Search Results (146)

The accurate evaluation of gastrointestinal (GI) diseases such as celiac disease (CeD) relies on the assessment of villous architecture, yet progress in imaging-based diagnostics, particularly video capsule endoscopy (VCE), is constrained by the absence of anatomically realistic and reproducible physical models of the intestinal mucosa. Existing benchtop phantoms typically reproduce gross luminal curvature but fail to capture the sub-millimeter villous microstructure, the optical scattering behavior, and the luminal folding of native mucosa that together shape its endoscopic appearance. We developed a modular fabrication framework for an anatomically realistic small intestinal phantom with controlled villous microstructure. High-resolution drop-on-demand photopolymer material jetting was used to print discrete patches of villous-like micropillar arrays with tunable height, diameter, and spacing parameterized from histological data spanning Marsh 0 to 3c classifications. The printed patches were then dyed for mucosal-color realism, bonded onto a polyester–spandex substrate, rolled into a continuous tube, and shaped with adjustable retainer rings to introduce luminal folds. Optical microscopy confirmed dimensional fidelity within ±10% of design values with patch-to-patch variation below 7%, and VCE imaging of healthy and atrophic configurations achieved structural similarity (SSIM) values of 0.625 and 0.761 against clinical mucosal imagery. This reproducible platform supports VCE device validation, imaging dataset generation, and clinician training in gastrointestinal imaging. Full article

The present work is based on an experimental determination of the mechanical properties of test bodies made using PolyJet technology from the two-component material Digital ABS Plus. The parameters of the 3D printing of the test bodies and their dimensions are presented. The testing methods and equipment for the studied parameters of hardness and roughness are selected. Roughness studies were conducted according to different test body positions and orientations. Hardness studies were carried out according to the Shore D and Rockwell M scales for three types of test bodies: after 3D printing of their surface; inside the test body; and after applying thermal treatment to the test bodies. These indicators are extremely important in the evaluation of details and the possibility of their implementation in the production process. Full article

Conventional typodonts for preclinical operative dentistry are idealised and lack the variability and tactile feedback of natural teeth; virtual-reality and haptic simulators remain costly for large cohorts. This study developed a reproducible, low-cost digital workflow for patient-specific, multi-material 3D-printed dental simulators and evaluated the models from a learner’s perspective. Intraoral and CBCT data from a single de-identified case were co-registered to a Virtual Patient. A modular tooth-socket architecture with trans-apical screw retention allowed repeatable individual tooth replacement; each tooth combined a variable-thickness enamel shell over a dentin core with multi-material carious lesions. Two fabrication routes (MSLA and PolyJet) and an adopted hybrid route (MSLA base, PolyJet teeth) were compared for cost, time and fidelity. The hybrid produced complete bimaxillary models at low consumable cost while preserving the source occlusion and contacts. Fifty dental students evaluated a PolyJet specimen hands-on: didactic utility scored highest (4.32 ± 0.65 on 1–5) and visual realism exceeded tactile realism (p < 0.001); 94% rated it at least comparable to a natural extracted tooth and 62% preferred it, while perceived hardness remained the main limitation. The workflow enables scalable in-house production of patient-specific simulators, with tactile realism the priority for material development. Full article

This publication focuses on the additive technology PolyJet and more specifically the photopolymer Digital ABS Plus. After a thorough analysis, it was concluded that this technology is suitable for both rapid prototyping of parts and rapid small-scale production of various products. The resulting parts can be implemented in a production process with different operating conditions. That is why it is interesting to investigate the Digital ABS Plus material at elevated temperatures. The temperatures at which the tests were performed are consistent with the values for heat deflection temperature (HDT) of the Digital ABS Plus material, described in the manufacturer’s technical data sheet, as well as with the results of high-temperature tests of parts obtained using Fused Deposition Modeling (FDM) technology. The investigated test pieces are subjected to annealing in order to increase their tensile strength and temperature resistance. The process is carried out in an oven with digital temperature control with a thermal profile according to a procedure approved by the manufacturer Stratasys. The obtained data from the mechanical properties before and after annealing of the Digital ABS Plus material are compared and depicted in a diagram. Full article

