Search Results (610)

Emerging composite materials are expanding the potential of additive manufacturing and enabling applications previously restricted by traditional manufacturing methods through their multi-phase nature and complex internal geometry. Additionally, these materials can be pyrolyzed to create dense metal, ceramic, and glass parts with geometries typically not achievable by traditional processes. Additive manufacturing of borosilicate glass composites can enable new applications in nuclear engineering, astronomy, and bone regrowth therapy. To elucidate the process–parameter relationship of borosilicate–polylactic acid (PLA) composites, mechanical test specimens were fabricated by fused-filament fabrication and compared with a pure PLA baseline. Optical and scanning electron microscopy were conducted to observe the specimen microstructure before and after testing. From the stress–strain curves, the highest compressive yield strength for the composite was 28.22 MPa, and the highest compressive yield strength for PLA was 49.30 MPa. Print orientation was found to benefit the composite material but have a detrimental effect on the pure matrix material. Borosilicate–PLA with 100% infill, 1 shell wall, and layer lines parallel to compression axis had an elastic modulus of 2.66 GPa. Microscopy revealed that lower-modulus composite specimens had the particulates re-distributed within the matrix. Tensile testing was done according to a polymer testing standard, which caused difficulties obtaining consistent fracture within the gauge length. Full article

The inherent trade-off between strength and toughness in structural materials remains a critical challenge. Inspired by the hierarchical architecture of fish scales, this study proposes a novel overlapping helical composite structure. Multi-material three dimensional (3D) printing technology was employed to fabricate single-edge notched bending specimens. Quasi-static three-point bending experiment was conducted to investigate the mechanical performance of a fish scale-inspired structure. The results show that compared to the stiff bulk structure, the bio-inspired design exhibits a 60.4% enhancement in apparent fracture toughness and a 157.5% increase in energy absorption despite a reduction in flexural modulus and strength. The significant improvement may be attributed to the synergistic effects of crack deflection, which transform the fracture mode from catastrophic brittle failure to progressive damage with a stable post-peak deformation stage. Furthermore, parametric studies reveal that both the linear helical angle and its nonlinear gradient distribution critically govern the toughening efficiency. An optimal linear angle of 19° provides the best overall performance, while a nonlinear gradient (e = 1.75) further shifts energy dissipation towards the post-peak deformation stage, achieving a higher toughening efficiency. This work establishes a fundamental understanding of an overlapping helical coupling toughening strategy and provides a promising design route for high-damage-tolerance composite structures. Full article

Auxetic polymers offer a route to deformation-activated sealing by transforming axial deformation into lateral expansion, enabling controlled conformity and retention within perforated structures. This paper presents the design-space-guided optimisation of a multi-material polymeric auxetic plug for mechanically activated sealing of circular perforation surrogates relevant to military ground-vehicle structures using a controlled thin-wall surrogate validation framework. The sealing combines an SLA-printed Elastic 50A photopolymer auxetic body with TPU 95A load-transfer and priming components. A parameterised re-entrant unit cell was optimised using response-surface design of experiments coupled with nonlinear finite-element analysis. The optimised geometry, with a height of 6 mm, length of 5 mm, strut thickness of 1.25 mm, and re-entrant angle of 31°, achieved a predicted negative Poisson’s ratio of −2.66 under 20% axial strain. Experimental validation using additively manufactured unit cells confirmed the intended auxetic deformation response. The optimised structure was then integrated into a multi-material plug and tested against a solid polymer benchmark, achieving sealing to approximately 22 kPa with improved anchoring across the tested 22–25 mm perforation range. The results establish a mechanism-driven pathway from polymer auxetic unit-cell optimisation to plug-level pressure-sealing performance, demonstrating the potential of multi-material auxetic architectures as deformation-activated sealing systems for temporary repair of perforated military ground-vehicle structures. Full article

