The Fabrication of Micro Beam from Photopolymer by Digital Light Processing 3D Printing Technology

There is increasing interest in the development of functional composite materials in the field of textiles/clothing, and 3D printing technology has been researched widely to allow practical applications. Previous studies have proposed solutions to improve the adhesion of composite fabrics produced by fused deposition modeling (FDM) technology, but analysis of the adhesion characteristics of fabric composites manufactured by digital light processing (DLP) is insufficient. In this study, the DLP method was used to print rectangular patterns on four textured fabrics (woven polyester (PET), Velour, Fleece, Pleated), peeling experiments and mechanical property tests were conducted on 3D-printed composite fabrics, and these results were compared with those of the FDM method to analyze adhesion based on the surface properties of the fabrics. For composite fabrics printed using the DLP method, a liquid photosensitive resin penetrates the fibers, resulting in greater adhesion of composite fabrics and accuracy of printed patterns than those prepared using FDM. The DLP-PET showed the best mechanical properties in all groups. This research verified that adhesion can be improved by the 3D printing method and the surface characteristics of the fabric and presents a new method to prepare composite fabrics with improved properties.

This study presents the design and fabrication results of an electrothermal micro-electro-mechanical system (MEMS) actuator. Unlike traditional one-directional U-shaped actuators, this bi-directional electrothermal (BET) micro-actuator can produce displacements in two directions as a single device. The BET micro-actuator was fabricated using two-photon polymerization (2PP) and digital light processing (DLP) methods, which are 3D printing techniques. These methods have been compared to see the success of BET micro-actuator fabrication. The compound of these methods and the essential coefficients through the 3D printing operation were applied. Evaluation experiments have demonstrated that in both methods, the 3D printer can print materials smaller than 95.7 μm size features. Though the same design was used for the 2PP and DLP methods, the supporting structures were not produced with the 2PP. The BET micro-actuator was manufactured by removing the supports from the original design in the 2PP. The number of supports, the diameter, and height on the arms of the micro-actuator is 18, 4 μm, and 6 μm, respectively. Although 4 μm diameter supports could be produced with the DLP, it was not possible to produce them with 3D printing device based on 2PP. Besides, the DLP was found to be better than the 2PP for the manufacturing of asymmetrical support structures. The fabrication process has been carried out successfully by two methods. When the fabrication success is compared, the surface quality and fabrication speed of the micro-actuator fabricated with DLP is better than the 2PP. Presented results show the efficiency of the 3D printing technology and the simplicity of fabrication of the micro-actuator via 2PP and DLP. An experimental study was carried out to characterize the relationship between displacement and input voltage for the micro-actuator. Experimental results show that the displacement range of the micro-actuator is 8 μm with DLP, while 6 μm with 2PP.

Digital light processing (DLP) is a projection-based vat photopolymerization 3D printing technique that attracts increasing attention due to its high resolution and accuracy. The projection-based layer-by-layer deposition in DLP uses precise light control to cure photopolymer resin quickly, providing a smooth surface finish due to the uniform layer curing process. Additionally, the extensive material selection in DLP 3D printing, notably including existing photopolymerizable materials, presents a significant advantage compared with other 3D printing techniques with limited material choices. Studies in DLP can be categorized into two main domains: material-level and system-level innovation. Regarding material-level innovations, the development of photocurable resins with tailored rheological, photocuring, mechanical, and functional properties is crucial for expanding the application prospects of DLP technology. In this review, we comprehensively review the state-of-the-art advancements in DLP 3D printing, focusing on material innovations centered on functional materials, particularly various smart materials for 4D printing, in addition to piezoelectric ceramics and their composites with their applications in DLP. Additionally, we discuss the development of recyclable DLP resins to promote sustainable manufacturing practices. The state-of-the-art system-level innovations are also delineated, including recent progress in multi-materials DLP, grayscale DLP, AI-assisted DLP, and other related developments. We also highlight the current challenges and propose potential directions for future development. Exciting areas such as the creation of photocurable materials with stimuli-responsive functionality, ceramic DLP, recyclable DLP, and AI-enhanced DLP are still in their nascent stages. By exploring concepts like AI-assisted DLP recycling technology, the integration of these aspects can unlock significant opportunities for applications driven by DLP technology. Through this review, we aim to stimulate further interest and encourage active collaborations in advancing DLP resin materials and systems, fostering innovations in this dynamic field.Graphical abstract

