Light Processing 3D Printing Technology Research Articles

Preparation of excellent performance ZTA ceramics and complex shaped components using digital light processing 3D printing technology

Complex cellular structured Al2O3 ceramics is difficult to fabricate due to its poor toughness. To overcome this limitation, La2O3 and ZrO2 were introduced into Al2O3 ceramics in digital light processing (DLP) 3D printing. The toughening of ZrO2 and in-situ formation of platelet grains by La2O3 addition dramatically increased the performance of printed ceramics (flexural strength of 556.6 MPa, fracture toughness of 6.94 MPa·m1/2, Vickers hardness of 18.88 GPa, and an apparent porosity of 0.09%), which exceeds most of those fabricated by traditional process. Furthermore, four different cellular structures were successfully fabricated with a Diamond-structure being the best (compressive strength of 40.62 MPa, Young’s modulus of 2.41 GPa, energy absorption of 0.45 MJ/m3, cellular density of 1.70 g/cm3, and specific strength of 23.83 MPa/(g/cm3)). This study presents a novel strategy for using DLP 3D printing technology in the fabrication of lightweight, high-strength and complex shaped ceramic components. It aims to expedite the rapid application of DLP 3D printing technology in various fields such as aerospace and medical.

AI-driven real-time failure detection in additive manufacturing

The optimisation of 3D printing parameters for manufacturing biomedical devices is an emerging interdisciplinary field that incorporates artificial intelligence techniques such as machine learning and deep learning. In this particular study, the focus is on the fabrication of biocompatible finger splints using digital light processing 3D printing technology, followed by UV curing, to evaluate their quality. By leveraging vibration data from printers, which cannot be captured through visual inspection of layer defects, this study aims to develop a predictive model for assessing the failures of printed parts. Here, a closed-loop detection system is proposed to identify failure phenomena in 3D resin printing, combining both cloud and edge computing technologies to effectively detect and address potential failures in the printing process.

Electrolyte-supported solid oxide fuel cells with ultra-thin honeycomb structure prepared by digital light processing 3D printing technology

A significant challenge in electrolyte-supported solid oxide fuel cells (SOFCs) pertains to the substantial thickness of the electrolyte, resulting in elevated operational temperatures that hinder commercial viability. In this research, we utilized digital light processing (DLP) 3D printing technology to fabricate ultra-thin honeycomb electrolyte-supported SOFCs and subsequently evaluated their performance. Through the use of ultraviolet absorbers, we achieved a shallow curing depth (60.3 μm), which facilitated the creation of ultra-thin electrolyte samples. We investigated the mechanical properties of electrolytes with various honeycomb structures, finding that the square honeycomb structure exhibited the highest mechanical integrity, with an average failure load of 1.01 N. Finally, we assessed the electrochemical performance, observing a substantial power density of 215.4 mW/cm2, representing a twofold increase compared to the 114 mW/cm2 achieved by the same method in a flat primary cell.

Self‐Powered Integrated Tactile Sensing System Based on Ultrastretchable, Self‐Healing and 3D Printable Ionic Conductive Hydrogel

AbstractSelf‐healing ionic conductive hydrogels have shown significant potential in applications like wearable electronics, soft robotics, and prosthetics because of their high strain sensitivity and mechanical and electrical recovery after damage. Despite the enormous interest in these materials, conventional fabrication techniques hamper their use in advanced devices since only limited geometries can be obtained, preventing proper conformability to the complexity of human or robotic bodies. Here, a photocurable hydrogel with excellent sensitivity to mechanical deformations based on a semi‐interpenetrating polymeric network is reported, which holds remarkable mechanical properties (ultimate tensile strain of 550%) and spontaneous self‐healing capabilities, with complete recovery of its strain sensitivity after damages. Furthermore, the developed material can be processed by digital light processing 3D printing technology to fabricate complex‐shaped strain sensors, increasing mechanical stress sensitivity with respect to simple sensor geometries, reaching an exceptional pressure detection limit below 1 Pa. Additionally, the hydrogel is used as an electrolyte in the fabrication of a laser‐induced graphene‐based supercapacitor, then incorporated into a 3D‐printed sensor to create a self‐powered, fully integrated device. These findings demonstrate that by using 3D printing, it is possible to produce multifunctional, self‐powered sensors, appropriately shaped depending on the various applications, without the use of bulky batteries.

