scholarly journals Directly Printed Hollow Connectors for Microfluidic Interconnection with UV-Assisted Coaxial 3D Printing

2020 ◽  
Vol 10 (10) ◽  
pp. 3384
Author(s):  
Qianwen Xu ◽  
Jeffery Lo ◽  
Shi-Wei Lee
Keyword(s):  
3D Printing ◽  
Sacrificial Layer ◽  
Gelation Time ◽  
Three Dimensional ◽  
Uv Curing ◽  
Channel Diameter ◽  
Uv Curable ◽  
Outer Flow ◽  
Coaxial Nozzle ◽  
Cure Time

Effective and reliable interconnections are crucial for microfluidics to connect with the macro world. Current microfluidic interfaces are still bulky, expensive, or with issues of clogging and material limitation. In this study, a novel ultraviolet (UV)-assisted coaxial three-dimensional (3D) printing approach was proposed to fabricate hollow microfluidic connectors with advantages of rapid prototyping, fixture-free, and materials compatible. An assembled coaxial nozzle was designed to enable co-flow extrusion, where the inner flow (water) served as the sacrificial layer and the outer flow (adhesive) was cured for shell formation. Furthermore, a converged UV-LED light source was attached to the coaxial nozzle for UV curing of adhesives. UV rheological characterizations were performed to study the UV curing kinematics, and the gelation time was employed to describe the state transition behaviors of UV curable adhesives used in the study. To explore requirements for successful hollow connectors direct printing, processing criteria such as co-flow regime and pre-cure time were investigated. The hollow connectors with an inner channel diameter of ~150 μ m and a height of 5 mm were successfully printed on polymethyl methacrylate (PMMA) and glass substrate. The integration feasibility of the proposed method was also demonstrated by the presented microfluidic device with printed hollow connectors.

scholarly journals Improving UV Curing in Organosolv Lignin-Containing Photopolymers for Stereolithography by Reduction and Acylation

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3473
Author(s):  
Jordan T. Sutton ◽  
Kalavathy Rajan ◽  
David P. Harper ◽  
Stephen C. Chmely
Keyword(s):  
Thermal Stability ◽  
3D Printing ◽  
Uv Curing ◽  
Uv Curable ◽  
Commercial Use ◽  
Organosolv Lignin ◽  
Resin Formulation ◽  
Modified Lignin ◽  
Unmodified Sample ◽  
Acylation Reactions

Despite recent successes in incorporating lignin into photoactive resins, lignin photo-properties can be detrimental to its application in UV-curable photopolymers, especially in specialized engineered resins for use in stereolithography printing. We report on chemical modification techniques employed to reduce UV absorption by lignin and the resulting mechanical, thermal, and cure properties of these modified lignin materials. Lignin was modified using reduction and acylation reactions and incorporated into a 3D printable resin formulation. UV–Vis absorption at the 3D printing range of 405 nm was reduced in all modified lignins compared to the unmodified sample by 25% to ≥ 60%. Resins made with the modified lignins showed an increase in stiffness and strength with lower thermal stability. Studying these techniques is an important step in developing lignin for use in UV-curing applications and further the effort to valorize lignin towards commercial use.

scholarly journals A Cohesive Zone Model for the Stamping Process Encountered During Three-Dimensional Printing of Fiber-Reinforced Soft Composites

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Clayson C. Spackman ◽  
James F. Nowak ◽  
Kristen L. Mills ◽  
Johnson Samuel
Keyword(s):  
3D Printing ◽  
Polymer Matrix ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Three Dimensional ◽  
Zone Model ◽  
Fiber Reinforced ◽  
Uv Curable ◽  
Stamping Process ◽  
Dimensional Printing