Digital light processing (DLP) three-dimensional (3D) printing is a type of stereolithography (SLA) process that uses a digital projector to selectively cure resin according to a mask image. Each exposure solidifies a planar component of the printed part, allowing full layers to be cured at once. The DLP approach produces better quality parts at a faster rate compared to other 3D printing methods. One of the challenges with DLP printing is the difficulty of incorporating multiple materials within the same part. As the part is cured within a liquid basin, resin switching introduces issues of cross-contamination, layer height variability, and significantly increased print times. In this paper, a novel technique for printing with multiple materials using the DLP method is introduced. The material handling challenges are addressed with the design of a material swapping mechanism, a material tower, and an active part cleaning system. The material tower is a compact design to facilitate the storage and retrieval of different materials during the printing process. A spray mechanism is used for cleaning excess resin from the part between material changes. Challenges encountered within the 3D printing research community are addressed, with a focus on improving the shortcomings of modern multi-material DLP printers.

Objective: Three-dimensional (3D) printing technology is highly promising for producing nanoceramic resin dental restorations. However, the effects of environmental stressors on the structural integrity and clinical performance of these restorations require further elucidation. To investigate the effects of Stereolithography (SLA) and digital light processing (DLP) 3D printing technologies on the physical-mechanical properties of a 3D-printed resin material used in dental applications. Methods: A total of 120 resin specimens (Senertek P-Crown V2) were fabricated using SLA and DLP technologies. The microhardness, flexural strength, and surface roughness of the specimens were evaluated under control and thermocycling conditions to evaluate their long-term performance. To assess statistical significance a two independent sample t-tests (P < 0.05) were used to analysis the data. Results: SLA samples exhibited significantly higher microhardness (P = 0.001) and flexural strength than DLP samples, both in the control state and after thermocycling. After thermocycling, the microhardness of SLA samples increased, whereas that of DLP samples decreased. Surface roughness values increased significantly in both SLA and DLP samples after thermocycling, with SLA samples exhibiting higher roughness values. Conclusion: SLA-printed resin demonstrated superior microhardness and flexural strength compared to DLP-printed resin. However, its long-term durability is affected by immersion and thermocycling. This study highlights the impact of water sorption, polymerization mechanisms, and surface morphology on material performance.

Three-dimensional printing is a rapidly developing area of technology and manufacturing in the field of oral surgery. The aim of this study was comparison of presurgical models made by two different types of three-dimensional (3D) printing technology. Digital reference models were printed 10 times using fused deposition modelling (FDM) and digital light processing (DLP) techniques. All 3D printed models were scanned using a technical scanner. The trueness, linear measurements, and printing time were evaluated. The diagnostic models were compared with the reference models using linear and mean deviation for trueness measurements with computer software. Paired t-tests were performed to compare the two types of 3D printing technology. A P value < 0.05 was considered statistically significant. For FDM printing, all average distances between the reference points were smaller than the corresponding distances measured on the reference model. For the DLP models, the average distances in the three measurements were smaller than the original. Only one average distance measurement was greater. The mean deviation for trueness was 0.1775 mm for the FDM group and 0.0861 mm for the DLP group. Mean printing time for a single model was 517.6 minutes in FDM technology and 285.3 minutes in DLP. This study confirms that presurgical models manufactured with FDM and DLP technologies are usable in oral surgery. Our findings will facilitate clinical decision-making regarding the best 3D printing technology to use when planning a surgical procedure.

