Print Materials Research Articles

Advances in 3-D printing: polymers, fabrication mechanisms, mass balance models and applications

AbstractIn Science and Engineering, additive manufacturing, which is synonymously known as 3-D printing is a layer-by-layer computer-aided approach that is used to produce high precision commercial industrial products. So far, 3-D printing techniques, which translate computer-aided virtual 3-D models into physical objects, are gaining traction globally. However, the current evolution from conventional molding and machining to rapid prototyping followed by rapid additive manufacturing prompts new challenges for engineers and scientists alike. This review is particularly prompted by novel innovations in 3-D printing with respect to emerging fabrication designs and mechanisms, printable polymeric materials, and current applications. Central to all spotlights is the discussion on 3-D printing techniques discussed under 3 broad categories; (i) extrusion-based methods, (ii) powder binding technologies and (iii) photopolymerization methods and corresponding polymer design aspects, processing parameters and mass balance models. Aspects of mass-balance models addressed in this review include models of multimaterial 3-D printing of viscoelastic inks, Newtonian fluid in extrusion, the Gaussian Beam model and multiscale computational simulations for prediction of macroscale properties of various polymeric materials. This review also highlights selected applications that demonstrate how polymer-based 3-D printing is being exploited in industry, and future perspectives.

Fragmented Encounter

This article traces the biography of Ernst Bachrich, a student of Arnold Schönberg. One focus is on the stories told by his self-published scores. Who printed them? How were the paper and printing materials sourced? Under what conditions were they dispersed? How did they end up where they are at present?

Melt Electrowriting of Polyhydroxyalkanoates for Enzymatically Degradable Scaffolds

AbstractMelt electrowriting (MEW) enables precise scaffold fabrication for biomedical applications. With a limited number of processable materials with short and tunable degradation times, polyhydroxyalkanoates (PHAs) present an interesting option. Here, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and a blend of PHBV and poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (PHBV+P34HB) are successfully melt electrowritten into scaffolds with various architectures. PHBV+P34HB exhibits greater thermal stability, making it a superior printing material compared to PHBV in MEW. The PHBV+P34HB scaffolds subjected to enzymatic degradation show tunable degradation times, governed by enzyme dilution, incubation time, and scaffold surface area. PHBV+P34HB scaffolds seeded with human dermal fibroblasts (HDFs), demonstrate enhanced cell adherence, proliferation, and spreading. The HDFs, when exposed to the enzyme solutions and enzymatic degradation residues, show good viability and proliferation rates. Additionally, HDFs grown on enzymatically pre‐incubated scaffolds do not show any difference in behavior compared those grown on control scaffolds. It is concluded that PHAs, as biobased materials with enzymatically tunable degradability rates, are an important addition to the already limited set of materials available for MEW technology.

Level of Satisfaction with the Library Resources and Services of Education Faculty and Students in Lone Agricultural State College in Bulacan

Academic libraries are an integral part of learning institutions, serving as crucial hubs for meeting the information and research needs of students and faculty. The study aimed to determine the level of satisfaction of users with library resources and services at a lone agricultural state higher education institution (HEI) in Bulacan, Philippines. A survey research design was employed to quantify the responses from education faculty and students, who were selected using a purposive sampling technique. The findings reveal that respondents are generally satisfied with the library’s resources, including the availability of printed materials, accessibility of online resources, provision of ICT equipment, and overall conduciveness of the learning environment. Both faculty and students expressed satisfaction with the quantity and quality of the library’s online and print materials in supporting their respective fields of study. Regarding library services, majority of respondents were satisfied with the institution’s library orientation, instruction, guidelines for borrowing books, service hours, reference support, reader’s advisory, information and referral, current awareness, indexing, and internet access. These services enable college librarians and staff to facilitate effective utilization of the library’s resources, allowing students to engage with books, journals, and other vital educational materials, as well as conduct individual and group studies. The degree to which the college community utilizes the library’s services and resources can serve as an indicator of the library's function and value in supporting the academic and research needs of the institution. Generally, this study provides valuable insights to guide the library in enhancing its offerings and ensuring sustained user satisfaction.