Fiber-reinforced soft composites (FrSCs) are seeing increasing use in applications involving soft actuators, four-dimensional printing, biomimetic composites, and embedded sensing. The three-dimensional (3D) printing of FrSCs is a layer-by-layer material deposition process that alternates between inkjet deposition of an ultraviolet (UV) curable polymer layer and the stamping of electrospun fibers onto the layer, to build the final part. While this process has been proven for complex 3D geometries, it suffers from poor fiber transfer efficiencies (FTEs) that affect the eventual fiber content in the printed part. In order to address this issue, it is critical to first understand the mechanics of the fiber transfer process. To this end, the objective of this paper is to develop a cohesive zone-based finite element model that captures the competition between the “fiber–carrier substrate” adhesion and the “fiber–polymer matrix” adhesion, encountered during the stamping process used for 3D printing FrSCs. The cohesive zone model (CZM) parameters are first calibrated using independent microscale fiber peeling experiments involving both the thin-film aluminum carrier substrate and the UV curable polymer matrix. The predictions of the calibrated model are then validated using fiber transfer experiments. The model parametric studies suggest the use of a roller-based stamping unit design to improve the FTE of the FrSC 3D printing process. Preliminary experiments confirm that for a 0.5 in diameter roller, this new design can increase the FTE to ∼97%, which is a substantial increase from the 55% efficiency value seen for the original flat-plate stamping platen design. The model has broader applications for the transfer-printing of soft material constructs at the submicron scale.

scholarly journals Efficacy evaluation of three-dimensional printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Yuan-Wei Zhang ◽  
Xin Xiao ◽  
Wen-Cheng Gao ◽  
Yan Xiao ◽  
Su-Li Zhang ◽  
...  
Keyword(s):  
3D Printing ◽  
Blood Loss ◽  
Three Dimensional ◽  
Operation Time ◽  
Varus Deformity ◽  
Conventional Group ◽  
Intraoperative Blood Loss ◽  
Cubitus Varus ◽  
Guide Plate ◽  
Significant Difference

Abstract Background This present study is aimed to retrospectively assess the efficacy of three-dimensional (3D) printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity. Material and methods Twenty-five patients (15 males and 10 females) with the cubitus varus deformity from June 2014 to December 2017 were included in this study and were enrolled into the conventional group (n = 11) and 3D printing group (n = 14) according to the different surgical approaches. The operation time, intraoperative blood loss, osteotomy degrees, osteotomy end union time, and postoperative complications between the two groups were observed and recorded. Results Compared with the conventional group, the 3D printing group has the advantages of shorter operation time, less intraoperative blood loss, higher rate of excellent correction, and higher rate of the parents’ excellent satisfaction with appearance after deformity correction (P < 0.001, P < 0.001, P = 0.019, P = 0.023). Nevertheless, no significant difference was presented in postoperative carrying angle of the deformed side and total complication rate between the two groups (P = 0.626, P = 0.371). Conclusions The operation assisted by 3D printing osteotomy guide plate to correct the adolescent cubitus varus deformity is feasible and effective, which might be an optional approach to promote the accurate osteotomy and optimize the efficacy.

scholarly journals Three-dimensional(3D) printing in forensic science–An emerging technology in India

2021 ◽  
Vol 1 ◽  
pp. 100006
Author(s):  
Gargi Jani ◽  
Abraham Johnson ◽  
Jeidson Marques ◽  
Ademir Franco
Keyword(s):  
3D Printing ◽  
Forensic Science ◽  
Three Dimensional ◽  
Emerging Technology

scholarly journals Efficient 3D printing via photooxidation of ketocoumarin based photopolymerization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoyu Zhao ◽  
Ye Zhao ◽  
Ming-De Li ◽  
Zhong’an Li ◽  
Haiyan Peng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Visible Light ◽  
Light Exposure ◽  
Three Dimensional ◽  
3D Printer ◽  
Light Penetration ◽  
Viable Solution

AbstractPhotopolymerization-based three-dimensional (3D) printing can enable customized manufacturing that is difficult to achieve through other traditional means. Nevertheless, it remains challenging to achieve efficient 3D printing due to the compromise between print speed and resolution. Herein, we report an efficient 3D printing approach based on the photooxidation of ketocoumarin that functions as the photosensitizer during photopolymerization, which can simultaneously deliver high print speed (5.1 cm h−1) and high print resolution (23 μm) on a common 3D printer. Mechanistically, the initiating radical and deethylated ketocoumarin are both generated upon visible light exposure, with the former giving rise to rapid photopolymerization and high print speed while the latter ensuring high print resolution by confining the light penetration. By comparison, the printed feature is hard to identify when the ketocoumarin encounters photoreduction due to the increased lateral photopolymerization. The proposed approach here provides a viable solution towards efficient additive manufacturing by controlling the photoreaction of photosensitizers during photopolymerization.

