Scale 3D Printing Research Articles

Desktop 3D printed anatomic models for minimally invasive direct coronary artery bypass

BackgroundThree-dimensional (3D) printing technology has impacted many clinical applications across medicine. However, 3D printing for Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) has not yet been reported in the peer-reviewed literature. The current observational cohort study aimed to evaluate the impact of half scaled (50% scale) 3D printed (3DP) anatomic models in the pre-procedural planning of MIDCAB.MethodsRetrospective analysis included 12 patients who underwent MIDCAB using 50% scale 3D printing between March and July 2020 (10 males, 2 females). Distances measured from CT scans and 3DP anatomic models were correlated with Operating Room (OR) measurements. The measurements were compared statistically using Tukey’s test. The correspondence between the predicted (3DP & CT) and observed best InterCostal Space (ICS) in the OR was recorded. Likert surveys from the 3D printing registry were provided to the surgeon to assess the utility of the model. The OR time saved by planning the procedure using 3DP anatomic models was estimated subjectively by the cardiothoracic surgeon.ResultsAll 12 patients were successfully grafted. The 3DP model predicted the optimal ICS in all cases (100%). The distances measured on the 3DP model corresponded well to the distances measured in the OR. The measurements were significantly different between the CT and 3DP (p < 0.05) as well as CT and OR (p < 0.05) groups, but not between the 3DP and OR group. The Likert responses suggested high clinical utility of 3D printing. The mean subjectively estimated OR time saved was 40 min.ConclusionThe 50% scaled 3DP anatomic models demonstrated high utility for MIDCAB and saved OR time while being resource efficient. The subjective benefits over routine care that used 3D visualization for surgical planning warrants further investigation.

From layer to building: Multiscale modeling of thermo-optical properties in 3D-printed facades

The challenge of building sector decarbonization has driven an integral rethinking of the way we design and build facades. Recently, large scale 3D-printing has emerged as an alternative manufacturing technique for novel facade components aiming at high operational efficiency and low environmental impact. Focusing on translucent polymer 3DPFs, this study tackles the challenges of modeling thermal and optical effects in geometrically complex components where interactions across multiple domains and scales occur. In particular, we introduce a novel method for modeling the irregular thermo-optical properties of 3DPFs, capable of capturing relevant effects often out of the scope of traditional modeling approaches. Our model accounts for geometry-dependent physical effects ranging from millimeter-scale fabrication details that impact optical behavior to centimeter-scale geometric features influencing heat and radiation transfer, extending up to the meter-scale implications for the building application. By employing computational techniques such as ray-tracing, computational fluid dynamics, and finite element analysis, we establish a model that offers detailed thermal and optical analysis to support performance-driven design iterations. Finally, demonstrating this approach in an office building context, we show that 3DPFs can match the performance of double glazing with dynamic shading, providing effective solar and thermal management over the year. This is achieved in a single, mono-material component with no active control, suggesting 3DPFs are a promising direction for low-environmental impact facade design.

Microscale Structure Additive Manufacturing Control Method Using Localized Electrochemical Deposition

Micro‐nano scale 3D printing is attracting attention as an alternative manufacturing method for a variety of applications in electronic information, biomedical, and sensing devices. Localized electrochemical deposition (LECD) based on nanopipettes is naturally superior and economical for the manufacturing of high‐freedom, impurity‐free metal conductors. However, flexible printing sacrifices roughness and straightness. Therefore, the present study initially establishes a simulation model for LECD and subsequently analyzes the key factors that influence the quality and stability of the deposited structure. Furthermore, an effective solution is proposed to enhance the surface quality. Second, a constant deposition current control method based on fuzzy proportional–intergral–derivaite (PID) is proposed to effectively suppress the fluctuation and improve the stability and quality of the deposited structure. Finally, compared with the open‐loop control method, the proposed constant current control method can reduce the radial fluctuation of the copper pillar structure by 87%, and effectively improve the surface quality of the structure. The proposed method provides a new idea to carry out LCED‐based 3D printing with high resolution at the micro‐nano scale.

