Printing System Research Articles

Fractal-fractional model for the receptor in a 3D printing system

A critical hurdle in three-dimensional printing is the low printing accuracy. In particular, the deformation of the printed object on the receptor makes accurate printing impossible due to insufficient solvent evaporation. We address this challenge by establishing a Murray-like receptor to control the morphology of the printed object, which can be used for accurate printing through efficient residual energy absorption and active vibration attenuation. A fractal oscillator is established and He’s frequency formulation is used to reveal the fractal response of the Murray-like receptor, and an experiment was carried out to show that the receptor system can keep the printed object in good shape without any deformation.

Comparison of mechanical properties of 3D printer resins for occlusal splints using different models of 3D printers.

Considering the development of new 3D printing technologies that use different printing techniques, further studies must be conducted to evaluate the impact of different printing systems on the mechanical properties of 3D-printed materials. This study aimed to evaluate the mechanical properties of 3D-printed materials for occlusal devices using different 3D printers and printing layer thicknesses. Ninety rectangular samples were manufactured and divided into nine groups according to the 3D printer model they were printed on (AnyCubic Mono X, Elegoo Mars 2, or FlashForge Hunter) and the layer thickness (20, 50, or 100 µm) and were subjected to superficial microhardness, flexural resistance, and elasticity modulus tests. The results were analyzed using two-way analysis of variance and Tukey's statistical tests, with a significance level of 5%. The type of 3D printer significantly affected superficial microhardness (p = 0.007). Flexural strength showed a significant interaction between the 3D printer and layer thickness (p = 0.005), with both factors independently influencing flexural strength (printer: p< 0.001, layer thickness: p< 0.001). Elasticity modulus was significantly influenced by the 3D printer type (p< 0.001) and the interaction between both factors (p = 0.004). The AnyCubic Mono X 3D printer with a 20 µm layer thickness exhibited more consistent mechanical properties than the other printers. Variations in printing systems and layer thicknesses can impact the mechanical properties of 3D-printed materials. Key words:CAD-CAM. Bruxism. Temporomandibular disorders. Mechanical tests; 3-D printing.Care Team.

The first magnetic resonance imaging compatible 3D printer

Background: The current study presents the development of a magnetic resonance imaging (MRI)-compatible silicone-based 3D printer capable of producing patient-specific implants within MRI scanners. Methods: The printing device incorporates 3 piezoelectrically-actuated linear motion stages assigned for navigating a custom-made silicone extruder to develop the desired 3D model based on preoperative MRI scans of the damaged anatomy. The structural components were manufactured on a rapid prototyping machine with thermoplastic and compactly assembled utilizing non-magnetic materials to ensure fit and safe functioning of the system within the MRI bore. Results: The printing system was successfully integrated with a high-field MRI scanner and operated safely while maintaining sufficient imaging quality. The robotic motion mechanism exhibited excellent repeatability and achieved submillimeter accuracy, demonstrating its capability for precise positioning of the extruder. Conclusion: The proposed 3D printer may hold promise as valuable tool for personalized tissue reconstruction by real-time printing with biocompatible silicone on the MRI table. However, challenges such as prolonged processing times and related high costs will possibly hinder its adoption in clinical practice.

Photopolymerization of Stainless Steel 420 Metal Suspension: Printing System and Process Development of Additive Manufacturing Technology toward High-Volume Production

As the metal additive manufacturing (AM) field evolves with an increasing demand for highly complex and customizable products, there is a critical need to close the gap in productivity between metal AM and traditional manufacturing (TM) processes such as continuous casting, machining, etc., designed for mass production. This paper presents the development of the scalable and expeditious additive manufacturing (SEAM) process, which hybridizes binder jet printing and stereolithography principles, and capitalizes on their advantages to improve productivity. The proposed SEAM process was applied to stainless steel 420 (SS420) and the processing conditions (green part printing, debinding, and sintering) were optimized. Finally, an SS420 turbine fabricated using these conditions successfully reached a relative density of 99.7%. The SEAM process is not only suitable for a high-volume production environment but is also capable of fabricating components with excellent accuracy and resolution. Once fully developed, the process is well-suited to bridge the productivity gap between metal AM and TM processes, making it an attractive candidate for further development and future commercialization as a feasible solution to high-volume production AM.

