Achieving High Porosity in Scaffold Building Using Electrohydrodynamic Jetting 3D Printing

Fused deposit modeling (FDM) 3D printing technology cannot generate scaffolds with high porosity while maintaining good integrity, anatomical-surface detail, or high surface area-to-volume ratio (S/V). Solvent casting and particulate leaching (SCPL) technique generates scaffolds with high porosity and high S/V. However, it is challenging to generate complex-shaped scaffolds; and solvent, particle and residual water removal are time consuming. Here we report techniques surmounting these problems, successfully generating a highly porous scaffold with the anatomical-shape characteristics of a human femur by polylactic acid polymer (PLA) and PLA-hydroxyapatite (HA) casting and salt leaching. The mold is water soluble and is easily removable. By perfusing with ethanol, water, and dry air sequentially, the solvent, salt, and residual water were removed 20 fold faster than utilizing conventional methods. The porosities are uniform throughout the femoral shaped scaffold generated with PLA or PLA-HA. Both scaffolds demonstrated good biocompatibility with the pre-osteoblasts (MC3T3-E1) fully attaching to the scaffold within 8 h. The cells demonstrated high viability and proliferation throughout the entire time course. The HA-incorporated scaffolds demonstrated significantly higher compressive strength, modulus and osteoinductivity as evidenced by higher levels of alkaline-phosphatase activity and calcium deposition. When 3D printing a 3D model at 95% porosity or above, our technology preserves integrity and surface detail when compared with FDM-generated scaffolds. Our technology can also generate scaffolds with a 31 fold larger S/V than FDM. We have developed a technology that is a versatile tool in creating personalized, patient-specific bone graft scaffolds efficiently with high porosity, good scaffold integrity, high anatomical-shaped surface detail and large S/V.

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Emulsion Inks for 3D Printing of High Porosity Materials

Macromolecular Rapid Communications ◽

10.1002/marc.201600236 ◽

2016 ◽

Vol 37 (16) ◽

pp. 1369-1374 ◽

Cited By ~ 32

Author(s):

Nicholas A. Sears ◽

Prachi S. Dhavalikar ◽

Elizabeth M. Cosgriff-Hernandez

Keyword(s):

3D Printing ◽

High Porosity

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Fabrication and properties of a high porosity h-BN–SiO2 ceramics fabricated by stereolithography-based 3D printing

Materials Letters ◽

10.1016/j.matlet.2018.10.058 ◽

2019 ◽

Vol 236 ◽

pp. 144-147 ◽

Cited By ~ 12

Author(s):

Zhuo Tian ◽

Yuping Yang ◽

Yong Wang ◽

Haidong Wu ◽

Wei Liu ◽

...

Keyword(s):

3D Printing ◽

High Porosity

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Sintering and Microstructures of SUS 316L Powder Produced by 3D Printing Process

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0180 ◽

2017 ◽

Vol 62 (2) ◽

pp. 1215-1218 ◽

Cited By ~ 3

Author(s):

W.J. Kim ◽

H.-H. Nguyen ◽

H.Y. Kim ◽

M.-T. Nguyen ◽

H.S. Park ◽

...

Keyword(s):

Surface Roughness ◽

3D Printing ◽

Selective Laser Sintering ◽

High Porosity ◽

Ceramic Powders ◽

Spherical Type ◽

Spherical Powder ◽

Surface Part ◽

Metal Polymer ◽

Type Sample

AbstractSelective laser sintering (SLS) is a type of laminating sintering technique, using CO2laser with (metal, polymer, and ceramic) powders. In this result, the flake SUS 316L was used to achieve a high porous product, and compare to spherical type. After SLS, the porosity of flake-type sample with 34% was quite higher than that of the spherical-type one that had only 11%. The surface roughness of the flake SLS sample were also investigated in both inner and surface parts. The results show that the deviation of the roughness of the surface part is about 64.40μm, while that of the internal one was about 117.65μm, which presents the containing of high porosity in the uneven surfaces. With the process using spherical powder, the sample was quite dense, however, some initial particles still remained as a result of less energy received at the beneath of the processing layer.

