3D Printing Strategy Research Articles

Graphene Aerogel Composites with Self-Organized Nanowires-Packed Honeycomb Structure for Highly Efficient Electromagnetic Wave Absorption

HighlightsA new strategy for elaborate regulation of microstructure was successfully introduced by the ice template‑assisted 3D printing and chemical vapor deposition strategy, including graphene nanoplate/silicon carbide nanowires hierarchical porous structure and graphene nanoplate/boron nitride composite heterogeneous interface.The composite exhibits excellent electromagnetic wave absorption performance with an RLmin of -37.8 dB and an EABmax of 9.2 GHz (from 8.8 to 18.0 GHz) at 2.5 mm. And the high-temperature absorption stability makes it a promising absorber candidate under high temperature and oxidizing atmosphere.

Phase change-mediated core-sheath 3D printing of hollow microlattice pseudocapacitive aerogel electrode with favorable electrochemical properties

Channel-interconnected regulation within 3D-printed pseudocapacitive electrode architecture to generate high active material loading/utilization and fast ion transport is pivotal but challenging for implementing high-performance pseudocapacitance system. Herein, we demonstrated an innovative phase change-mediated core-sheath direct ink writing (DIW) 3D printing strategy for controllably constructing pseudocapacitive hollow-microlattice graphene/NiCo2O4 aerogel (HGNA) electrode, with regular hollow channels in printed filaments and abundant well-interconnected hierarchical pores built by jointing tortuous pseudocapacitive graphene nanosheets. The unique architectural features facilitated highly efficient diffusion and infiltration of substance throughout the entire thick filaments from both “interior-exterior” and “exterior-interior” directions, thereby enabling high-level yet effective loading of active materials as well as unimpeded ion transport across the printed bulk-structured electrode. Kinetics analysis revealed that the capacitance of pseudocapacitive HGNA electrode was primarily contributed from fast kinetic process. An asymmetric device assembled with DIW-printed HGNA electrode boasted a high energy storage performance with capacitance of 3.43 F cm−2 and energy density of 1.01 mWh cm−2, while featuring remarkable cycling stability (87% after 8000 cycles) and superior capacity even at large electrode thickness. This work opens a promising route for processing rational pseudocapacitive electrode architectures toward high-capacity, fast-kinetics devices.

3D-Printing Functional Ceramic for One-Step Fabrication of Pd/C Catalytic Reactor

Catalysts are widely used in the chemical industry because of their environmental friendliness and low energy consumption. However, integrated fabrication of catalytic reactors (CRs) remains challenging. In this study, we propose the integrated manufacturing of a palladium-carbon (Pd/C) CR for the first time. The outer shell ink comprises Al2O3 powder and aluminum dihydrogen phosphate (AP), whereas the inner core ink consists of activated carbon powder, AP, and polymethylmethacrylate (PMMA). By integrating with the coaxial 3D printing strategy, the Pd/C CR can be freeform-designed with different core thicknesses, lengths, and shapes (W-type, L-type, and U-type). Based on this, a CR with excellent catalytic properties was further developed by loading palladium (Pd) particles. Typically, the resultant Pd/C CR with a length of 2.5 cm exhibits a catalytic efficiency of up to 97.6% after 60 min. This method of preparing Pd/C CR using coaxial 3D printing combines multimaterial 3D printing, integrated molding, and complex biomimetic structure fabrication. This offers a feasible and cost-effective solution that uses a simple fabrication process.

3D printing single‐stroke path planning, local reinforcement and performance testing of MBB beams and cantilever beams

Abstract3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) has been applied for the molding of composite complex structures due to the advantages of flexibility and one‐step forming. In this study, feature points simplification, merging and rearrangement were accomplished for Messerschmitt‐Bölkow‐Blohm (MBB) beam and cantilever beam to generate single‐stroke print paths for the specimens. For the significant stress areas in the finite element analysis results of these structures, a local reinforcement method using orthogonal layups was proposed, which was achieved by raising and lowering the print head and adjusting the fiber volume fraction during the printing. After experimental validation and failure modes analysis, the path planning significantly improved the peak load and structural stiffness of the specimens, and the local reinforcement further enhanced the equivalent specific strength and specific stiffness. This study provides a single‐stroke 3D printing strategy for complex structure molding in conjunction with parameter adjustments.Highlights A single‐stroke path planning was developed for MBB beams and cantilever beams, including simplification, merging and rearrangement methods for feature points. A local reinforcement method was proposed, which was achieved by raising and lowering the print head and adjusting the fiber volume fraction during the printing process. The effect of different print paths on specimen properties was investigated.