Droplet volume prediction methods in electrohydrodynamic jet printing based on multi-source data fusion

Electrohydrodynamic jet printing technology has garnered significant interest in additive manufacturing due to its advantages in higher resolution printing and greater viscosity material applicability. Nonetheless, the challenges associated with femtoliter-level droplets and the micrometer-scale printing space have rendered traditional optical observation methods for volume calculation impractical for integration into the printing systems. Obtaining the droplet volume accurately has become a formidable challenge in electrohydrodynamic printing. While existing research utilizes machine learning for the end-to-end prediction of process parameters to droplet volume, traditional prediction methods cannot achieve online prediction due to the complex spray states characteristic of electrohydrodynamic jet printing and pose integration difficulties within printing systems. This paper introduces a multi-source data fusion model suitable for electrohydrodynamic printing droplet volume prediction. The model employs the VGG network to extract features from Taylor cone images in the jetting state and synchronously fuse these with process parameter features. The fused features are then correlated with droplet volume labels through the MLP network for comprehensive model training. The performance of the proposed model has improved by 10% in prediction accuracy compared to single modal data. We integrated the prediction method into an electrohydrodynamic jet printing system and experimented with printing pixel-pit substrates. The results indicate that the prediction accuracy of the volume prediction system is over 92%. The printing efficiency has improved approximately 3 times compared to the traditional method, significantly enhancing overall performance.

Fabrication of a microfluidic system with in situ-integrated microlens arrays using electrohydrodynamic jet printing

Microfluidic systems with integrated microlenses enhance cellular analysis and observation and have gained significant attention in the biomedical field. However, the integration and design of microlenses in microfluidic systems remain challenging. In this study, we utilize a high-precision electrohydrodynamic jet (E-jet) printing system for in-situ integration of microlens. By incorporating a tilting illumination observation module into the E-jet printing system, the print nozzle can be accurately positioned 10 μm above the microchannel bottom, thereby mitigating the edge effect of the microfluidic channels. We have developed a microfluidic system embedding microlens arrays (MLAs) that enable parallel, multichannel cell counting. The microfluidic system comprises nine channels, each featuring a 50 μm diameter microlens printed along the central axis. Using microlenses enables non-contact cell counting by detecting light-intensity changes. Simulating and optimizing the microfluidic channel size enable cells to align on the centerline of the channel and pass over the focal region of the microlens via inertial forces. As the cells flow through the microlens, the intensity of the focal spots decreases by approximately 50 %. The microfluidic cell-counting system can function independently or be integrated with other microfluidic systems as a unit, thus enhancing the single-cell operational and analytical capabilities of microfluidic systems.

Tuning the Mechanical Properties of 3D-Printed Objects by Mixing Chain Transfer Agents in Norrish Type I Photoinitiated RAFT Polymerization.

Photoinduced 3D printing via photocontrolled reversible-deactivation radical polymerization (photoRDRP) techniques has emerged as a robust technique for creating polymeric materials. However, methods for precisely adjusting the mechanical properties of these materials remain limited. In this study, we present a facile approach for adjusting the mechanical properties of 3D-printed objects by adjusting the polymer dispersity within a Norrish type I photoinitiated reversible addition-fragmentation chain transfer (NTI-RAFT) polymerization-based 3D printing process. We investigated the effects of varying the concentrations and molar ratios of trithiocarbonate (BTPA) and xanthate (EXEP) on the mechanical properties of the printed materials. Our findings demonstrate that increased concentrations of RAFT agents or higher proportions of the more active BTPA lead to a decrease in Young's modulus and glass transition temperatures, along with an increase in elongation at break, which can be attributed to the enhanced homogeneity of the polymer network. Using a commercial LCD printer, the NTI-RAFT-based 3D printing system effectively produced materials with tailored mechanical properties, highlighting its potential for practical applications.