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3D PRINTING OF SHORT CARBON FIBER COMPOSITES VIA FRONTAL POLYMERIZATIONMORTEZA ZIAEE

10.12783/asc36/35949 ◽

2021 ◽

Author(s):

MORTEZA ZIAEE ◽

MOSTAFA YOURDKHANI

Keyword(s):

Additive Manufacturing ◽

Carbon Fiber ◽

3D Printing ◽

Flexural Modulus ◽

Frontal Polymerization ◽

Carbon Fiber Composites ◽

High Porosity ◽

Short Carbon Fiber ◽

Thermoset Resin ◽

Short Carbon

Additive manufacturing (AM) of polymer composites is a growing field in academic and industrial research environment. Majority of research in this field is focused on thermoplastic-based composites, as manufacturing of thermoset composites requires long cure cycles that make the additive manufacturing process quite challenging. Even though thermoplastic composites are easier to print, the ultimate performance of composites is limited by low fiber volume fraction, relatively high porosity, and low mechanical performance of host polymers. Recently, a novel curing strategy based on frontal polymerization (FP) has been developed that enables 3D printing of high-quality thermoset polymers. In this approach, a monomer solution with a gel-like viscosity is in-situ cured following the extrusion from printing nozzle by a self-sustaining reaction front. In the present work, we use dicyclopentadiene as a thermoset resin that can be frontally polymerized to a high-performance solid polymer. We add short carbon fiber reinforcements (L ~74 μm) to resin to fabricate mechanically robust 3D composite structures. Our results show that incorporation of short fibers substantially improves the flexural strength and flexural modulus of 3D-printed composites by ~50 % and ~410 %, respectively, compared to traditionally molded neat samples. Optical microscopy from the crosssection of flexural samples reveals that no voids was formed within deposition lines.

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Polylactic acid as a suitable material for 3D printing of protective masks in times of COVID-19 pandemic

PeerJ ◽

10.7717/peerj.10259 ◽

2020 ◽

Vol 8 ◽

pp. e10259

Author(s):

Eva Vaňková ◽

Petra Kašparová ◽

Josef Khun ◽

Anna Machková ◽

Jaroslav Julák ◽

...

Keyword(s):

3D Printing ◽

Polylactic Acid ◽

Sodium Hypochlorite ◽

Mechanical Damage ◽

Human Adenovirus ◽

Test System ◽

Fused Deposition Modelling ◽

High Porosity ◽

Suitable Material ◽

Fused Deposition

A critical lack of personal protective equipment has occurred during the COVID-19 pandemic. Polylactic acid (PLA), a polyester made from renewable natural resources, can be exploited for 3D printing of protective face masks using the Fused Deposition Modelling technique. Since the possible high porosity of this material raised questions regarding its suitability for protection against viruses, we have investigated its microstructure using scanning electron microscopy and aerosol generator and photometer certified as the test system according to the standards EN 143 and EN 149. Moreover, the efficiency of decontaminating PLA surfaces by conventional chemical disinfectants including 96% ethanol, 70% isopropanol, and a commercial disinfectant containing 0.85% sodium hypochlorite has been determined. We confirmed that the structure of PLA protective masks is compact and can be considered a sufficient barrier protection against particles of a size corresponding to microorganisms including viruses. Complete decontamination of PLA surfaces from externally applied Staphylococcus epidermidis, Escherichia coli, Candida albicans and SARS-CoV-2 was achieved using all disinfectants tested, and human adenovirus was completely inactivated by sodium hypochlorite-containing disinfectant. Natural contamination of PLA masks worn by test persons was decontaminated easily and efficiently by ethanol. No disinfectant caused major changes to the PLA surface properties, and the pore size did not change despite severe mechanical damage of the surface. Therefore, PLA may be regarded as a suitable material for 3D printing of protective masks during the current or future pandemic crises.

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Antibacterial Drug-Release Polydimethylsiloxane Coating for 3D-Printing Dental Polymer: Surface Alterations and Antimicrobial Effects

Pharmaceuticals ◽

10.3390/ph13100304 ◽

2020 ◽

Vol 13 (10) ◽

pp. 304

Author(s):

Hang-Nga Mai ◽

Dong Choon Hyun ◽

Ju Hayng Park ◽

Do-Yeon Kim ◽

Sang Min Lee ◽

...