Strain rate dependent mechanical properties of 3D printed polymer materials using the DLP technique

This narrative review aims to provide an overview of the mechanisms of 3D printing, the dental materials relevant to each mechanism, and the possible applications of these materials within different areas of dentistry. Subtopics within 3D printing technology in dentistry were identified and divided among five reviewers. Electronic searches of the Medline (PubMed) database were performed with the following search keywords: 3D printing, digital light processing, stereolithography, digital dentistry, dental materials, and a combination of the keywords. For this review, only studies or review papers investigating 3D printing technology for dental or medical applications were included. Due to the nature of this review, no formal evidence-based quality assessment was performed, and the search was limited to the English language without further restrictions. A total of 64 articles were included. The significant applications, applied materials, limitations, and future directions of 3D printing technology were reviewed. Subtopics include the chronological evolution of 3D printing technology, the mechanisms of 3D printing technologies along with different printable materials with unique biomechanical properties, and the wide range of applications for 3D printing in dentistry. This review article gives an overview of the history and evolution of 3D printing technology, as well as its associated advantages and disadvantages. Current 3D printing technologies include stereolithography, digital light processing, fused deposition modeling, selective laser sintering/melting, photopolymer jetting, powder binder, and 3D laser bioprinting. The main categories of 3D printing materials are polymers, metals, and ceramics. Despite limitations in printing accuracy and quality, 3D printing technology is now able to offer us a wide variety of potential applications in different fields of dentistry, including prosthodontics, implantology, oral and maxillofacial, orthodontics, endodontics, and periodontics. Understanding the existing spectrum of 3D printing applications in dentistry will serve to further expand its use in the dental field. Three-dimensional printing technology has brought about a paradigm shift in the delivery of clinical care in medicine and dentistry. The clinical use of 3D printing has created versatile applications which streamline our digital workflow. Technological advancements have also paved the way for the integration of new dental materials into dentistry.

Ceramic parts generally have poor machinability due to their high hardness and high brittleness. Researchers and industries have overcome the difficulty of machining ceramics and have manufactured parts with intricate geometry by using pre-ceramic polymers in stereolithography (SLA) 3D printing and using slurries based on ceramic powder and photopolymer resin in digital light processing (DLP) 3D printing, among other methods. This presentation will discuss the processes involved in the 3D printing of ceramic and ceramic composite parts via the DLP technique. A vital step in ceramic 3D printing is to optimize the printing parameters for a specific slurry formulation in hand. A systematic methodology to accomplish that step has been developed and can be adopted to 3D print any ceramic slurry. During the printing process in a DLP printer, the slurry solidifies into a 3D part layer-by-layer using UV light to cause photopolymerization in the resin, which hardens the resin and makes it function as glue holding ceramic particles in place. After printing and additional curing, parts are heat treated to remove the polymer present within them and to fuse the ceramic particles together. The key results include the printing of cubes with side length of 10 mm having complex features using a lunar regolith simulant named greenland anorthosite with and without graphene nanoplatelets as a reinforcement and the printing of one mold for dog bone samples using just greenland anorthosite having a length of 80 mm, width of 23 mm, and thickness of about 8 mm. In conclusion, complex ceramic parts and ceramic composites have been 3D printed applying the slurry optimization technique. The positive implication of this work is that more ceramic materials can be made available for applications demanding intricate shapes. A challenge for the future is to study the deformation experienced by 3D printed ceramics during sintering and to determine how to take that deformation into account in the part’s geometry so those parts can have desired dimensions after sintering.

Purpose: The novel 3 dimensional (3D)-printed spine quality assurance (QA) phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet, were developed and evaluated for spine stereotactic body radiation treatment (SBRT). Methods: The developed 3D-printed spine QA phantom consisted of an acrylic body and a 3D-printed spine phantom. DLP and Polyjet 3D printers using the high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. To verify dosimetric effects, the novel phantom was made it enable to insert films between each slabs of acrylic body phantom. Also, for measuring internal dose of spine, 3D-printed spine phantom was designed as divided laterally exactly in half. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield unit (HU) was measured based on each CT image. Intensity-modulated radiotherapy plans to deliver a fraction of a 16 Gy dose to a planning target volume (PTV) based on the two 3D-printing techniques were compared for target coverage and normal organ-sparing. Results: Image fusion demonstrated good reproducibility of the fabricated spine QA phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than for the Polyjet-generated phantom. The organs at risk received a lower dose when the DLP technique was used than when the Polyjet technique was used. Conclusion: This study confirmed that a novel 3D-printed phantom mimicking a high-density organ can be created based on CT images, and that a developed 3D-printed spine phantom could be utilized in patient-specific QA for SBRT. Despite using the same main material, DLP and Polyjet yielded different HU values. Therefore, the printing technique and materials must be carefully chosen in order to accurately produce a patient-specific QA phantom.