Optimization of 3D Printing Parameters of High Viscosity PEEK/30GF Composites.

The aim of this study was to optimize a set of technological parameters (travel speed, extruder temperature, and extrusion rate) for 3D printing with a PEEK-based composite reinforced with 30 wt.% glass fibers (GFs). For this purpose, both Taguchi and finite element methods (FEM) were utilized. The artificial neural networks (ANNs) were implemented for computer simulation of full-scale experiments. Computed tomography of the additively manufactured (AM) samples showed that the optimal 3D printing parameters were the extruder temperature of 460 °C, the travel speed of 20 mm/min, and the extrusion rate of 4 rpm (the microextruder screw rotation speed). These values correlated well with those obtained by computer simulation using the ANNs. In such cases, the homogeneous micro- and macro-structures were formed with minimal sample distortions and porosity levels within 10 vol.% of both structures. The most likely reason for porosity was the expansion of the molten polymer when it had been squeezed out from the microextruder nozzle. It was concluded that the mechanical properties of such samples can be improved both by changing the 3D printing strategy to ensure the preferential orientation of GFs along the building direction and by reducing porosity via post-printing treatment or ultrasonic compaction.

Systematic Evaluation of Adhesion and Fracture Toughness in Multi-Material Fused Deposition Material Extrusion.

Material extrusion (MEX) additive manufacturing has successfully fabricated assembly-free structures composed of different materials processed in the same manufacturing cycle. Materials with different mechanical properties can be employed for the fabrication of bio-inspired structures (i.e., stiff materials connected to soft materials), which are appealing for many fields, such as bio-medical and soft robotics. In the present paper, process parameters and 3D printing strategies are presented to improve the interfacial adhesion between carbon fiber-reinforced nylon (CFPA) and thermoplastic polyurethane (TPU), which are extruded in the same manufacturing cycle using a multi-material MEX setup. To achieve our goal, a double cantilever beam (DCB) test was used to evaluate the mode I fracture toughness. The results show that the application of a heating gun (assembled near the nozzle) provides a statistically significant increase in mean fracture toughness energy from 12.3 kJ/m2 to 33.4 kJ/m2. The underlying mechanism driving this finding was further investigated by quantifying porosity at the multi-material interface using an X-ray computed tomography (CT) system, in addition to quantifying thermal history. The results show that using both bead ironing and the hot air gun during the printing process leads to a reduction of 24% in the average void volume fraction. The findings from the DCB test and X-ray CT analysis agree well with the polymer healing theory, in which an increased thermal history led to an increased fracture toughness at the multi-material interface. Moreover, this study considers the thermal history of each printed layer to correlate the measured debonding energy with results obtained using the reptation theory.

A heterogeneous pore design algorithm for material extrusion additive manufacturing

Material extrusion additive manufacturing offers great potential for customizing matters with complex external contours, and filament diameter-adjustable 3D (FDA-3D) printing strategy provides fresh impetus to create heterogeneous porous structures inside these complex matters. However, the absence of supporting algorithms to implement FDA-3D printing severely hinders its widespread use. In this paper, we develop a heterogeneous pore design (HPD) algorithm aimed at advancing the development of FDA-3D printing for producing heterogeneous porous matters. The HPD algorithm consists of three sub-algorithms: model design, collapse compensation, and fabrication file (G-codes) generation. As proofs of concept, we utilize this algorithm to 3D print radial gradient and letter-embedded gradient materials following specific steps: (1) designing the heterogeneous porous models with collapse compensation in Grasshopper® and displaying them in Rhinocores®; (2) customizing and writing the corresponding G-codes files by following the material extrusion 3D printer's control rules; (3) upgrading a commercial extrusion printer to FDA-3D print the design models via the customized G-codes. Micro-computed tomography-based 3D reconstruction and quantified pore size maps for the fabricated objects demonstrate the high capability of this HPD algorithm. Overall, the HPD algorithm holds the potential to revolutionize material extrusion 3D printers cost-effectively, creating new possibilities for material extrusion of heterogeneous materials.