Optically accessible, 3D-printed flow chamber with integrated sensors for the monitoring of oral multispecies biofilm growth in vitro

The formation of pathogenic multispecies biofilms in the human oral cavity can lead to implant-associated infections, which may ultimately result in implant failure. These infections are neither easily detected nor readily treated. Due to high complexity of oral biofilms, detailed mechanisms of the bacterial dysbiotic shift are not yet even fully understood. In order to study oral biofilms in more detail and develop prevention strategies to fight implant-associated infections, in vitro biofilm models are sorely needed. In this study, we adapted an in vitro biofilm flow chamber model to include miniaturized transparent 3D-printed flow chambers with integrated optical pH sensors – thereby enabling the microscopic evaluation of biofilm growth as well as the monitoring of acidification in close proximity. Two different 3D printing materials were initially characterized with respect to their biocompatibility and surface topography. The functionality of the optically accessible miniaturized flow chambers was then tested using five-species biofilms (featuring the species Streptococcus oralis, Veillonella dispar, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis) and compared to biofilm growth on titanium specimens in the established flow chamber model. As confirmed by live/dead staining and fluorescence in situ hybridization via confocal laser scanning microscopy, the flow chamber setup proved to be suitable for growing reproducible oral biofilms under flow conditions while continuously monitoring biofilm pH. Therefore, the system is suitable for future research use with respect to biofilm dysbiosis and also has great potential for further parallelization and adaptation to achieve higher throughput as well as include additional optical sensors or sample materials.

Development and Characterization of 3D-Printed PLA/Exfoliated Graphite Composites for Enhanced Electrochemical Performance in Energy Storage Applications

This research introduces a new way to create a composite material (PLA/EG) for 3D printing. It combines polylactic acid (PLA) with exfoliated graphite (EG) using a physical mixing method, followed by direct mixing in a single-screw extruder. Structural and vibrational analyses using X-ray diffraction and Fourier transform infrared spectroscopy confirmed the PLA/EG’s formation (composite). The analysis also suggests physical adsorption as the primary interaction between the two materials. The exfoliated graphite acts as a barrier (thermal behavior), reducing heat transfer via TG. Electrochemical measurements reveal redox activity (cyclic voltammetry) with a specific capacitance of ~ 6 F g−1, low solution resistance, and negligible charge transfer resistance, indicating ion movement through a Warburg diffusion process. Additionally, in terms of complex behavior (electrochemical impedance spectroscopy), the PLA/EG’s actual capacitance C’(ω) displayed a value greater than 1000 μF cm−2, highlighting the composite’s effectiveness in storing charge. These results demonstrate that PLA/EG composites hold significant promise as electrodes in electronic devices. The methodology used in this study not only provides a practical way to create functional composites but also opens doors for new applications in electronics and energy storage.

Real-time in-situ ultrasound monitoring of soft hydrogel 3D printing with subwavelength resolution

3D bioprinting has excellent potential in tissue engineering, regenerative medicine, and drug delivery systems due to the ability to fabricate intricate structures that are challenging to make with conventional manufacturing methods. However, the complexity of parametric combinations and lack of product quality control have restricted soft hydrogel bioprinting from practical applications. Here we show an in-situ ultrasound monitoring system that reveals the alginate-gelatin hydrogel’s additive manufacturing process. We use this technique to understand the parameters that influenced transient printing behaviors and material properties in approximately real-time. This unique monitoring process can facilitate the detection of minor errors/flaws during the printing. By analyzing the ultrasonic reflected signals in both time and frequency domains, transient printing information can be obtained from 3D printed soft hydrogels during the processes with a depth subwavelength resolution approaching 0.78λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda$$\\end{document}. This in-situ technique monitors the printing behaviors regarding the constructed film, interlayer bonding, transient effective elastic constant, layer-wise surface roughness (elastic or plastic), nozzle indentation/scratching, and gravitational spreading. The simulation-verified experimental methods monitored fully infilled printing and gridded pattern printing conditions. Furthermore, the proposed ultrasound system also experimentally monitored the post-crosslinking process of alginate-gelatin hydrogel in CaCl2 solution. The results can optimize crosslinking time by balancing the hydrogel’s stiffness enhancement and geometrical distortion.