Preparation of high performance dense Al2O3 ceramics by digital light processing 3D printing technology

The incorporation of a significant amount of organic materials in the fabrication process of Al2O3 ceramics using digital light processing (DLP) 3D printing technology leads to a noticeable reduction in mechanical properties compared to those prepared using traditional methods. To enhance its mechanical performance of Al2O3 ceramics, the addition of MgO and MgO-Y2O3 sintering additives, along with a three-step curing method, has resulted in significant improvements. Al2O3 ceramics fabricated with the addition of MgO exhibited a flexural strength of 454.2 MPa, Vickers hardness of 20.24 GPa and apparent porosity of 0.15 %. Similarly, the addition of MgO-Y2O3 yielded Al2O3 ceramics with a flexural strength of 491.6 MPa, Vickers hardness of 20.91 GPa, and apparent porosity of 0.11 %. These values exceed the typical flexural strength of Al2O3 ceramics prepared using traditional methods. This research provides a fundamental basis for the production of high performance, dense, and complex shaped Al2O3 ceramics using DLP 3D printing technology.

Mechanical characterization of Al2O3 twisted honeycomb structures fabricated by digital light processing 3D printing

Inspired by the double-helix structure of biological DNA, low-volume fraction and high-strength Al2O3 twisted honeycomb structures with characteristics similar to those of helical structures in the z-axis were prepared by digital light processing 3D printing technology. As the twist angle increased, the compressive strength of the fabricated Al2O3 structure decreased, and the deformation mechanism of the Al2O3 structures gradually changed from stretching-dominated to bending-dominated, which can be predicted by the Gibson–Ashby model. The relationship between the effective elastic modulus and the volume fraction that can be modified by varying the wall thickness was described by the Pabst–Gregorova exponential relationship. The compressive strength of the Al2O3 structure with a twist angle of 0° can reach 62.4 MPa at a volume fraction of 13.3%, providing guidance to optimize lightweight structures of ceramics.

Development of polymeric/MXenes composites towards 3D printable electronics

3D printing is an emerging technology for many applications, including electronics. On the other hand, to gather the applications’ requirements with the possibility to produce complex 3-dimensional structures, the development of novel 3D printable materials is necessary. In this context, herein it is reported the synthesis of 3D printable photocurable resins embedding Ti3C2Tz-MXenes, a class of 2D layered materials with outstanding electrical and electronic properties. Stable inks suitable for Digital Light Processing 3D printing technology have been successfully synthesized and employed to fabricate complex 3D composite structures with high printing fidelity. To enhance the electrical conductivity of the material, annealing treatments have been performed, followed by a complete characterization of the so obtained materials. The results show that objects with improved electrical conductivity have been successfully obtained, opening new perspectives in towards the development of complex 3 dimensional electronic.

Sustained-Drug-Release, Strong, and Anti-Swelling Water-Lipid Biphasic Hydrogels Prepared via Digital Light Processing 3D Printing for Protection against Osteoarthritis: Demonstration in a Porcine Model.

Osteoarthritis is a serious disease affecting joint cartilage. Owing to poor blood supply, the meniscus and acetabular labrum of joints heal poorly after injury. However, the development of artificial alternatives to these components that have similar mechanical properties and cartilage-protection ability is challenging. In this study, a strong hydrogel with a biomimetic microstructure is prepared with an emulsion-type photosensitive resin, where both hydrophilic and hydrophobic monomers, photo-initiator, and drugs can be adopted. In this system, the hydrophobic monomer forms uniformly dispersed aggregates after curing, improving the mechanical properties of the hydrogel significantly. Furthermore, the coordination bonds between nontoxic Zr4+ cations and sulfonic acid groups prevent hydrogel swelling. In addition, the water-oil biphasic hydrogel ink enables the loading of water- and lipid-soluble drugs, yielding hydrogel scaffolds with sustained dual-drug release ability. Crucially, hydrogel scaffolds having excellent mechanical properties, low swelling, and sustained biphasic drug release ability can be prepared using digital light processing 3D printing technology, owing to the high curing rate of the hydrophobic photo-initiator. These hydrogel scaffolds are applied as meniscal and labral replacements in a porcine model and show great promise for the prevention of secondary osteoarthritis, demonstrating the broad potential clinical applications of this material.

