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Organic room temperature phosphorescence (RTP) from polymers holds significant promise for information encryption and anti‐counterfeiting applications. However, conventional patterning techniques limit the development of advanced RTP encryption, highlighting the need for an efficient method that achieves encryption processes quickly and conveniently. In this study, the UV laser marking machine is applied to create traceless phosphorescent patterns by leveraging the photothermal effect of the laser and the water‐absorbent quenching RTP property of polyacrylamide. A series of biaryl derivative phosphors with low π‐electron numbers are designed to limit UV absorption to below 355 nm, thereby preventing polymer sintering by the UV laser (355 nm). Additionally, two phosphorescent polymers, PB2COOH (phosphorescence lifetime τP = 2.34 s; phosphorescence quantum yield ΦP = 13.59%) and PBN (τP = 1.46 s; ΦP = 20.33%), possessing relatively excellent phosphorescent properties, are obtained. The controllable program and non‐contact processing of the marking machine enable the rapid realization of complex patterns, such as the Twelve Chinese Zodiac Signs, effectively overcoming the constraints of traditional techniques. Based on this laser technology, applications such as dual‐locking QR (quick response) codes, misleading double QR codes, labeling, and other advanced encryption methods are developed. [ABSTRACT FROM AUTHOR]

Herein, a novel metallization technique is reported for crystalline silicon heterojunction (SHJ) solar cells in which silver (Ag) fingers are printed on the SHJ substrates by dispensing Ag nanoparticle‐based inks through a needle and then sintered with a continuous‐wave carbon dioxide (CO2) laser. The impact of the Ag ink viscosity on the line quality and the line resistance is investigated on three Ag inks with different viscosities. Increasing ink viscosity yields higher Ag contact heights, larger aspect ratios, and lower line resistance values. The Ag line height increases from less than a micrometer to ≈18.62 ± 3.48 μm with the increasing viscosity. Photoluminescence imaging shows that the low‐resistance Ag metal contacts obtained do not result in any passivation damage of the SHJ substrate. This is because the wavelength of light emitted from the CO2 laser (i.e., 10.6 μm) leads to optical absorption in the Ag, but this light is effectively transparent to the transparent conductive oxide film, amorphous silicon films, and crystalline silicon substrate. Bulk resistivity values as low as 6.5 μΩ cm are obtained for the laser‐sintered Ag contact and printed using the Ag ink with the highest viscosity in this work. [ABSTRACT FROM AUTHOR]

Background: Exploring the integration of 3D‐printing technology in space maintainer (SM) manufacturing could offer innovative solutions and insights for enhancing SMs. Aim: To compare the clinical success, retention, and periodontal effect of traditional band–loop (TBL) SMs with 3D‐printed SMs. Design: Seventy children (mean age: 6.99 ± 1.18) were divided into two groups. Laser sintering (LS) group (n = 34): Patients were scanned with an intraoral scanner. SMs were produced with LS 3D‐printing method from a titanium‐based metal powder. T group (n = 36): Impressions were taken with alginate. SMs were produced by adjusting the bands and soldering the wires on the model. The retention and effects on oral hygiene of the SMs were evaluated at the sixth month. Preference for impression technique was assessed by a five‐question survey. Results: Thirty‐eight percent of T SMs and 66% of LS SMs failed (p =.007). The mean survival time was significantly higher in the T group (p =.035). No difference was found between the initial and control full‐mouth Gingival Index (GI) and Plaque Index (PI) values of the two groups. Both groups had increased GI/PI values in abutment teeth. Patients in the LS group interpreted their impression experience more positively. Conclusion: It is important to provide oral hygiene education before applying fixed SMs and utilize more digital workflow in paediatric dentistry. [ABSTRACT FROM AUTHOR]

Liquid metal is a compelling material for making soft and stretchable devices due to its high electrical conductivity and extreme stretchability. One way to pattern liquid metal is to nebulize it into small droplets, spray it onto a surface as a film, and then use a laser to "sinter" it into circuit patterns. Here, it is shown that including poly(amic acid) in the spray‐deposited film has multiple benefits: it (1) allows the unsintered regions to be removed easily, (2) lowers the power required for sintering, (3) converts to carbon upon exposure to create a carbon‐metal composite, and (4) increases the surface area of the film by 2632% compared to bulk EGaIn. The conductive liquid metal‐carbon circuits can also be transferred to a soft substrate to produce stretchable conductors. The circuits slightly increase in conductivity up to ≈30% strain and then decrease such that by 100% strain, the resistance is only ≈1.02 times its initial resistance. Lastly, the film is highly reactive with water molecules in the air, increasing in resistance over time in humid conditions. The high reactivity and surface area of the film indicate potential applications in batteries, catalysts, and capacitors. Meanwhile, the facile patterning indicates potential applications in soft circuits. [ABSTRACT FROM AUTHOR]

In rapid development, Selective Laser Sintering (SLS) creates prototypes by processing industrial materials, for example, polymers. Such materials are usually in powder form and fused by a laser beam. The manufacturing quality depends on the interaction between a high‐energy laser beam and the powdered material. However, in‐homogeneous temperature distribution, unstable laser powder, and inconsistent powder densities can cause defects in the final product, for example, Powder Bed Defects. Such factors can lead to irregularities, for example, warping, distortion, and inadequate powder bed fusion. These irregularities may affect the profitable SLS production. Consequently, detecting powder bed defects requires automation. An ensemble learning‐based approach is proposed for detecting defects in SLS powder bed images from this perceptive. The proposed approach first pre‐processes the images to reduce the computational complexity. Then, the Convolutional Neural Network (CNN) based ensembled models (off‐the‐shelf CNN, bagged CNN, and boosted CNN) are implemented and compared. The ensemble learning CNN (bagged and boosted CNN) is good for powder bed detection. The evaluation results indicate that the performance of bagged CNN is significant. It also indicates that preprocessing of the images, mainly cropping to the region of interest, improves the performance of the proposed approach. The training and testing accuracy of the bagged CNN is 96.1% and 95.1%, respectively. [ABSTRACT FROM AUTHOR]

Refractory metals offer exceptional benefits for high temperature electronics including high‐temperature resistance, corrosion resistance and excellent mechanical strength, while their high melting temperature and poor processibility poses challenges to manufacturing. Here this work reports a direct ink writing and tar‐mediated laser sintering (DIW‐TMLS) technique to fabricate three‐dimensional (3D) refractory metal devices for high temperature applications. Metallic inks with high viscosity and enhanced light absorbance are designed by utilizing coal tar as binder. The printed patterns are sintered into oxidation‐free porous metallic structures using a low‐power (<10 W) laser in ambient environment, and 3D freestanding architectures can be rapidly fabricated by one step. Several applications are presented, including a fractal pattern‐based strain gauge, an electrically small antenna (ESA) patterned on a hemisphere, and a wireless temperature sensor that can work up to 350 °C and withstand burning flames. The DIW‐TMLS technique paves a viable route for rapid patterning of various metal materials with wide applicability, high flexibility, and 3D conformability, expanding the possibilities of harsh environment sensors. [ABSTRACT FROM AUTHOR]