3d printing applied to building development around the world: a systematic literature review

The construction industry is undergoing a transformation towards automation, and 3D printing is at the forefront of this revolution. However, to optimise 3D printing in construction, it is crucial to consider the printer’s scale, the printing material’s rheological properties, and the printed structure’s mechanical properties. This paper provides an overview of the state of the art in this field, including the promising technologies, such as D-Shape and Contour Crafting, used in building applications. The paper also compares the use in 3D printing of conventional materials, like concrete, with non-conventional earth-based materials, such as sand, clay, and mud, or combinations with cementing materials. This review highlights the need for more research on alternative materials to concrete, particularly in developed countries. Nevertheless, earth-based materials offer significant potential for 3D printing in developing countries, where they are readily available. However, further research is necessary to improve the mechanical properties of 3D-printed elements, particularly for large-scale structures, to ensure their reliability and safety, making 3D printing a mainstream building method.

Development of Intelligent Construction Robots for In-situ Lunar Resource Utilization

Abstract: With the development of technologies such as 3D printing and artificial intelligence, robotic lunar construction has gradually become a reality. In recent years, many countries have conducted research on lunar construction, among which lunar in-situ resource utilization construction is the most promising option for lunar construction, and intelligent robot construction is the main method of in-situ resource utilization construction. This paper analyzes the trend of intelligent construction and the necessity of lunar construction, and concludes that lunar construction robots have great development prospects and value. Using "ISRU, intelligent construction robot, 3D printing" as keywords, using the method of literature analysis, literature retrieval is conducted on China National Knowledge Infrastructure and Google Scholar databases, and the types of lunar bases, the acquisition of lunar resources, the classification of intelligent construction robots, and the 3D printing technology and Fully adaptable robot assembly and construction technology in lunar in-situ resource utilization are analyzed. The concept, classification, function, auxiliary 3D printing technology and materials required for 3D printing are analyzed in detail. The assembled mortise and tenon structure, fully adaptable assembly robot technology and underground construction technology are described in detail. The intelligent construction technology involved in lunar in-situ resource utilization construction (ISRU) and how to adapt to the lunar environment for construction are systematically analyzed, and the challenges faced in realizing robotic lunar construction are briefly outlined. It provides ideas for scholars studying intelligent construction robots.

Utilization of Artificial Intelligence in the Creation of Patient Information on Laryngology Topics.

To evaluate and compare the readability and quality of patient information generated by Chat-Generative Pre-Trained Transformer-3.5 (ChatGPT) and the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) using validated instruments including Flesch-Kincaid Grade Level (FKGL), Flesch Reading Ease, DISCERN, and Patient Education Materials Assessment Tool for Printable Materials (PEMAT-P). ENTHealth.org and ChatGPT-3.5 were queried for patient information on laryngology topics. ChatGPT-3.5 was queried twice for a given topic to evaluate for reliability. This generated three de-identified text documents for each topic: one from AAO-HNS and two from ChatGPT (ChatGPT Output 1, ChatGPT Output 2). Grade level and reading ease were compared between the three sources using a one-way analysis of variance and Tukey's post hoc test. Independent t-tests were used to compare DISCERN and PEMAT understandability and actionability scores between AAO-HNS and ChatGPT Output 1. Material generated from ChatGPT Output 1 and ChatGPT Output 2 were at least two reading grade levels higher than that of material from AAO-HNS (p < 0.001). Regarding reading ease, ChatGPT Output 1 and ChatGPT Output 2 documents had significantly lower mean scores compared to AAO-HNS (p < 0.001). Moreover, ChatGPT Output 1 material on vocal cord paralysis had a lower PEMAT-P understandability compared to that of AAO-HNS material (p > 0.05). Patient information on the ENTHealth.org website for select laryngology topics was, on average, of a lower grade level and higher reading ease compared to that produced by ChatGPT, but interestingly with largely no difference in the quality of information provided. NA Laryngoscope, 2024.

