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The bionic application of electronic skin (e-skin) requires a high resolution close to that of human skin, while its long-term attachment to human body or robotic skin requires a ...porous structure that is air permeable and enables hair growth. To simultaneously meet the requirements of high resolution and porous structure, as well as improve the sensing performance, we propose a fully 3D printed e-skin with high-resolution and air permeable porous structure. The flexible substrate and electrodes are 3D printed by a direct ink writing extrusion printer. The sensitive material is 3D printed by a self-made low-viscosity liquid extrusion 3D print module. This e-skin has a high sensor density of 100/cm2, which is close to the resolution of the human fingertip skin. The piezoresistive sensor units of e-skin exhibit a highly linear resistance response and a relatively performance consistency between devices. Owing to the porous and breathable structure, better human comfort and mechanical heat dissipation are realized. This high-resolution e-skin is successfully applied to identify small-sized objects with complex contours.
We have proposed a vibration sensor based on a Michelson interferometer. The sensor was developed in the form of a triaxial accelerometer, calibrated, and ultimately validated with reference ...calibrated devices during blast operations. The sensing function principle is based on the push–pull principle of the mass–spring system of a total of three interferometers. A housing was designed and fabricated using 3D printing to allow the sensor to be operated in the field. Sensor calibration was carried out in an accredited laboratory. The measured sensitivity values were approximately 60 dB re rad/g for the vertical axis and 48–51 dB re rad/g for the horizontal axes in the frequency range of 1 to 50 Hz. The sensitivity values of the presented sensor are comparable to or surpass those of the Michelson-based sensors described in the state-of-the-art. The resulting amplitude–frequency calibration models of the sensor were assembled for all three orthogonal measurement axes so that the particle velocity can be measured. Finally, comparative measurement to reference seismic stations was carried out during a multi-hole bench blast at the Kotouc Stramberk quarry to validate the calibration models.
•Highly sensitive fiber optic sensor for the field of ground vibration measurement.•Three orthogonal components acceleration or particle velocity measurement.•Sensor encapsulated in 3D printed housing.•Tested in both the laboratory on calibration benches and in the field measurement.
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•3D printed composite scaffold containing magnesium phosphate/ polycaprolactone.•In situ bone tissue regeneration.•Repair of rat tibia defect model.•Repair of rabbit maxillofacial ...bone defect model.
The development of a scaffold that can be quickly prepared and used to repair maxillofacial bone defects is an urgent clinical need. 3D printing technology can prepare personalized bone defect substitutes according to the computed tomography (CT) data of the patient's defect location. Magnesium is a bioactive molecule that plays an important role in the process of bone repair. In this study, different contents of magnesium phosphate (Mg3(PO4)2) were incorporated into polycaprolactone (PCL), and a bone defect repair scaffold was prepared using 3D printing technology. In vitro results showed that PCL scaffolds containing 20 % Mg3(PO4)2 (PCL#20MgP) had the strongest ability to promote osteogenic differentiation. Micro-CT and histological staining results of the repair of tibial defects in rats also further proved that the PCL#20MgP scaffold had strong bone formation ability in vivo. The PCL#20MgP scaffold was used to repair the rabbit maxillofacial bone defect. The Micro-CT results also confirmed that PCL#20MgP had a better osteogenesis effect than the PCL scaffold. The PCL#20MgP scaffold has good clinical application prospects in the field of maxillofacial bone defect repair.
This study assesses the printability including the consolidation, solidification microstructure, and mechanical properties of the CoCrFeMnNi high entropy alloy fabricated by Laser Powder Bed Fusion. ...A range of print parameters was used for a comprehensive assessment of printability, providing a basis to establish the relationship between process, microstructure, and mechanical properties. The study demonstrates a high relative density of the alloy fabricated with energy density in the range 62.7–109.8 J/mm3. It is shown that the scan strategy plays an important role in consolidation. For the same energy density, the rotation of 67° between two consecutive layers tends to yield higher consolidation than other considered strategies. Moreover, the scan strategy is found to be most influential in microstructure development. The scan strategy rotation angle controls the extent to which epitaxial growth can occur, and hence the crystallographic texture and the grain morphology. Amongst four considered strategies, the 0°- and 90°-rotation meander led to the strongest preferred texture while the 67°-rotation resulted in weaker texture. The 67°-rotation strategies led to broadened grains with lower aspect ratios. The understanding of texture and grain size provides explanations to the observed mechanical properties (such as flow stress and plastic anisotropy) of the alloy.