Fabrication and mechanical properties of triply period minimal surface porous alumina ceramics based on Digital Light Processing 3D printing technology

Fabrication and mechanical properties of triply period minimal surface porous alumina ceramics based on Digital Light Processing 3D printing technology

3D printing of alumina ceramic heat sink with mini‐channels for thermal management

AbstractThermal management has become one of the most challenging issues for high‐power, integrated, and miniaturized electronic devices. In this paper, an alumina ceramic heat sink with mini‐channels was fabricated using a digital light processing 3D printing technology. Microstructures of the ceramic were investigated by scanning electron microscopy. A proper flow rate of water in the mini‐channels was figured out for efficient cooling by infrared thermal imaging and micro‐thermocouple characterizations. The ceramic heat sink was further integrated with a high‐power laser diode module; cooling performance was evaluated by investigating the thermal resistance of the ceramic heat sink and the optoelectronic property of the laser diode module. Results indicated that the laser diode module could be operated at high driving power of 115.6 W. This study provided a new strategy for a highly efficient thermal management of electronic devices and highlighted the technical potential of ceramic heat sink with more compact coolant channels.

Preparation and Properties of Functional Materials Based on Digital Light Processing 3D Printing

3D printing, known as the “new industrial revolution,” has set off an upsurge in the scientific and technological field in recent years, and 3D printing of digital light processing technology has even improved the performance and efficiency of 3D printing. This technology uses the projection principle to form; no matter the size of the workpiece, the forming speed is not affected. It uses very cheap lamp radiation, the system has no injection-molded components, there is no nozzle clogging problem of traditional molding systems, and maintenance costs are greatly reduced. In this paper, based on digital light processing 3D printing technology, light-curing reactive functional materials commonly used in digital light processing 3D printing are prepared. In the past, most of these materials were imported. In this paper, by adjusting the DLP technology, a water-soluble photocurable reflection material is constructed, a method for shaping the reaction material. It conducts experiments on the preparation and performance research of water-soluble photocurable reaction materials through formulation and process optimization. It prepared a water-soluble photocurable reactive functional material and compared it with traditional imported materials. Due to the characteristics of UV curing and good mechanical properties and water solubility, it provides a new idea for the preparation of 3D printing-related functional materials.

Fabrication of 5-fluorouracil-loaded tablets with hyperbranched polyester by digital light processing 3D printing technology

Three-dimensional (3D) printing technique offers the possibility of producing personalized drug products. However, the suitable printing materials for vat photopolymerization in biomedical applications are still limited. In this study, the hydroxyl-terminated hyperbranched polyester (HBPE) was synthesized by 1,1,1-trimethylolpropane as a core moiety and 2,2-bis(hydroxymethyl)propionic acid as a branched monomer. HBPE was then reacted with acrylic acid (AA) to produce acrylated hyperbranched polyester (AHBPE). NMR analysis indicated that the degree of branching and number of hydroxyl group of HBPE were 0.40 and 19.5, respectively, while the degree of acrylation of AHBPE was 84.0%. AA as a monomer, poly(ethylene glycol) dimethacrylate (PEGDMA) as a difunctional crosslinker, and AHBPE as a multifunctional crosslinker were employed as printing resins to fabricate 5-fluorouracil- (5-FU) loaded tablets by digital light processing 3D printing. A D-optimal mixture design was applied to optimize the composition of printing resins and investigate the influence of the component on the printing time and drug release. Results showed that the printing time and drug release increased with increasing AA content but they decreased with the increase of AHBPE content. Addition of AA to the printing resins was necessary to achieve more complete drug release. The premature drug release was effectively inhibited by the incorporation of AHBPE. The tablet printed with a composition of 47.5 wt% of AA, 32.5 wt% of PEGDMA and 20.0 wt% of AHBPE had the lowest drug release of 13.96% at 2 h and highest one of 53.10% at 12 h, which were close to the model predicted values of 14.64 and 55.31%, respectively. It exhibited sustained drug release over 24 h in simulated gastrointestinal fluid and followed anomalous transport mechanism. The results suggest that AHBPE is a potential crosslinker for use in vat photopolymerization 3D printing of personalized drug delivery.