Trueness of the apical and middle root portion segments of 3D-printed removable die and alveolar cast designs manufactured using stereolithographic 3D printing.

The present study evaluated the effects of the root portion design, segment (middle vs. apical), and part (die vs. cast) on the trueness of three-dimensional (3D)-printed removable die-cast complex. The trueness of apical and middle segments of the root portion of 45 3D-printed removable dies and casts with three different root portion designs (n = 15) was assessed using a metrology-grade computer program. The three removable dies and cast designs (root form [RF], conical [CON], and cylindric [CYL]) were created using professional computer-aided manufacturing computer programs (DentalCAD 3.1 Rijeka, and InLab CAD 22.0), and manufactured using stereolithographic 3D printer (Form3; FormLabs, Somerville, MA). Subsequently, the 3D-printed removable dies and casts were scanned by a single operator with an intraoral scanner (PrimeScan; Dentsply Sirona, Charlotte, NC), and their respective standard tessellation language files were aligned and compared to master reference files in a metrology-grade computer program (Geomagic Control X; 3D systems, Rock Hill, NC). The root mean square (RMS) values of the middle and apical segments for each removable die and cast were calculated and analyzed using a mixed model including a repeated measure 3-way analysis of variance (ANOVA) and post-hoc stepdown Bonferroni-corrected pairwise comparisons (α = 0.05). A statistically significant 3-way interaction between factors was detected, suggesting that the part (removable die or alveolar cast) and their design affected the RMS values of their apical and middle root portion segment. (p = 0.045). The post-hoc analysis identified significant differences between RMS values of the apical segments of the CON and CYL removable dies (p = 0.005). Significant differences were observed between the middle and apical segments of the CON (p < 0.001) and RF removable die designs (p = 0.004). No statistically significant differences were noticed between the RMS of the different alveolar cast designs (p > 0.05). Significant differences were detected between the apical and middle segments of the same alveolar cast design (p < 0.05). For the manufacturing trinomial and 3D printing strategy used in the present study, the interaction of the part, design, and segment affected the trueness of removable dies and alveolar casts. The trueness was higher on the middle segment on removable dies and alveolar casts in all designs used, except for CYL removable dies, where the trueness difference between segments was small. Higher trueness values may be achieved with designs with simple apical segment geometries.

Liquid metal hybrid antibacterial hydrogel scaffolds from 3D printing for wound healing

Hydrogels patches hold significant promise for wound healing. Endeavors have been dedicated to the improvement of hydrogel patch functionalities, with the aim of achieving systematic wound management. Herein, we present liquid metal (LM) hybrid antibacterial hydrogel scaffolds for wound healing via the 3D printing strategy. Gelatin/gellan gum-based hydrogel ink is adopted for printing the scaffolds, with LM microdroplets integrated within. Due to the excellent photothermal responsiveness of LM microdroplets, the LM hybrid scaffolds can convert the received near infrared light energy into heat energy, demonstrating controllable antibacterial ability. In addition, vascular endothelial growth factor is introduced into the scaffolds, which can be sustainably released and play an angiogenesis role. In vivo animal experiments demonstrate that this hydrogel scaffolds can effectively assit wound closure by eradicating bacterial infection and promoting angiogenesis. Thus, we believe that the proposed LM hybrid hydrogel scaffolds show promising prospects in wound treatment.