scholarly journals 3D Printing of High Viscosity Reinforced Silicone Elastomers

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2239
Author(s):  
Nicholas Rodriguez ◽  
Samantha Ruelas ◽  
Jean-Baptiste Forien ◽  
Nikola Dudukovic ◽  
Josh DeOtte ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
New Technologies ◽  
Three Dimensional ◽  
High Viscosity ◽  
Layer By Layer ◽  
Silicone Elastomers ◽  
Uv Curable ◽  
Octet Truss ◽  
Tunable Mechanical Properties

Recent advances in additive manufacturing, specifically direct ink writing (DIW) and ink-jetting, have enabled the production of elastomeric silicone parts with deterministic control over the structure, shape, and mechanical properties. These new technologies offer rapid prototyping advantages and find applications in various fields, including biomedical devices, prosthetics, metamaterials, and soft robotics. Stereolithography (SLA) is a complementary approach with the ability to print with finer features and potentially higher throughput. However, all high-performance silicone elastomers are composites of polysiloxane networks reinforced with particulate filler, and consequently, silicone resins tend to have high viscosities (gel- or paste-like), which complicates or completely inhibits the layer-by-layer recoating process central to most SLA technologies. Herein, the design and build of a digital light projection SLA printer suitable for handling high-viscosity resins is demonstrated. Further, a series of UV-curable silicone resins with thiol-ene crosslinking and reinforced by a combination of fumed silica and MQ resins are also described. The resulting silicone elastomers are shown to have tunable mechanical properties, with 100–350% elongation and ultimate tensile strength from 1 to 2.5 MPa. Three-dimensional printed features of 0.4 mm were achieved, and complexity is demonstrated by octet-truss lattices that display negative stiffness.

scholarly journals Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3887
Author(s):  
Watcharapong Pudkon ◽  
Chavee Laomeephol ◽  
Siriporn Damrongsakkul ◽  
Sorada Kanokpanont ◽  
Juthamas Ratanavaraporn
Keyword(s):  
3D Printing ◽  
Silk Fibroin ◽  
Biomedical Applications ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
Structure Stability ◽  
3 Dimensional ◽  
Critical Technology ◽  
Box Structure ◽  
High Degree

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.

scholarly journals Noncontact restoration of missing parts of stone Buddha statue based on three-dimensional virtual modeling and assembly simulation

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Young Hoon Jo ◽  
Seonghyuk Hong ◽  
Seong Yeon Jo ◽  
Yoon Mi Kwon
Keyword(s):  
3D Printing ◽  
Reference Model ◽  
Three Dimensional ◽  
Contact Method ◽  
Cultural Artifacts ◽  
Analog Simulation ◽  
Remarkable Case ◽  
Interface Surface ◽  
Restoration Technique ◽  
Assembly Simulation

Abstract Three-dimensional (3D) digital technology is an essential conservation method that complements the traditional restoration technique of cultural artifacts. In this study, 3D scanning, virtual restoration modeling, and 3D printing were used as a noncontact approach for restoring a damaged stone-seated Bodhisattva (stone Buddha statue). First, a 3D model with an average point density of 0.2 mm was created by integrating the fixed high-precision scanning of the exterior and the handheld mid-precision scanning of the interior excavated hole. Using a 3D deterioration map of the stone Buddha statue, the area of the missing parts was measured to be 400.1 cm2 (5.5% of the total area). Moreover, 257.1 cm2 (64.2% of the missing part area) of four parts, including the head, surrounding area of the Baekho, right ear, and right eye, for which symmetry was applicable for modeling or there could be ascertainable historical evidence for the total missing parts, was selected for restoration. The virtual restoration of the missing parts of the stone Buddha statue was performed using a haptic modeling system in the following order. First, the location of the three fragments detached from the head was determined. Next, a reference model was selected, and its symmetrization and modification with respect to the original model were conducted. Further, estimation modeling and outer shape description were achieved through historical research and consultation with experts. The heuristic-based assembly suitability of the created virtual restoration model (461 cm3) was verified by design mockup printing and digital–analog simulation. In particular, to address assembly interference, the interface surface was modified and reprocessed several times. Accordingly, the volume of the final design mockup decreased by 5.2% (437 cm3). Photopolymerization 3D printing technology was used for the actual restoration of the stone Buddha statue, and considering the surface roughness, the layer thickness of the material used for restoration was set at 0.10 mm. Finally, the surface of the printed output was colored to prevent yellowing and joined to the missing parts of the stone Buddha statue. This study presents a remarkable case of shifting from the traditional manual-contact method to the contactless digital method for restoring artifacts and is expected to largely contribute to increasing the usability of digital technologies in the restoration of cultural artifacts.