Accurate prediction of the mechanical performance of polymer components fabricated by fused deposition modelling (FDM) remains challenging owing to the complex nonlinear relationships between process parameters and material properties, limiting reliable process planning and broader industrial adoption of polymer additive manufacturing. This study develops and experimentally validates a heterogeneous multi-output stacked ensemble learning framework for the simultaneous prediction of tensile strength, flexural strength, compressive strength, Rockwell hardness, and Charpy impact strength of acrylonitrile styrene acrylate (ASA), a high-performance engineering thermoplastic with excellent weatherability and ultraviolet resistance that remains comparatively underexplored in data-driven FDM research. A Definitive Screening Design (DSD) was employed to investigate eight critical process parameters: extrusion temperature (ET), bed temperature (BT), infill density (ID), layer height (LH), print speed (PS), raster angle (RA), build orientation (BO), and cooling fan speed (CFS). Multiple supervised learning algorithms were systematically benchmarked, and the highest-performing complementary models were integrated into a heterogeneous stacked ensemble for simultaneous multi-output prediction. The proposed framework achieved an overall R² of 0.9943 with an overall RMSE of 0.9758, while the individual prediction models attained R² values ranging from 0.9898 to 0.9967. Beyond improving predictive accuracy, the proposed AI-assisted framework provides a data-driven basis for mechanical-property prediction and establishes a surrogate modelling framework that may subsequently be coupled with dedicated optimization or decision-making methods. Full article

Polylactic acid (PLA) is widely used in fused deposition modeling (FDM) due to its excellent mechanical properties and processability. However, its inherent brittleness significantly restricts its application in load-bearing and high-toughness scenarios. To address this limitation, this study establishes a multi-objective optimization framework that integrates single-factor experiments, Box–Behnken design (BBD), response surface methodology (RSM), and entropy weight-based objective weighting to simultaneously enhance the tensile strength, elongation at break, and flexural strength of FDM-printed PLA/thermoplastic polyurethane (TPU) blends. Through single-factor experiments, the optimal PLA/TPU blend ratio was determined as 80:20, achieving a tensile strength of 38.93 MPa, an elongation at break of 14.12%, and a flexural strength of 42.33 MPa—representing improvements of 39.4%, 15.7%, and 31.6%, respectively, over the 70:30 blend. Multi-scale characterization via FTIR, XRD, and SEM reveals that this enhanced performance arises from strong interfacial hydrogen bonding, a well-retained crystalline PLA framework, and the uniform dispersion of fine TPU domains. Subsequently, a four-factor, three-level BBD was employed to investigate the effects of printing speed, nozzle temperature, raster angle, and layer height on the mechanical properties. The entropy weight method assigned objective weights of 0.4924, 0.0901, and 0.4805 to the three properties, yielding a comprehensive score as the evaluation index. Unlike conventional approaches that rely solely on software-recommended optima from RSM models, this study critically compares two decision routes: secondary RSM modeling followed by continuous optimization versus direct ranking of BBD experimental data. Direct ranking identified the optimal parameter set (90 mm/s, 200 °C, 0° raster angle, 0.2 mm layer height) with a comprehensive score of 0.9614, surpassing the RSM-recommended route (70 mm/s, 200 °C, 0° raster angle, 0.2 mm layer height; score 0.7366) by 30.5%. This comparison demonstrates that, in strongly nonlinear FDM processes, software-based continuous optimization may converge to mathematically conservative suboptimal regions, whereas direct ranking of discrete experimental data preserves full physical responses and captures higher-order synergistic effects that the RSM model fails to account for. ANOVA results further confirm that raster angle is the most influential factor affecting the comprehensive score. Overall, this work bridges material formulation and printing parameter optimization for PLA/TPU blends, offering a validated strategy for high-performance FDM manufacturing. Full article

