Advances In Additive Manufacturing Techniques Research Articles

Printing continuous metal structures via polymer-assisted photochemical deposition

Patterning complex metallic structures via additive manufacturing (AM) has broad applications in energy, medical and aerospace industries. Current AM methods are often limited by high processing temperature, discontinuous film deposition and/or low product conductivity and reflectivity. We present a versatile room-temperature metal printing technique based on polymer-assisted photochemical deposition (PPD). Two-dimensional (2D) and three-dimensional (3D) printing of silver, gold and platinum structures with feature sizes as small as 5 µm are demonstrated on various substrates, including silicon, glass, polymers and biocompatible hydrogels. The PPD-printed metal films are continuous and smooth (roughness <3 nm) even at ultra-low thicknesses (<10 nm), and highly conductive (∼3×105 S cm−1) and reflective comparable to that of vacuum deposited counterparts. This breakthrough in advanced AM technique holds great promise for low-cost, fast and distributed manufacturing in optics, electronics and robotics.

Experimental investigation of the cooling performance of 3-D printed hybrid water-cooled heat sinks

An experimental characterization of hybrid water-cooled heat sinks for multi-core CPUs was conducted. The hybrid heat sinks consist of a water block containing fractal channel manifolds ending in an array of jet nozzles attached to a copper plate. Advanced additive manufacturing techniques were required for the fabrication of the heat sinks due to the manifolds complexity. The effects of the jet nozzles number and distribution, depth of the flood chamber, and surface enhancing features were investigated in terms of hydraulic and thermal performance. A minimum pressure drop variation was observed for different number of jet nozzles (16, 32, and 64 jets), which is consistent with previous simulation results. Alternatively, the pressure drop associated with a 3-mm size reduction of the flood chamber generated a two-fold increase in the pressure drop difference, but under 5% of the total pressure drop. A sharp temperature increase (~30 °C) was observed from idle operation within 10 s after applying a full load on the CPU and the system reached steady state in ~74 s. The highest core temperature was observed using the heat sink with 32 jets, while the heat sinks with 16 and 64 jets had similar thermal performance. Area enhancing features added to the copper plate produced negligible effects on the hydraulic performance, while average core temperature reductions up to 3 °C were measured using circular pin fins. To further analyze the thermo-hydraulic performance, the thermal resistance and the pumping power were calculated. The overall performance assessment was conducted using a metric formed by the combination of the thermal resistance and pumping power. This metric helped to identify the best heat sink based on the thermo-fluid characteristics, i.e., the lowest core temperature with the least pumping power.

Novel structural design method inspired by DNA and origami

Abstract In chiral metamaterials, the twist per axial strain (TPAS) is an important index to evaluate the tension-torsion coupling effect. Most chiral structures reported in current literatures have the appearance of lattice architectures, which possess limited TPAS. Inspired by DNA and origami structures, the proposed DNA-like chiral structure can generate a twist with the folding behavior of each unit. Theoretically, the value of TPAS of the proposed structure can achieve + ∞ , which provides a good basis to design metamaterials for target tension-torsion coupling properties. Also, we can design lattice structures based on the proposed DNA-origami concept. With the advanced additive manufacturing techniques, the proposed DNA-like structures can be used to fabricate shape memory morphing structures, smart propellers, artificial muscles, and biomechanical devices for applications in various fields of engineering.

Elastomeric Microlattice Impact Attenuators

Summary Impact-attenuating materials are designed to absorb impact energy through the collapse of pores within the material below a threshold force (or acceleration), thereby mitigating damage or injury. Recent advances in additive manufacturing techniques have enabled the fabrication of cellular materials with architected lattice topology. Here it is demonstrated that, via design of cellular architecture, the dynamic stress-strain response of elastomeric lattices can be tailored to achieve impact-attenuation performance exceeding state-of-the-art foams for both single- and multi-hit scenarios. The additional degrees of freedom in the design of the cellular architecture of lattice-based impact attenuators are then leveraged to optimize their performance for a typical helmet impact scenario wherein the contact area increases during deformation. An improvement over state-of-the-art vinyl-nitrile foam helmet pads is achieved during a standard helmet test, leading to lower head acceleration. This breakthrough could pave the way to helmets with improved injury protection.

