scholarly journals Poly(HDDA)-Based Polymers for Microfabrication and Mechanobiology

MRS Advances ◽  
2017 ◽  
Vol 2 (24) ◽  
pp. 1315-1321 ◽  
Author(s):  
Daniela Espinosa-Hoyos ◽  
Huifeng Du ◽  
Nicholas X. Fang ◽  
Krystyn J. Van Vliet
Keyword(s):  
Polyethylene Glycol ◽  
Additive Manufacturing ◽  
Progenitor Cell ◽  
Materials Processing ◽  
Biological Applications ◽  
Post Processing ◽  
Mechanical Stiffness ◽  
Processing Times ◽  
Low Stiffness ◽  
Cell Material Interactions

ABSTRACTMaterials processing and additive manufacturing afford exciting opportunities in biomedical research, including the study of cell-material interactions. However, some of the most efficient materials for microfabrication are not wholly suitable for biological applications, require extensive post-processing or exhibit high mechanical stiffness that limits the range of applications. Conversely, materials exhibiting high cytocompatibility and low stiffness require long processing times with typically decreased spatial resolution of features. Here, we investigated the use of hexanediol diacrylate (HDDA), a classic and efficient polymer for stereolithography, for oligodendrocyte progenitor cell (OPC) culture. We developed composite HDDA-polyethylene glycol acrylate hydrogels that exhibited high biocompatibility, mechanical stiffness in the range of muscle tissue, and high printing efficiency at ∼5 μm resolution.

scholarly journals Laser peening: A tool for additive manufacturing post-processing

2018 ◽  
Vol 24 ◽  
pp. 67-75 ◽  
Author(s):  
Lloyd Hackel ◽  
Jon R. Rankin ◽  
Alexander Rubenchik ◽  
Wayne E. King ◽  
Manyalibo Matthews
Keyword(s):  
Additive Manufacturing ◽  
Laser Peening ◽  
Post Processing

Open Uniaxial Test Machine (OpenUTM): Part 1 — A Low-Cost Electrohydraulic Test Frame for Additive Manufacturing Part Qualification

2018 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Test Machine ◽  
Mechanical Stiffness ◽  
Uniaxial Test ◽  
Bill Of Materials ◽  
Test Frame ◽  
Force Displacement

A wide variety of scientific and engineering activities require the use of testing machines in order to acquire data regarding the response of materials subjected to mechanical loads. This is particularly applicable to the domain of Additive Manufacturing (AM), where mechanical qualification is essential. Such machinery should be capable of applying loads at required levels and exhibit high mechanical stiffness. Accurate force, displacement, and strain measurements are also required. As a consequence, such testing machines are typically very costly. In the present paper we introduce the Open Uniaxial Test Machine (OpenUTM) project, aimed at providing a low-cost (less than $2500.00) material testing hardware/software framework. This paper will focus on the engineering design and hardware aspects of the OpenUTM project, with particular attention paid to the use of an electrohydraulic actuator (EHA) to provide test loads. A full bill of materials and drawings package is provided, in order to enable the use of the OpenUTM framework by research groups with minimal machine tooling. We introduce several case studies demonstrating the successful use of the OpenUTM frame in AM research efforts, including the testing and characterization of AM polymers and ceramics. We conclude with discussion of the software aspects of the OpenUTM framework, which will be elaborated upon in a follow-up paper (part two). We also present a series of potential avenues towards the improvement of the OpenUTM frame in future hardware iterations.

scholarly journals FEASIBILITY STUDY OF MICRO-LATTICE STRUCTURES BY MULTIPHOTON LITHOGRAPHY

2019 ◽  
Vol 25 ◽  
pp. 83-88
Author(s):  
Markus Wimmer ◽  
Zoltan Major
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Constant Density ◽  
Lattice Structures ◽  
Post Processing ◽  
Constant Frequency ◽  
Layer Height ◽  
Lithography Process ◽  
Multiphoton Lithography ◽  
Laser Firing

The paper describes the possibilities of additive manufacturing with multiphoton lithography. The basis of this technology is that a laser beam (with a certain wavelength) is fired into the mixture of a monomer and a photo-initiator. When the energy of the laser is high enough, the latter acts as a catalyser for the polymerization of the monomer compound. This study focuses on the influences of certain parameters of the multiphoton lithography process. One of the important aspects is the choice of the solvent for the post processing. In sequence to the solvent problem, the influence of the layer height is examined. Furthermore the limits and possibilities of the setup in use are investigated. As an example the differences in fabrication with the laser firing with "constant frequency" and "constant density" were subject of this investigation. The second goal of the study was to compare three different structures consisting of periodically repeating elements, scaled in size and number of elements per side.

