scholarly journals Printability of 3D Printed Hydrogel Scaffolds: Influence of Hydrogel Composition and Printing Parameters

2019 ◽  
Vol 10 (1) ◽  
pp. 292 ◽  
Author(s):  
Saman Naghieh ◽  
MD Sarker ◽  
N. K. Sharma ◽  
Zohra Barhoumi ◽  
Xiongbiao Chen
Keyword(s):  
Flow Behavior ◽  
Three Dimensional ◽  
Methyl Cellulose ◽  
Alginate Hydrogel ◽  
Hydrogel Scaffolds ◽  
Number Of Factors ◽  
3D Printed ◽  
The Difference ◽  
Printing Processes ◽  
Printing Parameters

Extrusion-based bioprinting of hydrogel scaffolds is challenging due to printing-related issues, such as the lack of capability to precisely print or deposit hydrogels onto three-dimensional (3D) scaffolds as designed. Printability is an index to measure the difference between the designed and fabricated scaffold in the printing process, which, however, is still under-explored. While studies have been reported on printing hydrogel scaffolds from one or more hydrogels, there is limited knowledge on the printability of hydrogels and their printing processes. This paper presented our study on the printability of 3D printed hydrogel scaffolds, with a focus on identifying the influence of hydrogel composition and printing parameters/conditions on printability. Using the hydrogels synthesized from pure alginate or alginate with gelatin and methyl-cellulose, we examined their flow behavior and mechanical properties, as well as their influence on printability. To characterize the printability, we examined the pore size, strand diameter, and other dimensions of the printed scaffolds. We then evaluated the printability in terms of pore/strand/angular/printability and irregularity. Our results revealed that the printability could be affected by a number of factors and among them, the most important were those related to the hydrogel composition and printing parameters. This study also presented a framework to evaluate alginate hydrogel printability in a systematic manner, which can be adopted and used in the studies of other hydrogels for bioprinting.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

scholarly journals Crystallization and Hardness Change of the Ti-Based Bulk Metallic Glass Manufactured by a Laser Powder Bed Fusion Process

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1049
Author(s):  
Ji-Hoon Jang ◽  
Hyung-Guin Kim ◽  
Hwi-Jun Kim ◽  
Dong-Geun Lee
Keyword(s):  
Energy Density ◽  
Amorphous Powder ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Scan Speed ◽  
3D Printed ◽  
Hardness Change ◽  
The Difference ◽  
Printing Processes

Ti-2.5Zr-5.0Hf-37.5Cu-7.5Ni-1.0Si-5.0Sn (at.%) BMG has been successfully manufactured in amorphous powder with a size of about 25 μm (D50). Using this amorphous powder, a Ti-based BMG was manufactured by an additive manufacturing process based on a laser powder bed fusion (LPBF) technique. In 3D printing processes using amorphous powders, it is necessary and important to understand the crystallization behavior due to the difference in energy density applied to the powders. An LPBF process has been carried out with various energy density conditions to minimize the inner defects and identify the sound mechanical properties of 3D-printed BMG parts. At the lowest energy density condition (3.0 J/mm3), the most pores were generated. Even if the same energy density (3.0 J/mm3) was applied, the rapid laser movement caused many pores to form inside the material. The relatively sound 3D-printed Ti-based BMG was successfully fabricated with a size of about 5 mm × 5 mm × 3 mm. Peaks at 41° and 44° showing crystallization were observed in all conditions. The higher the laser power was, the greater each peak intensity and the more crystallization (CuTi, Ti3Cu4, etc.) was present in the BMG, and the higher the scan speed, the more the internal defects were found.

scholarly journals 3D Printed Gelatin/Sodium Alginate Hydrogel Scaffolds Doped with Nano-Attapulgite for Bone Tissue Repair

2021 ◽  
Vol Volume 16 ◽  
pp. 8417-8432
Author(s):  
Chun Liu ◽  
Wen Qin ◽  
Yan Wang ◽  
Jiayi Ma ◽  
Jun Liu ◽  
...  
Keyword(s):  
Bone Tissue ◽  
Sodium Alginate ◽  
Tissue Repair ◽  
Alginate Hydrogel ◽  
Hydrogel Scaffolds ◽  
3D Printed

scholarly journals Multi-casting approach for vascular networks in cellularized hydrogels

2016 ◽  
Vol 13 (125) ◽  
pp. 20160768 ◽  
Author(s):  
Alexander W. Justin ◽  
Roger A. Brooks ◽  
Athina E. Markaki
Keyword(s):  
Three Dimensional ◽  
Cell Seeding ◽  
Vascular Networks ◽  
Alginate Hydrogel ◽  
Channel Network ◽  
Thermoplastic Material ◽  
Cell Staining ◽  
Complex Architectures ◽  
Immuno Histochemistry ◽  
3D Printed

