3D Printed Liquid Crystal Polymer Thermosiphon for Heat Transfer under Vacuum

Traditional 3D printing usually uses professional software such as SolidWorks and Maya for modeling. However, applying the software mentioned above to customize 3D food printing patterns has the problems of a solid professional operation and high skill requirements. In response to this problem, a pattern drawing software applied to 3D food printing equipment was designed. The software uses image processing technology and C# programming language, based on Windows operating system and. NET Framework, combined with SQLite database technology to achieve product pattern drawing and model export functions. Among them, the automatic extraction of the enclosed area realized by the flood filling algorithm is the core function of product pattern drawing; the automatic acquisition of the contour of the connected graph recognized by the canny edge detection algorithm is the crucial step of the model derivation. The test results show that the software can quickly implement template import, pattern drawing, model export, and other operations, which improves the efficiency and ease of operation of pattern drawing in 3D food printing; The model file exported by the software can be directly used in the layered printing process of a 3D printer, which provides a direction for promoting the application of 3D printing technology in the food industry.

Orientation behavior and thermal conductivity of liquid crystal polymer composites based on Three-Dimensional printing

Research and implementation of a non-supporting 3D printing method based on 5-axis dynamic slice algorithm

Recent advancements in three dimensional (3D) printing technologies have transformed both industrial practices and everyday applications. In the biomedical domain, 3D bioprinting at the cellular and tissue levels has emerged as a promising approach with significant potential. Although machine learning (ML) has been successfully applied in various aspects of conventional 3D printing, including process optimization, dimensional accuracy analysis, defect detection, and material property prediction, its adoption in the context of 3D bioprinting remains limited. This review examines the current ML techniques used in traditional 3D printing and explores their potential contributions to the development of bioprinting technologies. Notably, existing studies have demonstrated up to a 25% improvement in dimensional accuracy and a 30% reduction in printing time when ML is applied to scaffold optimization. We argue that the integration of ML could significantly influence the future development of 3D bioprinting, opening new avenues for innovation in biomedical engineering.

Abstract. The article is dedicated to analyzing the evolution of additive technologies from their inception to the present state. Special attention is given to the development of 3D printing technologies in construction. The research covers the historical context of the emergence of additive technologies, an analysis of current trends, and prospects for further development. Examples of successful applications of innovative 3D printing technologies are provided, and the main advantages and challenges associated with their implementation in construction are identified. An analysis of the additive technologies market in construction is conducted, revealing a positive trend toward further growth across all types of additive technologies, driven by their innovative potential, increasing demand, and integration into the manufacturing processes of various industries across countries. The article proposes the main directions for the further development and implementation of additive technologies in the construction sector. Key factors that will stimulate the development of the 3D printing market, such as the need for continuous improvement of hardware and materials, the reduction in the cost and availability of 3D printers (which will encourage their adoption by small enterprises), and the diversification of the 3D printing technology’s application areas based on user needs, are highlighted. A correlation between the development of the 3D printing market and other industrial sectors is identified. A comparative analysis of capital investments using traditional construction methods versus 3D printing technology across countries confirms the conclusions regarding the increased efficiency and cost reduction of projects through additive technologies, which is particularly relevant in the context of rebuilding Ukraine's damaged infrastructure. The prospects for the development of 3D printing technology in the construction industry, both in Ukraine and globally, are examined. A promising additive technology in construction, known as robocasting or direct ink printing, is studied. This technology serves as an alternative for manufacturing products with complex geometries that are practically impossible to create using traditional construction methods. Based on the conducted research, recommendations are formulated for creating favorable conditions for the development of additive technologies in Ukraine through the development of regulatory frameworks, technology accessibility, and the need for skilled workforce training.

Chapter 40 - Liquid Crystal Polymer

Process control in 3D printing (also known formally as Additive Manufacturing - AM) has largely been absent even in production systems. Simultaneously, computer vision has become more accessible with open source libraries (e.g. OpenCV, used successfully for traversing the state of California in an autonomous vehicle to win a DARPA Grand Challenge). 3D printing is particularly well suited to be enhanced by computer vision as fabrication is layer wise and predictable assuming correct operation. Big Area Additive Manufacturing (BAAM) — operating at significantly larger scales than traditional 3D printing — stands to benefit given the higher throughput of material (hundreds of pounds per hour) and the associated high costs of errant fabrication. Furthermore, minimum feature sizes in BAAM, such as individual layers, are sufficiently large to be analyzed with standard photography. With computer vision, sophisticated algorithms can be applied to identify problems early in the process that are not normally manifest until after process completion. Subtle and latent defects can be remediated before the onset of permanent damage or at a minimum the process can be aborted to avoid significant material loss. Fourier analysis can provide a useful perspective of the spatial periodicity of the layers of exposed surfaces during fabrication and this spectral information can inform the process of surface roughness, delamination, and deposition consistency in a data efficient manner. The large layer thickness of BAAM allow for Fourier analysis to be performed with standard photography. This paper explores the implementation and advantages of a low cost computer vision system that leverages OpenCV libraries operating on a Raspberry Pi Linux computer with simple yet high resolution photography — driven by the hypothesis that quality and yield of open source BAAM hardware can be dramatically enhanced.