This study investigates the mechanical behavior and anisotropy of cellular structures fabricated using PolyJet Matrix (PJM) technology from RGD 720 photopolymer resin. Standard ISO 527 specimens were produced at build orientations of 0°, 45°, and 90° to evaluate the influence of printing direction on tensile properties. Based on these results, the optimal 0° orientation was selected for further analysis of cellular structures, including hexagonal, spiral, and quasi-self-similar geometries, manufactured in both unfilled and silicone-filled configurations. Static tensile tests were performed to determine load–displacement characteristics, maximum load, and deformation behavior. The results reveal a strong dependence of mechanical properties on build orientation, with the highest strength observed at 0° and the lowest at 90°, confirming significant material anisotropy. This behavior was further quantified using first- and second-order anisotropy coefficients derived from experimental data. The introduction of silicone filling improved load-bearing capacity, reduced variability, and promoted a more ductile failure mechanism. Among the analyzed geometries, quasi-self-similar structures exhibited the best mechanical performance, while unfilled structures showed lower strength and higher deformation. The findings demonstrate that both build orientation and structural design are critical factors in optimizing the mechanical properties of additively manufactured components and provide a basis for designing tailored cellular structures for engineering applications. Full article

Non-uniform fiber deposition remains a critical limitation in electrospun poly(lactic acid) (PLA) coating systems. In the present study, experimental characterization was combined with numerical simulations to evaluate the influence of electrospinning parameters on fiber morphology, coating uniformity, and thickness distribution. A 3% PLA solution was electrospun under different processing conditions by varying the applied voltage, needle-to-collector distance, flow rate, and deposition time. The resulting coatings were further analyzed using numerical simulations performed with ANSYS Fluent 2020 R2 software. The results demonstrated that both solution-related and operational parameters strongly influence fiber morphology and spatial deposition behavior. Increasing the applied voltage promoted the formation of thinner fibers; however, excessively high voltage values generated jet instability associated with fiber fragmentation and spray formation. Furthermore, the deposited fibrous layers showed preferential accumulation in the central region of the collector, together with a gradual decrease in coating thickness toward the peripheral areas. A strong correlation was observed between the numerical simulations and the experimental results, confirming the reliability of the proposed modeling approach. Among the investigated conditions, the optimal electrospinning parameters were identified as an applied voltage of 16 kV, a needle-to-collector distance of 17 cm, and a flow rate of 2.5 mL/h. These conditions enabled the formation of homogeneous PLA nanofibers with minimal structural defects and improved substrate adhesion. The combined experimental and numerical approach provides valuable insight into the optimization of electrospinning parameters governing fiber formation and deposition behavior. Full article

Objectives: Commercial artificial teeth (AT) and three-dimensional printed teeth (3DPT) have been increasingly used in preclinical endodontic education; however, limitations regarding anatomical realism, tactile sensation, and procedural simulation continued to be reported. This study assessed students’ and evaluators’ perceptions regarding AT and PolyJet™ 3DPT fabricated with RGD525™, compared with natural teeth (NT), together with the quality of endodontic procedures performed using both artificial models. Methods: Undergraduate dental students with no previous experience using AT or 3DPT performed standardized endodontic procedures on both artificial models. Students and evaluators completed questionnaires regarding anatomical realism, tactile sensation, radiographic characteristics, educational applicability, and model preference. Procedural quality and errors were independently assessed radiographically by evaluators. Results: AT received more favorable perceptions regarding external anatomy, whereas 3DPT were more positively evaluated for internal anatomy, radiopacity, resistance of root canal walls and tactile sensation during instrumentation (p ≤ 0.002). NT remained the preferred training model, followed by 3DPT, while AT received the lowest preference ratings (p < 0.001). Evaluators consistently perceived 3DPT as more similar to NT than AT. Regarding treatment outcomes, 3DPT showed significantly higher scores for endodontic preparation, verifier fitting, and root canal filling (p < 0.05), while presenting significantly fewer procedural errors than AT (p < 0.001). Conclusions: PolyJet™ 3DPT fabricated with RGD525™ demonstrated promising applicability for preclinical endodontic training, combining favorable perceptions, fewer procedural errors, and potential for low-cost large-scale in-house production. Nevertheless, improvements in material realism and tactile simulation are still required. Full article