Investigation of a hybrid binder system for large scale 3D printing

AbstractLarge‐scale additive manufacturing of reactive suspensions, such as concrete, is being developed to freely create objects without the constraints of a formwork. One challenge in printing suspensions is the precise spatio‐temporal control over their rheological properties. For extrusion‐based processes the material must be pumpable to the nozzle of the printer, while once it has passed the nozzle, it must maintain its shape under the increasing pressure of subsequent layers. Therefore, it is beneficial if the material exhibits an appropriately designed rheology change at the nozzle. The objective of this work is to develop a printing suspension which achieves a rheological step change at the nozzle. Therefore, we create a hybrid binder system comprising of a fast, reactive organic component, which can be activated by heat and a second inorganic binder components, in our system the carbonation of calcium hydroxide, which delivers the final strength.The temperature dependent stiffening of the model suspensions is studied by oscillatory rheology at temperatures between 20 °C to 80 °C. For mechanical testing purposes, cuboid shaped samples are obtained by microwave heating followed by carbonation under ambient conditions. For the given porosity, the material reaches a compressive strength of up to 0.39 MPa in 10 seconds or up to 1.94 MPa in 10 minutes depending on the heating program. Subsequent carbonation for 7 days under ambient conditions gives a strength of up to 4.76 MPa.

Bibliographic analysis on 3D printing in the building and construction industry: Printing systems, material properties, challenges, and future trends

In recent years, significant advancements in the development of large-scale 3D printers and construction materials have been made to meet the demand for industrial scale 3D printing construction. It is significant to construct the buildings and structural components by using 3D concrete printing. Additive manufacturing (AM) main benefits are freedom of design, construction waste reduction, mass customization, and ability to manufacture the complex structures. The major issues including the optimization of printing material which possess the suitable properties for 3D concrete printing. However, this technology towards the green building construction seems to improve the conventional methods by reducing the requirement of human resource, high investment cost, and formworks. The research community's interest in 3D printing for architecture and construction has grown significantly over the last few years. This paper review the latest trend of research and state of the art technologies in 3D printing in building and construction by analyzing the publications from 2002 to 2022. Based on aforementioned analysis of publications, printing methods, concrete printing systems and influence of constituent’s materials and chemical admixtures on concrete material properties are briefly discussed. Finally, this paper discussed the challenges and limitations of current systems, as well as potential future work to improve their capability and print quality.

Progress in Sub-Micrometer Scale 3D Printing

In the first of a series of pieces from speakers at this summer’s Additive International summit (Nottingham, 13-14 July) Professor Martin Wegener from Germany’s Karlsruhe Institute of Technology (KIT) discusses recent advances in micrometer and nanometer scale 3D printing.

Experimental Analysis of Wax Micro-Droplet 3D Printing Based on a High-Voltage Electric Field-Driven Jet Deposition Technology

High-voltage electric field-driven jet deposition technology is a novel high resolution micro scale 3D printing method. In this paper, a novel micro 3D printing method is proposed to fabricate wax micro-structures. The mechanism of the Taylor cone generation and droplet eject deposition was analyzed, and a high-voltage electric field-driven jet printing experimental system was developed based on the principle of forming. The effects of process parameters, such as pulse voltages, gas pressures, pulse width, pulse frequency, and movement velocity, on wax printing were investigated. The experimental results show that the increasing of pulse width and duration of pulse high voltage increased at the same pulse frequency, resulting in the micro-droplet diameter being increased. The deposited droplet underwent a process of spreading, shrinking, and solidifying. The local remelting and bonding were acquired between the contact surfaces of the adjacent deposited droplets. According to the experiment results, a horizontal line and a vertical micro-column were fabricated by adjusting the process parameters; their size deviation was controlled within 2%. This research shows that it is feasible to fabricate the micro-scale wax structure using high-voltage electric field-driven jet deposition technology.

Laying the Groundwork for STEAM: Scaling and Supporting 3D Design and Printing in Higher Education

This perspective article outlines the design and development of a 3D Printing Ecosystem (3DPE) that aims to lay the groundwork for STEAM education. The 3DPE is a coordinated system of hardware, software, and people that has been intentionally designed to scale computer-aided design (CAD) and 3D printing (3DP) at an institutional level. CAD and 3DP are two prime examples of technologies that support STEAM by blending engineering with the arts. These technologies, however, are typically only taught in select university courses that focus on engineering, product development, and industrial design. In recent years, the availability of affordable, reliable, and highly maintainable 3D printers has created an opportunity to infuse CAD and 3DP as a shared set of literacies that can cross disciplinary boundaries. The 3DPE consists of a decentralized series of 3DP labs, a centralized 3DP server, and faculty training. Using a train-the-trainer model, the 3DPE supports STEAM education by training faculty in CAD and 3DP while also providing ongoing curricular support to infuse these skills into their courses through project-based learning. This article provides preliminary examples of how the 3DPE is supporting STEAM education and offers advice for others seeking to replicate the model.