Investigation on Ti-6Al-4V Microstructure Evolution in Selective Laser Melting

Selective laser melting (SLM) is an advanced additive manufacturing technique that can produce complex and accurate metal samples. Since the process performs local high heat input during a very short interaction time, the physical parameters in the solidification are difficult to measure experimentally. In this work, the microstructure evolution of Ti-6Al-4V alloy in additive manufacturing was studied. With the increase of scanning speed, the cooling rate and the temperature gradient of molten pool position increased, which was attributed to the gradual decrease of energy density. The phase-field simulation resulted in the overall microstructure morphology of columnar crystals owing to the very large temperature gradient and cooling rate obtained from the temperature field. Microsegregation was observed during dendritic formation, and the solute was enriched in the liquid phase near the dendritic tip and between the dendritic arms due to the lower equilibrium distribution coefficient. The scanning speed had an effect on the dendrite spacing.

The Use of Structurally Augmented 3D Printed Cages in Segmental Defects of the Tibial Shaft

Category:Trauma, Emerging TechnologyIntroduction/Purpose:Modern day management of segmental defects of the tibia shaft (SDTS) involve autologous nonvascularized grafts, autologous vascularized contralateral fibula grafts, as well as bone transport distraction osteogenesis, however single stage titanium cages with adjuvant biologics continue to demonstrate advantages. With the development of advanced additive manufacturing further modalities such as complex variable lattice structure and submicron texture may be incorporated into custom fit implants. We aim to further investigate the potential of this technology on osteoinduction, and hypothesize early bone in-growth.Methods:A retrospective analysis was performed on 3 patients undergoing custom cage implantation for SDTS. All three patients were male with an average age of 60, 2 patients were diabetic, and one was a smoker. All three cases were performed in the setting of post-infection salvage. Pertinent demographic and clinical history was retrieved through the medical record.Results:All three cases were uncomplicated in the post-surgical period, and early bone in-growth was demonstrated in successive follow-ups. One case was single-staged and built into a prior total ankle arthroplasty, the next was a deformity correcting intramedullary rod that became infected requiring two-stage salvage with an antibiotic spacer and subsequent custom cage with Intramedullary rod supplementation, and the third case was a two-stage trauma salvage initially using an antibiotic spacer with subsequent custom cage implantation.Conclusion:3D printed custom cages were found to be a safe and efficacious option for management of SDTS, with demonstrated early bone in-growth. Considering the incorporation of advanced additive manufacturing techniques, strong implementations may be present for salvage cases.

Design, Fabrication, and Mechanics of 3D Micro-/Nanolattices.

Over the past several decades, lattice materials have been developed and used as engineering materials for lightweight and stiff industrial structures. Recent advances in additive manufacturing techniques have prompted the emergence of architected materials with minimum characteristic sizes ranging from several micrometers to hundreds of nanometers. Taking advantage of the topological design, structural optimization, and size effects of nanomaterials, various 3D micro-/nanolattice materials composed of different materials exhibit combinations of superior mechanical properties, such as low density, high strength (even approaching the theoretical limits), large deformability, good recoverability, and flaw tolerance. As a result, some micro-/nanolattices occupy an unprecedented area in Ashby charts with a combination of different material properties. Here, recent advances in the fabrication and mechanics of micro-/nanolattices are described. First, various design principles and advanced techniques used for the fabrication of micro-/nanolattices are summarized. Then, the mechanical behaviors and properties of micro-/nanolattices are further described, including the compressive Young's modulus, strength, energy absorption, recoverability, and tensile behavior, with an emphasis on mechanistic insights and origins. Finally, the main challenges in the fabrication and mechanics of micro-/nanolattices are addressed and an outlook for further investigations and potential applications of micro-/nanolattices in the future is provided.

Elastomeric Microlattice Impact Attenuators

Impact attenuating materials fulfill an essential role in applications as diverse as protective packaging, shock isolators for electronics, vehicle interiors, and helmet padding. These materials are typically cellular in construction, and are designed to absorb impact energy through the collapse of pores within the material below a threshold force (or acceleration), thereby mitigating damage or injury. Polymer foams are the most common impact attenuating materials, and see widespread use in many industries. Recent advances in additive manufacturing techniques have enabled the fabrication of cellular materials with architected lattice topology. Here it is demonstrated that via design of cellular architecture the dynamic stress-strain response can be tailored, resulting in elastomeric lattices with impact attenuation performance significantly exceeding that of state-of-the-art foams for both single and multi-impact scenarios. Then, the additional degrees of freedom in the design of the cellular architecture of lattice based impact attenuators are leveraged to optimize their performance for a typical helmet impact scenario whereby the contact area increases during deformation. An improvement over state-of-the-art vinyl nitrile foam helmet pads is achieved during a standard helmet test leading to lower head acceleration. This breakthrough could pave the way to helmets with improved injury protection.

