3D printer technology is one of the innovations brought by the industrial age. It has been in our lives for many years. It is rapidly developing and used in many sectors like aviation and defence ...industry. This miracle manufacturing method has been frequently preferred for medical applications in recent years. In this study, 3D printer technology is introduced, various method of 3D printing are mentioned and the use of this technology in biomedical applications is referred. The use of 3D printing in surgery, pharmaceutical industry, disease modelling, development of customized implants and prostheses, organ printing, vet medicine and tissue engineering applications have been explained and this new method compared with traditional methods that used in the biomedical field. In addition, this study includes future opportunities that are expected to become widespread and developed in the future.
Fused deposition modelling (FDM) in contrast to injection moulding was studied to investigate the effect of processing technique on the mechanical behaviour of virgin ABS. FDM parameters were further ...altered in terms of varying raster angle and gap to further explore the potential of this technique. Results show that an adequate selection of FDM parameters is able to reach mechanical properties comparable to those of injection moulded parts in both static and dynamic loading modes. Here, a negative raster gap proved to be most significant in enhancing mechanical behaviour. A raster angle layup of −45°/+45° proves to offer maximum tensile and impact strength, whereas highest flexural strength was recorded for a 0/90° scaffolding system. In contrast, a positive gap drastically reduces the performance. Dimensional analysis further show no significant alterations of dimensions are to be expected with varying raster angle and gap.
This review article includes a description of additive manufacturing from its advantages and opportunities for the construction sector, highlighting the definition of a design methodology for ...cementitious material mixes suitable for 3D printing and the properties required of them. Included among the materials analyzed are conventional ones based on Ordinary Portland Cement (OPC) and non-conventional ones, with alkali-activated materials (geopolymers) to the fore. In United States, Europe and Asia this technology has interesting construction projects, however, in Latin America, 3D printing is still in the experimental phase, so it can be considered as a technology that is in the process of being adopted. The results obtained in the development and research phase in different countries such as Mexico, Brazil, Chile, Colombia, Guatemala, Peru, among others, are promising and it is projected as an industrial reality in the near future. This paper presents the main challenges and opportunities in implementing additive manufacturing.
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•3D technology could be considered to solve the current housing deficit in countries.•Locally available materials, native clays and soils, can be used in 3D printing.•Supplementary cementitious materials (SCM) and geopolymers can also be used.•3D printing must be recognized as a construction method by the construction codes.
In the last decade, the use of new technologies in the reconstruction of body tissues has greatly developed. Utilising stem cell technology, nanotechnology and scaffolding design has created new ...opportunities in tissue regeneration. The use of accurate engineering design in the creation of scaffolds, including 3D printers, has been widely considered. Three-dimensional printers, especially high precision bio-printers, have opened up a new way in the design of 3D tissue engineering scaffolds. In this article, a review of the latest applications of this technology in this promising area has been addressed.
Photopolymerization is an effective method to covalently cross-link polymer chains that can be shaped into several biomedical products and devices. Additionally, polymerization reaction may induce a ...fluid–solid phase transformation under physiological conditions and is ideal for in vivo cross-linking of injectable polymers. The photoinitiator is a key ingredient able to absorb the energy at a specific light wavelength and create radicals that convert the liquid monomer solution into polymers. The combination of photopolymerizable polymers, containing appropriate photoinitiators, and effective curing based on dedicated light sources offers the possibility to implement photopolymerization technology in 3D bioprinting systems. Hence, cell-laden structures with high cell viability and proliferation, high accuracy in production, and good control of scaffold geometry can be biofabricated. In this review, we provide an overview of photopolymerization technology, focusing our efforts on natural polymers, the chemistry involved, and their combination with appropriate photoinitiators to be used within 3D bioprinting and manufacturing of biomedical devices. The reviewed articles showed the impact of different factors that influence the success of the photopolymerization process and the final properties of the cross-linked materials.
•MIPs and graphene tablets for drug extraction from biological fluids.•Microextraction by packed sorbent for bioanalytical applications.•Liquid-phase microextraction based on supported liquid ...membranes compatible with biological fluids.•High-performance materials as extractant phases.•3D printing in microextraction for bioanalytical applications.
Biological samples are usually complex matrices due to the presence of proteins, salts and a variety of organic compounds with chemical properties similar to those of the target analytes. Therefore, sample preparation is often mandatory in order to isolate the analytes from troublesome matrices before instrumental analysis. Because the number of samples in drug development, doping analysis, forensic science, toxicological analysis, and preclinical and clinical assays is steadily increasing, novel high throughput sample preparation approaches are calling for. The key factors in this development are the miniaturization and the automation of the sample preparation approaches so as to cope with most of the twelve principles of green chemistry. In this review, recent trends in sample preparation and novel strategies will be discussed in detail with particular focus on sorptive and liquid-phase microextraction in bioanalysis. The actual applicability of selective sorbents is also considered. Additionally, the role of 3D printing in microextraction for bioanalytical methods will be pinpointed.