Bio-inspired synergistic humidity-responsive photonic system for security printing and information encryption

The proliferation of counterfeiting necessitates an urgent need for enhanced technique to safeguard the authenticity of sensitive items. Inspired by the elytra of Tmesisternus isabellae beetles, we designed a new synergistic humidity responsive photonic system (SHRPS) for security printing based on high quality photonic paper and active ink. The photonic paper itself is not sensitive to humidity; only the targeted areas activated by the active ink exhibit humidity responsiveness. We investigated factors influencing humidity responsiveness, including monomer composition, pH of active ink, and treatment period. We found the optimal monomer mixture contains 40% acrylic acid, and the active ink pH is 13. We also applied a scalable method to fabricate photonic paper, successfully overcome the challenge of large-scale fabrication of photonic crystals at room temperature. By integrating the perfect pair of SHRPS and inkjet printer, concealed information with various sizes and resolutions can be printed, invisible in ambient humidity and revealed by blowing air, presenting various humidity responsive ability of SHRPS for multilevel information encryption, which opens a new window for security printing system.

3D printing of hydrogel composite systems: Recent advances in technology for tissue engineering.

Three-dimensional (3D) printing of hydrogels is now an attractive area of research due to its capability to fabricate intricate, complex and highly customizable scaffold structures that can support cell adhesion and promote cell infiltration for tissue engineering. However, pure hydrogels alone lack the necessary mechanical stability and are too easily degraded to be used as printing ink. To overcome this problem, significant progress has been made in the 3D printing of hydrogel composites with improved mechanical performance and biofunctionality. Herein, we provide a brief overview of existing hydrogel composite 3D printing techniques including laser based-3D printing, nozzle based-3D printing, and inkjet printer based-3D printing systems. Based on the type of additives, we will discuss four main hydrogel composite systems in this review: polymer- or hydrogel-hydrogel composites, particle-reinforced hydrogel composites, fiber-reinforced hydrogel composites, and anisotropic filler-reinforced hydrogel composites. Additionally, several emerging potential applications of hydrogel composites in the field of tissue engineering and their accompanying challenges are discussed in parallel.

Dual‐Crosslinked Bioactive Hydrogel Scaffold for Accelerated Repair of Genital Tract Defect

AbstractReproductive health concerns like Mayer‐Rokitansky‐Küster‐Hauser (MRKH) syndrome are prevalent in today's society. MRKH syndrome is a condition that severely affects women's sexual life, fertility, and mental health and has a high prevalence of one out of 5000 female births. Vaginoplasty is the primary method to regain patients’ reproductive health. However, conventional vaginoplasty faces various challenges, including complex and non‐customized treatment procedures causing intense pains and complications. To bring new advances to vaginoplasty, a 3D‐printed hydrogel scaffold is developed to provide satisfactory mechanical support and bioactivity for accelerating defect repair after surgery. The hydrogel scaffold consisting of gelatin methacryloyl (gelMA) and carrageenan (Car) is custom 3D‐printed using an ambient temperature printing system. Furthermore, the scaffold undergoes dual‐crosslinking through chemical crosslinking of gelMA and ionic crosslinking of Car with magnesium ions (Mg2+). This dual‐crosslinking strategy substantially improves the overall mechanical properties of the scaffold and introduces bioactive Mg2+. The sustained release of Mg2+ plus the extracts from the dual‐crosslinked scaffold significantly promotes cell proliferation, migration and angiogenesis. In a preclinical rat model with penetrating genital tract defects mimicking vaginoplasty, the implantation of dual‐crosslinked scaffold repairs the penetrating wounds to near‐normal levels within one week, showing potential as an alternative for better regaining reproductive health.