Effect of layer band and heterogeneity of microstructure on electrochemical dissolution of laser solid formed Ti-6Al-4V alloy

Laser solid forming (LSF) is a newly advanced additive manufacturing technique which offers a huge potential in efficiency and cost savings for fabricating the components of aerospace titanium alloys with high performance. In this research, the macrostructure/microstructure and electrochemical dissolution features of the Ti-6Al-4V alloy produced by LSF and forging were investigated. The LSFed Ti-6Al-4V that included as-deposited and annealing heat treatment (HT) conditions contains three periodically distributed microstructural morphologies: fine microstructure zone (FMZ), coarse microstructure zone (CMZ), and layer band. All zones of the different microstructural morphology in an entire deposit are constituents of α-laths and a small amount remained in the β phase. An alternating structure of coarse and fine microstructures was observed along the deposition direction in the deposit. Layer bands are generally spaced above the CMZ. The CMZ is a constituent of a slightly coarser basket weave structure than that of the FMZ. However, the layer bands present the microstructure of colony α. Additionally, the α-laths are slightly coarsened by HT, and this simultaneously results in a more homogeneous microstructure compared with the as-deposited microstructure. Moreover, the forged Ti-6Al-4V possesses the most homogeneous microstructure and the largest size of the α phase. Simultaneously, a variety of dissolved morphology features were observed in the three types of samples after potentiodynamic polarization tests. The order of the surface macrosmooth level of these samples is forged &amp;gt; HT &amp;gt; as-deposited. For LSFed Ti-6Al-4V, the FMZs and the layer bands present a faster electrochemical dissolution rate than that of the CMZs. Consequently, the uneven surface is revealed by the distinct dissolution rate of different microstructural zones at the same LSFed sample. The forged Ti-6Al-4V alloys present a uniformly dissolved behavior, which is attributed to the homogeneity of the microstructure. The elimination of the layer bands and the homogenization of the microstructure of the LSFed Ti-6Al-4V are of great significance for improving the surface quality during electrochemical machining.

RangeFinder: Accelerating ball-interference queries against steady lattices

Advances in additive manufacturing techniques are enabling the fabrication of new microstructures and materials. These may often be defined in terms of a set of balls and of beams that each connects two balls. To support application needs, we must efficiently support structures with billions of beams. To address this challenge, we advocate steady lattices, which implicitly define a u×v×w array of groups of balls such that each consecutive pair of groups in a given direction is related by the same similarity transformation and such that the beams are defined to periodically connect the same corresponding, relatively-indexed pairs of balls. We propose an algorithm that accelerates the Ball-Interference Query (BIQ), which establishes which balls and beams of the lattice interfere with a query ball Q. Our RangeFinder solution reduces the asymptotic time-complexity of BIQ from O(uvw) to O(uv). For special cases, it reduces the complexity even further down to O(u) and O(1). In our tests, RangeFinder reduced the query time by up to a factor of 9420 times. RangeFinder does not use any spatial occupancy data structure and can be trivially parallelized. We demonstrate the effectiveness of RangeFinder on standard lattices and also on their multi-level Lattice-in-Lattice (LiL) variants.

In vitro degradation behavior and cytocompatibility of ZK30/bioactive glass composites fabricated by selective laser melting for biomedical applications