Pronounced magnetocaloric effects are typically observed in materials that often contain expensive and rare elements and are therefore costly to mass produce. However, they can rather be exploited on a small scale for miniaturized devices such as magnetic micro coolers, thermal sensors, and magnetic micropumps. Herein, a method is developed to generate magnetocaloric microstructures from an equiatomic iron–rhodium (FeRh) bulk target through a stepwise process. First, paramagnetic near‐to‐equiatomic solid‐solution FeRh nanoparticles (NPs) are generated through picosecond (ps)‐pulsed laser ablation in ethanol, which are then transformed into a printable ink and patterned using a continuous wave laser. Laser patterning not only leads to sintering of the NP ink but also triggers the phase transformation of the initial γ‐ to B2‐FeRh. At a laser fluence of 246 J cm−2, a partial (52%) phase transformation from γ‐ to B2‐FeRh is obtained, resulting in a magnetization increase of 35 Am2 kg−1 across the antiferromagnetic to ferromagnetic phase transition. This represents a ca. sixfold enhancement compared to previous furnace‐annealed FeRh ink. Finally, herein, the ability is demonstrated to create FeRh 2D structures with different geometries using laser sintering of magnetocaloric inks, which offers advantages such as micrometric spatial resolution, in situ annealing, and structure design flexibility. [ABSTRACT FROM AUTHOR]

Compared with silver nanowires and silver nanospheres, silver nanocubes and silver nanoplates with larger curvature structures like sharp vertices and edges have great potential in optical applications. In general, the controllable joining of silver nanomaterials has become an effective way to change the electrical and optical properties of silver nanomaterials in recent years. However, urgent research on the controllable joining of silver nanocubes or silver nanocubes is still rarely reported. After being thermal treated at 250 °C for 8 min, a good joining among silver nanocubes can be obtained without significant damage to the cubic structure. For laser sintering, with the increase of laser energy input, silver nanocubes gradually transform to spherical particles. Joining among few particles can be observed when silver nanocubes are scanned by 5 W of laser at 1.0 mm s−1. Obvious joining among silver nanocubes can be obtained by thermal treating at 300 °C for 5 min and laser scanning at 7 W at 0.2 mm s−1. Thermal heating is more suitable for forming different degrees of connection between silver nanocubes or between silver nanocubes, while laser treatment is suitable for changing the shape of silver nanocubes or silver nanocubes without obvious connection. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the impact of the print orientation of direct metal laser sintering (DMLS) posts and cores on the fracture resistance and failure patterns of endodontically treated mandibular premolar teeth. Materials and Methods: Sixty intact human mandibular premolars were endodontically treated. The teeth were then randomly divided into four groups (n = 15). Cobalt‐chromium (Co‐Cr) metal posts were fabricated by traditional casting (Group C), and DMLS method in 0‐, 45‐, and 90‐degree print orientations (Group DMLS 0, Group DMLS 45, and Group DMLS 90). The posts and cores were cemented with composite resin cement and subjected to compression test at a crosshead speed of 1 mm/min. Data was analyzed by using one‐way analysis of variance ANOVA and multiple comparison post hoc Tukey tests (α = 0.05). Specimens were viewed under a stereo microscope with x20 magnification to evaluate the fracture types. Results: No significant differences were found among the groups tested in terms of fracture resistance (p > 0.05). Group C and Group DMLS 0 group exhibited similar fracture patterns. Conclusions: It is possible to produce post and core restorations with the DMLS technique and use them clinically. Print orientation did not influence the fracture resistance. However, fracture patterns were different. Group C outperformed all DMLS groups in terms of fracture patterns. [ABSTRACT FROM AUTHOR]

As a 0D material, powder particles can be used to create almost any complicated engineering component by utilizing the high‐performance manufacturing capabilities of additive manufacturing (AM). Although powder‐based AM methods provide an outstanding practical value and development for modern manufacturing world, they continue to face challenges such as a lack of accessible categories, temperature restrictions, and poor performance of molded components. Therefore, researching for new AM materials and procedures has become an extremely necessary endeavor. For this purpose, a firm grasp of the current state of the art of powder‐based AM technologies is imperative. Hence, herein, a comprehensive review is presented on the most widely used powder‐based AM methods, and the materials used by these methods. For each method, the development and current state, operating principles, limitations, and future prospects are summarized. In contrast, for materials, their classifications, properties, and preparation methods are explored in great detail, while also commenting on the specific compatibilities between powder materials and powder methods. Industrial and commercialized applications of powder‐based AM are also presented in this work. Finally, the limitations of the current powder‐based technologies are highlighted, with comments regarding the future of this field. [ABSTRACT FROM AUTHOR]

Additive manufacturing of electronic devices is challenging because plastics and metals, which are both required as insulator and conductor, respectively, have very distinct thermal properties. Despite significant research efforts, the currently available electronic‐printing methods are still limited by low printing speeds and high manufacturing costs. In this work, a hybrid printing method is proposed that combines fused deposition modeling (FDM) with laser sintering to print thermoplastics and copper in a single process. A copper and copper‐oxide composite filament is developed that is compatible with FDM printing. The composite undergoes in situ reduction under laser exposure and produces a highly conductive copper network. Using the home‐developed 3D printer, 3D conductive vias embedded in thermoplastic dielectric are demonstrated. The printed copper electrodes have low resistivity of 4 × 10−4 Ω cm and are compatible with soldering. This novel metal‐deposition approach and setup prove a novel concept for developing modern electronics using additive manufacturing. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study compared the trueness of removable partial denture cobalt‐chromium (Co‐Cr) frameworks fabricated by 3D‐printed pattern casting and those fabricated by selective laser sintering (SLS) with different palate vault depths. Materials and methods: A partially edentulous Kennedy class II mod.1 maxillary model with a deep palatal vault was used, which was modified and duplicated to produce another model with medium palatal vault depth. After model scanning, the partial denture framework was designed using CAD software to fabricate 20 removable partial denture (RPD) frameworks. For each model, two types of frameworks were fabricated. For the 1st type, the 3D‐printed resin patterns were formed using a 3D printer, and then casting was performed (AM‐cast framework). For the 2nd type, a direct metal laser sintering machine was used for the RPD frameworks fabrication (SLS framework). 3D scanning of fabricated frameworks was performed, and the standard tessellation language (STL) file was superimposed over the STL file from the original design, and the average deviation was recorded. Data were statistically analyzed. Results: Two‐way ANOVA test was used, followed by the least significant difference (LSD) for pair‐wise comparisons to estimate any significant differences between groups. The RPD frameworks with high palatal vault depth represent larger discrepancies mean value than that with the medium palatal vault depth with a highly significant statistical difference. SLS shows less deviation than AM‐cast CO‐Cr frameworks with highly significant statistical differences whatever palatal vault depth. Conclusion: RPD metal frameworks fabricated with SLS have better accuracy compared to those fabricated by AM‐cast, regardless of the depth of the palatal vault. [ABSTRACT FROM AUTHOR]

