be broadly divided into ceramic materials (calcium phosphates) and biocompatible/bioactive synthetic polymers. This review summarizes the types of materials used to make scaffolds for cryo-preservable tissue-engineered bone grafts as well as the distinct methods adopted to create the scaffolds, including traditional scaffold fabrication methods (solvent-casting, gas-foaming, electrospinning, thermally induced phase separation) and more recent fabrication methods (fused deposition molding, stereolithography, selective laser sintering, Inkjet 3D printing, laser-assisted bioprinting and 3D bioprinting). This is followed by a short summation of the current osteochondrogenic models along with the required scaffold mechanical properties for in vivo applications. We then present a few results of the effects of freezing and thawing on the structural and mechanical integrity of PLLA scaffolds prepared by the thermally induced phase separation method and conclude this review article by summarizing the current regulatory requirements for tissue-engineered products.

Prediction model of part topography in curved surface inkjet 3D printing

Prediction model of part topography in curved surface inkjet 3D printing

Impact of Microfluidic Chip Electrophoresis in Modern Analysis: An Update on Recent Trends

Abstract: The recent development of microfluidics and lab-on-a-chip technology has substantially raised interest in analytical chemistry. Since, they have demonstrated to be extraordinarily adept at precise fluid control, cell manipulation, and signal output, microfluidic chips are a useful tool for quick and in-depth single-cell investigation. This technique is cost-effective, less time-consuming, automatic, high mobility, and fast separation technique. Due to the internal chip sizes, which range from micrometers to millimeters, consumption of the samples and reagents occurs at the nanoliter and picoliter levels. The microfluidic device can fit a variety of functions onto a few centimeter-long chips. In this article, we discussed numerous preparations of microfluidic chip electrophoresis and its recent advancements. This method is useful for the detection of various small amounts of content with less time and greater efficacy. It is also useful in cancer studies, 3D inkjet printing, immunoassay investigation in cell-cell interactions, analysis of nanoparticles, dielectrophoretic particle separation, plant alkaloids, and forensic science applications. This review, therefore, examines the use of various microfluidic chips in electrophoretic separation during 2017–2022. There are various papers found by search, indicating continuous activity in the research area along with studies to explain its material, method, and its efficacy.

3D culture of fibroblasts and neuronal cells on microfabricated free-floating carriers

3D cell culture is a relatively recent trend in biomedical research for artificially mimicking in vivo environment and providing three dimensions for the cells to grow in vitro, particularly with regard to surface-adherent mammalian cells. Different cells and research objectives require different culture conditions which has led to an increase in the diversity of 3D cell culture models. In this study, we show two independent on-carrier 3D cell culture models aimed at two different potential applications. Firstly, micron-scale porous spherical structures fabricated from poly (lactic-co-glycolic acid) or PLGA are used as 3D cell carriers so that the cells do not lose their physiologically relevant spherical shape. Secondly, millimetre-scale silk fibroin structures fabricated by 3D inkjet bioprinting are used as 3D cell carriers to demonstrate cell growth patterning in 3D for use in applications which require directed cell growth. The L929 fibroblasts demonstrated excellent adherence, cell-division and proliferation on the PLGA carriers, while the PC12 neuronal cells showed excellent adherence, proliferation and spread on the fibroin carriers without any evidence of cytotoxicity from the carriers. The present study thus proposes two models for 3D cell culture and demonstrates, firstly, that easily fabricable porous PLGA structures can act as excellent cell carriers for aiding cells easily retain their physiologically relevant 3D spherical shape in vitro, and secondly, that 3D inkjet printed silk fibroin structures can act as geometrically-shaped carriers for 3D cell patterning or directed cell growth in vitro. While the ‘fibroblasts on PLGA carriers’ model will help achieve more accurate results than the conventional 2D culture in cell research, such as drug discovery, and cell proliferation for adoptive cell transfer, such as stem cell therapy, the ‘neuronal cells on silk fibroin carriers’ model will help in research requiring patterned cell growth, such as treatment of neuropathies.