In practice, the poor formability and high degradation rate of Mg-based alloys are perceived as two major limitations for their more extensive applications in the biomedical field. Selective laser melting (SLM), as one of the advanced additive manufacturing techniques, is potential for the manufacturing of customized Mg-based implants with improved formability and corrosion resistance. Moreover, the integration of bioactive glass (BG) into Mg-based alloys could endow the materials with further enhanced corrosion resistance and favorable biological performance. In the current work, biomedical Mg-based biodegradable composites (ZK30/xBG, x = 0, 5, 10, 15 wt%) with ZK30 alloy as the matrix and BG (45S5) as the reinforcement were fabricated by SLM. The results showed that the BG particles homogeneously distributed in the matrices of SLM-fabricated ZK30/xBG composites. Meanwhile, the introduction of the BG particles led to improved microhardness of the composites. When immersed in simulated body fluid (SBF), more precipitations (primary Ca–P compounds and partial Mg(OH)2) formed on ZK30/10BG and ZK30/15BG surfaces compared to ZK30 and ZK30/5BG group. The hydrogen evolution and electrochemical polarization tests showed that corrosion resistance of various specimens was in the following order: ZK30/10BG > ZK30/5BG > ZK30/15BG > ZK30. In addition, the in vitro cell viability results showed that ZK30/10BG and ZK30/15BG were more cytocompatible than ZK30 and ZK30/5BG. Overall, these results indicate that the combination of SLM technique and BG integration could be used to manufacture ZK30/xBG composites with enhanced corrosion resistance and favorable formability. Moreover, the ZK30/10BG composite is promising for orthopedic applications considering its combination of favorable bioactivity, corrosion resistance and cytocompatibility.

&lt;i&gt;In Vitro&lt;/i&gt; and &lt;i&gt;in Vivo&lt;/i&gt; Study of Selective Laser Melted Porous Ti-Ta-Nb-Zr Scaffolds for Repairing Bone Defects

Porous titanium-tantalum-niobium-zirconium (Ti-Ta-Nb-Zr) scaffolds are novel low-modulus metal scaffolds resembling cancellous bone, currently available for orthopedic applications. However, these scaffolds manufactured using traditional methods present disadvantages such as irregular pore size, unsuitable mechanical features, and poor connectivity between pores. Metal-based porous structures scaffolds for bone-defect repair can be fabricated using advanced additive manufacturing techniques. Here, we used selective laser melting (SLM) technology to manufacture porous Ti-Ta-Nb-Zr scaffolds with controlled pore size of 300~400 μm. We evaluated the SLM-manufactured scaffold mechanical properties and osteogenesis in vitro and osteointegration in vivo. Porous Ti-Ta-Nb-Zr scaffolds yielded superior cell-proliferation and cell-adhesion results with human bone mesenchymal stem cells (hBMSCs) as compared with porous Ti6Al4V scaffolds. The ALP-activity measurement and semiquantitative alizarin red staining demonstrated enhanced osteogenic differentiation of hBMSCs in the Ti-Ta-Nb-Zr group than in Ti6Al4V group. Moreover, after the porous Ti-Ta-Nb-Zr or control scaffold was implanted into a cylindric bone defect in the rabbit lateral femoral condyle, the radiography of new bone regeneration showed that the bone-volume/total-volume ratio was higher in Ti-Ta-Nb-Zr scaffolds than in Ti6Al4V scaffolds. Histological analysis further indicated that the Ti-Ta-Nb-Zr scaffolds promoted bone regeneration and osseointegration more effectively than Ti6Al4V scaffolds. Thus, the SLM-manufactured porous Ti-Ta-Nb-Zr scaffolds not only exhibited regular pore shape and excellent connectivity, but also featured a controllable elastic modulus and compressive strength, and the scaffolds yielded superior osteogenesis and osseointegration results in vitro and in vivo than porous Ti6Al4V. Our findings demonstrate that the SLM-manufactured porous Ti-Ta-Nb-Zr scaffold holds considerable potential for orthopedic clinical application.

Topology optimization-guided lattice composites and their mechanical characterizations

Optimization design assisted with advanced additive manufacturing techniques opens an effective gate for us to create novel, lightweight, mechanically robust cellular materials. Among them, lattice materials with an ordered cellular architecture have been known for their high mechanical properties, low density and energy absorption capacity. Limitedly, what kinds of topologic architecture have the best performance? And how could we obtain the optimized architecture? To answer them, we here took up two challenging tasks to achieve a novel compression-resistant lattice: ① The topology optimization method was introduced to design the optimized topologic architecture. ② Metallization was used to form lattice composites to further enhance the mechanical properties of pristine polymer. The topology optimization-guided lattice with only 20% volume of solid materials quite resembles the microstructure of cuttlebone, giving an indication of a good compression-resistant ability. Furthermore, the synthesized composites exhibit high specific compressive modulus of 5417.02 MPa kg−1 and energy absorption efficiency of 78%. By in situ compressive tests, digital image correlation, finite element simulation and fracture analysis, the deformation mechanism, and fracture modes were unambiguously revealed. The design strategies and findings shed light on the realization of advanced materials with tailored mechanical properties.