This research study combines surface modification techniques with back‐end‐of‐line (BEOL) methods for cost‐effective, scalable front contact electrode deposition on III–V solar cells. Copper nanoparticle grids are deposited by inkjet printing on surface‐modified III–V solar cells. The deposition of a self‐assembled monolayer (such as 1,8‐octanedithiol) as an intermediate layer is a proven method for surface modification to improve the wettability of the substrate surface and the adhesion of the printed copper nanoparticle structures on the substrate to perform inkjet printing of coherent and narrow electrode structures. Then, the printed copper ink is converted to a conductive copper grid by a picosecond pulsed laser with optimized settings and an additional galvanic plating step is required for the thickening of inkjet‐printed and laser‐sintered seeding layer for solar cell applications. As a result, an ohmic copper contact on III–V layer with low contact resistivity (5 mΩ cm2) is realized successfully. The processed solar cell shows a functioning behavior with 20% conversion efficiency. [ABSTRACT FROM AUTHOR]

Printed magnetic field sensors enable a new generation of human‐machine interfaces and contactless switches for resource‐efficient printed interactive electronics. As printed magnetoresistors rely on scarce or hard to manufacture magnetosensitive powders, their scalability and demonstration of printing with industry‐grade technologies are the key material science challenges. Here, the authors report dispenser printing of a commodity scale nonmagnetic bismuth‐based paste processed by large area laser sintering to obtain printed magnetoresistive sensors. The sensors are printed on different substrates including ceramics, paper, and polymer foils. It is validated experimentally that the peculiar quantum large orbital magnetoresistive effect remains effective in printed bismuth sensors, allowing their operation in high magnetic fields. The sensors reveal up to 146% resistance change at 5 T at room temperature with a maximum resolution of 2.8 μT. If printed on flexible foils, these sensors show resilience to bending deformation for more than 2000 bending cycles and withstand even thermal forming, as relevant for smart wearables and in‐mold electronics. The freedom in the substrate choice and sensor design enabled by dispenser printing allows to implement the proposed sensor technology for different applications focused on touchless interactive platforms, such as advertisement materials, interactive wallpapers, and printed security panels. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a niche process that has seen extensive growth and adoption in the past decade in the industrial sector. Among the AM techniques present on the market today there are identified only a few methods allowing the 3D printing of metallic materials to be of special interest for their applications in various domains like the automotive, aeronautical, and healthcare industries. The most important questions needing answers are how to produce components from metallic materials that have superior qualities like versatility, wear resistance, ease of customization, and ease of integration with existing components. Compared to traditional metalworking methods where it has been studied how the metal behaves and morphs during the process and where it is known exactly what to do in order to modify the properties of the resulting component into a favor metal, AM changes everything, forcing a researcher to start from the beginning. While the technology is starting to be used more and more, the need to find production methods leads to consistent quality products and with outstanding material properties. New methods need to be developed to help attune the properties of the 3D printed parts to the requirements of their respective uses. The present study refers to 3D metal additive manufacturing (MAM), providing an overview on the process itself and its possible results as well as hurdles with added methods to overcome them. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), also known as 3D printing, is associated with significant promise in the manufacturing sector. However, it has been shown that the risk of build failure has a substantial impact on the costs of AM and that this results from a relatively high level of process instability. Importantly, for such a promising technology, the effects of the risk of build failure on energy consumption have not yet been studied, which creates a significant gap in the knowledge of the real environmental performance of AM. This research addresses this gap by investigating the energy consumption of AM subject to the possibility of build failure. This is done by constructing a novel expected energy consumption model, integrating process energy consumption, the energy embedded in the raw material, and the probability of build failure as a function of the number of layers deposited. Model parameters are obtained from a series of build experiments conducted on the AM technology variant polymeric laser sintering, also known as laser powder bed fusion of polymers. The energy consumption model shows that the risk of build failure accounts for a substantial share of overall expected energy consumption, amounting to up to approximately 31% at full capacity utilization. Additionally, this paper uncovers a complex relationship between the risk of build failure and efficiency gains in per unit energy consumption resulting from increasing levels of capacity utilization (Supporting Information S1). [ABSTRACT FROM AUTHOR]

The laser sintering (LS) process has been a very established additive manufacturing (AM) process for many years. Disadvantages of LS are the low material variety and the thermal damage of the not processed material. The low temperature laser sintering attacks at this point and processes powder material at a build chamber temperature lower than the recrystallization temperature. This drastic reduction in temperature results in significantly less thermal damage to the material. This work deals with the low temperature laser sintering (LTLS) of polyamide 12 (PA12) on a commercial, unmodified laser sintering system to compare it to standardly laser sintered PA12 and to create the basis for low temperature laser sintering of high temperature materials on such a system. Initial results by changing the exposure parameters and by fixing parts on a build platform show a processing of PA12 on an EOS P396 at a build chamber temperature of 80°C instead of standard approx. 175°C, which prevents thermal damage of the material. An extensive study of exposure parameters is carried out and the mechanical properties are considered. Furthermore, a first transfer of the method and the results to PA6 is obtained. [ABSTRACT FROM AUTHOR]

Purpose: To compare the load to fracture of cobalt‐chromium (Co‐Cr) 3‐unit posterior fixed partial denture (FPD) frameworks manufactured by conventional and digital techniques and to evaluate the influence of the framework design on the fracture load. Material and methods: Eighty 3‐unit Co‐Cr posterior FPD frameworks were fabricated with two designs: intermediate pontic (n = 40) and cantilever (n = 40). Each design was randomly divided into four groups (n = 10): casting, direct metal laser sintering, soft metal milling, and hard metal milling. After thermal cycling, all specimens were subjected to a 3‐point bending test until fracture. Data were statistically analyzed using one‐way ANOVA, Welch and Brown‐Forsythe test, Ryan‐Einot‐Gabriel‐Welsch F and Tamhane T2 post hoc test, Student's t test, and Weibull statistics (α = 0.05). Results: Significant differences (p < 0.001; F = 39.59) were found among intermediate pontic frameworks (except between laser sintering and hard metal milling), and cantilevered frameworks (F = 36.75) (except between laser sintering and hard metal milling, and casting and soft metal milling). The cantilever groups showed load to fracture values significantly lower than those of the intermediate pontic (p < 0.001; F = 28.29). The Weibull statistics corroborated the results. Conclusions: Hard metal milling and laser sintered frameworks exhibited the highest load to fracture values. However, all tested frameworks demonstrated clinically acceptable load to fracture values. The framework design directly affected the fracture load, with drastically lower values in cantilevered frameworks. [ABSTRACT FROM AUTHOR]