Meniscal transplantation and regeneration using functionalized polyurethane bionic scaffold and digital light processing 3D printing

Owing to the limited healing ability, the repair of meniscal injury and prevention of secondary osteoarthritis pose considerable challenges for clinicians and researchers. While tissue engineering technology is a promising method, many difficulties, including the construction of the meniscus scaffold with appropriate mechanical properties and its functionalization to promote the regeneration of meniscus tissue, remain to be addressed. In this study, a novel structurally and functionally optimized tissue engineering meniscus scaffold with mechanical properties and spatial structure similar to those of a natural meniscus is prepared using digital light processing 3D printing technology. Kartogenin-loaded polyurethane scaffolds with a specific structure designed using finite element analysis are printed, and their surface is modified using polydopamine. The optimized scaffolds exhibit superior performance in promoting meniscus regeneration, protecting articular cartilage, and mitigating the development of osteoarthritis. Moreover, this study addresses challenges posed by polyurethane, which is found in most widely used commercial meniscus grafts, including unsatisfactory biocompatibility with stem cells and unavailability of a fine 3D structure. Although further research in preclinical applications is required, the results of this study in terms of a next-generation clinical meniscus biomaterial repair strategy are promising.

Three-dimensional printing of gyroid-structured composite bioceramic scaffolds with tuneable degradability

Customisation of bioactivity and degradability of porous bioceramic scaffolds is a formidable challenge in the field of regenerative medicine. In this study, we developed gyroid-structured ternary composite scaffolds (biphasic calcium phosphate (BCP) and 45S5 bioglass® (BG)) using digital light processing 3D printing technology based on material and structural design. Additionally, the mechanical strength, bioactivity, degradability, and biocompatibility of the composite ceramic scaffolds were evaluated. The results revealed that BG reacted with BCP to generate major active crystalline phases of CaSiO3 and Na3Ca6(PO4)5. These active crystalline phases accelerated the exchange rate of Si4+, Ca2+, and PO43− with HCO3− in simulated body fluids and resulted in the rapid formation of carbonated hydroxyapatite (CHA), analogous to the formation of natural bone tissue. Interestingly, the precipitated CHA showed petal- and needle-like morphologies, which provided a large surface area to promote cell adhesion and proliferation. Furthermore, an increase in the BG content improved the degradability of ternary composite scaffolds after soaking in Tris-HCl solution. The tuneable degradability increased by three times at 30 wt% BG and sharply increased by 6.8 times at 40 wt% BG. This study provides a promising strategy to design scaffolds with improved bioactivity and tuneable degradability to assist a diverse population suffering from orthopedic conditions.

Fabrication of alumina ceramics with functional gradient structures by digital light processing 3D printing technology

Alumina ceramics with different unit numbers and gradient modes were prepared by digital light processing (DLP) 3D printing technology. The side length of each functional gradient structure was 10 mm, the porosity ratio was controlled to 70%, and the number of units were (1 × 1 × 1 unit) and (2 × 2 × 2 unit) respectively. The different gradient modes were named FCC, GFCC-1, GFCC-2 and GFCC-3. SEM, XRD, and other characterization methods proved that these gradient structures of alumina ceramics had only α-Al2O3 phase and good surface morphology. The mechanical properties and energy absorption properties of alumina ceramics with different functional gradient structures were studied by compression test. The results show that the gradient structure with 1 × 1 × 1 unit has better mechanical properties and energy absorption properties when the number of units is different. When the number of units is the same, GFCC-2 and GFCC-3 gradient structures have better compressive performance and energy absorption potential than FCC structures. The GFCC-2 gradient structure with 1 × 1 × 1 unit has a maximum compressive strength of 19.62 MPa and a maximum energy absorption value of 2.72 × 105 J/m3. The good performance of such functional gradient structures can provide new ideas for the design of lightweight and compressive energy absorption structures in the future.

3D printing of dual cross-linked hydrogel for fingerprint-like iontronic pressure sensor

Hydrogels with intrinsic high stretchability and flexibility are extremely attractive for soft electronics. However, the existing complicated and laborious methods (such as mold curing) to fabricate microstructured hydrogel (MH) still limit the development of hydrogel-based sensors for flexible devices. Herein, we use digital light processing 3D printing technology to rapidly construct double-network (DN) ionic conductive hydrogel, and then design and print fingerprint-like MH film to manufacture an iontronic pressure sensor. In particular, the DN hydrogel consists of acrylamide/acrylic acid to form a covalently cross-linked network, and magnesium chloride is introduced to form an ionic cross-linked physical network in the hydrogel. The printability (with resolution 150 μm) and mechanical property tunability of DN hydrogel enable the convenient fabrication of sensors. With the biomimetic fingerprint MH film, the iontronic pressure sensor not only has a high sensitivity (0.06 kPa−1), but also has a large detection range (26 Pa–70 kPa) and good stability (200 cycles of pressure loading). We demonstrated that our sensor can be applied to realize tactile sensing in a prosthetic application and detect human motion. With the easy strategy of constructing DN hydrogel with microstructures by 3D printing technology, hydrogel-based sensors are anticipated to be employed in more smart electronics.

