- 标题
- 摘要
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- 实验方案
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Laser printing of micro-electronic communication systems for smart implants applications
摘要： Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium alloy for implant’s fabrication. In this sense, this work presents a promising approach to print communication systems by using laser technology, aiming integrate the smart components on titanium implants. Laser has been employed as a versatile tool to modify the surface in different ways, such as texturing, oxidizing and sintering. Silver wires have been printed on Ti6Al4V surface in order to conduct electrical current. To minimize current loss for the substrate, titanium oxide layer has been produced by different methods (laser and anodization). Laser sintering (LS) has been also compared to a conventional method (Hot-pressing- HP) to consolidate the silver powder into the cavities. In comparison to the conventional techniques, laser demonstrated to be a competitive approach to oxidizing the surface and also for consolidating the micro-wires on Ti6Al4V surface. Consequently, the micro-wires printed by laser approach presented satisfactory results in terms of electrical resistance, actuating as the conductor path for electrical current, with values of 0.0131 Ω, which is similar to the resistance of the wire printed in an insulator substrate.
关键词： Ti6Al4V titanium alloy,Laser oxidation,Implants,Laser surface modification,Nd:YAG laser,Laser sintering
更新于2025-09-23 15:21:01
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Continuous-Wave Laser-Induced Transfer of Metal Nanoparticles to Arbitrary Polymer Substrates
摘要： Laser-induced forward transfer (LIFT) and selective laser sintering (SLS) are two distinct laser processes that can be applied to metal nanoparticle (NP) ink for the fabrication of a conductive layer on various substrates. A pulsed laser and a continuous-wave (CW) laser are utilized respectively in the conventional LIFT and SLS processes; however, in this study, CW laser-induced transfer of the metal NP is proposed to achieve simultaneous sintering and transfer of the metal NP to a wide range of polymer substrates. At the optimum laser parameters, it was shown that a high-quality uniform metal conductor was created on the acceptor substrate while the metal NP was sharply detached from the donor substrate, and we anticipate that such an asymmetric transfer phenomenon is related to the di?erence in the adhesion strengths. The resultant metal electrode exhibits a low resistivity that is comparable to its bulk counterpart, together with strong adhesion to the target polymer substrate. The versatility of the proposed process in terms of the target substrate and applicable metal NPs brightens its prospects as a facile manufacturing scheme for ?exible electronics.
关键词： selective laser sintering,flexible electronics,metal nanoparticle ink,laser-induced forward transfer
更新于2025-09-23 15:21:01
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Selective Laser Sintering 3D Printing a?? An Overview of the Technology and Pharmaceutical Applications
摘要： Food and Drug Administration (FDA) has approved a drug product (Spritam?) and many medical devices manufactured by 3-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects and potential pharmaceutical applications.
关键词： in-process monitoring,selective laser sintering,personalized medication,3D printing,quality defects,pharmaceuticals
更新于2025-09-23 15:21:01
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Semi-supervised deep learning based framework for assessing manufacturability of cellular structures in direct metal laser sintering process
摘要： In recent years, metal cellular structures have drawn attentions in various industrial sectors due to their design freedoms and abilities to achieve multi-functional mechanical properties. However, metal cellular structures are dif?cult to fabricate due to their complex geometries, even with modern additive manufacturing technologies such as the direct metal laser sintering (DMLS) process. Assessing the manufacturability of metal cellular structures via a DMLS process is a challenging task as the geometric features of the structures are complex. Besides, via a DMLS process, the manufacturability also depends on the cumulative deformation of the layers during the manufacturing process. Existing methods on Design for Additive Manufacturing (DFAM) provide design guidelines that are based on past successful printed designs. However, they are not effective in predicting the manufacturability of metal cellular structures. In this paper, we propose a semi-supervised deep learning based manufacturability assessment (SSDLMA) framework to assess whether a metal cellular structure can be successfully manufactured from a given DMLS process. To enable ef?cient learning, we represent the complex cellular structures as 3D binary arrays with a simple yet ef?cient voxelisation method. We then train a deep learning based classi?er using only a small amount of experimental data by adopting a semi-supervised learning approach. By running real experiments and comparing with existing DFAM methods and machine learning models, we demonstrate the advantages of the proposed SSDLMA framework. The proposed framework can be extended to predict the manufacturability of various other complex geometries beyond cellular structure in a reliable way even with a small number of training data.
关键词： Design for additive manufacturing,Manufacturability analysis,Direct metal laser sintering,Semi-supervised deep learning,Cellular structures
更新于2025-09-23 15:21:01
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Effect of the Ce3+ concentration on laser-sintered YAG ceramics for white LEDs applications
摘要： This paper describes the laser sintering and luminescence properties of Y3Al5O12 (YAG) phosphors doped with different concentrations of Ce3+ and synthesized using the polymeric precursor method. The ceramics were sintered by a new laser sintering technique in which a CO2 laser is employed as the heating source. The resultant ceramics exhibited a homogeneous microstructure with narrow grain size distribution and high relative density. The introduction of Ce3+ ions led to luminescence quenching at a concentration above 0.5 mol% and a redshift of the emission spectrum band with increasing cerium concentration. The excitation spectrum showed two characteristic bands centered at 340 nm and 460 nm and a relative change in their intensity by change the Ce3+ concentration. The presence of a single valence (Ce3+) of cerium was determined by X-ray absorption near edge structure measurements.
