Support Removal on Thin-Walled Parts Produced by Laser Powder Bed Fusion.

Support removal is one of the thorny issues faced by laser powder bed fusion (LPBF). In particular, the efficient and safe removal of support structures from the thin-walled parts and obtaining high-quality surfaces still remains a challenge owing to their sensitivity to machining. An in-depth understanding of the material response behavior of LPBF thin-walled parts when removing support structures is necessary for overcoming this challenge.

Novel 3D printable PEEK-HA-MgSiO composite material for spine implants: biocompatibility and imaging compatibility assessments.

Purpose: To develop a novel 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (MgSiO) composite material with enhanced properties for potential use in tumour, osteoporosis and other spinal conditions. We aim to evaluate biocompatibility and imaging compatibility of the material.

Methods: Materials were prepared in three different compositions, namely composite A: 75 weight % PEEK, 20 weight % HA, 5 weight % MgSiO; composite B: 70 weight% PEEK, 25 weight % HA, 5 weight % MgSiO; and composite C: 65 weight % PEEK, 30 weight % HA, 5 weight % MgSiO.

Design and 3D printing of novel titanium spine rods with lower flexural modulus and stiffness profile with optimised imaging compatibility.

Purpose: To manufacture and test 3D printed novel design titanium spine rods with lower flexural modulus and stiffness compared to standard solid titanium rods for use in metastatic spine tumour surgery (MSTS) and osteoporosis.

Methods: Novel design titanium spine rods were designed and 3D printed. Three-point bending test was performed to assess mechanical performance of rods, while a French bender was used to assess intraoperative rod contourability.

Metallic 4D Printing of Laser Stimulation.

4D printing of metallic shape-morphing systems can be applied in many fields, including aerospace, smart manufacturing, naval equipment, and biomedical engineering. The existing forming materials for metallic 4D printing are still very limited except shape memory alloys. Herein, a 4D printing method to endow non-shape-memory metallic materials with active properties is presented, which could overcome the shape-forming limitation of traditional material processing technologies.

Gaussian curvature-driven direction of cell fate toward osteogenesis with triply periodic minimal surface scaffolds.

Leaf photosynthesis, coral mineralization, and trabecular bone growth depend on triply periodic minimal surfaces (TPMSs) with hyperboloidal structure on every surface point with varying Gaussian curvatures. However, translation of this structure into tissue-engineered bone grafts is challenging. This article reports the design and fabrication of high-resolution three-dimensional TPMS scaffolds embodying biomimicking hyperboloidal topography with different Gaussian curvatures, composed of body inherent β-tricalcium phosphate, by stereolithography-based three-dimensional printing and sintering.

A biomechanical evaluation on Cubic, Octet, and TPMS gyroid Ti6Al4V lattice structures fabricated by selective laser melting and the effects of their debris on human osteoblast-like cells.

Lattice structures are widely used in orthopedic implants due to their unique features, such as high strength-to-weight ratios and adjustable biomechanical properties. Based on the type of unit cell geometry, lattice structures may be classified into two types: strut-based structures and sheet-based structures. In this study, strut-based structures (Cubic & Octet) and sheet-based structure (triply periodic minimal surface (TPMS) gyroid) were investigated.

A comparative investigation on the mechanical properties and cytotoxicity of Cubic, Octet, and TPMS gyroid structures fabricated by selective laser melting of stainless steel 316L.

Metallic lattice structures can be fabricated by selective laser melting (SLM) with purposefully designed pores and controlled pore sizes that can bio mimic the natural bone, providing adequate mechanical and biological support for the patients. Strut-based structures, like Cubic, Octet; and sheet-based structures, like triply periodic minimal surface (TPMS) gyroid, have been studied extensively in the past. However, it lacks enough comparative study on the mechanical properties and cytotoxicity among these structures.

Evolution of materials for implants in metastatic spine disease till date - Have we found an ideal material?

"Metastatic Spine Disease" (MSD) often requires surgical intervention and instrumentation with spinal implants. Ti6Al4V is widely used in metastatic spine tumor surgery (MSTS) and is the current implant material of choice due to improved biocompatibility, mechanical properties, and compatibility with imaging modalities compared to stainless steel. However, it is still not the ideal implant material due to the following issues.

Metal-based additive manufacturing condition monitoring methods: From measurement to control.

Compared with other additive manufacturing processes, the metal-based additive manufacturing (MAM) can build higher precision and higher density parts, and have unique advantages in the applications to automotive, medical, and aerospace industries. However, the quality defects of builds, such as dimensional accuracy, layer morphology, mechanical and metallurgical defects, have been hindering the wide applications of MAM technologies. These decrease the repeatability and consistency of build quality.

Can Polyether Ether Ketone Dethrone Titanium as the Choice Implant Material for Metastatic Spine Tumor Surgery?

Instrumentation during metastatic spine tumor surgery (MSTS) provides stability to the spinal column in patients with pathologic fracture or iatrogenic instability produced while undergoing extensive decompression. Titanium is the current implant material of choice in MSTS. However, it hinders radiotherapy planning and generates artifacts, with magnetic resonance imaging and computed tomography scans used for postoperative evaluation of tumor recurrence and/or complications.

A study of Titanium and Magnesium particle-induced oxidative stress and toxicity to human osteoblasts.

Hybrid implants combine both Titanium (Ti) and Magnesium (Mg) are prevalent nowadays. The long-term implications of Ti and Mg implants within the human body are not yet fully understood. Many implant failure cases due to inflammation, allergic responses, and aspect loosening have been reported frequently.