This study aimed to evaluate the aging effect (6 and 12 months), relative to baseline (0 months), on the dimensional accuracy, morphological stability, and shaping behavior of PolyJet™ 3D-printed teeth (3DPT) produced in two printing orientations (X and Y axes). Specimens (XA0, XA6, XA12, YA0, YA6, YA12) were analyzed using microcomputed tomography before and after root canal preparation with the ProTaper Gold^® system. Preoperative analysis included canal volume, centroid, total tooth volume, and total tooth area. Aging-related changes were observed, with significant differences between XA0 and XA12 (p < 0.05), whereas no differences were detected among Y-axis groups (p > 0.05). These findings indicate that X-axis specimens are not comparable over time, while Y-axis specimens maintain baseline consistency. Postoperative evaluation revealed significant differences across aging conditions for most endodontic preparation parameters. Within the limitations of this study, aging had a limited effect on dimensional accuracy but influenced the shaping behavior of 3DPT. Based on these findings, future studies using PolyJet™ 3DPT should report the printing batch and the storage time between fabrication and experimental use, as these factors may influence the comparability and reliability of the results. Full article

Superhydrophobic fiber films, as a typical superhydrophobic material, have advantages such as self-cleaning, non-wettability, and pollution resistance. They can be widely used in oil-water separation, antibacterial, anti-pollution, anti-icing, and self-cleaning fields. Traditional electrospun superhydrophobic fiber films face difficulties in fabricating fibers with large contact angles due to the non-Newtonian fluid flow and Taylor cone jet trajectory limitations. To address this challenge, this study develops a novel ultrasonic-magnetic field coupling electrospinning strategy for fabricating poly(methyl methacrylate)-polystyrene (PMMA-PS) fibrous films with enhanced superhydrophobicity. Physical, chemical, and contact angle measurements were used to analyze the morphology, composition, and hydrophobic properties of the fabricated films. The results showed that by controlling the blend ratio of PMMA and PS and optimizing the electrospinning process with ultrasonic vibration and magnetic field coupling, PMMA-PS fibers with better fiber refinement, closer spindle-shaped arrangements, and significantly increased roughness were successfully fabricated. When using 15% PMMA and 15% PS solutions, the static contact angle of the resulting fiber films reached 173.1°, demonstrating the best superhydrophobicity. The study suggests that optimizing the surface morphology of the nanofibers is an effective method to improve hydrophobicity and provides a new approach for fabricating superhydrophobic fiber films. Full article

Background: Flexible surgical instruments for Robot-Assisted Minimally Invasive Surgery (RAMIS) face a critical limitation: the inability to rotate the distal head while the instrument is in a bent configuration, which restricts the maneuverability in narrow surgical workspaces. Methods: This paper presents a novel 4-degree-of-freedom (DOF) flexible laparoscopic instrument with a 10 mm diameter, incorporating a 3D-printed flexible element. The design enables independent bending (0–90°), continuous distal head rotation (360°), gripper actuation (0–60°), and rod rotation (180°). A constant-curvature kinematic model was developed. The instrument was manufactured using PolyJet 3D printing technology and integrated with the ATHENA parallel robot for proof-of-concept experimental validation. Results: Experimental tests demonstrated successful independent 360° distal head rotation across the full bending range (0–90°), validated through simulated surgical procedures including stomach retraction. Quantitative characterization using optical motion capture revealed a maximum angular deflection of 79.85° at 670 g applied load, with tip displacements of 74.95 mm (X) and 91.18 mm (Y). The measured grasping force was approximately 2 N, tip position repeatability was ±2.86 mm, and fatigue testing demonstrated no degradation after 500 bending cycles, confirmed by digital microscope inspection. The instrument performed multiple manipulation tasks, including elastic band transfer, wire path navigation, spring manipulation, and tissue grasping. Conclusions: The proposed instrument addresses a significant white spot in surgical robotics by adding an additional functional capability enabling grasper reorientation without repositioning the entire instrument. Full article