Fully Water-Soluble, High-Performance Transient Sensors on a Versatile Galactomannan Substrate Derived from the Endosperm.

Green electronics on biodegradable substrates from natural sources have gained broad interest because of the advantages of being biodegradable, recyclable, sustainable, and cost-efficient. This study presents a low-cost, yet simple extraction and purification method that explores aqueous extraction and precipitation with ethanol for the synthesis of galactomannan films. In salient contrast to the other materials of natural origin, the process to obtain galactomannan films is energy efficient and environmentally friendly. As an alternative biodegradable material, galactomannan has direct relevance to the recent emerging biodegradable or transient electronics. The galactomannan substrate with temperature sensors and electrodes fabricated from zinc, a biodegradable material noted for its essential biological function, demonstrates a high-precision measurement of temperature and high-fidelity monitoring of electrophysiological signals (electromyogram or electrocardiogram). The resulting disposable sensors disappear without a trace in water and produce environmentally benign end products that could even be used for alkaline soil amendments. The set of materials explored in this study is also stable in organic solutions, enabling solvent-based fabrication that may be combined with recent advances in additive manufacturing techniques for a novel manufacturing method.

Behavior of auxetic structures under compression and impact forces

In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilize normal materials that follow Hooke’s law but still show the properties of negative Poisson’s ratios (NPR). One potential application is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industrial workers, law enforcement and military personnel, and athletes. This paper reports an integrated theoretical, computational, and experimental investigation conducted for typical auxetic materials that exhibit NPR properties. Parametric 3D CAD models of auxetic structures such as re-entrant hexagonal cells and arrowheads were developed. Then, key structural characteristics of protection pads were evaluated through static analyses of FEA models. Finally, impact analyses were conducted through dynamic simulations of FEA models to validate the results obtained from the static analyses. Efforts were also made to relate the individual and/or combined effect of auxetic structures and materials to the overall stiffness and shock-absorption performance of the protection pads. An advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic structures. Three different materials typically used for fused deposition modeling technology, namely polylactic acid (PLA) and thermoplastic polyurethane material (NinjaFlex® and SemiFlex®), were used for different stiffness and shock-absorption properties. The 3D printed prototypes were then tested and the results were compared to the computational predictions. The results showed that the auxetic material could be effective in reducing the shock forces. Each structure and material combination demonstrated unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Auxetic structures showed better shock absorption performance than non-auxetic ones. The mechanism for ideal input force distribution or shunting could be suggested for designing protectors using various shapes, thicknesses, and materials of auxetic materials to reduce the risk of injury.

Design and Optimization of 3-D Frequency-Selective Surfaces Based on a Multiobjective Lazy Ant Colony Optimization Algorithm

Frequency-selective surfaces (FSSs) have many applications in spatial filtering of electromagnetic waves and are commonly used in antennas, polarizers, radomes, and intelligent architecture. Conventional FSS designs have ranged from canonical shapes and fractal patterns on planar surfaces to miniaturized and multilayer designs, with stable filtering responses up to 50°. Much less work has been done on 3-D FSS designs, which include multiresonant structures or cavities that offer improved angular stability, with fields of view up to 60°. Recent advances in additive manufacturing techniques have made fully 3-D FSS designs increasingly popular; however, powerful design tools to exploit such fabrication methods are currently unavailable. In this paper, multiobjective lazy ant colony optimization (MOLACO), an adaptive combinatorial optimization algorithm based on ant colony optimization, is introduced and applied to the problem of polarization and angle independent 3-D FSS design. It will be shown that the MOLACO algorithm generates several innovative and unintuitive unit cell geometries with a single-zero, single-pole response, less than 1% shift from center frequencies and −10 dB rejection and 3 dB transmission bandwidths between 6%–12% for angles of incidence up to 80° in TE and TM polarizations. Comparisons are made between designs generated by MOLACO and existing FSS designs.