Al2O3‐based green ceramics are prepared by isostatic cold pressing technology. The prepared green ceramics are pre‐sintered at the temperature from room temperature to 1100°C, and then Al2O3 ceramics are prepared by laser sintering. The effects of pre‐sintering temperatures and laser parameters on mechanical properties and the sintering quality are analyzed. The results show that good crystallinity of Al2O3 particles is obtained at a higher pre‐sintering temperature. The flexural strength and density of green ceramics increase with the temperature of heat treatment. The flexural strength decreases slightly at ∼200°C due to the paraffin binder disintegration. The pre‐sintering temperature and laser processing parameters have a significant influence on the sintering quality. With the increase of laser power and laser frequency, dynamic grain growth occurs, and then grains are refined. The majority of plate‐like grains are transformed into long cylindrical‐like grains in the severe densification process. However, porous flocculation microstructures are generated on the samples pre‐sintered at 1100°C after laser sintering, which is due to the material gasification in atmospheric environment during sintering by infrared laser. More uniform microstructure and better sintering quality of samples pre‐sintered at 500°C can be achieved after laser sintering with a relatively narrower grain size distribution. [ABSTRACT FROM AUTHOR]

Commercial UHMWPE powder of 60 µm size (d50) embossed with 2–5 wt% of nanosilica is used as a support for the preparation of core–shell HDPE@silica@UHMWPE particles. The HDPE shell is generated by polymerization of ethylene in toluene slurry after treatment of the silica@UHMWPE with a methyl aluminoxane activated bisimine pyridine iron complex. Heat pressing the powder gives a solid material with identifiable original UHMWPE particles and a layer from fusion of UHMWPE and the surrounding HDPE shell; the properties match those of the UHMWPE base material. The powder flow properties of the HDPE@silica@UHMWPE are insufficient for a powder bed fusion process, a value for the flow function between 2 and 3 is measured in a ring shear tester. Additivation with nanosilica helps to overcome the insufficient flowability and allows the material to be recoated in a power bed fusion system. Laser sintering gives evidence for a substantial mixing and welding of the HDPE shells and UHMWPE. Caking at the surface of the built parts hinders the manufacturing of isolated parts. Further additivation with carbon black reduces the caking; however, the welding within the HDPE@silica@UHMWPE material is much less strong. [ABSTRACT FROM AUTHOR]

The growing demand for flexible and wearable hybrid electronics has triggered the need for advanced manufacturing techniques with versatile printing capabilities. Complex ink formulations, use of surfactants/contaminants, limited source materials, and the need for high‐temperature heat treatments for sintering are major issues facing the current inkjet and aerosol printing methods. Here, the nanomanufacturing of flexible hybrid electronics (FHE) by dry printing silver and indium tin oxide on flexible substrates using a novel laser‐based additive nanomanufacturing process is reported. The electrical resistance of the printed lines is tailored during the print process by tuning the geometry and structure of the printed samples. Different FHE designs are fabricated and tested to check the performance of the devices. Mechanical reliability tests including cycling, bending, and stretching confirm the expected performance of the printed samples under different strain levels. This transformative liquid‐free process allows the on‐demand formation and in situ laser crystallization of nanoparticles for printing pure materials for future flexible and wearable electronics and sensors. [ABSTRACT FROM AUTHOR]

The manufacturing technology of thermoelectric materials is laborious and expensive often including complex and time‐intensive preparation steps. In this work, a laser sintering process of the oxide‐based thermoelectric material Ca3Co4O9 is investigated. Samples based on spray‐coated Ca3Co4O9 were prepared and subsequently sintered under various laser parameters and investigated in terms of the microstructure and thermoelectric properties. Here, the combination of laser sintering and subsequent thermal sintering proved to be a promising concept for the preparation of thermoelectric films. Laser sintering can thus make a great contribution in improving the processing of thermoelectric materials, especially when films are applied that cannot be sintered under pressure. [ABSTRACT FROM AUTHOR]

Peri‐implant diseases are one of the main causes of dental implant failure. New strategies for dental implants manufacturing have been developed to prevent the accumulation of bacteria and related inflammatory reactions. The main aim of this work was to develop laser‐treated titanium surfaces covered with silver that generate a electrical dipole to inhibit the oral bacteria accumulation. Two approaches were developed for that purpose. In one approach a pattern of different titanium dioxide thickness was produced on the titanium surface, using a Q‐Switched Nd:YAG laser system operating at 1064 nm. The second approach was to incorporate silver particles on a laser textured titanium surface. The incorporation of the silver was performed by laser sintering and hot‐pressing approaches. The anti‐biofilm effect of the discs were tested against biofilms involving 14 different bacterial strains growth for 24 and 72 hr. The morphological aspects of the surfaces were evaluated by optical and field emission guns scanning electronical microscopy (FEGSEM) and therefore the wettability and roughness were also assessed. Physicochemical analyses revealed that the test surfaces were hydrophilic and moderately rough. The oxidized titanium surfaces showed no signs of antibacterial effects when compared to polished discs. However, the discs with silver revealed a decrease of accumulation of Porphyromonas gingivalis and Prevotella intermedia strains. Thus, the combination of Nd:YAG laser irradiation and hot‐pressing was effective to produce silver‐based patterns on titanium surfaces to inhibit the growth of pathogenic bacterial species. The laser parameters can be optimized to achieve different patterns, roughness, and thickness of the modified titanium layer regarding the type and region of the implant. [ABSTRACT FROM AUTHOR]

This contribution demonstrates and discusses electrically tunable polymer planar Bragg gratings based on bulk cyclic olefin copolymers. A lithographic single‐writing‐step method and femtosecond laser reductive sintering of copper(II) oxide nanoparticles are subsequently employed in order to generate buried photonic structures and copper conducting paths on top of the polymer substrate. This way, the necessary number of process steps for fabricating a planar polymer‐based electro‐optical device is greatly reduced. The response of a fully electrified grating structure follows temperature changes, induced by the copper conducting path, with sensitivities up to −31 pm K−1. Dilatometric measurements show that the specimen's behavior is correlated to the situationally reduced thermal expansion of the bulk polymer substrate. In consequence, the tuning response of the photonic platform follows a second order polynomial, whereas a direct current of 30 mA, which correlates to a power consumption of 18.3 mW, leads to a local temperature increase and a residual Bragg wavelength shift of 19.6 K and −547 pm, respectively. Moreover, the outstanding flexibility of the proposed fabrication concept is underlined by demonstrating alternative conducting path geometries, whereas one of the additional designs is adapted to control the spectral width of the Bragg grating's reflection peak. [ABSTRACT FROM AUTHOR]