Large Scale 3D Printing: Influence of Fillers on Warp Deformation and on Mechanical Properties of Printed Polypropylene Components

AbstractAdditive manufacturing processes are still on the way from a prototyping process to an established serial production process. Often the limiting factors are the variety and costs of materials compared with standard materials. Polypropylene is a commonly used material in series production. The processing of polypropylene in additive‐ and extrusion‐based manufacturing processes is still a challenge. A big issue in pellet‐based large scale additive manufacturing of polypropylene is to achieve dimensional accuracy of the printed parts. Due to the semi‐crystalline nature of polypropylene and its low adhesive force on standard printing surfaces (aluminum) the fabricated parts tend to warp and deviate from the geometric shape. In this paper the influence of a melt adhesive and different filler types (glass fibers, glass bubbles, and talcum) on the warpage behavior of 3D printed polypropylene parts is investigated. Another issue in additive manufacturing is the mechanical properties of the fabricated parts compared to injection molded parts. The mechanical properties of 3D printed parts often show a dependency on the print direction, especially in case of using fillers with an anisotropic shape (fibers). In this study the influence of different fillers on mechanical properties and process indicated orientation is analyzed.

Electric-field-driven jet deposition micro-nano 3D printing based on a single-plate electrode

<p indent="0mm">Micro/nano-scale 3D printing has become one of the most popular research topics of additive manufacturing due to its wide range of applications in biological tissue engineering, flexible electronics, new energy, new materials, microelectromechanical systems, and many other fields. Recent work on micro/nano-scale 3D printing has presented a series of advanced techniques, such as microstereolithography, two-photon stereolithography, micro-laser sintering, electrochemical fabrication, and electrohydrodynamic (EHD) jet printing, to directly fabricate 3D micro/nano-scale structures. However, these existing technologies are still faced with challenges in realizing multi-material, macro/micro multi-scale 3D printing. Here, we propose a new electric-field-driven jet deposition micro/nano-scale 3D printing based on a single-plate electrode. Differing from the traditional EHD printing with two counter electrodes and our previously proposed electric-field-driven jet deposition 3D printing with a single nozzle electrode, this 3D printing is achieved using technology based on a self-induced electrostatic field. In this method, the nozzle is no longer used as the electrode, and only a single-plate electrode is needed to connect to the positive electrode of high voltage power supply while the negative electrode is directly grounded, which not only overcomes the mandatory requirement of nozzle conductivity in traditional EHD jet printing, but also solves the discharge and breakdown problem of printing conductive materials on the conductive substrate. The micro/nano-scale additive manufacturing by this proposed method can be achieved by combining the necking effect of Taylor cone formed by the self-induced electrostatic field between the printing material on the nozzle tip and the top surface of the substrate, and multi-layer precise stacking by the polarization charges attraction between the printing material and the already printed materials on the substrate. In addition, considering the high-resolution and high-efficiency printing of various materials with different viscosities, we propose two working modes, including the pulsed cone-jet mode and the continuous cone-jet mode. To prove the advantages and features of the proposed method, we carried out a series of research work systematically. Firstly, the printing mechanism is revealed through theoretical analysis and numerical simulation. The higher the conductivity of the single-plate electrode is and the lower the conductivity of the nozzle is, the greater the electric field intensity is. Then, the feasibility of printing with the nozzle (conductive steel nozzle and non-conductive glass nozzle), substrate (conductive copper plate, semiconductor silicon wafer, and insulating glass plate), and printing material (conductive silver paste and non-conductive polymer) has been verified by systematic experiments. Finally, three typical cases, micro “wall” structure of polylactic acid (PLA) with a line width of <sc>1.139 μm</sc> and a high aspect ratio of 46.8:1, high-performance (transmittance of 90.17% and sheet resistance of 4.26 Ω/sq) transparent electrode made of high viscosity silver paste, and multi-layer 3D scaffold with a line width of <sc>20 µm</sc> and a total height of <sc>200 µm,</sc> have been printed successfully. The new method has been proved to have unique technical advantages in high-resolution printing, multi-material, and macro/micro multi-scale printing. Therefore, it provides a new solution with low cost and high universality for micro/nano-scale additive manufacturing and macro/micro cross scale 3D printing, especially in the field of biological tissue engineering and printing electronics.