Background: Iodine is an essential micronutrient required for foetal development, cognitive function, and metabolic regulation; however, suboptimal iodine status remains a public health concern in Europe and other regions. Improving food literacy related to iodine may support healthier dietary choices during adolescence, a critical life stage for establishing long-term habits. This intervention development study describes the development of The ABC of Iodine Teaching Programme within the EUthyroid2 project, designed to enhance iodine-related knowledge and awareness among adolescents aged 13–17 years across six regions (UK, Republic of Cyprus, Slovenia, Germany, Bangladesh, and Pakistan). Methods: The intervention was developed according to the Behaviour Change Wheel, targeting capability, opportunity, and motivation, and informed by guidance for complex interventions. The programme was comprised of three flexible, culturally adapted modules integrating lectures on iodine physiology, deficiency risks, WHO recommendations, and locally relevant dietary sources. Active learning strategies, including collaborative tasks and personalised feedback through an Iodine Feedback Tool, were included. Materials were translated and adapted to local contexts and implemented in a hybrid format combining printed booklets with QR-linked digital resources. Results: The primary outcome of the intervention development process was The ABC of Iodine Teaching Programme, a multi-component, scalable educational intervention aligned with principles of food literacy, active learning and behaviour change theory. It incorporated behaviour change techniques and context-specific adaptations to facilitate engagement and knowledge acquisition in school settings. The programme is currently under evaluation in participating regions. Conclusions: This study presents the systematic development of a complex teaching programme. By combining behaviour change theory with innovative and context-sensitive educational strategies, The ABC of Iodine Teaching Programme provides a flexible and scalable framework for improving iodine-related food literacy among adolescents. Its effectiveness will be determined through the ongoing evaluation studies. Full article

Polymer-based three-dimensional (3D) printing has evolved from a prototyping approach toward a manufacturing strategy with emerging clinical relevance for individualized dosage forms, local drug depots, microneedle systems, microfluidic cartridges, biosensor housings and integrated theranostic platforms. Its value arises from the simultaneous control of polymer chemistry, device architecture and process history: infill, porosity, shell thickness, crosslink density, swelling, degradation and surface chemistry can be used as design variables rather than incidental manufacturing outcomes. This review critically synthesizes recent progress in polymer-enabled additive manufacturing for drug delivery and diagnostic applications, with emphasis on thermoplastic and biodegradable polymers, hydrogels, photopolymers, elastomers, conductive composites, stimuli-responsive networks and bioinks. Fused deposition modelling, hot-melt extrusion, semi-solid extrusion, vat photopolymerization, two-photon polymerization, selective laser sintering, binder jetting and inkjet/aerosol jet approaches are compared in relation to drug stability, diagnostic compatibility, feature resolution, scalability and regulatory risk. Particular attention is given to geometry-controlled release, multi-drug printlets, microneedles, implants, scaffold-based local therapy, microfluidic diagnostics, electrochemical biosensors and wearable or closed-loop systems. Translation is discussed through quality-by-design, critical material attributes, critical process parameters, process analytical technology, extractables/leachables, sterilization, point-of-care manufacturing, data integrity and clinical evidence requirements. Future advances should connect polymer–process–property relationships with clinically meaningful use cases, verified quality attributes and realistic regulatory pathways. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

This paper presents the design and development of a laboratory-scale 3D printing platform intended for research on sustainable construction materials. The growing interest in low-carbon and locally available materials, including clay, geopolymers, recycled aggregates, and bio-based composites, has increased the need for flexible experimental printing systems. However, most existing construction 3D printers are designed for industrial applications and remain costly, bulky, or limited to specific material categories. The proposed platform was developed using a Model-Based Systems Engineering approach in order to structure the design process and establish links between user needs, system requirements, functions, and physical components. The platform is based on modular Cartesian architecture and includes interchangeable extrusion systems. A syringe extruder is used for relatively fluid materials such as clay slurries, ceramic pastes, gypsum-based mixtures, and fluid geopolymers, while a screw extruder is designed for more viscous materials such as mortars, cement-based mixtures, and dense geopolymer pastes. The system also integrates motion-control components, material feeding devices, monitoring elements, and safety functions to ensure stable and repeatable printing conditions. The platform is intended to support the evaluation of printability, material flow, layer deposition, dimensional stability, and interlayer bonding. By combining a flexible hardware configuration with an MBSE-based design methodology, the proposed system provides a practical research tool for the development and validation of sustainable construction materials. It also creates opportunities for future work on multi-material printing, automated process control, and digital manufacturing applications. Full article

