Influence of surface engineering on 3D printed Ti lattice structure towards enhanced tissue integration: An in vitro and in vivo study

Reconstruction of segmental defects are popularly approached with surface engineered additively manufactured scaffolds owing to its enhanced post-surgery tissue integration properties. The present work is aimed at fabrication of Ti lattice structures using 3D printing, with a novel approach of silane chemistry-based surface modification of those Ti-surfaces with osteogenic peptides (OGP). The lattice structures with 0.6 mm strut-diameter having 0.5 mm inter-strut distance were chosen for fabrication using an extrusion-based 3D printing. Based on the evidence, it could be concluded that extrusion-based 3D printing is an optimal alternative as compared to those high cost incurring additive manufacturing processes. Therefore, OGP were grafted on the pristine Ti-surfaces using a silane chemistry based novel vapour deposition process. In vitro assessments of the surface modified scaffolds using human amniotic derived mesenchymal stem cells showed evidence of enhanced cell adhesion and viability. In vivo subcutaneous study in rat models of the surface modified Ti-scaffolds also showed enhanced tissue integration in terms of Collagen I deposition around the boundary of the tissue-integrated struts as compared to those of pristine scaffolds. The study has established that the novel surface modification technique is capable to engineer the Ti-surfaces towards enhanced tissue integration in vivo

3D Printed Silicone Meniscus Implants: Influence of the 3D Printing Process on Properties of Silicone Implants

Osteoarthritis of the knee with meniscal pathologies is a severe meniscal pathology suffered by the aging population worldwide. However, conventional meniscal substitutes are not 3D-printable and lack the customizability of 3D printed implants and are not mechanically robust enough for human implantation. Similarly, 3D printed hydrogel scaffolds suffer from drawbacks of being mechanically weak and as a result patients are unable to execute immediate post-surgical weight-bearing ambulation and rehabilitation. To solve this problem, we have developed a 3D silicone meniscus implant which is (1) cytocompatible, (2) resistant to cyclic loading and mechanically similar to native meniscus, and (3) directly 3D printable. The main focus of this study is to determine whether the purity, composition, structure, dimensions and mechanical properties of silicone implants are affected by the use of a custom-made in-house 3D-printer. We have used the phosphate buffer saline (PBS) absorption test, Fourier transform infrared (FTIR) spectroscopy, surface profilometry, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) to effectively assess and compare material properties between molded and 3D printed silicone samples

Advances in Tissue Engineering Approaches for Craniomaxillofacial Bone Reconstruction

Trauma, congenital abnormalities and pathologies such as cancer can cause significant defects in craniofacial bone. Regeneration of the bone in the craniofacial area presents a unique set of challenges due to its complexity and association with various other tissues. Bone grafts and bone cement are the traditional treatment options but pose their own issues with regards to integration and morbidity. This has driven the search for materials which mimic the natural bone and can act as scaffolds to guide bone growth. Novel technology and computer aided manufacturing have allowed us to control material parameters such as mechanical strength and pore geometry. In this chapter, we elaborate the current status of materials and techniques used in fabrication of scaffolds for craniomaxillofacial bone tissue engineering and discuss the future prospects for advancements

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

Integrated lab-on-chip technology for zebrafish embryo sorting and larvae immobilization for drug discovery

The major current hurdle to widespread deployment of zebrafish embryos and larvae in large-scale drug discovery is the problem of enabling analytical platforms with high throughput. In order to spearhead drug discovery using zebrafish as a model, platforms need to determine pre-test sorting of organisms to ensure quality control and standardisation, and determine that their in-test positioning is suitable for high-content imaging with modules for flexible drug delivery. Manual procedures for sorting hundreds of embryos are very monotonous and therefore liable to significant analytical errors caused by operators’ fatigue. In this thesis, we present an innovative proof-of-concept design for a micromechanical large-particle in-flow sorter. This thesis investigated infra-red sensor detection and image acquisition and compared them for their ability to distinguish between viable and dead embryos. High-definition additive manufacturing systems for fabrication of 3D printed moulds of the type used in soft lithography were also explored. 3D printing using SLA provides a rapid microfabrication of the moulds with high definition and optical transparency, as is confirmed by both scanning electron microscopy and confocal microscopy. SLA technologies may be applied for the rapid and accurate fabrication of millifluidic devices that can trap millimetre-sized specimens such as living zebrafish larvae. We applied this new manufacturing method in a proof-of-concept prototype device capable of trapping and immobilising living zebrafish larvae for the purpose of recording heart rate variations in cardio-toxicity experiments. Static conventional culture plates limit the throughput data, and is not suitable for modern compound library screening, while currently available conventional microtiter well plates require manual pipetting, which is labour intensive and time consuming. This research offers promising avenues for the development of a miniaturised, automated system for handling and manipulating zebrafish embryos and larvae, using innovative microfluidic lab-on-chip (LOC) technologies and additive manufacturing technologies