Effective extrusion-based 3D printing system design for cementitious-based materials

The widespread popularity of additive manufacturing in most industries ranging from biomedical to aerospace suggests a transformation in manufacturing, which has recently also emerged in the construction sector. This paper presents an active system for the extrusion-based 3D printing of cementitious materials. The system can be extended to other materials and scaled up with slight hardware modifications. The proposed system uses an unconventional yet simplistic approach to generate a consistent output of material throughout the printing process. The effectiveness of the extruder is demonstrated through an extensive printing and testing of various cementitious-based materials. The printing and material parameters, which are essential for high mechanical strength printed object were investigated and optimized through a logical iterative loop of trials. The results showed the shape retention of 3D printed objects using the proposed design of extrusion-based system in conjunction with optimized rheology of cementitious-based materials was encouraging for larger scale 3D printing.

Terra–ink additive earth manufacturing for emergency architecture

In recent years, natural disaster and military conflicts forced vast numbers of people to flee their home countries, contributing to the migration crisis we are facing today. According to the UNHCR, the number of forcibly displaced people worldwide reached the highest level since World War II. Post-disaster housing is by nature diverse and dynamic, having to satisfy unique socio-cultural and economical requirements. Currently, however, housing emergencies are tackled inefficiently. Post-disaster housing strategies are characterized by a high economic impact and waste production, and a low adaptability to location-based needs. As an outcome, low quality temporary shelters are provided, which often exceed by far their serving time. Focusing on temporary shelters suitable for the transitioning period between emergency accommodation and permanent housing, TERRA-ink addresses new construction methods that allow for time and cost efficiency, but also for flexibility to adapt to different contexts. TERRA-ink aims to develop a method for layering local soil, by implementing 3D printing technologies. With the aid of such a construction system, the goal is to create durable structures that can be easily de-constructed once they served their purpose. The use of locally sourced materials in combination with additive manufacturing is investigated aiming at reductions in financial investments, resources and human labor, as well as at simplified logistics, low environmental impact and adaptability to different situations and requirements. Such a building system has the potential of combining low-and high-tech technologies, in order to facilitate a fully open and universal solution for large scale 3D-printing using any type of soil.

Fabrication of micro-scale radiation shielding structures using tungsten nanoink through electrohydrodynamic inkjet printing

Electronics components used in space and strategic missions are exposed to harsh radiation environments, which could cause operational malfunction of the system through lattice displacement or ionization effects. One potential solution is to use tungsten as radiation shielding. Tungsten is a very effective material in shielding electronic components and manufacturing gratings for x-ray imaging. However, intrinsic properties of tungsten (e.g. density, chemical/thermal inertness and hardness) post a significant challenge of fabricating the material into micro-scale and delicate structures, especially in electronic device fabrication. To address the problem, we designed a new tungsten nanoink and developed a straightforward approach to create tungsten micro-structures by 3D printing. Various microstructures down to 10 µm resolution have been patterned and fabricated by electrohydrodynamic inkjet (e-jet) printing using tungsten nanoink. By optimizing process parameters (voltage modality) and materials properties (ink formulation), the dimension and morphology of the structures can be precisely controlled. An AC-modulated voltage was employed during the e-jet printing process to make the patterns much more controllable and stable. Multi-layer tungsten lines were characterized by x-ray imaging and exhibited excellent absorption of x-ray radiation. With the same thickness, printed lines showed nearly 1/3 absorptivity of x-ray radiation of bulk tungsten, leading to significant radiation attenuation effectiveness. Tungsten nanoink is a new material used in e-jet printing that has not been reported in the literature to the best of authors’ knowledge. The study establishes a new methodology of manufacturing micro-nano scale shielding components for electronic devices and rapid prototyping of gratings and collimators in radiography for medical and inspection applications. The research also provides practical guidance to fabricate high melting-point metals via nanoink and micro/nano scale 3D printing.