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•Highly consolidated CoNiCrFeMn is achieved in Laser Powder Bed Fusion using an energy density between 62.7 and 109.8 kJ/m3•Scanning strategy has a significant impact on consolidation of CoNiCrFeMn in Laser Powder Bed Fusion.•Microstructure and plastic anisotropy are governed by scanning strategy, in particular the angle of rotation between layers.•CoNiCrFeMn fabricated via Laser Powder Bed Fusion has excellent strength and good ductility.
Cardiac 3D Printing and its Future Directions Vukicevic, Marija, PhD; Mosadegh, Bobak, PhD; Min, James K., MD ...
JACC. Cardiovascular imaging,
02/2017, Volume:
10, Issue:
2
Journal Article
Peer reviewed
Open access
Abstract Three-dimensional (3D) printing is at the crossroads of printer and materials engineering, noninvasive diagnostic imaging, computer-aided design, and structural heart intervention. ...Cardiovascular applications of this technology development include the use of patient-specific 3D models for medical teaching, exploration of valve and vessel function, surgical and catheter-based procedural planning, and early work in designing and refining the latest innovations in percutaneous structural devices. In this review, we discuss the methods and materials being used for 3D printing today. We discuss the basic principles of clinical image segmentation, including coregistration of multiple imaging datasets to create an anatomic model of interest. With applications in congenital heart disease, coronary artery disease, and surgical and catheter-based structural disease, 3D printing is a new tool that is challenging how we image, plan, and carry out cardiovascular interventions.
ZTC4 alloy prepared by electron beam melting was hot isostatically pressed, the macro-and microstructure were characterized by stereo microscopy and optical microscopy, the tensile properties were ...tested and the fracture profiles were characterized using scanning electron microscopy. The results show that: The vertical deposition samples exhibit coarsen epitaxial columnar grains and the parallel samples show equiaxed grains, and microstructure are basket-weave α+β phase. The vertical deposition samples exhibit very high ultimate tensile strength and yield strength but poor ductility with elongation and shrinkage, and show generally more planar and faceted fracture morphology. The anisotropy in tensile properties is mainly due to the difference in the orientation of the columnar grains with respect to the tensile test direction, and the characteristics of the minor fracture plane are mainly related to the α colonies.
Inkjet is a versatile non‐contact printing technique that uses droplets of ink jetted from nozzles to print on a variety of substrates. Although some modern piezoelectric printheads support high ...viscosity fluids (>10 cP), they are currently expensive and may not be suited for many benchtop experiments in research environment. Here, the design, fabrication by 3D‐printing (no cleanroom processes or silicon micromachining are involved) and testing of a multi‐purpose single‐nozzle piezoelectric dispenser/printhead for medium‐viscosity fluids (10–60 cP) is reported. Custom control electronics are developed to drive the printhead. The design features a 200 μm diameter nozzle, suitable for nL drop generation with solutions containing nm sized particles, thus allowing the deposition of μm thick layers of functional inks in a single printing pass. The inkjet dispenser is first tested with glycerol solutions, resulting in drops of 1.9–3.6 nL with typical drop velocity of 0.5–1.3 m s−1. The developed piezoelectric dispensing system is then demonstrated in the printing of a two‐layer capacitive sensor, using silver nanoparticle ink (conductive ink) and a transparent encapsulant ink (dielectric ink). The reported piezoelectric dispenser design can be optimized for many research purposes, allowing the dispensing of functional chemicals, materials, and biomolecules.
Inkjet is a versatile non‐contact printing technique that uses droplets of ink to print on a variety of substrates. The design, fabrication by 3D‐printing and testing of a low‐cost, multi‐purpose single‐nozzle piezoelectric dispenser/printhead for medium‐viscosity fluids (10–60 cP) is reported – this design can be optimized for many research purposes, allowing the dispensing of functional chemicals, materials, and biomolecules.