Liquid crystal elastomers with near-ambient temperature-responsiveness (NAT-LCEs) have been extensively studied for building biocompatible, low-power consumption devices and robotics. However, conventional manufacturing methods face limitations in programmability (e.g., molding) or low nematic order (e.g., DIW printing). Here, a hybrid cooling strategy is proposed for programmable three-dimensional (3D) printing of NAT-LCEs with enhanced nematic order, intricate shape forming, and morphing capability. By integrating a low-temperature nozzle and a cooling platform into a 3D printer, the resulting temperature field synergistically facilitates mesogen alignment during extrusion and disruption-free ultraviolet (UV) cross-linking. This method achieves a nematic order 3000% higher than NAT-LCEs fabricated using traditional room temperature 3D printing. Enabled by shifting of transition temperature during hybrid cooling printing, printed sheets spontaneously turn into 3D structures after release from the platform, exhibiting bidirectional deformation with heating and cooling. By adjusting the nozzle and plate temperatures, NAT-LCEs with graded properties can be fabricated for intricate shape morphing. A wristband system with enhanced heart rate monitoring is also developed based on 3D-printed NAT-LCE. Our method facilitates developments in soft robotics, biomedical devices, and wearable electronics.

Purpose3D printing technology has the characteristics of fast forming and low cost and can manufacture parts with complex structures. At present, it has been widely used in various manufacturing fields. However, traditional 3-axis printing has limitations of the support structure and step effect due to its low degree of freedom. The purpose of this paper is to propose a robotic 3D printing system that can realize support-free printing of parts with complex structures.Design/methodology/approachA robotic 3D printing system consisting of a 6-degrees of freedom robotic manipulator with a material extrusion system is proposed for multi-axis additive manufacturing applications. And the authors propose an approximation method for the extrusion value E based on the accumulated arc length of the already printed points, which is used to realize the synchronous movement between multiple systems. Compared with the traditional 3-axis printing system, the proposed robotic 3D printing system can provide greater flexibility when printing complex structures and even realize curved layer printing.FindingsTwo printing experiments show that compared with traditional 3D printing, a multi-axis 3D printing system saves 47% and 79% of materials, respectively, and the mechanical properties of curved layer printing using a multi-axis 3D printing system are also better than that of 3-axis printing.Originality/valueThis paper shows a simple and effective method to realize the synchronous movement between multiple systems so as to develop a robotic 3D printing system that can realize support-free printing and verifies the feasibility of the system through experiments.

Abstract: Bioprinting technology has emerged as a powerful tool for building tissue and organ structures for drug discovery and regenerative medicine applications. In general, bioprinting uses a computer-controlled three-dimensional (3D) printing device to accurately deposit cells and biomaterials into precise geometries with the goal of creating anatomically correct biological structures. While traditional 3D printing uses metals, plastics, and polymers as printing materials or "ink", bioprinting deals with living cells and biological matrix. Hence, there are significant challenges to make a transition from traditional 3D printing to bioprinting, and ultimately achieve functional outcomes in bioprinted tissues. Therefore, it is critical that there is new technology development and in-depth basic research in bioprinted tissues, such as developing novel biomaterials specifically for use in bioprinting and biofabrication techniques, understanding the cell–matrix remodeling for the desired mechanical properties, and functional outcomes, establishing proper vascular perfusion, etc. Currently, there is active research going on bioprinting technology and its potential as a future source for tissue implants. This review paper overviews the current state of the art in bioprinting technology and focuses on the outcomes of the bioprinted tissues and their potential applications in drug discovery and regenerative medicine. Current challenges and limitations are highlighted, and future directions for next-generation bioprinting technology are also presented. Keywords: 3D bioprinting, vascularization, tissue regeneration, 3D tissue model, biofabrication, regenerative medicine

The development in three-dimensional (3D) printing technology or additive manufacturing has provided a superior alternative to existing casting methods. However, the distortion and cracking due to residual stress and the direct measurement of the 3D printing process pose major challenges. Therefore, the finite element method (FEM) analysis was used to confirm changes in the variables having a major influence on the quality. The process of melting and solidification of the powder using a laser was simulated by constructing a thermal-structure two-way coupled analysis. The heat transfer and residual stress were confirmed to be produced by the laser heat input. Subsequently, the analysis model was verified by confirming that a phenomenon similar to the analysis occurred with the 3D printing specimen. Using this study, the residual stress and distortion are expected to be minimized while improving the production efficiency of 3D printing.