scholarly journals An Overview on the Rheology, Mechanical Properties, Durability, 3D Printing, and Microstructural Performance of Nanomaterials in Cementitious Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2950
Author(s):  
Hongwei Song ◽  
Xinle Li
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Research Area ◽  
Cementitious Composites ◽  
Split Tensile Strength ◽  
Contour Crafting ◽  
Wide Range ◽  
Active Research

The most active research area is nanotechnology in cementitious composites, which has a wide range of applications and has achieved popularity over the last three decades. Nanoparticles (NPs) have emerged as possible materials to be used in the field of civil engineering. Previous research has concentrated on evaluating the effect of different NPs in cementitious materials to alter material characteristics. In order to provide a broad understanding of how nanomaterials (NMs) can be used, this paper critically evaluates previous research on the influence of rheology, mechanical properties, durability, 3D printing, and microstructural performance on cementitious materials. The flow properties of fresh cementitious composites can be measured using rheology and slump. Mechanical properties such as compressive, flexural, and split tensile strength reveal hardened properties. The necessary tests for determining a NM’s durability in concrete are shrinkage, pore structure and porosity, and permeability. The advent of modern 3D printing technologies is suitable for structural printing, such as contour crafting and binder jetting. Three-dimensional (3D) printing has opened up new avenues for the building and construction industry to become more digital. Regardless of the material science, a range of problems must be tackled, including developing smart cementitious composites suitable for 3D structural printing. According to the scanning electron microscopy results, the addition of NMs to cementitious materials results in a denser and improved microstructure with more hydration products. This paper provides valuable information and details about the rheology, mechanical properties, durability, 3D printing, and microstructural performance of cementitious materials with NMs and encourages further research.

scholarly journals Cloud Manufacturing, Internet of Things-Assisted Manufacturing and 3D Printing Technology: Reliable Tools for Sustainable Construction

2021 ◽  
Vol 13 (13) ◽  
pp. 7327
Author(s):  
Rajesh Singh ◽  
Anita Gehlot ◽  
Shaik Vaseem Akram ◽  
Lovi Raj Gupta ◽  
Manoj Kumar Jena ◽  
...  
Keyword(s):  
3D Printing ◽  
Internet Of Things ◽  
Materials Science ◽  
Predictive Analytics ◽  
Residential Buildings ◽  
Three Dimensional ◽  
Cloud Manufacturing ◽  
Service Evaluation ◽  
Sustainable Construction ◽  
Access Technology

The United Nations (UN) 2030 agenda on sustainable development goals (SDGs) encourages us to implement sustainable infrastructure and services for confronting challenges such as large energy consumption, solid waste generation, depletion of water resources and emission of greenhouse gases in the construction industry. Therefore, to overcome challenges and establishing sustainable construction, there is a requirement to integrate information technology with innovative manufacturing processes and materials science. Moreover, the wide implementation of three-dimensional printing (3DP) technology in constructing monuments, artistic objects, and residential buildings has gained attention. The integration of the Internet of Things (IoT), cloud manufacturing (CM), and 3DP allows us to digitalize the construction for providing reliable and digitalized features to the users. In this review article, we discuss the opportunities and challenges of implementing the IoT, CM, and 3D printing (3DP) technologies in building constructions for achieving sustainability. The recent convergence research of cloud development and 3D printing (3DP) are being explored in the article by categorizing them into multiple sections including 3D printing resource access technology, 3D printing cloud platform (3D–PCP) service architectures, 3D printing service optimized configuration technology, 3D printing service evaluation technology, and 3D service control and monitoring technology. This paper also examines and analyzes the limitations of existing research and, moreover, the article provides key recommendations such as automation with robotics, predictive analytics in 3DP, eco-friendly 3DP, and 5G technology-based IoT-based CM for future enhancements.

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