Design of a Robotic 3D Printing System

Abstract Additive manufacturing enables the production of complex shapes with a large degree of freedom compared to conventional manufacturing techniques such as injection molding, thermoforming or pressing. In particular, the creation of moving parts, complex structures and large-scale printing remains underexplored and research is constantly expanding. Due to design limitations related to the construction of currently available printers, 3D printing technology is increasingly being combined with robotics. Using a robot to 3D print products eliminates the need to design complex printer structures, which ultimately should simplify the process of manufacturing large-scale products and shorten the time required for preparation and production. The paper deals with the description of the designed 3D printing system and the procedure of the steps of creating a robotic simulation model with the generation of a control program for the FDM 3D printing process by an industrial robot.

Understanding Business Model of Digital Journalism in Indonesia

The transformation in the media landscape in Indonesia is underscored by the emergence of digital-centric media entities and a new mode of news production distinctly divergent from traditional journalism. The purpose of this study is to examine the evolving business model of digital journalism, a sector experiencing rapid growth following the advent of the internet, social media, and the consolidation of online journalism since 2010. Employing a qualitative-descriptive method, this research is designed to capture the digital journalism business model in Indonesia's post-traditional print and broadcast media systems. From 2021 to 2023, the authors meticulously observed the contents and management of selected news media outlets, conducted semi-structured interviews, and gathered pertinent documents. The key question of this study centers on the nature of the business model underpinning journalism on digital platforms and its repercussions for the interest of news production and publication. The study reveals that business models for digital news media remain unstandardized, and the ecosystem of platform-based journalism has yet to achieve a healthy climate. From the perspective of digital news consumption, the prevailing culture of gratuitous (free) news culture and the concern of keeping trusted news media pose significant obstacles for news corporations in sustaining their operations.

High‐Precision Materials Printer for Fast Prototyping of Electronic Devices Based on 2D Materials

AbstractThere is an increasing interest in printed electronics driven principally by flexible and wearable applications. The interest stems from the ability to fabricate electronic devices, such as Field Effect Transistors (FET), more efficiently in terms of materials use and cost‐effectively than traditional lithographic techniques. Challenges persist in achieving high resolution and accuracy in defining device geometry. In the study, a high‐resolution materials printer able to achieve resolutions in the micron range, surpassing the capabilities of commercially available printers is successfully designed and fabricated. The printer incorporates an all‐in‐one printing system, comprising Inkjet and a Dip Pen Nanolithography (DPN) technique, enabling both additive and subtractive manufacturing at the microscale. The experiments demonstrate the successful fabrication of FETs based on 2D materials (2DMs), with micrometric channel lengths exhibiting a high degree of controllability and repeatability, even when contacting limited channel regions as micrometer‐sized molybdenum disulfide (MoS2) flakes. Electrical characterizations of the fabricated devices underscore the significant technological advancements achieved by the prototypes.

Dimensional Accuracy of Different Three-Dimensional Printing Models as a Function of Varying the Printing Parameters.

Even in digital workflows, models are required for fitting during the fabrication of dental prostheses. This study examined the influence of different parameters on the dimensional accuracy of three-dimensionally printed models. A stereolithographic data record was generated from a master model (SOLL). With digital light processing (DLP) and stereolithography (SLA) printing systems, 126 models were produced in several printing runs-SolFlex350 (S) (DLP, n = 24), CaraPrint 4.0 (C) (DLP, n = 48) and Form2 (F) (SLA, n = 54)-and their accuracy was compared with plaster and milled polyurethane models. In addition to the positioning on the build platform, a distinction was made between parallel and across arrangement of the models to the printer's front, solid and hollow models, and printing with and without support structures. For accuracy assessment, five measurement sections were defined on the model (A-E) and measured using a calibrated digital calliper and digital scans in combination with the GOM Inspect Professional software 2021. The mean deviation between the measurement methods for all distances was 79 µm. The mean deviation of the models from the digital SOLL model were 207.1 µm for the S series, 25.1 µm for the C series and 141.8 µm for the F series. While positioning did not have an influence, there were clinically relevant differences mainly regarding the choice of printer, but also individually in alignment, model structure and support structures.