This study evaluates the accuracy of drill guides fabricated in medical-grade, biocompatible materials for static, computer-aided implant surgery (sCAIS). The virtually planned drill guides of ten completed patient cases were printed (n = 40) using professional (Material Jetting (MJ)) and consumer-level three-dimensional (3D) printing technologies, namely, Stereolithography (SLA), Fused Filament Fabrication (FFF), and Digital Light Processing (DLP). After printing and post-processing, the drill guides were digitized using an optical scanner. Subsequently, the drill guide’s original (reference) data and the surface scans of the digitized 3D-printed drill guide were superimposed to evaluate their incongruencies. The accuracy of the 3D-printed drill guides was calculated by determining the root mean square (RMS) values. Additionally, cast models of the planned cases were used to check that the drill guides fitted manually. The RMS (mean ± SD) values for the accuracy of 3D-printed drill guides were—MJ (0.09 ± 0.01 mm), SLA (0.12 ± 0.02 mm), FFF (0.18 ± 0.04 mm), and DLP (0.25 ± 0.05 mm). Upon a subjective assessment, all drill guides could be mounted on the cast models without hindrance. The results revealed statistically significant differences (p < 0.01) in all except the MJ- and SLA-printed drill guides. Although the measured differences in accuracy were statistically significant, the deviations were negligible from a clinical point of view. Within the limits of this study, we conclude that consumer-level 3D printers can produce surgical guides with a similar accuracy to a high-end, professional 3D printer with reduced costs.

ABSTRACT: Stereolithography (SLA) 3D printing technology is increasingly applied in geomechanics, petroleum engineering, geothermal, and CO2 storage research, particularly in fracture flow and mechanics. To understand the mechanical characteristics of 3D printed materials, we conducted laboratory experiments examining the effect of printing orientation on the properties of three specimens. These specimens were printed using a FormLabs (3B+) 3D printer at layering angles of 0°, 45°, and 90°, with a resolution of 100μm, and sized 1-inch in diameter and 2-inches in length. We performed triaxial compressive tests, ultrasonic elastic wave velocity measurements, and unconfined compressive strength (UCS) tests using an Autolab 1500 test frame. Incremental confining pressures from 1 MPa to 20 MPa were applied to explore static and dynamic mechanical properties. The UCS tests showed that all samples exhibited ductile behavior with similar stiffness and yield strength across different layering angles, demonstrating a stiffness of approximately 4 GPa and compressional wave velocities between 2555-2580 m/s at zero confining pressure. The findings confirm the mechanical and acoustic consistency of the samples, supporting their suitability for advanced geomechanical applications. 1. INTRODUCTION Three-dimensional (3D) printing technology, also known as advanced manufacturing (AM), is a rapidly developing field that has revolutionized manufacturing processes across various industries including aerospace (Richter &amp; Lipson, 2011), automotive (Rahim &amp; Maidin, 2014), healthcare (Logan &amp; Duddy, 1998), petroleum engineering (Li et al., 2021), and geomechanics (Phillips et al., 2021). This technology uses computer-aided design (CAD) to create three-dimensional objects by adding material layer by layer using almost any type of material such as polymers, and ceramics. Thermoplastic urethane and metals can also be employed as raw material (Gopinathan &amp; Noh, 2018). There are several techniques involved in 3D printing, including Fused Deposition Modeling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), Digital Light Processing (DLP), Binder Jetting, and Material Jetting. Each technique has its advantages and disadvantages (Jandyal et al., 2022), and the choice of technique depends on the type of object being printed, the desired resolution, and the available materials. With the increasing popularity and availability of 3D printing technology, it is now relatively easy to create custom objects, prototypes, and even entire structures using 3D printing. Among the available techniques, SLA is known for producing high-resolution objects with smooth surfaces. SLA was first developed in the early 1980s by Kodama, 1981 and called Rapid Prototyping (RP).