Highly Processable Ionogels with Mechanical Robustness

AbstractCurrently, the increasing needs of conductive ionogels with intricate shapes and high processability by individual requirements of next‐generation flexible electronics constitute significant challenges. Here, the design of highly processable ionogels is reported with mechanical robustness by self‐assembly of a common triblock copolymer into a precursor in functional mixed ionic liquids (ILs) containing conductivity‐enhancing and polymerizable strength‐enhancing components. The subsequent in situ polymerization of the precursor forms physical‐co‐chemical cross‐linked networks, in which the entanglement between physical and chemical cross‐linked networks and microphase separation give rise to mechanical robustness of as‐fabricated ionogel. The viscosity of the self‐assembled precursor can be rationally tuned, which makes the fabrication process compatible with diverse technologies including inkjet printing, spray coating, and 3D printing. By virtue of highly processable capability of the designed ionogels, an auxetic‐structured ionogel can be easily generated using 3D printing, which exhibits greatly improved sensitivity and thus is able to monitor tiny deformations. This study that relies on designing functional mixed ILs as the dispersion phase rather than focusing on synthesizing new‐type polymers establishes a new route for versatile and programmable fabrication of high‐performance ionogels for broader applications.

Fabrication of 3D structure with heterogeneous compositions using inkjet printing process

Inkjet based 3D printing technology discharges fine ink droplets from multiple printer heads to perform patterning and depositing in the target locations. The inkjet 3D printing can be differentiated from other 3D printing processes. It can print multiple materials simultaneously by using multiple printer heads, thus it is appropriate to create heterogeneous complex structure such as electronic devices. This study demonstrated the inkjet 3D printing to manufacture multi-layer composite structures using photocurable SiO2 ink and intense pulsed light (IPL) sinterable conductive Cu ink. The rheology and deposition behavior of each ink were investigated so that it could be applied for inkjet 3D printing. The various shape of 3D structures which are consist of insulative and conductive layers were fabricated to study the applicability of inkjet 3D printing in the electronics.

Impact dynamics of ferrofluid droplet on a PDMS substrate under the influence of magnetic field

We report the impact dynamics of a ferrofluid droplet on a PDMS substrate in the presence of a non-uniform magnetic field. Based on high-speed imaging, we unravel the various characteristic behaviors of the impinging ferrofluid droplet under the influence of a vertically applied magnetic field. We show that the magnetic, viscous, inertial, and interfacial energies non-trivially affect the equilibrium shape of the impacting ferrofluid droplet. Consequently, we reveal that the collective role of these forces ensures the ferrofluid droplet exhibits essentially three typical equilibrium shapes, i.e., no spike, single spike, and multiple spikes assemblies. Based on a phase diagram, we demonstrate the role of various dynamic forces in dictating the droplet’s equilibrium shape. We report the universality constant exhibited by the non-dimensionalized droplet diameter (ratio of the droplet’s equilibrium diameter to the semi-minor axis width of the ellipsoidal droplet just before impact), irrespective of the magnetic Bond number, on a PDMS substrate to be around 1.3. Consequently, we investigated the internal flow domain of the ferrofluid flow field in the presence of a magnetic field, essentially to understand its characteristic spreading behavior. Following bright-field visualization, we observed chain-like clustering of the magnetic nanoparticles inside the ferrofluid flow domain in a direction perpendicular to the magnet. Insights from bright field visualization enable us to qualitatively argue that the chaining phenomena of the nano-sized particles (present inside ferrofluid) in a direction perpendicular to the substrate ensure the formation of single/multiple assemblies of spikes. In addition, we also argue that the chain-formation of the magnetic nanoparticles increases the viscous force of the ferrofluid droplet in the presence of a magnetic field. This augmented viscous energy of the fluid in the presence of a magnetic field ensures the inverse relationship of the spreading diameter with magnetic field strength. The inference of the present study could be beneficial in the rational design of wide-ranging applications, such as ink-jet printing or 3D printing, requiring controlled droplet spreading phenomena.

Environmental impact analysis of surface printing and 3D inkjet printing applications using an imine based covalent organic framework: A life cycle assessment study

Covalent organic frameworks (COFs) are emerging materials with structural modularity that allows their application in many fields. The aim of this work is to determine the environmental impact of using an imine based covalent organic framework (RT-COF-1) for both surface printing (Case A) and 3D inkjet printing (Case B) by applying Life Cycle Assessment (LCA) methodology. Experimental data on RT-COF-1 synthesis as well as results obtained by simulation of their precursors production, 1,3,5-tris-(4-aminophenyl) benzene (TAPB) and 1,3,5-benzenetricarbaldehyde (BTCA), are used. LCA results show that monomer synthesis is the most important contributor to environmental impacts in both case studies. On the other hand, the contribution of solvents used in Case A is also remarkable. The comparison between both case studies indicates that the environmental impacts of Case B is lower than that of Case A (reduction within 5%–65%). Finally, LCA results of Case B are compared to other materials used for 3D-printing, such as polymerizable ionic liquids (PILs). The results show that RT–COF–1 compares favourably with PILs in five of nine impact categories, being especially relevant the reductions achieved in the abiotic depletion and acidification potential (>90%), in the primary energy consumption (⁓35%) and carbon footprint (⁓50%), suggesting the potential of RT–COF–1 as 3D-printing material from an environmental perspective. This work is a first step for further research to highlight the main environmental burdens of using COF-based materials in this application.