Filament formation mechanisms in yield-stress fluid-enabled embedded ink writing

Embedded ink writing (EIW), an emerging material extrusion-based three-dimensional (3D) printing strategy, has demonstrated great potential for diverse applications. EIW consists of three key components: support bath, ink, and printing conditions. Filament formation in EIW is significantly affected by the coupling effects of these components, which is still unclear. This work aims to fundamentally unveil the filament formation processes and mechanisms within support bath materials with various rheological properties. A broader range of path speed is utilized to ensure the formation of diverse representative filaments from low- and high-viscosity hydrogel inks. By varying the combination of support bath, ink, and printing conditions, ten types of filaments are observed during EIW and their formation mechanisms are explained in detail. Particularly, when designing a support bath for EIW, thixotropic time serves as the baseline to determine the functionality of the bath. A relatively long thixotropic time can facilitate the formation of well-defined filaments. In addition, the support bath’s yield stress decides the allowed maximum path speed. High yield stress is necessary if path speed is targeted in a higher range. Based on the experimental findings, a position-shape-size evaluation system is established and proposed for comprehensively evaluating printed filaments, which is helpful in filtering suitable filaments for EIW. Finally, complex 3D structures including a human nose and a human ear are printed at a high speed within the support bath with suitable rheological properties to bridge the gap between filament formation mechanisms and practical 3D printing applications.

3D printing for the reinterpretation of architectural heritage: Proposal of a model

3D printing for the reinterpretation of architectural heritage stands out as one of the most efficient ways of using contemporary printing technologies in terms of architecture. The aim of the study is to present a comprehensive methodology on how to use 3D printing techniques for reinterpretation of architectural heritage. In this context, the scope of the study consists of pioneering information obtained from literature studies focusing on the details of the use of three-dimensional printing techniques in the promotion, preservation and remodeling of cultural heritage and architectural heritage components. The method of the study was determined as identifying leading themes through literature research and presenting a method proposal by grouping conceptually related themes. The unique value of the study is important in that the model to be created offers a potential to affect mass production tools, offices and local governments by incorporating contemporary architectural heritage products into a modeling process that can produce more innovative and faster solutions. The findings of the study show that the different techniques used can respond to different detail scales and different contextual challenges. Each modeling method and strategy creates different feedback mechanisms, mediating the recognition of the architectural heritage element by larger user groups or the more effective protection of the architectural heritage element. In the model presented as a result of the study, which mediates the gathering of the techniques used in different sample projects on a common working ground with a series of successive strategies, a comprehensive basis for which 3D printing solution will be used for which problem is presented and solution suggestions are offered for a case-oriented 3D printing strategy.

Advancing Tissue Culture with Light-Driven 3D-Printed Microfluidic Devices.

Three-dimensional (3D) printing presents a compelling alternative for fabricating microfluidic devices, circumventing certain limitations associated with traditional soft lithography methods. Microfluidics play a crucial role in the biomedical sciences, particularly in the creation of tissue spheroids and pharmaceutical research. Among the various 3D printing techniques, light-driven methods such as stereolithography (SLA), digital light processing (DLP), and photopolymer inkjet printing have gained prominence in microfluidics due to their rapid prototyping capabilities, high-resolution printing, and low processing temperatures. This review offers a comprehensive overview of light-driven 3D printing techniques used in the fabrication of advanced microfluidic devices. It explores biomedical applications for 3D-printed microfluidics and provides insights into their potential impact and functionality within the biomedical field. We further summarize three light-driven 3D printing strategies for producing biomedical microfluidic systems: direct construction of microfluidic devices for cell culture, PDMS-based microfluidic devices for tissue engineering, and a modular SLA-printed microfluidic chip to co-culture and monitor cells.

3D Printing Strategy in Manufacturing of Health Monitoring Devices

3D Printing Strategy in Manufacturing of Health Monitoring Devices

A new 3D printing strategy by enhancing shear-induced alignment of gelled nanomaterial inks resulting in stronger and ductile cellulose films

Cellulose nanofibrils (CNFs) are derived from biomass and have significant potential as fossil-based plastic alternatives used in disposable electronics. Controlling the nanostructure of fibrils is the key to obtaining strong mechanical properties and high optical transparency. Vacuum filtration is usually used to prepare the CNFs film in the literature; however, such a process cannot control the structure of the CNFs film, which limits the transparency and mechanical strength of the film. Here, direct ink writing (DIW), a pressure-controlled extrusion process, is proposed to fabricate the CNFs film, which can significantly harness the alignment of fibrils by exerting shear stress force on the filaments. The printed films by DIW have a compact structure, and the degree of fibril alignment quantified by the small angle X-ray diffraction (SAXS) increases by 24 % compared to the vacuum filtration process. Such a process favors the establishment of the chemical bond (or interaction) between molecules, therefore leading to considerably high tensile strength (245 ± 8 MPa), elongation at break (2.2 ± 0.5 %), and good transparency. Thus, proposed DIW provides a new strategy for fabricating aligned CNFs films in a controlled manner with tunable macroscale properties. Moreover, this work provides theoretical guidance for employing CNFs as structural and reinforcing materials to design disposable electronics.