Fabrication of Yb-doped silica micro-structured optical fibers from UV-curable nano-composites and their application in temperature sensing

A novel scheme for fabricating Yb-doped silica micro structured optical fibers and their application in high-temperature optical fiber sensing are reported. The Yb-doped silica micro structured optical fiber preforms consisted of Yb-doped silica core rods (0.1 wt% for Yb2O3) and holey pure silica claddings fabricated by UV-curable tube molding technology and digital light processing 3D printing technology, respectively. The silica preforms were drawn using the rod-in-tube method to Yb-doped silica micro structured optical fibers without severe distortion. The doped micro structured fibers were applied to high-temperature sensing from 296.15 to 653.15 K. The proposed technology is expected to be effective for the fabrication of various types of rare-earth-ion-doped silica micro structured optical fibers that can be used in fiber sensors, lasers, and amplifiers.

Digital Light Processing 4D Printing of Transparent, Strong, Highly Conductive Hydrogels.

Hydrogels have excellent biocompatibility, transparency, stretchability, and ionic conductivity, but their fabrication through photopolymerization-based 3D printing is limited due to the low solubility of hydrophobic photoinitiators and lack of efficient hydrophilic photoinitiators. Herein, a type of microemulsion is synthesized and the common hydrophobic photoinitiator can be adopted and finally, a series of transparent hydrogels with high strength (up to 22.9 MPa), elasticity (up to 583%), and ionic conductivity (up to 9.64 S m-1) are fabricated through digital light processing 3D printing technology. Objects with complex structures and a high printing resolution are printed. Hydrogels with both high strength and high ionic conductivity are obtained through chemical crosslinking and ion coordination effect. Dual-material 3D printing is applied to package the hydrogel with elastomers. Due to the high sensitivity and reliability under both stretching and compressive deformation, the hydrogel sensors are applied to monitor various human motions. In addition, the hydrogel exhibits solvent-induced dehydration and excellent water-activated shape memory properties, which are greatly beneficial for its storage and applications in the biomedical field.

Fabrication of hollow lattice alumina ceramic with good mechanical properties by Digital Light Processing 3D printing technology

In this study, two configurations of alumina (Al2O3) ceramics (hollow lattice structure and solid lattice structure) were prepared by DLP 3D printing technology. When sintered at 1600 °C for 4 h, dense alumina ceramics with an average grain size of 4.38 ± 1.26 μm can be obtained. The Al2O3 ceramics prepared by DLP process have good forming precision and shape. The dimension error can be controlled about 0.2 mm. The compressive strength of solid block is 572 MPa. The maximum compressive strength of solid lattice (2.0 mm in diameter and 45% in porosity) is 9.70 MPa. The maximum compressive strength of hollow lattice (2.0 mm in diameter, 0.3 mm in thickness and 70% in porosity) is 4.30 MPa. The thermal simulation results show that the temperature of the hollow lattice (diameter 1.2 mm, porosity 76%) with 500 °C upper surface transferring to the lower surface is only 88.6 °C, which is lower than 133 °C of the solid lattice. Hollow lattice structure can effectively reduce heat loss and improve energy efficiency. The hollow lattice structure Al2O3 ceramics formed by DLP technology is expected to be used in industrial thermal insulation applications.

3D printing of HAp/xSiO2 ceramic scaffolds for potential bone graft reconstruction

HAp has drawn great attention in recent years for its similarity to the inorganic component of bone and can be used as a biocompatible implant. However, the application is limited for its poor shape ability and low degradation ability. With the help of Digital Light Processing 3D printing technology, this study proposed a method for the fabrication of bone remodeling scaffolds with high complexity. In addition, this study found that the silica addition will help densify the HAp ceramic and make it transform to a more biodegradable TCP phase at low sintering temperature.