Recent Advances in the Applications of Additive Manufacturing (3D Printing) in Drug Delivery: A Comprehensive Review.

There has been a tremendous increase in the investigations of three-dimensional (3D) printing for biomedical and pharmaceutical applications, and drug delivery in particular, ever since the US FDA approved the first 3D printed medicine, SPRITAM® (levetiracetam) in 2015. Three-dimensional printing, also known as additive manufacturing, involves various manufacturing techniques like fused-deposition modeling, 3D inkjet, stereolithography, direct powder extrusion, and selective laser sintering, among other 3D printing techniques, which are based on the digitally controlled layer-by-layer deposition of materials to form various geometries of printlets. In contrast to conventional manufacturing methods, 3D printing technologies provide the unique and important opportunity for the fabrication of personalized dosage forms, which is an important aspect in addressing diverse patient medical needs. There is however the need to speed up the use of 3D printing in the biopharmaceutical industry and clinical settings, and this can be made possible through the integration of modern technologies like artificial intelligence, machine learning, and Internet of Things, into additive manufacturing. This will lead to less human involvement and expertise, independent, streamlined, and intelligent production of personalized medicines. Four-dimensional (4D) printing is another important additive manufacturing technique similar to 3D printing, but adds a 4th dimension defined as time, to the printing. This paper aims to give a detailed review of the applications and principles of operation of various 3D printing technologies in drug delivery, and the materials used in 3D printing, and highlight the challenges and opportunities of additive manufacturing, while introducing the concept of 4D printing and its pharmaceutical applications.

3D printing of graphene oxide/carbon nanotubes hydrogel circuits for multifunctional fire alarm and protection

Hydrogel circuit materials have a wide range of applications, especially in the field of flexible electronics. However, developing smart hydrogel circuit materials with remarkable properties remains a difficult problem. Based on the flexible design of circuit structure and direct inkjet 3D printing technology, we designed a printable conductive sodium alginate/graphene/carbon nanotube (SGC) ink and achieved three-dimensional graphene-based flexible circuits with high resolution and multifunction. Compared with previous work, the addition of GO, SWCNT and Ca2+ make SGC have excellent conductivity and flame retardancy. The conductivity of SGC reaches 24.11S/m, which is 3 times higher than SA hydrogel. And the LOI is above 99.7%, which is far higher than most conductive polymer. We have conducted preliminary explorations and provided theoretical basis for the 3D printing of multifunctional SGC hydrogels with complex structures, which are expected to be applied in the field of flexible circuits, fire protection and artificial electronic skin.

Modification of hydroxyapatite (HA) powder by carboxymethyl chitosan (CMCS) for 3D printing bioceramic bone scaffolds

The poor mechanical properties of 3D printed HA bone scaffold is always a challenge in tissue engineering, to address this issue, carboxymethyl chitosan (CMCS) was proposed to modify HA bone scaffolds by a physical blending method in this research. A series of HA and HA/CMCS composite ceramic scaffolds were printed by using piezoelectric inkjet 3D printing technology, and their properties were investigated in terms of forming quality, structural morphology, mechanical properties, degradability, cytotoxicity, and cell adhesion growth. The results of forming quality and structural morphology show that with the increase of CMCS content, the forming quality of the samples deteriorated, the pore size and porosity increased. However, when the content of CMCS reached 5 wt%, obvious cracks appeared on the surface of the sample, and the forming quality was relatively poor. The mechanical testing results indicated the toughness of composites could be enhanced by incorporating CMCS into HA, which was attributed to the higher strength connections of the CMCS polymer network between HA particles and the stronger interaction between HA and CMCS molecules. FTIR spectra further revealed the strong hydrogen bonding interaction between CMCS and HA. Moreover, the degradation rate and mineralization ability of the sample increased with the content of CMCS, but the compressive strength during degradation increased with the CMCS content, indicating that incorporating CMCS into HA cannot only improve the mechanical property and biological activity of the scaffold but also makes up the defect of slow degradation of pure HA scaffold. Finally, the cytotoxicity, cell adhesion, and cell proliferation tests show that HA and HA/CMCS composite samples had good cytocompatibility, HA/CMCS sample with 3 wt% CMCS possessed the best bioactivity. In summary, HA/CMCS composite powder with 3 wt% CMCS content is the optimal matrix material for 3D printing bone scaffolds.