Cost and Time Reduction of Industrial Mold Design and Manufacturing by Implementing Additive Manufacturing for Premature Neonatal Prong.

For a long time, molding was one of the most important methods of producing metal, ceramic, and polymer materials. The two essential factors in this method were always cost and time. Technology advancements have made it possible to design in 3D using a computer and additive manufacturing. This article covers methods for using 3D printers to save time and money in the process of creating the final product. The "Prong" molds for premature neonatal respiratory aid were designed and produced based on neonatologists' considerations. The study was conducted on fifteen very low birth neonates at Alzahra Hospital in Tabriz University from September 2017 to September 2019. In the first section, we described dental plaster material for molding. When using this material, the printing material must be selected and the parameters, like melting temperature and printer speed, must be controlled to achieve acceptable quality for the final sample. CAD software can be used to print various objects if the final 3D design is appropriate. We used additive manufacturing technology to create a new design and successfully resolved bubble issues at a low cost through a combination of creativity and experimentation. The new mold has cavities that allow the silicon to occupy the entire space and escape any bubbles. The use of 3D printers allows us to achieve the best design for the prong mold while reducing both production costs and time. The ultimate mold made of aluminum was finally produced by the CNC machine. The final product was tested at Al-Zahra Hospital in Tabriz, Iran, and the results were satisfactory, with no reports of necrosis on the babies' noses.

Interaction between material and process parameters during 3D concrete extrusion process

Extrusion of cement-based materials in additive manufacturing is influenced by a complex interaction of various material and process parameters. This study aims to investigate the impact of rheological properties and printing parameters on the extrudability of cement-based materials as well as the interaction between rheological properties of print materials and extrusion speed, as a key printing process parameter. 20 different print materials with diverse rheological properties were extruded at 10 different extrusion speeds. The effect of material parameters (i.e. rheological properties) and process parameters (i.e., extrusion speed) and their interaction during the extrusion process were evaluated using filament continuity, conformity and consistency. At a constant printing speed, a higher yield stress adversely impacted filament continuity in mixtures with a yield stress of over 260 Pa, whereas viscosity showed minimal influence on filament quality within the tested range of the rheological properties. The results of this study highlighted a significant correlation between material and process parameters and that adapting process parameters to variations in material properties is crucial for meeting printing criteria. The filament consistency of the mixtures with high yield stress was more sensitive to change in the extrusion speed than that of mixtures with low yield stress. An opposite trend, however, was observed for filament conformity where low yield stress mixtures showed a higher sensitivity to the extrusion speed. A procedure was suggested and applied to determine the optimum extrusion speed. Optimal extrusion speeds enabled printing mixtures with a broader spectrum of rheological properties with an acceptable visual quality, filament conformity and consistency requirements. With extrusion speed adjustment, the extrudability window was expanded from dynamic yield stress of 108–126 Pa to 108–263 Pa and plastic viscosity of 8.2–12.3 Pa.s to 5.1–16.4 Pa.s.

Digitizing the Appearance of 3D Printing Materials Using a Spectrophotometer

Digitizing the Appearance of 3D Printing Materials Using a Spectrophotometer

3D printable earth-based alkali activated “ink”: Effect of alkali concentration and binder-to-aggregate ratio