Scanning‐Laser‐Based Microstereolithography of Microfluidic Chips with Micron Resolution

AbstractThe constant improvement of stereolithography (SL) in terms of achievable resolution and printing time has sparked high expectations that SL will enable the rapid prototyping of truly microfluidic chips with features below 100 µm. However, most commercial high‐resolution stereolithography devices are based on Digital Light Processing (DLP) and thus sacrifice lateral printing size for resolution. Consequently, even 10 years after the advent of microstereolithography there is no commercialized 3D printing system that can effectively fulfill all the demands to replace soft lithography for microfluidic prototyping. In this work, for the first time, This study demonstrates that a commercial laser‐based stereolithography device is capable of manufacturing microfluidic chips with embedded channels smaller than 100 µm with a footprint of 7.24 × 0.3 cm2. A chip fabricated in poly(ethylene glycol) diacrylate (PEGDA) that can readily be used for fluid mixing, is presented in this study. This research shows that the accessibility of high‐resolution chips with footprints of several cm2, using laser‐based stereolithography, enables the manufacturing of truly microfluidic systems with high impact on prototyping and manufacturing.

Dual‐Interface Competitive Fracture Model for Curvature‐Based Transfer Printing Method

AbstractTransfer printing is a key technology in the fabrication of flexible electronics. Transfer printing method based on curvature provides a simple and effective way to transfer films onto weakly adhesive or even adhesiveless surfaces, overcoming the shortage of traditional transfer printing methods that it is difficult to print functional materials from strong interface to weak interface and can only be applicable to surfaces with certain interfacial strength. So far, the theoretical principle of the curvature‐based transfer printing method has not yet been developed. In this article, a dual‐interface competitive fracture model is established to analyze the mechanism of printing and picking up processes and quantitatively provide the critical transfer printing radius in terms of material and geometric properties of the transfer printing system. This model is verified to be both correct and widely applicable by rich experimental results, providing a new and reliable theory for the fabrication of inorganic flexible electronics.

High-performance color and fluorescence switching of cotton fabrics via light-induced proton transfer strategy of spiropyran sulfonate molecule

Light-responsive color-switching materials have garnered persistent interest recently due to their passive response to external stimuli and manifestation of notable visual color variations. Nonetheless, their development into high-end products has been hindered by unsatisfactory overall performance, characterized by challenges such as the inability to combine color contrast and retention time, poor repeatability, and reliance on a single coloring mode. Herein, we present a negative photochromic cotton fabric (NPCF) capable of real-time dual output of optical signals (color change or fluorescence emission), featuring high color contrast and resolution, excellent reversibility, and facile multicolor printing. These attributes stem from the utilization of a unique photoinduced proton transfer (PPT) strategy exhibited by the designed and synthesized spiropyran sulfonate molecule (MC-NO2). Guided by this strategy, NPCF demonstrates significant color changes and fluorescence switching in a real-time and highly reversible manner, leveraging the remote non-contact and non-destructive nature of visible light. Moreover, direct blending of MC-NO2 with commercially available water-soluble non-stimuli-responsive dyes enables customization of various photosensitive color systems for straightforward multi-color printing, aligning well with the environmental principles of green printing. This study serves as a valuable reference for the advancement and design of diverse high-performance, switchable materials suitable for the production of high-end products.