scholarly journals A Comprehensive 3D-Molded Bone Flap Protocol for Patient-Specific Cranioplasty

2021 ◽  
Author(s):  
Raphael Bertani ◽  
Caio Moreno Perret Novo ◽  
Pedro Henrique Freitas ◽  
Amanda Amorin Nunes ◽  
Thiago Nunes Palhares ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Selective Laser Sintering ◽  
Operating Time ◽  
Ct Scanning ◽  
Patient Specific ◽  
Manufacturing Cost ◽  
Post Processing ◽  
Cross Sectional ◽  
Cranial Defect

Abstract We present a detailed step-by-step approach for the low-cost production and surgical implantation of cranial prostheses, aimed at restoring aesthetics, cerebral protection, and facilitating neurological rehabilitation. This protocol uses combined scan computed tomography (CT) cross-sectional images, in DICOM format, along with a 3D printing (additive manufacturing) setup. The in-house developed software InVesalius®️ is an open-source tool for medical imaging manipulation. The protocol describes image acquisition (CT scanning) procedures, and image post-processing procedures such as image segmentation, surface/volume rendering, mesh generation of a 3D digital model of the cranial defect and the desired prostheses, and their preparation for use in 3D printers. Furthermore, the protocol describes a detailed powder bed fusion additive manufacturing process, known as Selective Laser Sintering (SLS), using Polyamide (PA12) as feedstock to produce a 3-piece customized printed set per patient. Each set consists of a “cranial defect printout” and a “testing prosthesis” to assemble parts for precision testing, and a cranial “prostheses mold” in 2 parts to allow for the intraoperative modeling of the final implant cast using the medical grade Poly(methyl methacrylate) (PMMA) in a time span of a few min. The entire 3D processing time, including modelling, design, production, post-processing and qualification, takes approximately 42 h. Modeling the PMMA flap with a critical thickness of 4 mm by means of Finite Element Method (FEM) assures mechanical and impact properties to be slightly weaker than the bone tissue around it, a safety design to prevent fracturing the skull after a possible subsequent episode of head injury. On a parallel track, the Protocol seeks to provide guidance in the context of equipment, manufacturing cost and troubleshooting. Customized 3D PMMA prostheses offers a reduced operating time, good biocompatibility, and great functional and aesthetic outcomes. Additionally, it offers greater than 15-fold cost advantage over the usage of other materials, including metallic parts produced by additive manufacturing.

scholarly journals Design and Validation of Integrated Clamping Interfaces for Post-Processing and Robotic Handling in Additive Manufacturing

2021 ◽  
Author(s):  
Julian Ferchow ◽  
Dominik Kälin ◽  
Gokula Englberger ◽  
Marcel Schlüssel ◽  
Christoph Klahn ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Machining Process ◽  
Post Processing ◽  
Maximum Displacement ◽  
Build Time ◽  
Clean Interface ◽  
Tool Accessibility ◽  
Form Deviation ◽  
Metallic Parts ◽  
Subtractive Machining

Abstract Additive manufacturing (AM), particularly laser-based powder bed fusion of metals (LPBF), enables the fabrication of complex and customized metallic parts. However, 20–40% of the total manufacturing costs are usually attributed to post-processing steps. To reduce the costs of extensive post-processing, the process chain for AM parts has to be automated. Accordingly, robotic gripping and handling processes, as well as an efficient clamping for subtractive machining of AM parts, are key challenges. This study introduces and validates integrated bolts acting as a handling and clamping interface of AM parts. The bolts are integrated into the part design and manufactured in the same LPBF process. The bolts can be easily removed after the machining process using a wrench. This feasibility study investigates different bolt elements. The experiments and simulations conducted in the study show that a force of 250 N resulted in a maximum displacement of 12.5 µm. The milling results of the LPBF parts reveal a maximum roughness value, Ra, of 1.42 µm, which is comparable to that of a standard clamping system. After the bolt removal, a maximum residual height of 0.067 mm remains. Two case studies are conducted to analyze the form deviation, the effect of bolts on build time and material volume and to demonstrate the application of the bolts. Thus, the major contribution of this study is the design and the validation of standardized interfaces for robotic handling and clamping of complex AM parts. The novelties are a simple and clean interface removal, less material consumption, less support structure required and finally an achievement of a five-side tool accessibility by combining the interfaces with a three-jaw chuck.

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