Vascularization is essential for living tissue and remains a major challenge in the field of tissue engineering. A lack of a perfusable channel network within a large and densely populated tissue engineered construct leads to necrotic core formation, preventing fabrication of functional tissues and organs. We report a new method for producing a hierarchical, three-dimensional (3D) and perfusable vasculature in a large, cellularized fibrin hydrogel. Bifurcating channels, varying in size from 1 mm to 200–250 µm, are formed using a novel process in which we convert a 3D printed thermoplastic material into a gelatin network template, by way of an intermediate alginate hydrogel. This enables a CAD-based model design, which is highly customizable, reproducible, and which can yield highly complex architectures, to be made into a removable material, which can be used in cellular environments. Our approach yields constructs with a uniform and high density of cells in the bulk, made from bioactive collagen and fibrin hydrogels. Using standard cell staining and immuno-histochemistry techniques, we showed good cell seeding and the presence of tight junctions between channel endothelial cells, and high cell viability and cell spreading in the bulk hydrogel.

scholarly journals The potential of the incorporated collagen microspheres in alginate hydrogel as an engineered three-dimensional microenvironment to attenuate apoptosis in human pancreatic islets

2020 ◽  
Author(s):  
Maryam Kaviani ◽  
Somayeh Keshtkar ◽  
Fatemeh Sabet Sarvestani ◽  
Negar Azarpira ◽  
Ramin Yaghobi ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Caspase 3 ◽  
Three Dimensional ◽  
Alginate Hydrogel ◽  
Human Pancreatic Islets ◽  
Hydrogel Scaffolds ◽  
Promising Tool ◽  
Extracellular Matrix Components ◽  
Peptide Secretion ◽  
Secretion Assay

Abstract Background: Tissue engineering is considered as a promising tool for remodeling the native cells microenvironment. In the present study, the effect of alginate hydrogel and collagen microspheres integrated with extracellular matrix components were evaluated in the decrement of apoptosis in human pancreatic islets. Methods: For three dimensional culture, the islets were encapsulated in collagen microspheres, containing laminin and collagen IV and embedded in alginate scaffold for one week. After that the islets were examined in terms of viability, apoptosis, genes and proteins expression including BAX, BCL2, active caspase-3, and insulin. Moreover, the islets function was evaluated through glucose-induced insulin and C-peptide secretion assay. In order to evaluate the structure of the scaffolds and the morphology of the pancreatic islets in three-dimensional microenvironments, we performed scanning electron microscopy. Results: Our findings showed that the designed hydrogel scaffolds significantly improved the islets viability using the reduction of activated caspase-3 and TUNEL positive cells. Conclusion: The reconstruction of the destructed matrix with alginate hydrogels and collagen microspheres might be an effective step to promote the culture of the islets.

Effect of tip clearance dimension on unsteadiness in a low-reaction aspirated transonic compressor rotor

2020 ◽  
Vol 234 (6) ◽  
pp. 1181-1194 ◽  
Author(s):  
Wei Zhu ◽  
Le Cai ◽  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Unsteady Flow ◽  
Vortex Breakdown ◽  
Numerical Study ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Axial Acceleration ◽  
The Difference

A three-dimensional, multi-passage unsteady numerical study was conducted to enhance the understanding of unsteady flow phenomena in the tip region of highly loaded compressors. The first-stage rotor of a three-stage transonic low-reaction compressor was chosen as the computational model. Three different tip clearance sizes were calculated to demonstrate the effect of the tip clearance dimension on the unsteadiness in the rotor tip region. It was found that the unsteadiness existed at the vicinity of the stall point when the tip clearance size was larger than the design value. The unsteadiness in the tip region appeared as a “multi-passage structure” in the nine-passage unsteady simulation and it propagated along the circumferential direction. Tip leakage vortex breakdown was the source of unsteady flow behavior. Besides, special attention was paid to the difference between the conventional transonic rotor and the low-reaction rotor. The scale of the flow separation downstream of the shock wave was controllable for the low-reaction rotor even at near-stall conditions. The boundary layer would reattach to the blade surface due to local axial acceleration. Finally, attempts were made to study the stall mechanism of the low-reaction rotor.

scholarly journals A Review on Kinetic Energy Harvesting with Focus on 3D Printed Electromagnetic Vibration Harvesters

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6961
Author(s):  
Philipp Gawron ◽  
Thomas M. Wendt ◽  
Lukas Stiglmeier ◽  
Nikolai Hangst ◽  
Urban B. Himmelsbach
Keyword(s):  
Energy Harvesting ◽  
Three Dimensional ◽  
Research Gaps ◽  
Three Dimensional Printing ◽  
Energy Harvesters ◽  
Electromagnetic Vibration ◽  
3D Printed ◽  
Iot Devices ◽  
Printing Processes ◽  
Dimensional Printing

The increasing amount of Internet of Things (IoT) devices and wearables require a reliable energy source. Energy harvesting can power these devices without changing batteries. Three-dimensional printing allows us to manufacture tailored harvesting devices in an easy and fast way. This paper presents the development of hybrid and non-hybrid 3D printed electromagnetic vibration energy harvesters. Various harvesting approaches, their utilised geometry, functional principle, power output and the applied printing processes are shown. The gathered harvesters are analysed, challenges examined and research gaps in the field identified. The advantages and challenges of 3D printing harvesters are discussed. Reported applications and strategies to improve the performance of printed harvesting devices are presented.