Electrospinning of poly(lactic acid) (PLA) commonly relies on toxic organic solvents, which limit its sustainability and biomedical applicability. In this work, a green electrospinning process was developed using dimethyl carbonate (DMC), a biodegradable and low-toxicity solvent, combined with acetone as a volatile co-solvent to promote efficient jet solidification. Three commercial PLA grades were evaluated for solubility and spinnability, and PLA 4043D was identified as the most suitable for DMC and acetone systems. The electrospinning parameters, including solvent ratio, flow rate, and applied voltage, were systematically optimized to achieve stable jet formation and uniform fiber morphology. Under optimized conditions, the process produced continuous, bead-free nanofibers with a mean diameter of ~1 µm and uniform nanoscale surface porosity resulting from differential solvent evaporation. The resulting fibers were characterized in terms of morphology, structure, thermal behavior, and mechanical performance, confirming increased amorphous content, high porosity (about 78%), and tensile strength of ~3 MPa for the selected electrospinning condition. This study demonstrates that DMC-based solvent systems enable a sustainable and potentially biocompatible route, considering the lower toxicity of the solvents employed, offering a green alternative to conventional toxic processes for the fabrication of medical scaffolds. Full article

This study aimed to identify the optimal printing orientation (X, Y, or Z axis) and positioning of a mandibular molar presenting an isthmus using PolyJet™ technology. The influence of these parameters on dimensional accuracy and on the behavior of 3D-printed teeth (3DPT) during endodontic preparation with ProTaper Gold^® system was evaluated. Six groups (XA, XB, YA, YB, ZA, ZB; n = 10) were printed with different axis orientations and distinct isthmus positions relative to the build platform. All samples underwent micro-computed tomography scanning before and after endodontic preparation. Regarding preoperative analyses—canal volume, centroids, and total tooth volume and area—no significant differences were found between groups XA–YA or XB–YB (p > 0.05), supporting their comparability. In contrast, groups ZA and ZB differed significantly from all others (p < 0.05), failing to meet equivalence required for further comparison, and were therefore excluded. Postoperative evaluation—volume change, centroid displacement, transportation, and unprepared areas—revealed no significant differences between XA–YA and XB–YB. Within the limitations of this study, both printing orientation and position affected the accuracy and repeatability of 3DPT, with positioning exerting the greatest influence, while their behavior towards endodontic preparation remained consistent across orientations. Full article

The study presented an analysis of the behaviour of cellular structures under bending, produced using the PolyJet Matrix (PJM) additive manufacturing method with photopolymer resin. Structures with regular cell geometry were designed to achieve a balance between stiffness, weight reduction, and energy absorption capacity. The aim of this study was to investigate the influence of unit-cell topology (quasi-similar, spiral, hexagonal honeycomb, and their core–skin hybrid combinations) on the flexural properties and deformation mechanisms of PolyJet-printed photopolymer beams under three-point bending. Additionally, all cellular configurations were fully infiltrated with a low-modulus platinum-cure silicone to evaluate the effect of complete polymer–elastomer interpenetration on load-bearing capacity, stiffness, ductility, and energy absorption. All tests were performed according to bending standard on specimens fabricated using a Stratasys Objet Connex350 printer with RGD720 photopolymer at 16 µm layer thickness. The results showed that the dominant failure mechanism was local buckling and gradual collapse of the cell walls. Among the silicone-filled cellular beams, the QS-Silicone configuration exhibited the best overall flexural performance, achieving a mean peak load of 37.7 ± 4.2 N, mid-span deflection at peak load of 11.4 ± 1.1 mm, and absorbed energy to peak load of 0.43 ± 0.06 J. This hybrid core–skin design (quasi-similar core + spiral skin) provided the optimum compromise between load-bearing capacity and deformation capacity within the infiltrated series. In contrast, the fully dense solid reference reached a significantly higher peak load of 136.6 ± 10.2 N, but failed in a brittle manner at only ~3 mm deflection, characteristic of UV-cured rigid photopolymers. All open-cell silicone-filled lattices displayed pseudo-ductile behaviour with extended post-peak softening, enabled by large-scale elastic buckling and silicone deformation and progressive buckling of the thin photopolymer struts. The results provided a foundation for optimising the geometry and material composition of photopolymer–silicone hybrid structures for lightweight applications with controlled stiffness-to-weight ratios. Full article