关键词： laser sintering,ceramics,photoluminescence,LED,YAG
更新于2025-09-23 15:21:01
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Detection of powder bed defects in selective laser sintering using convolutional neural network
摘要： The presence of defects in a powder bed fusion (PBF) process can lead to the formation of flaws in consolidated parts. Powder bed defects (PBDs) have different sizes and shapes and occur in different locations in the built area. Those variations pose great challenges to their detection. In this study, a deep convolution neural network was applied to detect three typical types of PBDs in a selective laser sintering (SLS) process, namely warpage, part shifting, and short feed, which were intentionally generated by varying the process conditions. Images of the powder bed were captured using a digital camera, which were split into three single-channel images corresponding to the color channels in the color image. A deep residual neural network was then used to extract multiscale features, and a region proposal network was adopted to detect the object-level defect bounding box. In the final stage, a fully convolutional neural network was proposed to generate instance-level defect regions in the bounding box. Our results demonstrated that this method had higher accuracy and efficiency and was able to cope with geometrical distortion and image blurring, in comparison to the defect detection methods reported previously. Also, the detection system was cost-effective and could be easily installed outside the chamber of a PBF system. This study lays the groundwork for the development of a variety of automated technologies for additive manufacturing, such as real-time powder layer quality inspection and 3D quality certificate generation for finish parts.
关键词： Defect,Neural network,Selective laser sintering,Powder bed fusion,Detection
更新于2025-09-23 15:21:01
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Investigation of the track width-dependent melt pool characteristics during laser-sintering of polyamide 12 in correlation to various focus diameters
摘要： Factors such as not only costs, production time, reproducibility, but also the quality of the components are decisive factors in assessing the economic efficiency of a manufacturing process. With additive manufacturing processes, component production is made possible directly from a 3D CAD model. This means that small series and prototypes can already be produced economically today. In this area, the laser-sintering process, in particular, offers great potential for series production due to its high strength values and ductility. With laser-sintering systems that allow an optical widening of the laser focus, a faster exposure of the component and thus a shortening of the building time is possible. We developed a laser-sintering system whose laser focus diameter is adjustable in its cross-sectional area from 0.47 to 2 mm. The goal for the future is to produce large-area components significantly faster by widening the focus diameter, thus making laser-sintering more productive. In this paper, the focus-dependent melt pool formation is examined in correlation to different hatch distances during the laser-sintering of polyamide 12. For this purpose, a test specimen was developed which can display single tracks as well as a multitude of different track widths for all feasible focus level variations. This knowledge is required to determine and investigate the track width-dependent melt pool formation as a function of the focal diameter of the component cross sections.
关键词： Laser-sintering,Focus diameter,Single track,Polyamide 12
更新于2025-09-23 15:21:01
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Effects of raw material ratio and post-treatment on properties of soda lime glass-ceramics fabricated by selective laser sintering
摘要： A reliable method for fabricating soda lime glass-ceramics by selective laser sintering was demonstrated. The effect of the ratio of glass powder to epoxy resin and sintering process on the properties and microstructure of glass-ceramics was investigated. Research shows that: with the improvement of glass powder proportion, sintering shrinkage rate declined and mechanical strength could be improved gradually. When the mass ratio of glass powder and epoxy resin powder was 18:1 and heat-holding at 740℃ for 3 h, the shrinkage rate of the sample was 21.11% and the bending strength reached 95.45 MPa. Therefore, this research laid a foundation for 3D printing to fabricate high performance and complex structure glass-ceramics.
关键词： Selective Laser Sintering,3D printing,Glass-ceramics,Sintering
更新于2025-09-23 15:19:57
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Laser sintering of Cu@Ag core-shell nanoparticles for printed electronics applications
摘要： Bimetallic Cu@Ag core-shell nanoparticles (NPs) were synthesized by the reduction of copper 2-[2-(2-methoxyethoxy)ethoxy]acetate with hydrazine hydrate in benzyl alcohol followed by the reduction of silver ions on the copper surface using a galvanic replacement reaction. Ink consisting of the as-synthesized Cu@Ag NPs dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) was prepared. Thin layers were spin coated on polyimide films using the developed ink. The conductive layer formed in air in the optimized conditions showed an electrical resistivity of 28.5 lX·cm.
关键词： Conductive inks,Laser sintering,Printed electronics,Copper,Core-shell nanoparticles,Silver
更新于2025-09-23 15:19:57
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Temperature field distribution in polymer particles during surface-selective laser sintering
摘要： The dynamics of polymer particle heating by laser irradiation during surface-selective laser sintering (SSLS) has been studied both experimentally and theoretically. Water aerosol wetting of the polymer particle surface was applied to increase the absorbance of thulium fiber laser radiation at 1.96 μm. Theoretical modeling of the laser-induced thermal processes was performed in thermolabile polylactic-co-glycolic acid powder coated with a thin water layer. Temperature gradients on the surface and inside the sintered particle volume were evaluated and analyzed. It was shown that for certain optimized SSLS parameters an effective sintering process can be achieved by delicate melting of the particle surface only, without noticeable changes in the chemical and phase compositions of the internal domains.
关键词： surface-selective laser sintering,thermal imaging,polymer particles,wetting,analysis of thermal processes
更新于2025-09-23 15:19:57