Abstract3D printing is a fabrication method that has attracted worldwide attention in recent years, providing a convenient and economical method for the fabrication of 3D structures. With the development of this technology and the reduction of operating costs, the application of 3D printing is greatly expanded. This paper focuses on the application progress of 3D printing in the preparation of photocatalysts. Considering the advantage that photopolymerization‐based 3D printing technology can better control the structure and active component distribution of photocatalytic products, the realization possibility of one‐step digital light processing (DLP) printing photocatalyst products is particularly prospected. In addition, the latest research progress of photocatalytic materials and 3D printing technology is also summarized, and the problems that need to be broken through in the future development of DLP‐3D printing technology are discussed.

Nowadays, 3D printing technology is the national theme in Vietnam. Most countries have national strategies in research and development and widely apply 3D design and printing to all industries, organizations and people. 3D printing technology has been applied in many industries such as automotive, aviation, health, construction, electronics ... Almost all Digital Light Processing (DLP) 3D printing machine on ​​domestic market are imported from Chinese, Korean manufacturers ... with medium quality but high cost. The paper presents a study of application of selected design methods and tools of engineering design process to design DLP 3D printer driver with lower cost but equivalent quality with the other machine in series on the market that are imported from China.

As the importance of visual aids increases, textbooks are including more figures and images to help with students' understanding. These visual aids enable students to learn concepts more effectively by hearing and seeing them simultaneously. However, for students who are visually impaired (that is, blind or have low vision), reading and understanding a textbook poses challenges. Teachers of students who are visually impaired have difficulty teaching with textbooks because they are compelled to explain and describe the complex figures and content verbally. Even after being explained, the image or concept might still remain nebulous for the student. Therefore, to help both students and their teachers, instructional materials should be prepared with easy, cheap, and customizable methods such as three-dimensional (3D) printing. Instead of seeing and hearing, students can use their sense of touch to recognize the 3D tactile aids, which might improve their learning and memory processes. Recently, 3D printing technology has emerged as an exciting technological tool for creating sophisticated and custom-made objects with relatively low-cost materials (Melchels, Feijen, & Grijpma, 2010; Peltola, Melchels, Grijpma, & Kellomaki, 2008; Pham & Gault, 1998). 3D printing is the process of fabricating 3D objects by building up materials layer by layer with a specific layer thickness in the range of 100 to 400 micrometers (^m). The most important advantage of 3D printing is its ability to build new objects in a customized way. Thus, 3D printing can be a powerful tool to make tactile patterns or objects related to textbooks. Stangl et al. tried to make 3D-printed picture books for visually impaired children (Stangl, Kim, & Yeh, 2014). They transcribed the images of the classic book Goodnight Moon, by Margaret Wise Brown, by printing features with different plastic layers. However, this study presented only plane-based shapes and not complete 3D objects. In this research, we investigate how 3D printing technology could be utilized for instructional materials that allow visually impaired students to have full access to high-quality instruction in history class. Researchers from the 3D Printing Group of the Korea Institute of Science and Technology (KIST) provided the Seoul National School for the Blind with tactile instructional materials and resizable braille made by 3D printers as shown in Figure 1. The teacher provided side-by-side hands-on instruction to guide students in understanding the characteristics of the shapes and their meanings. Students also used their hands to independently explore the 3D materials, allowing them to appropriately feel the historical pictures, maps, or relics. This procedure reinforced delivery of the lecture immensely since it clarified potential misunderstanding of text descriptions. The resulting implication was that the 3D instructional materials were beneficial and more suitable to help visually impaired students successfully comprehend content taught in the classroom. METHODS Three different types of 3D printing methods were utilized: (1) fused deposition modeling (FDM); (2) three-dimensional printing (3DP); and (3) digital light processing (DLP). The 3D printing process involves multiple stages, as shown in Figure 2. All 3D printing techniques are based on the use of computer-aided design (CAD) information that describes the geometry and size of the objects to be printed. The CAD data is converted to an STL (STereoLithography) file format which has extensive triangular coordination of 3D surface geometry (Chen, Ng, & Wang, 1999). Once the file is in a printable format, the 3D model is sliced into a series of digital crosssectional layers of specific thickness. Then the designed structure is built through a layerby-layer fabrication process with each layer thickness being 100 |m. When the printing is completed, the last step involves post-treatment operations to the object to improve its softness, durability, and safety. …