In this paper, we report an ultra‐fast sintering phenomenon of alumina achieved by the scanning laser irradiation method. Using CO2 laser irradiation, we found that micrometer‐sized alumina powder (d50 = 1.2 µm) can be sintered close to full density within a few tens of seconds. The microstructure of laser‐sintered alumina was different from that of the furnace‐sintered alumina. The relative density and grain size of the laser‐sintered alumina gradually decreased from the center of the laser beam to the edge. Anisotropy of the grain size was measured along and perpendicular to the scanning direction. This anisotropy decreased as the scanning speed decreased from 0.1 mm/s to 0.01 mm/s. The sintering master curve of grain size versus relative density, which reflects the sintering mechanism, was found to be affected by the laser scanning speed. When the laser scanning speed was 0.1 mm/s, grain size suppression was found for the almost fully dense alumina. However, at lower scanning speed (e.g., 0.01 mm/s), there was significant grain growth in the regions where the relative density was greater than 90%. These results clearly indicate that alumina can be sintered, in the solid‐state, to a high density in a short time using scanning laser and the microstructure is different from the furnace‐sintered alumina. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of femtosecond laser (Fs) and/or air‐abrasion protocols on surface roughness (Ra) of zirconia and resin bond strength. Eighty zirconia samples were randomly divided into eight subgroups according to surface treatment protocols: Control (C), Air‐abrasion before sintering (ABS), Air‐abrasion after sintering (AAS), Air‐abrasion before and after sintering (ABS + AAS), Fs laser before sintering (FBS), Fs laser before sintering + air‐abrasion after sintering (FBS + AAS), Fs laser after sintering (FAS), and Fs laser after sintering + air‐abrasion after sintering (FAS + AAS). Measurements of Ra values were obtained using a surface profilometer. Surface morphological properties were evaluated with scanning electron microscopy (SEM), and crystallographic changes were examined by X‐Ray diffractometry (XRD). Self‐adhesive resin cement was bonded to zirconia samples, and shear bond strength (SBS) tests were performed. The data were statistically analyzed by one‐way ANOVA, followed by Tamhane tests. The control group displayed the lowest Ra and SBS values among all groups. The highest Ra and SBS values were found in the FBS and FBS + AAS groups. Air‐abrasion applied before sintering significantly increased the Ra of specimens. FAS, FAS + AAS, and ABS + AAS groups exhibited higher SBS values than AAS and ABS (p <.05). Air‐abrasion applied after Fs laser did not produce any significant change in the Ra and SBS compared to Fs laser alone (p >.05). Femtosecond laser application may be a promising method to enhance the surface roughness of zirconia and improve resin bond strength. Air‐abrasion at pre‐ and post‐sintered stages may also be a viable surface treatment option. [ABSTRACT FROM AUTHOR]

The open flow reactor is a kind of reactor with at least one side open to the atmosphere. Open channels have the advantages of simple surface modification, direct cleaning, and relatively simple manufacturing methods. In this article, laser sintering is used to prepare a new type of open flow micro‐reactor. Laser sintering can adjust the surface wettability of phenolic resin to produce hydrophilic and hydrophobic regions, which lead to the formation of open flow reactors. Laminar flow and mixing processes, which usually happen in regular flow reactors, are also observed in the open‐channel reactor. The phenolic resin film can be doped with iron to catalyze the degradation of organic pollutants when they flow along the channel. The catalytic efficiency can still be maintained at about 80% after 8 h degradation. This work will inspire the development of open flow reactors and further expand the practical application of laser‐sintered materials. [ABSTRACT FROM AUTHOR]

Auricular reconstruction is a technically demanding procedure requiring significant surgical expertise, as the current gold standard involves hand carving of the costal cartilage into an auricular framework and re‐implantation of the tissue. 3D‐printing presents a powerful tool that can reduce technical demands associated with the procedure. Our group compared clinical, radiological, histological, and biomechanical outcomes in single‐ and two‐stage 3D‐printed auricular tissue scaffolds in an athymic rodent model. Briefly, an external anatomic envelope of a human auricle was created using DICOM computed tomography (CT) images and modified in design to create a two‐stage, lock‐in‐key base and elevating platform. Single‐ and two‐stage scaffolds were 3D‐printed by laser sintering poly‐L‐caprolactone (PCL) then implanted subcutaneously in five athymic rats each. Rats were monitored for ulcer formation, site infection, and scaffold distortion weekly, and scaffolds were explanted at 8 weeks with analysis using microCT and histologic staining. Nonlinear finite element analysis was performed to determine areas of high strain in relation to ulcer formation. Scaffolds demonstrated precise anatomic appearance and maintenance of integrity of both anterior and posterior auricular surfaces and scaffold projection, with no statistically significant differences in complications noted between the single‐ and two‐staged implantation. While minor superficial ulcers occurred most commonly at the lateral and superior helix coincident with finite element predictions of high skin strains, evidence of robust tissue ingrowth and angiogenesis was visible grossly and histologically. This promising preclinical small animal model supports future initiatives for making clinically viable options for an ear tissue scaffold. [ABSTRACT FROM AUTHOR]

A tolerance analysis approach based on interval arithmetic (IA) is proposed for heterogeneous three‐dimensional (3D) printed patch antennas. Four key parameters—patch length, width, substrate thickness, and material properties—are considered that can introduce errors in the analysis results. Investigating the comprehensive effect of these parameters on resonant frequency and the E/H pattern of the patch is difficult and time‐consuming when classical numerical simulations are employed. Thus, in this work, the four parameters are modeled as interval variables, and the equations between error and resonant frequency and the E/H pattern are derived using IA. Then, for the given tolerances (error intervals), the corresponding resonant frequency interval and E/H pattern interval are calculated using the proposed approach and compared with HFSS simulation results. Some samples of the patch antenna are fabricated via a self‐developed heterogeneous 3D printer, which employs ink injection and laser sintering to fabricate the patch and the microstrip; furthermore, ultraviolet (UV) resin injection and curing are used to fabricate the substrate. The transmission performance of the samples is evaluated by comparing simulation and measurement results to verify the effectiveness of the proposed IA‐based approach. [ABSTRACT FROM AUTHOR]

Large area projection sintering (LAPS) promises to be a new method in the field of additive manufacturing. Developed in the Mechanical Engineering Department, University of South Florida, LAPS uses long exposure times over a broad area of powder to fuse into dense, reproducible materials. In contrast, LS, a common powder‐based additive manufacturing, uses a focused beam of light scanned quickly over the material. Local regions of concentrated high‐energy bursts of light lead to higher peak temperatures and differing cooling dynamics and overall crystallinity. The mechanical properties of laser sintered specimens suffer because of uneven particle fusion. LAPS offers the capacity to fine‐tune fusion properties through enhanced thermodynamic control of the heating and cooling profiles for sintering. Further research is required to identify the relationship between LAPS build settings and part properties to enable the fabrication of custom parts with desired properties. This study examines the influence of LAPS sintering parameters on chemical structures, crystallinity, mechanical, and thermal properties of polyamide‐12 specimens using powder X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, small‐angle X‐ray scattering, scanning electron microscopy, and microhardness testing. It was observed that higher crystallinity was imparted to specimens that were sintered for a shorter time and vice versa. [ABSTRACT FROM AUTHOR]