Functions and applications of metallic and metallic oxide nanoparticles in orthopedic implants and scaffolds.

Bone defects and diseases are devastating, and can lead to severe functional deficits or even permanent disability. Nevertheless, orthopedic implants and scaffolds can facilitate the growth of incipient bone and help us to treat bone defects and diseases. Currently, a wide range of biomaterials with distinct biocompatibility, biodegradability, porosity, and mechanical strength is used in bone-related research.

Intelligent modeling and monitoring of micro-droplet profiles in 3D printing.

The inkjet 3D printing has been one of the most studied and applied additive manufacturing (AM) processes in electronic industry. In this AM process, the forming quality is greatly influenced by the micro-droplet deposition and substrate temperature. While most studies focus on the formation mechanism of droplets, there are few studies on the quantitative evaluation of the droplet surface profile and its qualitative correlation with temperature changes.

Fabrication of Ti + Mg composites by three-dimensional printing of porous Ti and subsequent pressureless infiltration of biodegradable Mg.

A semi-degradable Ti + Mg composite with superior compression and cytotoxicity properties have been successfully fabricated using ink jet 3D printing followed by capillary mediated pressureless infiltration technique targeting orthopaedic implant applications. The composite exhibited low modulus (~5.2 GPa) and high ultimate compressive strength (~418 MPa) properties matching that of the human cortical bone.

An effective dual-factor modified 3D-printed PCL scaffold for bone defect repair.

Numerous bioactive molecules produced in cells are involved in the process of bone formation. We consider that appropriate, simultaneous application of two types of bioactive molecules would accelerate the regeneration of tissues and organs. Therefore, we combined aspirin-loaded liposomes (Asp@Lipo) and bone forming peptide-1 (BFP-1) on three dimensional-printed polycaprolactone (PCL) scaffold and determined whether this system improved bone regeneration outcomes.

Experiments on the Ultrasonic Bonding Additive Manufacturing of Metallic Glass and Crystalline Metal Composite.

Ultrasonic vibrations were applied to weld Ni-based metallic glass ribbons with Al and Cu ribbons to manufacture high-performance metallic glass and crystalline metal composites with accumulating formation characteristics. The effects of ultrasonic vibration energy on the interfaces of the composite samples were studied. The ultrasonic vibrations enabled solid-state bonding of metallic glass and crystalline metals.

Taguchi's methods to optimize the properties and bioactivity of 3D printed polycaprolactone/mineral trioxide aggregate scaffold: Theoretical predictions and experimental validation.

Mineral trioxide aggregate (MTA) can provide bioactivity to poly-caprolactone (PCL), which is an inert polymer used to print scaffolds. However, testing all combinations of scaffold characteristics (e.g.

Electrohydrodynamic Jet 3D Printed Nerve Guide Conduits (NGCs) for Peripheral Nerve Injury Repair.

The prevalence of peripheral nerve injuries resulting in loss of motor function, sensory function, or both, is on the rise. Artificial Nerve Guide Conduits (NGCs) are considered an effective alternative treatment for autologous nerve grafts, which is the current gold-standard for treating peripheral nerve injuries. In this study, Polycaprolactone-based three-dimensional porous NGCs are fabricated using Electrohydrodynamic jet 3D printing (EHD-jetting) for the first time.

Computational Design and Optimization of Nerve Guidance Conduits for Improved Mechanical Properties and Permeability.

Nerve guidance conduits (NGCs) are tubular tissue engineering scaffolds used for nerve regeneration. The poor mechanical properties and porosity have always compromised their performances for guiding and supporting axonal growth. Therefore, in order to improve the properties of NGCs, the computational design approach was adopted to investigate the effects of different NGC structural features on their various properties, and finally, design an ideal NGC with mechanical properties matching human nerves and high porosity and permeability.

3D-Printed PCL/rGO Conductive Scaffolds for Peripheral Nerve Injury Repair.

The incidence of peripheral nerve injuries is on the rise and the current gold standard for treatment of such injuries is nerve autografting. Given the severe limitations of nerve autografts which include donor site morbidity and limited supply, neural guide conduits (NGCs) are considered as an effective alternative treatment. Conductivity is a desired property of an ideal NGC.

Triply Periodic Minimal Surfaces Sheet Scaffolds for Tissue Engineering Applications: An Optimization Approach toward Biomimetic Scaffold Design.

Biomimetic scaffold design is gaining attention in the field of tissue engineering lately. Recently, triply periodic minimal surfaces (TPMSs) have attracted the attention of tissue engineering scientists for fabrication of biomimetic porous scaffolds. TPMS scaffolds offer several advantages, which include a high surface area to volume ratio, less stress concentration, and increased permeability compared to the traditional lattice structures, thereby aiding in better cell adhesion, migration, and proliferation.

Pluronic F127 blended polycaprolactone scaffolds via e-jetting for esophageal tissue engineering.

Several attempts have been made to fabricate esophageal tissue engineering scaffolds. However, most of these scaffolds possess randomly oriented fibres and uncontrollable pore sizes. In order to mimic the native esophageal tissue structure, electro-hydrodynamic jetting (e-jetting) was used in this study to fabricate scaffolds with aligned fibres and controlled pore size.

In situ monitoring of selective laser melting using plume and spatter signatures by deep belief networks.

Critical quality issues such as high porosity, cracks, and delamination are common in current selective laser melting (SLM) manufactured components. This study provides a flexible and integrated method for in situ process monitoring and melted state recognition during the SLM process, and it is useful for process optimization to decrease part quality issues. The part qualities are captured by images obtained from an off-axis setup with a near-infrared (NIR) camera.