This research attempts to investigate the effect of activator concentration (4 mol/L (M) and 8M) and binder-to-aggregate (B:A) ratio (ranging from 1:1 to 1:3 by weight) on extrudability and buildability of 3D printable natural earth-based alkali-activated materials (EAAM). It is found that natural clay in soil, used to replace 25 % of M-sand, imparts higher thixotropy, evident from 90 to 100 % recovery in viscosity compared to 65–80 % for corresponding control (containing only M-sand and no soil). Presence of clay increases the dynamic yield stress than control but reduces the plastic viscosity by 80 – 90 % in EAAM compared to corresponding control where interlocking between sand particles resists smooth extrusion of the material. EAAMs made with 8M NaOH have higher flow retention and maintain 95–100 % recovery in viscosity for longer duration than 4M EAAM. This contributes to superior extrusion quality of 8M EAAM than 4M EAAM. The findings suggest that binder content can be reduced as concentration of NaOH is increased from 4M to 8M. This is evident from lower layer deformation (0.09 % of original height) under self-weight and higher 3D printed buildable height of at least 457 mm in 8M EAAM with B:A of 1:2 compared to a maximum of 375 mm for 4M EAAM at higher B:A of 1:1. Ratios of wet compressive strength to dry compressive strength vary between 0.92 and 1.09 in 8M EAAM compared to 0.79 – 0.85 for 4M EAAM at 28-day age, suggesting lower sensitivity to moisture due to improved clay stabilization. Based on the strength and moisture sensitivity, the developed material can serve as a low-carbon and durable alternative to Portland cement in the construction of masonry elements in buildings, including cavity walls, panels, flooring tiles and façade members.

3D Printing with Self-Healing Materials and Applications

3D printing also called as the additive manufacturing. It is revolutionizing various industries by enabling the production of complex objects directly from digital models. This technology offers significant advantages over traditional manufacturing methods. Especially in reducing material waste and increased design flexibility. The range of 3D printing application contains healthcare to aerospace, reflecting its growing importance in modern society. Recently, 3D printing advancements have introduced in self-healing (SH) materials, it saved limitations related to the durability and repairability of printed objects. SH materials are categorized into external and internal systems. External SH materials use embedded healing agents that repair damage through chemical reactions, while internal systems rely on dynamic bonding within the material itself. This innovation not only extends the functional life of 3D printed items but also supports trends in mass customization and sustainability. This paper explores the mechanisms, types, and applications of SH materials in 3D printing, and mainly focus on their potential to enhance product longevity and functionality across medical, construction, and consumer goods sectors.

Hydrogel 3D printing with direct and indirect extruder

The advancement of additive manufacturing technology or 3-Dimesion printing (3D printing) allows for the creation of parts with intricate designs, resulting in less material waste compared to conventional manufacturing methods. Although current 3D printers primarily use plastic or metal materials, there is a growing interest in using biomaterials for 3D printing. To facilitate this trend, developing and designing 3D printers capable of using hydrogel materials is crucial. In this research, the 3D printer with direct and indirect extruders for hydrogel material is designed, calculated, and manufactured. Then, the 3D printer is tested with conductive sodium alginate 5% + 5% activated carbon by weight. In addition, the electrical conductivity of the material is measured. Through meticulous research and development, a 3D printer capable of printing hydrogel materials has been successfully manufactured, setting the stage for further exploration and the creation of environmentally friendly 3D biomedical printing materials.

FDM 3D Printing and Properties of WF/PBAT/PLA Composites

Fused deposition molding (FDM) is a commonly used 3D printing method, and polylactic acid (PLA) has become one of the most important raw materials for this technology due to its excellent warping resistance. However, its mechanical properties are insufficient. Polybutylene adipate terephthalate (PBAT) is characterized by high toughness and low rigidity, which can complement the performance of PLA. The biodegradable polymers produced by blending the two have thus been used to replace petroleum-based plastics in recent years, but the high cost of the blends has limited their wide applications. Introducing plant fibers into the blends can not only maintain biodegradability and improve the overall performance of the plastics but also reduce their costs greatly. In this study, the PBAT/PLA blends with a mass ratio of 70/30 were selected and mixed with wood flour (WF) to prepare ternary composites using a FDM 3D printing technique. The effects of WF dosage on the mechanical properties, thermal properties, surface wettability, and melt flowability of the composites were investigated. The results showed that the proper amount of WF could improve the tensile and flexural moduli of the composites, as well as the crystallinity and hydrophobicity of the printed specimens increased with the content of WF, while the melt flow rate decreased gradually. Compared to PBAT/PLA blends, WF/PBAT/PLA composites are less costly, and the composite containing 20 wt.% WF has the best comprehensive performance, showing great potential as raw material for FDM 3D printing.