A mechanically enhanced electroactive hydrogel for 3D printing using a multileg long chain crosslinker

Electroactive hydrogels (EAHs) are receiving attention in soft robotics. 3D printing makes EAHs even more attractive, due to the diversification and elaboration of actuations. However, 3D printing needs a large amount of photoinitiator for faster printing, which makes the printed hydrogels so brittle that they cannot produce large scale 3D printing. Here, we developed a 3D printable EAH based on poly(3-sulfopropyl acrylate, potassium salt) (PSPA) using glycidyl methacrylated hyaluronic acid (GMHA) as a mechanically enhancing multileg long chain (MLLC) crosslinker. The MLLC crosslinking improved the stretchability of the PSPA-based hydrogel to 49% from 28%, while maintaining the same level of electroactivity. Additionally, the fracture toughness of the PSPA-based hydrogel remarkably increased from 11 to 40 J m−2 with crosslinking by the MLLC. Using the mechanically enhanced EAH, i.e. the GMHA–PSPA EAH, the 3D printing of elaborate structures, e.g. ‘Leaning Tower of Pisa’ and a hand, and their electroactuation were successfully demonstrated.

The Use of Polypropylene and High-Density Polyethylene on Cork Plastic Composites for Large Scale 3D Printing

This work focuses on studying the possibility of 3D printing of composite materials composed by cork and a polymer matrix (CPC). Initially the cork was mixed with two types of polymers (HDPE and PP) in different proportions and later processed using extrusion and injection. The composites were tested to study the physical, chemical and mechanical properties. The material was then tested on a large-scale 3D printer to study its feasibility and the ability to produce new products through 3D printing. Attention was focused on the use of pure cork, varying the concentration of cork and coupling agent in thermoplastic matrix composites of PP and HDPE. It was demonstrated that the increase of 5wt.% of coupling agent in the two types of polymers significantly improved the mechanical properties and adhesion between the phases but the increase in cork concentration decreased mechanical properties and crystallinity. The CPCs with PP showed to have better mechanical properties, better aesthetic and internal structural quality, and easier processability than those with HDPE matrix. Nevertheless, the HDPE CPCs showed a high degree of crystallization. Concerning 3D printing, with the filament obtained was demonstrated the possibility of making new products based on natural cork fibers, showing promising results, although additional research is still needed to optimize the process.

Experimental research on transition from scale 3D printing to full-size printing in construction

Abstract The inevitable trend in the development of construction 3D printing is to change from printing the reduced size model to printing the full-size structure. While full-size printing is a mega-scale automated manufacturing process, and will face enormous challenges, e.g., blindly printing full-size buildings inevitably causes losses or accidents due to a mistake in the 3D design models or print parameters. This research proposes a method for evaluating the rationality of the models and optimizing the parameters of the full-size 3D printing, based on the scale 3D printing. A case study of a 15-m-span 3D printing landscape bridge is presented to illustrate the proposed method. A series of tests of the printing scaled models and full-size structures are conducted using an industrial printer and a five-axis printing equipment. The maximum deviation between the 3D printed bridge and the design model is within 0.9 mm, and the average is within 0.1 mm. The optimal parameters for the full-size printing such as a layer resolution of 4 mm are determined. Experimental findings indicate that it is feasible to apply the proposed method to print full-size structures, and avoid losses due to the models or parameters errors. In addition, the applications of the scale 3D printing in building lifecycle under the traditional construction mode are systematically discussed. Recommended materials and print parameters for scale 3D printing at different stages of the building lifecycle are introduced.

Surgical Treatment for Posterior Dislocation of Hip Combined with Acetabular Fractures Using Preoperative Virtual Simulation and Three-Dimensional Printing Model-Assisted Precontoured Plate Fixation Techniques.