Untreated osteochondral defects will develop into osteoarthritis, affecting patients’ quality of life. Since articular cartilage and subchondral bone exhibit distinct biological characteristics, repairing osteochondral defects remains a major challenge. Previous studies have tried to fabricate multilayer scaffolds with traditional methods or 3D printing technology. However, the efficacy is unsatisfactory because of poor control over internal structures or a lack of integrity between adjacent layers, severely compromising repair outcomes. Therefore, there is a need for a biomimetic scaffold that can simultaneously boost osteochondral defect regeneration in both structure and function. Herein, an integrated bilayer scaffold with precisely controlled structures is successfully 3D-printed in one step via digital light processing (DLP) technology. The upper layer has both ‘lotus- and radial-’ distribution pores, and the bottom layer has ‘lotus-’ pores to guide and facilitate the migration of chondrocytes and bone marrow mesenchymal stem cells, respectively, to the defect area. Tuning pore sizes could modulate the mechanical properties of scaffolds easily. Results show that 3D-printed porous structures allow significantly more cells to infiltrate into the area of ‘lotus- and radial-’ distribution pores during cell migration assay, subcutaneous implantation, and in situ transplantation, which are essential for osteochondral repair. Transplantation of this 3D-printed bilayer scaffold exhibits a promising osteochondral repair effect in rabbits. Incorporation of Kartogenin into the upper layer of scaffolds further induces better cartilage formation. Combining small molecules/drugs and precisely size-controlled and layer-specific porous structure via DLP technology, this 3D-printed bilayer scaffold is expected to be a potential strategy for osteochondral regeneration.

The need to automate the construction process for civil infrastructures has been perpetually propelled by the reported number of detrimental site accidents, enormous time, and material wastages in the current labor-intensive approaches. Additive 3D printing applications in the construction sector could revolutionize the construction sites. The 3D printing technologies will be an eco-friendly variant and will relax the formwork requirement, giving wider build customizability when compared to the traditional construction methods. The notable advantages of 3D printing over conventional construction techniques include safer work ambiance, reduced cost and time for construction. The first objective of this research work is to identify the concrete mixture that is readily available for 3D printing and establish their material characteristics. This work serves up a model schema for researchers to look up and identify desired mixture properties for instantaneous concrete printing. In this study, ready-to-print fresh cementitious mixtures were characterized for printability and buildability based on their rheological and mechanical properties. Admixtures such as Silica fume and Superplasticizer were added to the ordinary Portland cement in different proportions to test and improve the yield stress and attain the desired viscosity for 3D printing. The other objective is to study the impacts of using different nozzle geometries in the printed constructs. In the additive 3D printing process, choosing the right nozzle geometry before printing is critical as it affects the surface finish as well as the mechanical properties of the constructs. This study utilizes point cloud data of the printed samples obtained from Structured Light System- a scanning technique to measure the contour deviation and surface roughness. The compression strength of the mixtures was determined to explore the mechanical properties, by conducting compression tests as per the ASTM standards. A comparative study on the compression strength of 3D printed constructs with precast was made to identify the impacts of nozzle geometry in the compression strength. To summarize, a concrete extrusion system has been built and the concrete flow properties that are desirable for instantaneous 3D printing have been identified. The rheological properties, printability, and buildability of all the identified concrete mixtures were evaluated and the best mixture proportions were advanced for printing constructs. The nozzle geometry study has established the impacts on the contour as well as the mechanical properties on the constructs, and hence urging the need to choose the right nozzle geometry before 3D printing.

Volumetric additive manufacturing is a novel 3D printing method to form parts in a single exposure, in contrast to traditional stereolithography 3D printing which builds parts layer-by-layer. Photopolymerizable resin is exposed with grayscale images from different angles over 360 degrees to deliver a 3D distribution of light energy which cures the resin to form the desired part. The exposure images are calculated using computed tomography (CT), the same principles which are used to convert X-ray images obtained during a computerized axial tomography (CAT) scan to reconstruct a 3D volume of the patient. A digital micromirror device is used to project the sequence of calculated exposure images into a cylindrical vial of resin as it is rotated thus exposing over 360 degrees. The polymerization kinetics of the resin, the alignment of the resin vial to the projected images, and the uniformity of the illumination field are all tightly coupled together and must all be understood and controlled to generate quality parts. Projecting a good image is challenging as the vial and resin are essentially a strong cylindrical lens located at the image plane, and the desired build space is not a plane but a volume. We perform an analysis of the cylindrical lensing on the image quality (and thus the print quality) and investigate methods to correct for the lensing. We demonstrate different methods to improve print quality and discuss the benefits and limitations of each technique.

A review of 4D printing: Materials, structures, and designs towards the printing of biomedical wearable devices