Functional nanomaterials, such as functionalized nanoparticles, nanofibers, nanocrystals, MXene and liposomes, have emerged as game-changers in tissue engineering, enabling precise modulation of cellular behaviors and dynamic biomimetic microenvironments. This review comprehensively summarizes and discusses the cutting-edge applications of nanomaterials in tissue regeneration (including bone, skin, neural and cardiac tissue regeneration), with a focus on their unique physicochemical properties (e.g., stimuli-responsiveness, nano-topography) and hybrid system design. Recent breakthroughs include 4D-printed shape-memory nanocomposites for irregular bone defects and “smart” wound dressings integrating antibacterial nanoparticles with real-time biosensing. However, clinical adoption remains constrained by unresolved challenges in biocompatibility, scalability of nanomanufacturing, and regulatory ambiguities. We critically analyze these barriers and propose a translational roadmap leveraging AI-driven material design and multi-omics validation platforms to accelerate commercialization. Full article

This in vitro study compared the fracture load of multilayer zirconia onlay restorations with different yttria contents after thermomechanical aging. Standardized CAD/CAM-fabricated onlay restorations were produced from three multilayer zirconia materials: one color-gradient material (KATANA Zirconia UTML; 5Y-TZP) and two strength-gradient materials (KATANA Zirconia YML, 3–5Y-TZP; IPS e.max ZirCAD MT Multi, 4–5Y-TZP) (n = 10/group). The restorations were cemented onto three-dimensionally printed resin dies and subjected to 240,000 loading cycles and 5000 thermal cycles. Fracture load was measured using a universal testing machine, and the data were analyzed by one-way analysis of variance, Tukey’s post hoc test, and Weibull analysis (α = 0.05). Fracture load differed significantly among the materials (p = 0.017). The UTML group (395.73 N) exhibited a significantly lower fracture load than the YML group (618.19 N), whereas the ZirCAD MT Multi group (565.24 N) did not differ significantly from either of the other two groups. Weibull analysis revealed no significant differences in modulus among the groups, whereas the characteristic load of the UTML group was significantly lower than that of the other two materials (p = 0.002). Within the conditions of this in vitro study, the strength-gradient materials, which contain lower yttria concentrations in their underlying layers, showed higher fracture loads after thermomechanical aging than the color-gradient material. These findings are limited to the tested laboratory conditions and require clinical confirmation. Full article

As the population ages, the demand for customizable, resorbable bone implants in tissue engineering has intensified, outstripping the limitations of traditional autografts and allografts. While silicate-based bioactive glasses dominate bioactive glass research, borate-based bioactive glasses (BBGs) present distinct biomimetic advantages due to their accelerated degradation kinetics and superior ion-release profiles. However, producing highly pure, homogeneous BBG powders tailored for additive manufacturing remains a severe bottleneck. This study reports the development of a highly efficient synthesis protocol and subsequent Digital Light Processing (DLP) 3D printing of BBG scaffolds. An aqueous-based precursor mixture was processed via spray drying and a customized multi-stage thermal pretreatment sequence up to 800 °C to mitigate material loss, minimize oxide evaporation, and completely eliminate carbonates. Subsequent “flash melting” at 1150 °C for 20 min yielded an amorphous, high-purity borate–phosphate glass network (68.1B₂O₃-3.8Na₂O-18.9CaO-4.9MgO-4.3P₂O₅, in wt%). Differential scanning calorimetry (DSC) revealed a glass transition temperature ($T_g$) of 625 °C, while in situ X-ray diffraction localized the onset of crystal nucleation between 706 °C and 723 °C. Following fine planetary milling to achieve a highly dense particle packing distribution (D_v50 = 5.4 µm, D_n50 = 0.6 µm), the optimized BBG powder was successfully loaded into an acrylate-based photosensitive slurry (51.2 wt% solid loading) to manufacture complex 3D biomimetic gyroid scaffolds via DLP. While the structural feasibility of printing high-resolution gyroid porous architectures is validated, post-printing evaluation highlighted a narrow thermal processing window; sintering at 660 °C optimized particle coalescence while minimizing microstructural de-densification caused by closed porosity expansion (which reaches 48.4% at 675 °C). This scalable synthesis-to-printing workflow offers a crucial steppingstone toward next-generation fully resorbable bone tissue scaffolds. Full article