Process–Structure–Properties in Polymer Additive Manufacturing

Additive manufacturing (AM) methods have grown and evolved rapidly in recent years. AM for polymers is an exciting field and has great potential in transformative and translational research in many fields, such as biomedical, aerospace, and even electronics. Current methods for polymer AM include material extrusion, material jetting, vat polymerisation, and powder bed fusion. With the promise of more applications, detailed understanding of AM—from the processability of the feedstock to the relationship between the process–structure–properties of AM parts—has become more critical. More research work is needed in material development to widen the choice of materials for polymer additive manufacturing. Modelling and simulations of the process will allow the prediction of microstructures and mechanical properties of the fabricated parts while complementing the understanding of the physical phenomena that occurs during the AM processes. In this book, state-of-the-art reviews and current research are collated, which focus on the process–structure–properties relationships in polymer additive manufacturing

Characterization and Modelling of Composites, Volume II

Composites have been increasingly used in various structural components in the aerospace, marine, automotive, and wind energy sectors. Composites’ material characterization is a vital part of the product development and production process. Physical, mechanical, and chemical characterization helps developers to further their understanding of products and materials, thus ensuring quality control. Achieving an in-depth understanding and consequent improvement of the general performance of these materials, however, still requires complex material modeling and simulation tools, which are often multiscale and encompass multiphysics. This Special Issue is aimed at soliciting promising, recent developments in composite modeling, simulation, and characterization, in both design and manufacturing areas, including experimental as well as industrial-scale case studies. All submitted manuscripts will undergo a rigorous review and will only be considered for publication if they meet journal standards

Fibre-reinforced additive manufacturing: from design guidelines to advanced lattice structures

In pursuit of achieving ultimate lightweight designs with additive manufacturing (AM), engineers across industries are increasingly gravitating towards composites and architected cellular solids; more precisely, fibre-reinforced polymers and functionally graded lattices (FGLs). Control over material anisotropy and the cell topology in design for AM (DfAM) offer immense scope for customising a part’s properties and for the efficient use of material. This research expands the knowledge on the design with fibre-reinforced AM (FRAM) and the elastic-plastic performance of FGLs. Novel toolpath strategies, design guidelines and assessment criteria for FRAM were developed. For this purpose, an open-source solution was proposed, successfully overcoming the limitations of commercial printers. The effect of infill patterns on structural performance, economy, and manufacturability was examined. It was demonstrated how print paths informed by stress trajectories and key geometric features can outperform conventional patterns, laying the groundwork for more sophisticated process planning. A compilation of the first comprehensive database on fibre-reinforced FGLs provided insights into the effect of grading on the elastic performance and energy absorption capability, subject to strut-and surface-based lattices, build direction and fibre volume fraction. It was elucidated how grading the unit cell density within a lattice offers the possibility of tailoring the stiffness and achieving higher energy absorption than ungraded lattices. Vice versa, grading the unit cell size of lattices yielded no effect on the performance and is thus exclusively governed by the density. These findings help exploit the lightweight potential of FGLs through better informed DfAM. A new and efficient methodology for predicting the elastic-plastic characteristics of FGLs under large strain deformation, assuming homogenised material properties, was presented. A phenomenological constitutive model that was calibrated based upon interpolated material data of uniform density lattices facilitated a computationally inexpensive simulation approach and thus helps streamline the design workflow with architected lattices.Open Acces