This study investigates the applications of 3D printing technology in the wiring process used in the field of electronic packaging. A Cu wiring process is developed to replace the expensive Ag‐based alternative primarily used in commercial 3D electronic circuit printing as per industry standards. The substrates needed for our experiments are developed using a 3D printer assembled prior to the research, through which poly‐ether‐ether‐ketone (PEEK) proves to be a high‐strength, high heat‐resistance material capable of undergoing the packaging process. The Cu wiring process is performed via laser sintering in ambient condition using a Cu micro/nanoparticle paste. Adopting this method minimizes the cost and duration of the process without relying on inert atmosphere generation. The optimum laser sintering condition for the Cu paste is found to be two consecutive scans at 20 W. Energy dispersive X‐ray spectroscopy (EDS) measurements show that the oxidation of the surface is about 1.35%, and further oxidation is prevented through epoxy molding. The touch sensor by Cu wiring module operate optimally even a month after its manufacture. 3D printing technology proves to be capable of replacing the wiring process used for electronic packaging. [ABSTRACT FROM AUTHOR]

Rapid laser reactive sintering (RLRS) is an additive manufacturing process which enables the quick and efficient fabrication of a wide range of ceramic-based cells with various geometries and microstructures. Herein, the preparation of La0.8Sr0.2CrO3-δ interconnects by RLRS for solid-oxide fuel/electrolysis cells (SOFC/ECs) is demonstrated. Uniform perovskite structure without residual intermediate phases can be achieved by CO2 laser irradiation at 103W with a scanning speed of 0.07-0.10mm s-1. Narrowing the width of the underlying MgO substrate and deposition of a terpineol-based slurry with a solid loading level of less than 4 gm-2 are found to be critical parameters to avoid cracking and delamination. The optimum laser conditions balance Cr loss and densification of La0.8Sr0.2CrO3-δ resulting in an 11-μm-thick RLRS-derived La0.8Sr0.2CrO3-δ film having a high relative density of 80--95% with a low area specific resistance (ASR) of 0.003 Ω cm² at 600 °C. This ASR is more than 30 times lower than that of furnace-sintered La0.8Sr0.2CrO3-δ in the same thickness range. The RLRS technique is promising for quick and efficient preparation of dense and thin La0.8Sr0.2CrO3-δ which are key components for highly compact SOFC/ECs. [ABSTRACT FROM AUTHOR]

This study presents a new fabrication method for touch screen sensors using inexpensive, flexible, and transparent polyethylene terephthalate (PET) films. In the proposed method, a transparent capacitive touch sensor array is implemented with two independent axes of invisible electrodes consisting of indium tin oxide (ITO) patterns and bridge electrodes. A low‐cost implementation of the bridge electrodes is achieved by using near‐field electrospinning (NFES) method for the conductive lines with linewidth of 3–5 µm. Then, the printed bridge electrode is sintered using green laser without damaging the PET film. It is demonstrated that two transparent electrodes deposited on a single sheet of PET film can detect the touch location by scanning the driving signal while simultaneously measuring the capacitances from the sensing lines connected via bridge electrodes. [ABSTRACT FROM AUTHOR]

Material development is key for continuing the exponential growth in the field of 3D printing. However, 3D printing of polymers by laser powder bed fusion (PBF‐LB) still is limited to a few polymer powder materials, which restricts the range of applications. Tailoring the chemical, rheological, mechanical, or optical properties of the feedstock powder to the requirements of the laser printing process poses a significant challenge. In order to meet global trends in the commercialization of desktop 3D printers, the use of inexpensive and compact diode lasers for PBF‐LB in the visible or near‐infrared range is highly desired. However, at present, only black objects can be printed by desktop laser printers since only commercial carbon black‐based composite powders meet their laser absorption requirements. In this study, a route for tuning the absorption properties of thermoplastic polyurethane polymers and incorporating color into printed objects by using minute amounts (i.e., 0.01 vol%) of highly dispersed plasmonic silver nanoparticles is reported, presenting a new way for colored parts to be produced through laser 3D printing. [ABSTRACT FROM AUTHOR]

The polymer laser sintering (PLS) process is one of the most promising additive manufacturing (AM) technologies for polymeric materials. However, the technique has challenges because the physical, mechanical, and chemical properties of the polymeric powder deteriorate due to the high temperatures prevailing in the build chamber during manufacture. These high temperatures cause agglomeration of powder, which leads to a decrease in the flowability of powder. There is also a related drop in the coalescence of the powder granules during PLS, which results in porosity that undermines the mechanical integrity of printed parts. Moreover, the viscosity of the melt increases due to cross-linking of molecular chains. This, in turn, increases the tensile strength of the printed components at the expense of the percentage elongation at break. Thus, high prolonged processing temperatures decrease the reusability of polymeric materials used in PLS. In this paper, a review of the studies conducted to investigate ways of reducing the effects of high temperature on polymeric powders is presented. [ABSTRACT FROM AUTHOR]

With the continuous development of the electronics industry, in order to meet the requirements of electronic equipment to reduce the size and increase power consumption, the development of high thermal conductivity materials is crucial. In this study, thermally conductive polylactic acid (PLA) composites were prepared by constructing graphene and alumina (Al2O3) hybrid filler network, and it was further successfully used in additive manufacturing. Due to the synergistic effect of Al2O3 and graphene, the resulting composite achieved the thermal conductivity of 2.4 Wm−1 K−1 with 70 wt% Al2O3 and 1 wt% graphene, which are superior to data reported in the literature in the same filler condition. The Al2O3 and graphene hybrid filler network reduced the agglomeration of graphene and the thermal contact resistance between the fillers, thereby leading a faster cooling rate. Furthermore, the obtained thermally conductive PLA composite has good thermal stability at a normal temperature. The PLA composite powder obtained by the cryogenic pulverization can be used in the laser sintering additive manufacturing process to prepare a heat conductive material with a complicated shape. [ABSTRACT FROM AUTHOR]

Prototypes of a special conformal load‐bearing antenna array (CLAA) which has nondevelopable surface, are designed, fabricated, and tested, and the effect of the substrate curvature radius on its EM performance is also researched in this work. A novel three‐dimensional (3‐D) printing technology and fabrication equipment based on micro‐droplet spraying and metal laser sintering are proposed to create patch array and divider network on a non‐developable curved rigid substrate. In order to compare with conventional technology (such as chemical etching), a planar CLAA prototype with two patches, operating frequency at 5GHz, is designed and fabricated by two different technologies, the surface roughness, fabrication tolerance, and EM performance are tested and compared. Finally, a spherical CLAA prototype with eight patches, operating frequency at 13GHz, is designed and fabricated by the novel 3D printing, measured EM performance demonstrate the applicability of additive manufacturing for this special CLAA. [ABSTRACT FROM AUTHOR]