Study on the quality of reproduction of graphical linear micro-images using electrophotographic printing

Today’s market of visual graphic communication includes many various advertising, publishing and packaging products printed on different materials. Many products are printed using conventional printing technologies such as offset printing or flexography, in addition to digital ones like Electrophotography and Ink Jet. The graphic images on prints often contain extremely fine graphic details, such as micro-lines or micro-text elements, which are part of various identification, security markings, codes, etc. It is a very important task to optimally model these micro-images on printed graphic communication products at the design stage, in order to ensure their brightness, legibility and geometric dimensions meet the requirements, not only immediately after printing, but also, for example, after a certain period during the life cycle of the printed product after exposure to the sunlight spectrum, or to other mechanical or environmental effects. This paper presents a methodology and results for the assessment of the quality of the reproduction of fine image details, i.e. the micro-lines of different widths arranged on the print in different directions. A specially developed original digital press quality control wedge with monochromatic micro-lines, microtext and screen dots bars of CMYK colours was applied to assess the accuracy of micro-image reproduction. In this part of the study, the wedge fields with positive micro-lines arranged in different directions individually and in groups were analysed. The width of the micro-lines was measured under the microscope to assess the accuracy of the dimensional reproduction and the deviations from the nominal value. To assess the influence of different parameters of the system “printing press-paper-inks” on the reproduction of image microelements, the prints for this part of the study were printed using electrophotographic printing techniques on different dry-toner printing presses on different types of paper. The width and deviations of the micro-lines on the print were measured along the print direction, perpendicular and at 45˚ to the print direction. Measurements of the reproduction accuracy of monochrome micro-line images, printed on dry-toner electrophotographic presses, showed that the accuracy of micro-line reproduction depends not only on the printing system, its resolution and the characteristics of the paper, but also on the direction of the positioning of the micro-lines on the printed sheet. The obtained results allow us to compare the capability of digital printing systems to reproduce linear micro-images on visual graphic communication products of any size and geometric orientation, to select optimal systems for printing specific products, and to model the layout of micro-images on products at the design stage, by assessing the orientation of the micro-images on the printed sheet.

3D Printing Systems Designed for the Factory Floor

Markforged is enabling more resilient and flexible supply chains with its 3D printers by bringing industrial production to the point of need. We caught up with Daniel Leong, senior product manager, to hear more

High-precision and Large-Scale Vat Photopolymerization Printing based on "Spatial-Pixel Integration Compensation" method

Vat photopolymerization (VPP) is widely known for its exceptional printing accuracy, but effectively controlling stitching errors to achieve high-precision, large-scale printing remains a significant challenge. This study introduces a novel compensation method, termed "Spatial-Pixel Integration Compensation" (SPIC), to address this key obstacle. SPIC combines Spatial Motion Compensation to initially control stitching errors between adjacent sub-images to be within 100 µm and Pixel Compensation for precise adjustments, further reducing stitching errors. Integrating SPIC with our high-precision printing system resulted in a remarkable reduction of stitching errors by a factor exceeding 40. Crucially, this method minimizes the stitching error between any two sub-images to be less than one pixel point, specifically below 4 µm. Notably, SPIC is the first method specifically focused on effectively controlling and reducing stitching errors to achieve large-scale printing while maintaining high precision. To validate the practical applicability of the SPIC method, we used SPIC to print both Zig-Zag and herringbone structures (HBS) and achieved high-precision large-scale manufacturing with dimensions of 44 mm × 33 mm. In the HBS structure, the minimum feature size was 14.2 µm, and the printing error was less than 1 µm. These printed structures were used as molds to fabricate proof-of-concept polydimethylsiloxane (PDMS) microfluidic chips, demonstrating the successful mixing of rhodamine B and ethanol within the microfluidic channels. Furthermore, SPIC was extended to the printing of complex three-dimensional (3D) Triple-Periodic Minimal Surface (TPMS) structures, successfully producing TPMS-Gyroid and TPMS-Diamond structures with a minimum feature size of 20 µm and a printing error below 1.5 µm. These results demonstrate that the SPIC algorithm effectively enables high-precision, large-scale printing. This work significantly advances the application of VPP technology in fields requiring complex, high-precision, and large-scale 3D structures and provides valuable insights for future research in high-precision and large-scale printing.