Direct 3D printing of triple-responsive nanocomposite hydrogel microneedles for controllable drug delivery

Hydrogel microneedle patches have emerged as promising platforms for painless, minimally invasive, safe, and portable transdermal drug administration. However, the conventional mold-based fabrication processes and inherent single-functionality of such microneedles present significant hurdles to broader implementation. Herein, we have developed a novel approach utilizing a precursor solution of robust nanocomposite hydrogels to formulate photo-printable inks suitable for the direct 3D printing of high-precision, triple-responsive hydrogel microneedle patches through digital light processing (DLP) technology. The ink formulation comprises four functionally diverse monomers including 2-(dimethylamino)ethyl methacrylate, N-isopropylacrylamide, acrylic acid, and acrylamide, which were crosslinked by aluminum hydroxide nanoparticles (AH NPs) acting as both reinforcing agents and crosslinking centers. This results in the formation of a nanocomposite hydrogel characterized by exceptional mechanical strength, an essential attribute for the 3D printing of hydrogel microneeedle patches. Furthermore, this innovative 3D printing strategy facilitates facile customization of microneedle geometry and patch dimensions. As a proof-of-concept, we employed the fabricated hydrogel microneedles for transdermal delivery of bovine serum albumin (BSA). Importantly, these hydrogel microneedles displayed no cytotoxic effects and exhibited triple sensitivity to pH, temperature and glucose levels, thereby enabling more precise on-demand drug delivery. This study provides a universal method for the rapid fabrication of hydrogel microneedles with smart responsiveness for transdermal drug delivery applications.

Empowering Rehabilitation: Design and Structural Analysis of a Low-Cost 3D-Printed Smart Orthosis.

Three-dimensional (3D) printing of polymer materials encompasses a wide range of applications and innovations. Polymer-based 3D printing, also known as additive manufacturing, has gained significant attention due to its versatility, cost-effectiveness, and potential to revolutionize various industries. The current paper focuses on obtaining a durable low-cost rehabilitation knee orthosis. Researchers propose that the entire structure should be obtained using modern equipment within the additive manufacturing domain-3D printing. The researchers focus on determining, through a 3D analysis of the entire 3D model assembly, which parts present a high degree of stress when a kinematic simulation is developed. The entire 3D model of the orthosis starts based on the result obtained from a 3D scanning of the knee joint of a patient, providing a precise fixation, and allowing for direct personalization. Based on the results and identification of the critical parts, there will be used different materials and a combination of 3D printing strategies to validate the physical model of the entire orthosis. For the manufacturing process, the researchers use two types of low-cost fused filament fabrication (FFF), which are easy to find on the worldwide market. The motivation for manufacturing the entire assembly using 3D printing techniques is the short time in which complex shapes can be obtained, which is relevant for the present study. The main purpose of the present research is to advance orthotic technology by developing an innovative knee brace made of 3D-printed polymers that are designed to be lightweight, easy-to-use, and provide comfort and functionality to patients during the rehabilitation process.

A novel microwave assisted multi-material 3D printing strategy to architect lamellar piezoelectric generators for intelligent sensing