Background and Purpose Hip dislocation combined with acetabular fracture remains a challenging condition for orthopedic surgeons. In this study, we utilized a computer-assisted simulation and three-dimensional (3D) printing technology to treat patients with hip dislocation combined with acetabular fracture. We hypothesized that the 3D printing-assisted method would shorten the internal fixation time and surgical time. Methods We retrospectively reviewed 16 patients diagnosed with traumatic posterior dislocation of hip combined with acetabular fractures and treated with plate fixation from September 2013 to August 2017. Patients were divided into two groups: (1) traditional method and (2) 3D printing groups. In the traditional method group, the plates were contoured during the surgery, whereas in the 3D printing group, the patient's pelvic computed tomography image was transformed to the 3D medical image software for processing preoperatively. The fracture reduction was simulated by the computer. Thereafter, the 1:1 scale 3D printing model was used to design the surgical plan and contour patient-specific plates preoperatively. Results The internal fixation time was significantly shorter in the 3D printing group than in the traditional method group (-33 min, P<0.05). The mean operative time was shorter than that in the traditional method group (-43 min). However, blood loss and postoperative radiograph results were similar between the groups. The complication rate was lower in the 3D printing group (2/7) than in the traditional method group (5/9). Interpretation Computer-assisted simulation with 3D printing technology is a more efficient method for treating hip dislocation combined with acetabular fractures.

Machine vision assisted micro-filament detection for real-time monitoring of electrohydrodynamic inkjet printing

Electrohydrodynamic inkjet printing (e-jet printing) is one type of micro/nano scale 3D printing technique that automatically deposits functional materials to form 3D structures on the substrate. Unlike traditional thermal or acoustic inkjet printing, e-jet printing utilizes high electrical forces that enable the ink to overcome surface tension at the tip of micro nozzles. The droplets and filaments coming out from the nozzle have dimensions much smaller than the dimensions of the nozzle, thus printing geometries in micro and nano scale. E-jet printing process parameters could affect the final quality attributes of fabricated constructs. Currently, assessment of these critical geometries and attributes must be performed offline using optical microscopy or scanning electron microscopy. This drawback affected the efficiency of micro/nano printing from translation into industrial practice. The research in this paper focused on fundamental research to enable in-situ monitoring of e-jet printing using a real-time images characterization technique. In conclusion, the study in this paper investigated using machine vision for real-time monitoring of micro/nano scale 3D printing. The method worked well for micro-filament detection in e-jet printing, and may be further implemented into feedback control system of complicated e-jet printing. However, the optical machine vision was limited to micro scale detection. One of the future research topic is to develop nano scale in-situ detection mechanism for e-jet printing.

In-situ real-time characterization of micro-filaments for electrohydrodynamic ink-jet printing using machine vision

Electrohydrodynamic ink-jet printing (e-jet printing) is one of micro/nano scale 3D printing techniques that automatically deposit functional materials to form 3D structures on the substrate. Unlike traditional thermal or acoustic inkjet printing, e-jet printing utilizes high electrical forces that enable the ink to overcome surface tension at the tip of micro needles. The filaments/droplets coming out from the needle have dimensions much smaller than the dimensions of the nozzle, thus printing geometries in micro and nano scale. Process parameters in e-jet printing could affect the final quality attributes of fabricated constructs. Currently, assessment of these critical geometries and attributes must be performed offline using optical microscopy or scanning electron microscopy. This drawback affected the efficiency of micro/nano printing from translation into industrial practice. The research in this paper focused on fundamental research to enable in-situ monitoring of e-jet printing using a real-time image characterization technique. In conclusion, the study in this paper investigated using machine vision for real-time monitoring of micro scale 3D printing. The method worked well for characterization of micro-filaments, and may be further implemented into feedback control system of complicated e-jet printing. However, the optical machine vision was limited to micro scale detection. One of the future research topic is to develop nano scale in-situ characterization mechanism for e-jet printing.

PolyBrick 3.0: live signatures through DNA hydrogels and digital ceramics

This paper reflects upon new questions of material compatibility through integrating advanced processes of additive manufacturing in ceramics with cutting-edge research in DNA hydrogel development. The work engages advances in material science, three-dimensional (3D) printing, micro-scale mould making, DNA hydrogels, and material practices derived from crafts, and computational design disciplines. The paper outlines innovative use of micro scale 3D printing technologies for the digital fabrication and production of nonstandard and inscribed ceramic block components. 3D printed ceramic blocks are differentiated via the first architectural component glazed with DNA hydrogel and impregnated with a living signature. Readily available 3D Printing technology is used to produce recognisable signatures containing decodable intelligence prescribed through DNA coding. We have designed a system that allows for 3D printed parts to exist at a microscale in the form of an architectural component and glaze mould, allowing for the opportunistic deposition of DNA intelligence.