The research methodology involved creating a 3D sample model that featured both flat and cylindrical surfaces inclined at angles ranging from 0° to 90° relative to the XY plane. The study investigated the surface topography of additively manufactured samples produced using various technologies, including Fused Filament Fabrication (FFF), masked Stereolithography (mSLA), PolyJet (PJ), and Selective Laser Sintering (SLS). The focus was on how material type, print angle, and measurement location influenced the results. The materials used in the study included PLA, PETG, acrylic resins, PA2200, and VeroClear. Due to the optical properties of the materials used, measurements were carried out on replicas that were prepared using a RepliSet F5 silicone compound from Struers. Consequently, a methodology was developed for measuring surface roughness using the Alicona microscope based on these replicas. A 10× objective lens was used during the measurements, and the pixel size was 0.88 µm × 0.88 µm. Each time, an area of approximately 1 mm × 4 mm was measured. The lowest roughness values were observed for mSLA samples (Sa = 6.72–8.54 µm, Spk + Sk + Svk = 33.36–42.16 µm), whereas SLS exhibited the highest roughness (Sa = 27.86 µm, Spk + Sk + Svk = 183.79 µm). PJ samples exhibited intermediate roughness with significant anisotropy (Sa = 11.65 µm, Spk + Sk + Svk = 72.1 µm), which was strongly influenced by the print angle. FFF surfaces showed directional patterns and layer-dependent roughness, with the Sa parameter being the same (12.44 µm) for both PETG and PLA materials. The steepest slopes were observed for SLS surfaces (Sdq = 7.67), while mSLA exhibited the flattest microstructure (Sdq = 0.48–0.89). Statistical analysis confirmed that material type significantly influenced topography in mSLA, while print angle strongly affected PJ and FFF (although for FFF, further studies would be beneficial). The results of the research conducted can be used to develop a methodology for optimizing the printing process to achieve the required geometric surface structure. Full article

This work presents a multifactorial strategy for reusing waste thermoplastics and generating multifunctional filaments for additive manufacturing. Acrylonitrile–butadiene–styrene (ABS) waste and commercial poly(methyl methacrylate) (PMMA) were compounded with carbon black (CB), graphene (G), or graphene foam (GF) at different loadings and extruded into composite filaments. The aim is to couple filler-induced bulk modifications with atmospheric pressure plasma jet (APPJ) surface coatings of TiO₂ and graphene oxide (GO) to obtain waste-derived filaments with tunable morphology, wettability, and thermal stability for advanced 3D-printed architectures. The filaments were subsequently coated with TiO₂ and/or GO using an APPJ process, which tailored surface wettability and enabled the formation of photocatalytically relevant interfaces. Digital optical microscopy and SEM revealed that CB, G, and GF were reasonably well dispersed in both polymer matrices but induced distinct surface and cross-sectional morphologies, including a carbon-rich outer crust in ABS and filler-dependent porosity in PMMA. For ABS composites, static contact-angle measurements show that APPJ coatings broaden the apparent wettability window from ~60–80° for uncoated filaments to ~40–50° (TiO₂/GO) up to >90° (GO), corresponding to a ≈150% increase in contact-angle span. For PMMA/CB composites, TiO₂/GO coatings expand the accessible contact-angle range to ~15–125° while maintaining surface energies around 50 mN m⁻¹. TGA/DSC analyses confirm that the composites and coatings remain thermally stable within typical extrusion and APPJ processing ranges, with graphene showing only ≈3% mass loss over the explored temperature range, compared with ≈65% for CB and ≈10% for GF. Fused deposition modeling trials verify the printability and dimensional fidelity of ABS-based composite filaments, whereas PMMA composites were too brittle for reliable FDM printing. Overall, combining waste polymer reuse, tailored carbonaceous fillers, and APPJ TiO₂/GO coatings provides a versatile route to design surface-engineered filaments for applications such as photocatalysis, microfluidics, and soft robotics within a circular polymer manufacturing framework. Full article