Precision 4D Printing of Multifunctional Olive Oil‐Based Acrylate Photo‐resin for Biomedical Applications

AbstractSince the advent of 3D printing technology, a significant effort has been made to develop new 3D printable materials. Despite the recent progress in the field of 3D printing, the limited availability of photoactive resins has motivated continuous research endeavors to develop novel photoresins with multifunctional capabilities. Herein a biobased photoresin derived is reported from modified olive oil, designed for high‐resolution solvent‐free 4D printing with multifunctional capabilities. The physicochemical properties of the printed polymers are fine‐tuned using acrylic acid as a diluent cum comonomer. The mechanical properties of the printed polymers are similar to various soft tissues, such as ligaments, articular cartilage, and soft collagenous bone, showcasing its potential for soft tissue engineering applications. While the excellent temperature‐responsive shape memory 4D attributes coupled with exceptional antimicrobial properties toward gram‐negative and gram‐positive bacteria highlight the multifunctional nature of the printed polymers. Moreover, the printed polymers exhibited outstanding hemocompatibility and good cytocompatibility toward mouse fibroblast cells, suggesting their potential soft tissue engineering applications. In sum, the newly developed biobased resin can be employed to minimize the environmental impact of additive manufacturing while being competitive with existing fossil‐based photoresins, thereby meeting the growing demand for advanced photoresins with superior high‐resolution printing and smart properties for biomedical applications.

Leveraging Blood Components for 3D Printing Applications Through Programmable Ink Engineering Approaches.

This study proposes a tunable ink engineering methodology to allow 3D printing processability of highly bioactive but otherwise low-viscous and unprintable blood-derived materials. The hypothesis relies on improving the viscoelasticity and shear thinning behavior of platelet lysates (PL) and albumins (BSA) solutions by covalent coupling, enabling simultaneous extrusion and photocrosslinking upon filament deposition. The available amine groups on proteins (PL and BSA) are exploited for coupling with carboxyl groups present in methacrylated proteins (hPLMA and BSAMA), by leveraging carbodiimide chemistry. This reaction enabled the creation of a pre-gel from these extremely low-viscous materials (≈ 1Pa), with precise tuning of the reaction, resulting in inks with a range of controlled viscosities and elasticities. Shape-fidelity analysis is performed on 3D-printed multilayered constructs, demonstrating the ability to reach clinically relevant sizes (>2cm in size). After photocrosslinking, the scaffolds showcased a mechanically robust structure with sustained protein release over time. Bioactivity is evaluated using human adipose-derived stem cells, resulting in increased viability and metabolic activity over time. The herein described research methodology widens the possibilities for the use of low-viscosity materials in 3D printing but also enables the direct application of patient and blood-derived materials in precision medicine.

Copper Paste Printed Paper‐Based Dual‐Band Antenna for Wearable Wireless Electronics

AbstractWearable wireless electronics is becoming a significant research area because of the unique features of this technology. Within this field printed antennas are the key electrical component accomplishing the signal transmission and energy harvesting tasks and at the same these antennas need to be lightweight, environmentally friendly, safe to wear, and easy to conform. Currently, the majority of available paper‐based antennas are designed for RFID, sensing, UWB, WLAN, and medical applications, with just a few being utilized in wearable applications, particularly for wireless body area network (WBAN). Furthermore, few studies have been conducted on the usage of printable copper conductive materials and low‐temperature plasma technique for the fabrication of such antennas. This study demonstrates the realization of a dual‐band paper‐based wearable antenna by screen‐printing of a plasma‐sintered conductive copper paste. The copper paste, composed of 51 wt% solid particles, can easily produce desired conductive patterns on photo paper after printing and a subsequent plasma sintering, with a good adhesion. The antenna designed on photopaper operates in the frequency bands of 1.73–2.55 GHz and 7.66–8.89 GHz. Free‐space simulation and measurement results reveal that the antenna exhibits stable radiation performance in the targeted WBAN (2.4–2.4835 GHz) and X uplink (7.9–8.4 GHz) frequency bands, together with low profile, excellent conformality and acceptable SAR values on the body and no electronic waste formed after disposal, making it a competitive candidate for usage in wearable wireless electronics.