A numerical approach to study the post-yield softening in cellular solids: role of microstructural ordering and cell size distribution

Designing meta-materials and cellular solids with biomimetic structures has received increasing attention in the past few years partially due to advances in additive manufacturing techniques that have enabled the fabrication of advanced materials with arbitrarily complex microarchitectures and novel functionalities. To impact on this trend, it is essential to develop our understanding about the role of microstructure on mechanical responses of these structures. Although a large literature exists on the general subject, the role of microstructure on the post-yield instability is not yet adequately documented. This research introduces a numerical approach to study the post-yield instability in 2D infinite honeycombs as a bottleneck for understanding the instability in more complex 3D systems. Two distinct algorithms are used to systematically vary the ordering in the microstructure of regular hexagonal honeycombs and the mean cell size in the microstructure of Voronoi honeycombs. Finite elements together with a nonlinear homogenization technique are incorporated to quantify the instability responses. Finally, the contribution of microstructure on initial post-yield instability—the slope and magnitude of stress drop after yielding—is statistically investigated. It is found that changing the degree of ordering in the microstructure with respect to a parent symmetry can systematically vary the post-yield instability properties. However, systematic variation of the cell size distribution in absence of ordering in the microstructure cannot remarkably change the post-yield instability in the meta-material. Instead, a tailored cell size distribution can systematically influence its yield strength and plateau stress.

Three-Dimensional Printing of Highly Conductive Carbon Nanotube Microarchitectures with Fluid Ink

Moving printed electronics to three dimensions essentially requires advanced additive manufacturing techniques yielding multifunctionality materials and high spatial resolution. Here, we report the meniscus-guided 3D printing of highly conductive multiwall carbon nanotube (MWNT) microarchitectures that exploit rapid solidification of a fluid ink meniscus formed by pulling a micronozzle. To achieve high-quality printing with continuous ink flow through a confined nozzle geometry, that is, without agglomeration and nozzle clogging, we design a polyvinylpyrrolidone-wrapped MWNT ink with uniform dispersion and appropriate rheological properties. The developed technique can produce various desired 3D microstructures, with a high MWNT concentration of up to 75 wt % being obtained via post-thermal treatment. Successful demonstrations of electronic components such as sensing transducers, emitters, and radio frequency inductors are also described herein. We expect that the technique presented in this study will facilitate selection of diverse materials in 3D printing and enhance the freedom of integration for advanced conceptual devices.

Cellulose Nanofibril Hydrogel Tubes as Sacrificial Templates for Freestanding Tubular Cell Constructs.

The merging of defined nanoscale building blocks with advanced additive manufacturing techniques is of eminent importance for the preparation of multiscale and highly functional materials with de novo designed hierarchical architectures. Here, we demonstrate that hydrogels of cellulose nanofibrils (CNF) can be processed into complex shapes, and used as a sacrificial template to prepare freestanding cell constructs. We showcase our approach for the fabrication of hollow fibers using a controlled extrusion through a circular die into a coagulation bath. The dimensions of the hollow fibers are tunable, and the final tubes combine the nanofibrillar porosity of the CNF hydrogel with a submillimeter wall thickness and centimeter-scale length provided by the additive manufacturing technique. We demonstrate that covalent and supramolecular cross-linking of the CNFs can be used to tailor the mechanical properties of the hydrogel tubes within 1 order of magnitude and in an attractive range for the mechanosensation of cells. The resulting tubes are highly biocompatible and allow for the growth of mouse fibroblasts into confluent cell layers in their inner lumen. A detailed screening of several cellulases enables degradation of the scaffolding, temporary CNF hydrogel tube in a quick and highly cell-friendly way, and allows the isolation of coherent cell tubes. We foresee that the growing capabilities of hydrogel printing techniques in combination with the attractive features of CNFs-sustainable, globally abundant, biocompatible and enzymatically degradable-will allow making plant-based biomaterials with hierarchical structures and on-demand degradation useful, for instance, to engineer complex tissue structures to replace animal models, and for implants.

Shrinking the Supply Chain for Implantable Coronary Stent Devices.

Stenting treatments for the management of disease in the heart, arterial and venous systems, biliary ducts, urethras, ureters, oesophageal tract and prostate have made enormous technical advances since their introduction into clinical use. The progression from metallic to polymer based bio-absorbable stents, coupled with the advances in additive manufacturing techniques, present a unique opportunity to completely re-envision the design, manufacture, and supply chain of stents. This paper looks at current stenting trends and proposes a future where the stent supply chain is condensed from ~150days to ~20min. The Cardiologist therefore has the opportunity to become a designer, manufacturer and user with patients receiving custom stents specific to their unique pathology that will be generated, delivered and deployed in the Cath-lab. The paper will outline this potentially revolutionary development and consider the technical challenges that will need to be overcome in order to achieve these ambitious goals. A high level overview of the generating eluting stents in situ program-GENESIS-is outlined including some early experimental work.