Combining sol‐gel processing and laser sintering is a promising way for fabricating functional ceramic deposition with high dimensional resolution. In this work, crack‐free silica tracks on a silica substrate with a thickness from ~360 nm to ~950 nm, have been obtained by direct exposure to a CO2 laser beam. At a fixed scanning speed, the density and microstructures of the silica deposition can be precisely controlled by varying the laser output power. The porosity of the laser‐sintered silica tracks ranged from close to 0% to ~60%. When the thickness of the silica deposition exceeded the critical thickness (eg, ~2.2 µm before firing), cracks occurred in both laser‐sintered and furnace‐sintered samples. Cracks propagated along the edge of the laser‐sintered track, resulting in the crack‐free track. However, for the furnace heat‐treated counterpart, the cracks spread randomly. To understand the laser sintering effect, we established a finite element model (FEM) to calculate the temperature profile of the substrate during laser scanning, which agreed well with the one‐dimensional analytical model. The FEM model confirmed that laser sintering was the main thermal effect and the calculated temperature profile can be used to predict the microstructure of the laser‐sintered tracks. Combining these results, we were able to fabricate, predesigned patterned (Clemson tiger paw) silica films with high density using a galvo scanner. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) powder with spherical morphology and suitable particle size for selective laser sintering (SLS) was successfully produced by dissolution-precipitation method. The influence of preparation condition on properties of PP powder was investigated. The experimental results show that the optimal preparation conditions are as follows: dissolution temperature being about 166°C, pressure being about 0.7MPa, and the solid-to-solvent ratio being about 0.067g/ml. The prepared PP powder displayed a narrow size distribution with the mean size of about 42.7μm and the apparent density of powder about 0.40 g/cm3. The specimens produced by laser sintering of the PP powder showed smooth appearance and good dimensional accuracy. The tensile strength and impact strength of the sintered parts were 27.9MPa and 6.3KJ/m2, respectively, which are basically equal to the properties of the injection molded parts. [ABSTRACT FROM AUTHOR]

Purpose: To compare the marginal and internal fit of cobalt‐chromium (Co‐Cr) alloy copings fabricated by with lost wax technique (LW), computer‐aided design and computer‐aided manufacturing (CAD/CAM), and direct metal laser sintering (DMLS). Materials and Methods: Thirty‐six tissue level, straight titanium abutments were screwed onto implant replicas. All specimens were embedded in acrylic resin and randomly divided into 3 subgroups according to the fabrication of metal coping: LW, CAD/CAM, and DMLS. In total, 36 (n = 12/group) Co‐Cr implant‐supported metal copings were prepared. Marginal, intermarginal, axial, and occlusal fits of each coping were measured using the silicone replica technique. The data were evaluated statistically using one‐way ANOVA and Bonferioni post‐hoc test (α = 0.05). Results: The CAD/CAM group showed significantly lower marginal fit than the LW group and DMLS groups (p < 0.001). The marginal fit of the LW group was not significantly different from the DMLS group (p = 0.721). No significant difference found among the fabrication methods in terms of intermarginal fit (p = 0.913). The CAD/CAM group showed lower axial fit than the LW group (p = 0.026), but there was no statistical difference between the DMLS group and the LW (p = 0.999) and CAD/CAM groups (p = 0.247). No significant differences found among the fabrication methods in terms of occlusal fit (p = 0.158). Conclusions: The LW and DMLS groups showed better marginal fit compared to the CAD/CAM group; however, the CAD/CAM group was better than the LW group in terms of axial fit. All fabrication methods demonstrated similar intermarginal and occlusal fit. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) have raised a lot of interest, especially as adsorbing materials, because of their unique and well‐defined pore structures. One of the main challenges in the utilization of MOFs is their crystalline and powdery nature, which makes their use inconvenient in practice. Three‐dimensional printing has been suggested as a potential solution to overcome this problem. We used selective laser sintering (SLS) to print highly porous flow‐through filters containing the MOF copper(II) benzene‐1,3,5‐tricarboxylate (HKUST‐1). These filters were printed simply by mixing HKUST‐1 with an easily printable nylon‐12 polymer matrix. By using the SLS, powdery particles were fused together in such a way that the structure of the printed solid material resembles the structure of a powder bed. The MOF additive is firmly attached only on the surface of partially fused polymer particles and therefore remains accessible to fluids passing through the filter. Powder X‐ray analysis of the printed object confirmed that printing did not have any negative impact on the structure of the MOF. CO2‐adsorption studies also showed that the activity of the MOF was not affected by the printing process. SLS offers a straightforward and easy way to fabricate tailor‐made MOF‐containing filters for practical applications. Printing MOFs: In a new approach to metal‐organic framework (MOF) chemistry, selective laser sintering 3D printing was used to prepare macroscopic objects, in which MOF crystals are firmly anchored onto a polymeric support structure. The MOFs retain their functional properties throughout the 3D printing process. [ABSTRACT FROM AUTHOR]

Polyamide 12 (PA12) powder was exposed for up to 3 h to low pressure air plasma treatment (LP‐PT) and several minutes by two different atmospheric pressure plasma jets (APPJ) i.e., kINPen (K‐APPJ) and Hairline (H‐APPJ). The chemical and physical changes resulting from LP‐PT were observed by a combination of Scanning Electron Microscopy (SEM), Hot Stage Microscopy (HSM) and Fourier transform infrared spectroscopy (FTIR), which demonstrated significant changes between the plasma treated and untreated PA12 powders. PA12 exposed to LP‐PT showed an increase in wettability, was relatively porous, and possessed a higher density, which resulted from the surface functionalization and materials removal during the plasma exposure. However, it showed poor melt behavior under heating conditions typical for Laser Sintering. In contrast, brief PJ treatments demonstrated similar changes in porosity, but crucially, retained the favorable melt characteristics of PA12 powder. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a novel texture design for implants surface functionalization, through the creation of line‐shaped textures on Ti6Al4V surfaces and subsequent sintering of hydroxyapatite (HAp) powder into the designated locations. HAp‐rich locations were designed to avoid HAp detachment during insertion, thus guaranteeing an effective osseointegration. This process starts by creating textured lines using a Nd:YAG laser, filling these lines with HAp powder and sintering HAp using a CO2 laser. The adhesion of HAp is known to be influenced by HAp sintering parameters, especially laser power and scanning speed and also by the textured lines manufacturing. Different laser parameters combinations were used to assess the sintering and adhesion of HAp to the textured lines. HAp adhesion was assessed by performing high energy ultrasonic cavitation tests and sliding tests mimicking an implant insertion, with Ti6Al4V/HAp specimens sliding against animal bone. The HAp content retained after these tests was measured and results showed that an excellent HAp sintering and adhesion was achieved when using a scan speed of 1 mm/s and laser power between 9 and 9.6 W. It is important to emphasize that results indicated that the HAp bioactivity was maintained when using these conditions, validating this functionalization process for the production of hip prosthesis with improved bioactivity. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1534–1545, 2018. [ABSTRACT FROM AUTHOR]

