Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

3D printing, more formally known as Additive Manufacturing (AM), is already being adopted for rapid prototyping and soon rapid manufacturing. This review provides a brief discussion about AM and also the most employed AM technologies for polymers. The commonly-used ASTM and ISO mechanical test standards which have been used by various research groups to test the strength of the 3D-printed parts have been reported. Also, a summary of an exhaustive amount of literature regarding the mechanical properties of 3D-printed parts is included, specifically, properties under different loading types such as tensile, bending, compressive, fatigue, impact and others. Properties at low temperatures have also been discussed. Further, the effects of fillers as well as post-processing on the mechanical properties have also been discussed. Lastly, several important questions to consider in the standardization of mechanical test methods have been raised.

Mechanical characterization of 3D-printed polymers

The success of an implant depends on the type of biomaterial used for its fabrication. An ideal implant material should be biocompatible, inert, mechanically durable, and easily moldable. The ability to build patient specific implants incorporated with bioactive drugs, cells, and proteins has made 3D printing technology revolutionary in medical and pharmaceutical fields. A vast variety of biomaterials are currently being used in medical 3D printing, including metals, ceramics, polymers, and composites. With continuous research and progress in biomaterials used in 3D printing, there has been a rapid growth in applications of 3D printing in manufacturing customized implants, prostheses, drug delivery devices, and 3D scaffolds for tissue engineering and regenerative medicine. The current review focuses on the novel biomaterials used in variety of 3D printing technologies for clinical applications. Most common types of medical 3D printing technologies, including fused deposition modeling, extrusion based bioprinting, inkjet, and polyjet printing techniques, their clinical applications, different types of biomaterials currently used by researchers, and key limitations are discussed in detail.

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Novel Biomaterials Used in Medical 3D Printing Techniques.

Additive manufacturing, which is referred to as 3D printing, is a new developed process of fabricating metallic, ceramic, plastic and concrete materials. The goal of this article is to provide an overview of 3D printing processing methods and discuss their pros and cons. A comparison with other technologies such as injection molding and cutting-based machinery was discussed. Various modeling approaches and tools at all scale levels were depicted. We have presented a case study concerning the effect of pores formation in the mechanical properties of 3D printed polymer composites using FDM process. The mechanical behavior of 3D printed composites was determined using the homogenization technique based on the RVE notion. Recent uses of this technology in the area of electronics, aerospace and biomedical engineering were highlighted. Finally, important benefits and limitations were identified in order to clarify and motivate future works in this field.

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Additive manufacturing of polymer composites: Processing and modeling approaches

4D printing of shape memory polyurethane via stereolithography

Anisotropic damage inferred to 3D printed polymers using fused deposition modelling and subject to severe compression

The combination of experimental and numerical approaches is attempted to shed more light on 3D microstructural imperfections and mechanical performance of 3D printed acrylonitrile butadiene styrene parts. The starting point is the virtual building of airy structures using a reverse engineering approach. This approach combines microstructure generator, finite element model, and optimization strategy to propose virtual airy structures satisfying structural and mechanical criteria up to a desired porosity content of 60%. Optimal structures are printed using fused deposition modeling and X-ray microtomography is used to assess all microstructural defects. Compression testing is performed for load levels above 50% of reduction in sample height. The main outcome of this work is the demonstration of small amount of process induced porosity inducing high pore connectivity. The interdependence of process induced and desired porosity reveals genuine microstructural effects that are only characteristics of 3D printed materials.

Explaining the Difference Between Real Part and Virtual Design of 3D Printed Porous Polymer at the Microstructural Level

Background: Blood is an essential fluid of the body. Safety of blood and blood products is of global concern in transfusion medicine especially as it concerns the transfusion of transmissible infections (TTIs). Objective : This study was aimed to established the prevalence of haemoparasites in voluntary blood donors at Livingspring Hospital, Igbogbo, Lagos State. Methods: A cross-sectional study with a quantitative approach carried out on all voluntary blood donors during lockdown, 2020. Blood samples were collected from 100 donors into EDTA containers with age range 18-50 years. Donors were made up of 75 males and 25 females. Samples were processed using Giemsa techniques and were examined microscopically for haemoparasites. Descriptive and inferential analysis were carried out at p <0.05 significance level with 95% confidence interval. Results: The overall prevalence of haemoparasites among donors was established at the rate of 35% (35/100). Of the 100 donors, 35% were positive haemoparasites, of which 33% of the donors were positive for Plasmodium falciparum while 2% were positive for Loa loa . However, findings were statistically not significant ( p <0.05). Conclusion: It is imperative to screen blood samples to ensure safety of complete patient healthcare and service delivery.

Omar Ben Hassana

Papers

Anisotropic damage inferred to 3D printed polymers using fused deposition modelling and subject to severe compression

Explaining the Difference Between Real Part and Virtual Design of 3D Printed Porous Polymer at the Microstructural Level

Prevalence of Haemoparasites among Blood Donors in Livingspring Hospital, Igbogbo, Ikorodu, Lagos