Keyword(s):

Antibacterial Activity ◽

3D Printing ◽

Culture Media ◽

Mesoporous Silica Nanoparticles ◽

Polymer Surface ◽

Surface Irregularity ◽

Antibacterial Drug ◽

High Porosity ◽

Coating Film ◽

Bacterial Colony

Polymers are the most commonly used material for three-dimensional (3D) printing in dentistry; however, the high porosity and water absorptiveness of the material adversely influence biofilm formation on the surface of the 3D-printed dental prostheses. This study evaluated the effects of a newly developed chlorhexidine (CHX)-loaded polydimethylsiloxane (PDMS)-based coating material on the surface microstructure, surface wettability and antibacterial activity of 3D-printing dental polymer. First, mesoporous silica nanoparticles (MSN) were used to encapsulate CHX, and the combination was added to PDMS to synthesize the antibacterial agent-releasing coating substance. Then, a thin coating film was formed on the 3D-printing polymer specimens using oxygen plasma and thermal treatment. The results show that using the coating substance significantly reduced the surface irregularity and increased the hydrophobicity of the specimens. Remarkably, the culture media containing coated specimens had a significantly lower number of bacterial colony formation units than the noncoated specimens, thereby indicating the effective antibacterial activity of the coating.

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Development of bioinks for 3D printing microporous, sintered calcium phosphate scaffolds

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-021-06569-9 ◽

2021 ◽

Vol 32 (8) ◽

Author(s):

Sergio A. Montelongo ◽

Gennifer Chiou ◽

Joo L. Ong ◽

Rena Bizios ◽

Teja Guda

Keyword(s):

Calcium Phosphate ◽

3D Printing ◽

Mechanical Strength ◽

Biomedical Applications ◽

Alternative Methods ◽

High Porosity ◽

Calcium Phosphate Ceramic ◽

3D Print ◽

Beta Tricalcium Phosphate ◽

Strength And Stiffness

AbstractBeta-tricalcium phosphate (β-TCP)-based bioinks were developed to support direct-ink 3D printing-based manufacturing of macroporous scaffolds. Binding of the gelatin:β-TCP ink compositions was optimized by adding carboxymethylcellulose (CMC) to maximize the β-TCP content while maintaining printability. Post-sintering, the gelatin:β-TCP:CMC inks resulted in uniform grain size, uniform shrinkage of the printed structure, and included microporosity within the ceramic. The mechanical properties of the inks improved with increasing β-TCP content. The gelatin:β-TCP:CMC ink (25:75 gelatin:β-TCP and 3% CMC) optimized for mechanical strength was used to 3D print several architectures of macroporous scaffolds by varying the print nozzle tip diameter and pore spacing during the 3D printing process (compressive strength of 13.1 ± 2.51 MPa and elastic modulus of 696 ± 108 MPa was achieved). The sintered, macroporous β-TCP scaffolds demonstrated both high porosity and pore size but retained mechanical strength and stiffness compared to macroporous, calcium phosphate ceramic scaffolds manufactured using alternative methods. The high interconnected porosity (45–60%) and fluid conductance (between 1.04 ×10−9 and 2.27 × 10−9 m4s/kg) of the β-TCP scaffolds tested, and the ability to finely tune the architecture using 3D printing, resulted in the development of novel bioink formulations and made available a versatile manufacturing process with broad applicability in producing substrates suitable for biomedical applications.

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Microscopy of porous ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154160 ◽

1989 ◽

Vol 47 ◽

pp. 438-439

Author(s):

H. M. Kerch ◽

R. A. Gerhardt

Keyword(s):

Porous Ceramics ◽

Specimen Preparation ◽

High Porosity ◽

Ion Milling ◽

Forming Process ◽

Preparation Methods ◽

Pore Texture ◽

Proper Design ◽

And Function ◽

Function Information

Highly porous ceramics are employed in a variety of engineering applications due to their unique mechanical, optical, and electrical characteristics. In order to achieve proper design and function, information about the pore structure must be obtained. Parameters of importance include pore size, pore volume, and size distribution, as well as pore texture and geometry. A quantitative determination of these features for high porosity materials by a microscopic technique is usually not done because artifacts introduced by either the sample preparation method or the image forming process of the microscope make interpretation difficult.Scanning electron microscopy for both fractured and polished surfaces has been utilized extensively for examining pore structures. However, there is uncertainty in distinguishing between topography and pores for the fractured specimen and sample pullout obscures the true morphology for samples that are polished. In addition, very small pores (nm range) cannot be resolved in the S.E.M. On the other hand, T.E.M. has better resolution but the specimen preparation methods involved such as powder dispersion, ion milling, and chemical etching may incur problems ranging from preferential widening of pores to partial or complete destruction of the pore network.

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