Cross-contamination during metal powder blending in multi-material laser powder bed fusion (PBF-LB/M) is a common production challenge and a key barrier to the wider industrial adoption of the process. In the present investigation, the effect of different CuCr1Zr foreign-particle cross-contamination rates of up to 5.0 wt.%, simulating different cross-contamination levels in an AlSi10Mg feedstock for PBF-LB/M, is examined. The resulting metallurgical features and tensile mechanical properties of the produced components were compared to those of reference specimens manufactured from uncontaminated powder. A microstructural analysis of CuCr1Zr contaminated samples revealed characteristic Cu-rich regions, demonstrating that the higher the level of cross-contamination is, the larger these regions are. Tensile yield stress is almost linearly increased with the contamination level while the opposite trend is noticed for tensile elongation at fracture. Two different stages of strain-hardening were noticed, with Stage I exhibiting a lower strain-hardening exponent, while higher strain-hardening exponents (>0.27) were noticed for Stage II, with the latter decreasing with increasing cross-contamination level. The tensile mechanical behaviour of PBF-LB/M specimens was evaluated for the first time with appropriate quality indices, which were initially developed for similar cast aluminium alloys. Overall, the quality index accounting for global tensile performance was decreased for all build directions with increasing cross-contamination level. Despite the lower quality index at the non-contamination level, the inclined (45°) printed specimens presented quality indices that were almost unaffected by the cross-contamination level. Full article

Additive manufacturing has evolved beyond monomaterial fabrication, enabling the integration of dissimilar polymers within a single structure to achieve spatially tailored properties. In Fused Filament Fabrication (FFF), however, the discrete, layer-wise deposition and inherent material incompatibilities make the interfacial region a critical determinant of structural integrity. Rather than acting as a simple boundary, the interface governs stress transfer, damage initiation, and failure propagation, especially in biodegradable polymer systems where thermal and rheological mismatches are pronounced. This study investigates bi-component FFF structures manufactured from PLA and PLA/PHA using mechanically interlocked interface geometries (T-type and dovetail configurations). Mechanical performance was assessed through tensile, flexural, and Charpy impact testing, complemented by fracture analysis, surface topography evaluation, and X-ray Computed Tomography (XCT) for internal defect characterization. The results establish correlations between interface design, defect distribution, and overall structural response. Full article

Additive manufacturing [AM; three-dimensional (3D) printing] is reshaping heterogeneous photocatalysis by enabling architected materials and devices that span from centimeter-scale monoliths to micro- and lab-on-chip reactors. Heterogeneous photocatalysts have traditionally been deployed as powders or simple coatings, which offer high activity but suffer from mass-transfer limitations, poor light utilization and difficult recovery. Three-dimensional (3D) printing now allows precise control over macroscopic geometry, internal channel networks and micro-/nano-scale surface texturing, creating structured photocatalysts and microreactors that can be tailored for specific photon and flow fields. In contrast to recent reviews that primarily survey materials development or additive-manufacturing routes, this work focuses on photocatalytic microreactors and lab-on-chip devices as multi-scale reactors in which catalyst composition, architected geometry, photon management and hydrodynamics are co-designed across length scales. We summarize three-dimensional 3D-printed photocatalytic systems based on polymer–oxide composites, ceramic scaffolds such as zinc oxide (ZnO)/titanium dioxide (TiO₂) clay monoliths, and laser-written titanium dioxide (TiO₂) nano-architectures, with particular emphasis on microfluidic and lab-on-chip implementations fabricated by fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA), digital light processing (DLP) and laser direct writing (LDW). Based on the literature data and representative case studies, we examine how architected lattices, sponges and microreactor chips affect key performance metrics—apparent rate constants, apparent quantum yield (AQY) and space–time yield (STY)—for the degradation of dyes, antibiotics, detergents and other emerging contaminants in realistic matrices, and we compile reported values to illustrate emerging performance trends and limitations. Representative case studies highlight 3D-printed manganese-doped zinc oxide (Mn:ZnO)-decorated sponges used as modular cartridges for greywater and detergent treatment, as well as laser-written titanium dioxide (TiO₂) nano-photocatalysts integrated into microchannels to couple structured light fields with controlled residence times. Finally, we outline materials and process challenges—including ultraviolet (UV) aging of polymer supports, the energy intensity of ceramic sintering and the lack of standardized testing protocols—and identify future research directions formulti-scalee modeling and techno-economic evaluation of three-dimensional (3D)-printed photocatalytic microreactors and devices. Full article