•A framework for performance-based laboratory testing of printing concrete was proposed.•A laboratory-scale linear concrete printer was built for experimental study of printing mixtures.•Four ...printing mixtures were designed to study effects of Nano-clay, silica fume and fiber inclusion.•Layer settlement and cylinder stability tests were developed to study shape stability.•Inclusion of silica fume and Nano-clay enhance shape stability of fresh printing mixture.
In this study, a framework for performance-based laboratory testing of cementitious mixtures for construction-scale 3D printing is developed, where workability of a fresh “printing mixture” is studied in terms of print quality, shape stability, and printability window. Print quality is described using measures of surface quality and dimensions of printed layers. Details of two proposed test methods for evaluation of shape stability, namely, “layer settlement” and “cylinder stability” are also provided. Experimental study of four different mixtures revealed that inclusion of silica fume and Nano-clay significantly enhance shape stability. The results of five conventional test methods, as well as four proposed tests are used to discuss the performance of mixtures.
Nerve guidance conduits (NGCs) have been drawing considerable attention as an aid to promote regeneration of injured axons across damaged peripheral nerves. Ideally, NGCs should include physical and ...topographic axon guidance cues embedded as part of their composition. Over the past decades, much progress has been made in the development of NGCs that promote directional axonal regrowth so as to repair severed nerves. This paper briefly reviews the recent designs and fabrication techniques of NGCs for peripheral nerve regeneration. Studies associated with versatile design and preparation of NGCs fabricated with either conventional or rapid prototyping (RP) techniques have been examined and reviewed. The effect of topographic features of the filler material as well as porous structure of NGCs on axonal regeneration has also been examined from the previous studies. While such strategies as macroscale channels, lumen size, groove geometry, use of hydrogel/matrix, and unidirectional freeze‐dried surface are seen to promote nerve regeneration, shortcomings such as axonal dispersion and wrong target reinnervation still remain unsolved. On this basis, future research directions are identified and discussed.
The physical and topographical features of an NGC regulates the functional regeneration of a damaged peripheral nerve. In this study, the authors reviewed various strategic design approaches for axonal growth. Several conventional, rapid prototyping, and nanoscale fabrication technique have been identified as being very promising for NGC fabrication.
The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving “acoustic tweezers” in biology, chemistry, ...engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner.
Wire + arc additive manufacturing components contain significant residual stresses, which manifest in distortion. High-pressure rolling was applied to each layer of a linear Ti-6Al-4V wire + arc ...additive manufacturing component in between deposition passes. In rolled specimens, out-of-plane distortion was more than halved; a change in the deposits' geometry due to plastic deformation was observed and process repeatability was increased. The Contour method of residual stresses measurements showed that although the specimens still exhibited tensile stresses (up to 500 MPa), their magnitude was reduced by 60%, particularly at the interface between deposit and substrate. The results were validated with neutron diffraction measurements, which were in good agreement away from the baseplate.
This paper is part of a Themed Issue on Measurement, modelling and mitigation of residual stress.
•A high-thixotropy 3D printing concrete has been successfully developed.•Such concrete had lower drying shrinkage, normal elastic modulus and Poisson’s ratio.•The rheological properties and ...anisotropy of such concrete were systematically investigated.•A series of large-scale components industry–scale were applied into public transportation.
3D printing is a promising technology in construction industry. Unlike conventional construction process, 3D printing buildings are extruded by a nozzle layer-over-layer without the requirement of formwork. This paper investigates the rheological and harden properties of the high-thixotropy 3D printing concrete. Flowability, rheological property (viscosity, yield stress, thixotropy) and open time are considered as critical wet properties to control the printable property (pumpability, extrudability and buildability) of such concrete material. Five different mixtures are systematically investigated to obtain the optimum mix and then it’s used to study the harden property, such as anisotropy (compression and flexural), elastic modulus and drying shrinkage. At last, a large-scale components-bus station preliminarily was prepared by using this technology.
Three-dimensional (3D) printing is an emerging technology aiding diagnostics, education, and interventional, and surgical planning in congenital heart disease (CHD). Three-dimensional printing has ...been derived from computed tomography, cardiac magnetic resonance, and 3D echocardiography. However, individually the imaging modalities may not provide adequate visualization of complex CHD. The integration of the strengths of two or more imaging modalities has the potential to enhance visualization of cardiac pathomorphology. We describe the feasibility of hybrid 3D printing from two imaging modalities in a patient with congenitally corrected transposition of the great arteries (L-TGA). Hybrid 3D printing may be useful as an additional tool for cardiologists and cardiothoracic surgeons in planning interventions in children and adults with CHD.
The incorporation of 3D imaging into diagnostic and interventional echocardiography has rapidly expanded in recent years. Applications such as multiplanar reconstruction that were once considered ...research tools and required off-cart analysis can now readily be performed at the point of image acquisition and in real-time during live image acquisition for procedural guidance. While the application and quality of 3D images have significantly improved in recent years, there remains a noticeable lag in the evolution of artificial intelligence that would further simplify the interpretative processes, both during live sessions and offline analyses. Users are still required to mentally reconstruct sliced images during multiplanar reconstruction based on color-coded planes. While this may be an effortless task for the seasoned echocardiographer, it can be a challenging task for echocardiographers who are less familiar with 3D imaging and multiplanar reconstruction. This article describes the utility of using 3D markers to aid in image interpretation.
The 3-dimensional (3D) printing technologies, referred to as additive manufacturing (AM) or rapid prototyping (RP), have acquired reputation over the past few years for art, architectural modeling, ...lightweight machines, and tissue engineering applications. Among these applications, tissue engineering field using 3D printing has attracted the attention from many researchers. 3D bioprinting has an advantage in the manufacture of a scaffold for tissue engineering applications, because of rapid-fabrication, high-precision, and customized-production, etc. In this review, we will introduce the principles and the current state of the 3D bioprinting methods. Focusing on some of studies that are being current application for biomedical and tissue engineering fields using printed 3D scaffolds.
L’impression 3D a investi le champ médical dès le début du 21e siècle. Elle s’est démocratisée au fil des années pour devenir aujourd’hui un outil accessible à coût quasiment nul à condition d’avoir ...une imprimante 3D à disposition. Le chirurgien peut ainsi selon ses besoins l’intégrer facilement à sa pratique et ses techniques au bloc opératoire, sous réserve d’un apprentissage des logiciels de traitement de l’image tridimensionnelle.
Afin d’illustrer l’ensemble du processus, de la genèse et traitement de l’image tridimensionnelle à son application au bloc opératoire, nous décrivons le cas d’un patient amputé du pavillon de l’oreille gauche, dont la reconstruction a été guidée par un modèle 3D imprimé à partir de son oreille droite.
3D printing has been used in the medical field since the beginning of the 21st century. Over the years, it has been democratized and has become an accessible tool at almost no cost, provided that a 3D printer is available. The surgeon can thus easily integrate it into his practice and techniques in the operating room, provided that he learns to use 3D image processing software. In order to illustrate the whole process, from the genesis and processing of the 3D image to its application in the operating room, we describe the case of a patient with a left auricle amputation, whose reconstruction was guided by a 3D model printed from his right ear.
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