Metal additive manufacturing plays a vital role in new generations of manufacturing. As one of the most used alloys, field's metal can be used in many applications such as mold fabrication, radiation ...shielding, and more. This research demonstrates the ability to fabricate functional parts using the field's alloy at the micron level. With the good thermal conductivity and low thermal negative thermal expansion coefficient, printing temperatures and printing speed are mapped for single layer printing at a given nozzle size for printing width and height performance stability optimization. Printing temperatures and printing speeds were optimized with the same evaluation criteria. Classic 3D printing challenges have been printed testing technology readiness including overhang, bridges, and infills. Varieties of 3D parts are fabricated and prove functional for computed tomography imagery marking tags and micro‐volume liquid capacitance measurements. It demonstrates that the capability of high‐resolution printing also improves the printing time efficiency when small features are not required.
Three‐dimensional (3D) features such as overhangs, bridges, and various 3D infill patterns are fabricated by electric field‐assisted direct writing technology. A case study of a single marker application demonstrated how the printed 3D parts function as X‐ray body markers identifying six degrees of freedom.
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•Industrial scale substrate with complex structure was prepared using 3D printing.•The structure significantly influences the turbulence flow regime within the channels.•Conversions ...of CH4, CO and hydrocarbons are higher on the 3D printed structure.•3D printed substrates are promising for emission control in dual-fuel engines.
A full size ceramic substrate was successfully prepared using a robocasting 3D printer and tested as a methane oxidation catalyst in the after treatment system (ATS) of a heavy-duty diesel engine, converted to co-combust (dual fuel) with natural gas (NG). The 3D printed substrate performance exceeded that of a commercially sourced straight-channelled DOC over most working conditions, despite the 3D printed structure having a lower precious group metal (PGM) loading and channels per square inch (CPSI) density. At moderate and high inlet temperatures, where the reaction rate is limited by internal and external mass transfer, the enhanced catalytic activity of the 3D printed substrate is attributed to the generation of internal turbulence, which increases oxidation rates of methane (CH4) and non-methane hydrocarbons (NMHC). In contrast, there is relatively little difference between the catalytic activity of the 3D and straight-channelled substrates at low temperatures (e.g. cold start up), where the reaction is kinetically controlled and the additional turbulence/mass transfer of the 3D printed complex structure did not measurably alter the catalytic converter performance. Computational fluid dynamics (CFD) confirmed the increased turbulence within the channels of the 3D printed structure. We also report the effects of NG substitution on the fuel combustion efficiency under different engine load settings. The findings provide proof of concept evidence that 3D printing is a suitable means of designing a catalytic converter prototype with higher reaction activity than a conventionally extruded structure. This has significant implications for the design and potential mass production of new catalytic converters with enhanced efficiencies.
Fused Deposition Modeling (FDM) is one of the most common polymer 3D printing technologies used in many applications today. However, limited volume capacity for 3D printing large parts or components ...is the usual downside of this technology, especially desktop 3D printers. Hence, to offset this limitation, the 3D-printed parts are often designed in multiple pieces and assembled after printing, which requires post-processing called cold welding. Such welds are also quite strong but not as strong as a single-piece print. Therefore, finding suitable parameters or settings that can provide substantial strength for cold-welded 3D-printed parts will be beneficial. This study aims to determine the failing behavior and shear strength of ABS FDM 3D-printed single-lap joint using ABS glue as adhesive. Specimens were printed with varying raster angles (+45o/-45o and 0o/90o) and layer thickness (290 μm, 190 μm, and 90 μm) to investigate the effects on the adhesion or shear strength and failure mode of the acetone welded 3D-printed joints. Results show that raster angle and layer thickness significantly affected the shear strength of acetone welded materials. Single-lap joint test sample printed with +45o/-45o raster angle reveals higher shear strength than specimens printed with 0o/90o raster angle. Results also indicated that the gaps between the raster and voids between adjacent filaments of 3D-printed parts affects the adhesion and failure mode of a single-lap joint.
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