While the advances in thermoplastic additive manufacturing (3D printing) cover the free-form fabrication of piezoelectric materials, the chief obstacles to the use of 3D printed piezoelectric generator (PEG) are the weak weld within the part and imperfect polarization. Herein, a microwave assisted multi-material 3D printing strategy is proposed to fabricate multiple PEGs consisting of periodically intercalated piezoelectric & conductive layers. The interfacial regulation performed between piezoelectric ceramics and matrix leads to sufficient polarization under the electric field, thus generating the substantially enhanced piezoelectricity. Benefiting from the unique design of embedded electrode with 3D graphene nanoplatelets (GNPs) network, the polarization charge density greatly increases. Then the microwave irradiation technology is employed to realize the intense selective heating of the GNPs to weld polymer interfaces, further improving the piezoelectric output. As a result, the output current of the 3D lamellar PEG is nearly 18 times higher than that of conventional sandwich structure PEG. With significant advantages of the enhanced electromechanical coupling performance, the fabrication strategy is expected to create multifunctional sensors with complex geometries. Based on the above method, the 3D printed biomimetic lamellar denture is developed for health monitoring and Morse code transmission, demonstrating its enormous potential in real-life applications.

Revolutionising engineering pedagogy: The role of 3D printing in modern engineering education

ABSTRACT This paper presents a comprehensive study on the integration of 3D printing technology in biomedical robotics education with undergraduate students learning about the design of robotic systems. The research investigated the effectiveness of this new teaching strategy in enhancing students’ understanding of complex engineering principles by comparing their learning experiences, and academic performance with results from traditional teaching methods. The students’ learning and performance were evaluated through a survey and grade analysis. The Mann – Whitney U test was used to analyse the data, revealing statistically significant improvements in both student satisfaction and grades. The Mann-Whitney U test results show a clear preference for the 2017 3D printing and project-based learning strategy over the 2016 traditional method. With a U-value of 0 and a critical U-value at p < 0.05 being 23, coupled with a z-score of −3.742, the data significantly indicates enhanced student outcomes with the newer teaching approach compared to conventional methods. The study also found that 3D printing technology fostered creativity, critical thinking, and enhanced spatial visualisation skills among students. However, we also identify potential challenges, including equipment maintenance, safety concerns, and the need for faculty expertise. The study concludes by providing potential strategies to overcome these challenges. This research offers valuable insights for educators and policy-makers in leveraging technology for improved learning outcomes in engineering education.

Mechanical behavior of nacre-inspired CFRP composites by 3D printing

High-performance carbon fiber reinforced polymer (CFRP) composites are essential for many structural applications, however, properties such as strength and toughness are often considered mutually exclusive in CFRP composites. Inspired by the biological structure of nacre, this study offers a new 3D printing strategy for manufacturing nacre-inspired CFRP composites, aiming to overcome the limitations of traditional materials. The geometric parameters of the nacre-inspired brick composites, including waviness angle and aspect ratio were considered to systematically investigate their respective roles in achieving both strength and toughness and reveal the failure and deformation mechanisms through tensile and three-point bending tests. The results indicated the interlocking and appropriate aspect ratio nacre-inspired CFRP composites provides distinct advantages in enhancing both the overall strength and toughness of the structure under tensile loading. It is further shown that the bending property exhibited a significant sensitivity to the waviness angle. As the waviness angle gradually increases from negative to positive, the bending resistance of the sample decreases. The findings regarding deformation, failure modes, and toughening mechanisms shed light on how geometric parameters affect the mechanical performance of the nacre-inspired CFRP composites.

Developing a 3D strategy: Pipelines and recommendations for 3D structured light scanning of archaeological artefacts

Archaeology has faced increased pressure to digitise collections and make artefacts available and accessible to a wider audience. 3D imaging involves producing a 3D digital or printed model of an object or site. 3D models have the potential to augment the traditional approaches to museum engagement whilst breaking down the barriers to access, whether through providing 3D printed proxies in museums or sharing digital models online. 3D imaging has clear value in archaeology and public engagement but there is no standardisation or accessible pipelines available for achieving professional 3D imaging output. There is very little consensus in 3D modelling and worldwide, digital collections are being created with no methodological consistency. This research observed each stage necessary for producing high-quality 3D models with structured light scanning (SLS) technology. SLS was effective on a range of textures that may be encountered in archaeological scenarios, although highly reflective objects, or pale objects with black areas, may fail to be captured even with an altered strategy. In order to make the 3D model most representative of the archaeological find, it is recommended that a range of scanner settings such as brightness or shutter speed are tested on the object before committing these settings to the rest of the scans. Generalised 3D scanning pipelines are provided to inform archaeological teams on a 3D digital and printing strategy.