Chiral metastructures consisting of ring (polygonal or cubic) nodes and elastic bending ligaments exhibit excellent design flexibility for compliant structures. In this paper, based on rigid cubic node rotation and the kinematic geometrical relations of a three‐dimensional (3D) isotropic anti‐tetrachiral structure, an analytical expression for the modulus of the 3D isotropic anti‐tetrachiral structure is derived from strain energy analysis. The nylon powder Selected Laser Sintering (SLS) additive manufacturing technique is employed for fabricating two types of 3D isotropic anti‐tetrachiral specimens with different geometrical parameters; then comparison between experiments, finite element analysis (FEA), and theoretical studies is performed for verifying the analytical formula. The mechanical properties of 3D isotropic anti‐tetrachiral structures can be tuned with two independent dimensionless geometrical parameters. The proposed 3D anti‐tetrachiral structures can be employed for designing advanced structures against impact damages, realizing flexibility of industrial components, and optimizing the vibration attenuation abilities of engineering structures. [ABSTRACT FROM AUTHOR]

ABSTRACT Polymer laser sintering (LS) is an important additive manufacturing (AM) technology. Individual and complex parts are directly produced from CAD data without the need of specific tools. The raw material is a polymer powder, which is deposited layerwise and melted selectively with a laser. Built parts are embedded in residual unmolten powder, the so-called part cake, which undergoes thermal ageing effects due to the exposure to high temperatures for long times during the manufacturing process. Hence, the recyclability of the unmolten powder is limited. This article focuses on a fundamental analysis of the ageing kinetics dependent on time, temperature, and oxygen content in the gas atmosphere. A model is developed and applied to measured, position-dependent process temperature histories to successfully predict the ageing distribution within a part cake. The results can be used to optimize the thermal process management in LS and to develop new efficient powder recycling methods. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45435. [ABSTRACT FROM AUTHOR]

In this work, the feasibility of processing polylactic acid (PLA) and a PLA/nanoclay composite by laser sintering (LS) were investigated. The morphology of both the PLA and PLA/nanoclay powder was examined by scanning electron microscopy. LS process parameters, especially powder bed temperature, laser power, and laser scan count were studied. The effect of the addition of nanoclay on the thermal and flexural properties of LS PLA parts was examined. The results showed that PLA/nanoclay required a lower processing powder bed temperature compared with neat PLA. Under the same powder bed temperature, PLA/nanoclay parts exhibited an improvement in flexural modulus compared with neat PLA. Flexural modulus was increased significantly with double scan for both neat PLA and PLA/nanoclay LS parts. POLYM. COMPOS., 38:2570-2576, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Clothing could be described as architecture in motion. Julia Koerner, a designer based between Salzburg and Los Angeles, operates at the crossroads between architecture and product design. She has recently been working on a number of projects in the couture field, both independently and in collaboration. Here she describes how these creations - largely inspired by the forms and growth patterns of nature - have utilised various additive manufacturing techniques to explore the possibilities of folding, nesting and smocking in digital space. From seamlessness to the ability to adapt to temperature, light and emotion, these garments appear to naturally grow on the body or to animate it. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) receives an increasing industrial interest thanks to its advantages in the economic production of highly complex and small-series components. Especially laser sintering (LS) is in this context of particular interest for the production of plastic components, as it is generally deemed the most robust AM technology for polymer parts and therefore is expected to enable AM for functional components in the near future. However, to date, designers are often confronted with a severe lack of knowledge on the possible mechanical behavior of AM components. More specifically, the unit-to-unit variability, heterogeneity (within-part variation), and anisotropy of the mechanical properties very often prove to be substantial and therefore require more elaborated studies in order to take these effects into account in the engineering of reliable components. Moreover, typical experimental results that are used for the determination of the elastic stiffness tensor are subject to variability, caused by the influence of the difference in thermal history between produced parts. This work therefore focuses first on the identification and quantification of the variability and heterogeneity in the quasi-static response of laser sintering-polyamide 12 (LS-PA12) components. Second, also the anisotropy in this quasi-static response is studied. For the first part, uniaxial tensile tests are performed and the variability on the quasi-static properties is quantified by means of statistical analysis. Also, the elastic stiffness tensor is identified based on these tests. Next, the heterogeneity in the tested specimens is investigated by means of digital image correlation. Finally, in order to study the anisotropy in the quasi-static properties, the Virtual Fields Method is applied to determine the variability in the elastic stiffness tensor of the LS-PA12 material. A variability with a coefficient of variance of up to 6.5% on Young's modulus was measured. It was also found that the production planning has an important influence on the homogeneity of the mechanical properties of the produced parts. Finally, the Virtual Fields Method showed that, contrary to most literature on the topic, the elastic properties of LS-PA12 material is best described using an isotropic material model. [ABSTRACT FROM AUTHOR]

A novel maskless fabrication method for highly flexible Cu random network transparent conductor has been developed by random nanocrack generation and subsequent Cu nanoparticle ink filling, transfer, and oxidation‐free laser sintering without the aid of conventional photolithography or vacuum metal deposition steps. Use of random nanocrack on a silicon as a transfer printing template enables large area, high resolution network patterning, and fabrication in a simple maskless manner. At the same time, the laser sintering process allows low temperature, fast processing time, and oxidation suppression of Cu nanoparticle under ambient atmosphere. The fabricated Cu metal network establishes strong adhesion to plastic substrates, thus mechanical stability against tensile and compressive bending is attainable. Moreover, the template‐assisted Cu metal network fabrication method minimizes waste of Cu nanoparticle as compared with other methods. A simple touch screen using Cu metal network‐based transparent conductor is also demonstrated. [ABSTRACT FROM AUTHOR]

In this article, we present an experimental study validating the concept of the reinforced-core auxetic assemblies. The main distinctive feature of these assemblies is the presence of a reinforcing core in the microstructural units that increases the shear stiffness and thus produces negative Poisson's ratio. We tested a number of prototypes manufactured using the stereolithography and selective laser sintering methods. To measure the deformations, we employed the close-range photogrammetry method, which enables monitoring of locations of unlimited number of points from digital images. We developed a procedure for multi-point measurement of planar deformations using a single digital camera. This procedure allows for continuous measurement of deformations without interruption to the loading sequence. Camera selfcalibration is based on multiple images of stable reference points, which enables high accuracy of the measurements even using a consumer grade digital camera. We compare the obtained experimental results with a simplified continuum model. We demonstrate a good agreement between the theoretical predictions and the experimental results. [ABSTRACT FROM AUTHOR]