scholarly journals In Situ Controlled Surface Microstructure of 3D Printed Ti Alloy to Promote Its Osteointegration

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 815 ◽  
Author(s):  
Lijun Shan ◽  
Abdul Kadhum ◽  
M.S.H. Al-Furjan ◽  
Wenjian Weng ◽  
Youping Gong ◽  
...  
Keyword(s):  
3D Printing ◽  
Osteogenic Differentiation ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Ti Alloy ◽  
Differentiation Potential ◽  
Composite Surface ◽  
3D Printed ◽  
Printing Parameters

It is well known that three-dimensional (3D) printing is an emerging technology used to produce customized implants and surface characteristics of implants, strongly deciding their osseointegration ability. In this study, Ti alloy microspheres were printed under selected rational printing parameters in order to tailor the surface micro-characteristics of the printed implants during additive manufacturing by an in situ, controlled way. The laser path and hatching space were responsible for the appearance of the stripy structure (S), while the bulbous structure (B) and bulbous–stripy composite surface (BS) were determined by contour scanning. A nano-sized structure could be superposed by hydrothermal treatment. The cytocompatibility was evaluated by culturing Mouse calvaria-derived preosteoblastic cells (MC3T3-E1). The results showed that three typical microstructured surfaces, S, B, and BS, could be achieved by varying the 3D printing parameters. Moreover, the osteogenic differentiation potential of the S, B, and BS surfaces could be significantly enhanced, and the addition of nano-sized structures could be further improved. The BS surface with nano-sized structure demonstrated the optimum osteogenic differentiation potential. The present research demonstrated an in situ, controlled way to tailor and optimize the surface structures in micro-size during the 3D printing process for an implant with higher osseointegration ability.

THE APPLICATION OF WELD-BASED ADDITIVE MANUFACTURING STEEL TO STRUCTURAL ENGINEERING

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Vittoria Laghi ◽  
Michele Palermo ◽  
Giada Gasparini ◽  
Stefano Silvestri ◽  
Tomaso Trombetti
Keyword(s):  
Additive Manufacturing ◽  
Structural Engineering ◽  
Mechanical Characteristics ◽  
Manufacturing Processes ◽  
Building Structures ◽  
Welded Steel ◽  
3D Printed ◽  
Printing Processes ◽  
Suitable Technique ◽  
Printing Parameters

The present work aims at providing the first considerations upon the application of innovative manufacturing technology for civil engineering purposes. In particular, among the 3D printing processes currently available, Weld-Based Additive Manufacturing (WAM) results to be the most suitable technique for the realization of innovative structural forms in metal material. The great potential of taking the printing head "out of the box" allows for the construction of innovative shapes by adding layer upon layer of welded steel. In particular, the study is focused on the realization of the first 3D-printed steel footbridge by a Dutch company held in Amsterdam, called MX3D, and its Additive manufacturing process, which results in specific constraints and limitations to be taken into account for design purposes. First, the design issues are described, by considering the printing parameters to be adopted for the realization of large-dimensions structures, and then the implications in terms of specific geometrical and mechanical characteristics are studied. These first engineering evaluations are intended to pave the way towards the development of a ground-breaking technology for the fully-automated design and construction of novel 3D-printed building structures through innovative robotic manufacturing processes whose parameters are still not fully known

scholarly journals Surface Quality of 3D-Printed Models as a Function of Various Printing Parameters

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1970 ◽  
Author(s):  
Christin Arnold ◽  
Delf Monsees ◽  
Jeremias Hey ◽  
Ramona Schweyen
Keyword(s):  
Surface Roughness ◽  
Support Structures ◽  
Roughness Index ◽  
Data Record ◽  
3D Printed ◽  
The Mean ◽  
Printing Processes ◽  
Printing Parameters ◽  
Required Quality

Although 3D-printing is common in dentistry, the technique does not produce the required quality for all target applications. Resin type, printing resolution, positioning, alignment, target structure, and the type and number of support structures may influence the surface roughness of printed objects, and this study investigates the effects of these variables. A stereolithographic data record was generated from a master model. Twelve printing processes were executed with a stereolithography Desktop 3D Printer, including models aligned across and parallel to the printer front as well as solid and hollow models. Three layer thicknesses were used, and in half of all processes, the models were inclined at 15°. For comparison, eight gypsum models and milled polyurethane models were manufactured. The mean roughness index of each model was determined with a perthometer. Surface roughness values were approximately 0.65 µm (master), 0.87–4.44 µm (printed), 2.32–2.57 µm (milled), 1.72–1.86 µm (cast plaster/alginate casting), and 0.98–1.03 µm (cast plaster/polyether casting). The layer height and type and number of support structures influenced the surface roughness of printed models (p ≤ 0.05), but positioning, structure, and alignment did not.

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