Additive manufacturing (AM) is an attractive manufacturing technology in tooling applications. It provides unique opportunities to manufacture tools with complex shapes, containing inner channels for ...conformal cooling. In this investigation, H13, a widely used tool steel, was manufactured using a laser powder bed fusion method. Microstructure, tensile mechanical properties, hardness, and porosity of the AM H13 after stress relieve (SR), standard hardening and tempering (SR + HT), and hot isostatic pressing (SR + HIP + HT) were investigated. It was found that the microstructure of directly solidified colonies of prior austenite, which is typical for AM, disappeared after austenitizing at the hardening heat treatment. In specimens SR + HT and SR + HIP + HT, a microstructure similar to the conventional but finer was observed. Electron microscopy showed that SR and SR + HT specimens contained lack of fusion, and spherical gas porosity, which resulted in remarkable scatter in the observed elongation to break values. Application of HIP resulted in the highest strength values, higher than those observed for conventional H13 heat treated in the same way. The conclusion is that HIP promotes reduction of porosity and lack of fusion defects and can be efficiently used to improve the mechanical properties of AM H13 tool steel.
Purpose
– This study aims to quantify the ultimate tensile strength and the nominal strain at break (ɛf) of printed parts made from polylactic acid (PLA) with a Replicating Rapid prototyper (Rep-Rap) ...3D printer, by varying three important process parameters: layer thickness, infill orientation and the number of shell perimeters. Little information is currently available about mechanical properties of parts printed using open-source, low-cost 3D printers.
Design/methodology/approach
– A computer-aided design model of a tensile test specimen was created, conforming to the ASTM:D638. Experiments were designed, based on a central composite design. A set of 60 specimens, obtained from combinations of selected parameters, was printed on a Rep-Rap Prusa I3 in PLA. Testing was performed using a JJ Instruments – T5002-type tensile testing machine and the load was measured using a load cell of 1,100 N.
Findings
– This study investigated the main impact of each process parameter on mechanical properties and the effects of interactions. The use of a response surface methodology allowed the proposition of an empirical model which connects process parameters and mechanical properties. Even though results showed a high variability, additional ideas on how to understand the impact of process parameters are suggested in this paper.
Originality/value
– On the basis of experimental results, it is possible to obtain practical suggestions to set common process parameters in relation to mechanical properties. Experiments discussed in the present paper provide a variety of data and insight regarding the relationship among the main process parameters and the stiffness and strength of fused deposition modeling-printed parts made from PLA. In particular, this paper underlines the shortage in existing literature concerning the impact of process parameters on the elastic modulus and the strain to failure for the PLA. The experimental data produced show a good degree of compliance with analytical formulations and other data found in literature.
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•Bio-based inks comprising nanocellulose and pectin were assessed for 3D printing.•The shear-thinning properties of carboxylated cellulose nanofibrils were exploited.•The ability of ...low methoxy-pectin to be fast crosslinked with Ca2+ was valued.•The newly developed inks could be appealing as platforms for tissue engineering.
The assessment of several ink formulations for 3D printing based on two natural macromolecular compounds is presented. In the current research we have exploited the fast crosslinking potential of pectin and the remarkable shear-thinning properties of carboxylated cellulose nanofibrils, which is known to induce a desired viscoelastic behavior. Prior to 3D printing, the viscoelastic properties of the polysaccharide inks were evaluated by rheological measurements and injectability tests. The reliance of the printing parameters on the ink composition was established through one-dimensional lines printing, the base units of 3D-structures. The performance of the 3D-printed structures after ionic cross-linking was evaluated in terms of mechanical properties and rehydration behavior. MicroCT was also used to evaluate the morphology of the 3D-printed objects regarding the effect of pectin/nanocellulose ratio on the geometrical features of scaffolds. The proportionality between the two polymers proved to be the determining factor for the firmness and strength of the printed objects.
•A fault detection model can be built only using normal condition signals measured in the 3D printers.•The 1D convolutional generative adversarial encoder can build a deep feature space oriented to ...the detection task.•In comparison with the single sensor approach, fusing velocity and angle signals improve the fault detection rate.•An isolation forest-based or SVM-based discriminative function can be used to characterize the deep feature space.
Collecting data from mechanical systems in abnormal conditions is expensive and time consuming. Consequently, fault detection approaches based on classical supervised learning working with both normal and abnormal data are not applicable in some condition-based maintenance tasks. To address this problem, this paper proposes Fusing Convolutional Generative Adversarial Encoders (fCGAE) method to create fault detection models from only normal data. Firstly, to obtain an adequate deep feature space, encoder models based on 1D convolutional neural networks are created. Then, these encoders are optimized in an unsupervised way through Bidirectional Generative Adversarial Networks. Finally, the multi-channel features collected from the system are merged with One-Class Support Vector Machine. fCGAE is applied to fault detection in 3D printers, where experimental results in two fault detection cases show excellent generalization capabilities and better performance compared to peer methods.
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