Commercial 3D Research Articles

Multilayered Manufacturing Method for Microfluidic Systems Using Low-Cost, Resin-Based Three-Dimensional Printing

This work presents a multilamination method for fabricating microfluidic devices or analytical microsystems using commercial 3D printers and photocurable resins as primary components. The developed method was validated by fabricating devices for the colorimetric measurement of copper ions in aqueous solutions, achieving results comparable to traditional cyclic olefin copolymer (COC) systems. The microfluidic platforms demonstrated stability and functionality over a twelve-week testing period. Channels with minimum dimensions of 0.4 mm × 0.4 mm were fabricated, and the feasibility of using resin modules for optical applications was demonstrated. This study highlights the potential of combining 3D printing with multilamination procedures as a versatile alternative, offering flexibility through the selection of a variety of available resins and commercial printers, as well as the ease of design development. This method offers significant reductions in cost, time, and manufacturing complexity by eliminating the need for equipment such as CNC machines, presses, and ovens, which are typically required in other multilamination technologies like LTCC and COC.

Optimization of a micro-scale air–liquid-interface model of human proximal airway epithelium for moderate throughput drug screening for SARS-CoV-2

BackgroundMany respiratory viruses attack the airway epithelium and cause a wide spectrum of diseases for which we have limited therapies. To date, a few primary human stem cell-based models of the proximal airway have been reported for drug discovery but scaling them up to a higher throughput platform remains a significant challenge. As a result, most of the drug screening assays for respiratory viruses are performed on commercial cell line-based 2D cultures that provide limited translational ability.MethodsWe optimized a primary human stem cell-based mucociliary airway epithelium model of SARS-CoV-2 infection, in 96-well air–liquid-interface (ALI) format, which is amenable to moderate throughput drug screening. We tested the model against SARS-CoV-2 parental strain (Wuhan) and variants Beta, Delta, and Omicron. We applied this model to screen 2100 compounds from targeted drug libraries using a high throughput-high content image-based quantification method.ResultsThe model recapitulated the heterogeneity of infection among patients with SARS-CoV-2 parental strain and variants. While there were heterogeneous responses across variants for host factor targeting compounds, the two direct-acting antivirals we tested, Remdesivir and Paxlovid, showed consistent efficacy in reducing infection across all variants and donors. Using the model, we characterized a new antiviral drug effective against both the parental strain and the Omicron variant.ConclusionThis study demonstrates that the 96-well ALI model of primary human mucociliary epithelium can recapitulate the heterogeneity of infection among different donors and SARS-CoV-2 variants and can be used for moderate throughput screening. Compounds that target host factors showed variability among patients in response to SARS-CoV-2, while direct-acting antivirals were effective against SARS-CoV-2 despite the heterogeneity of patients tested.

Stress Release of Zincophilic N-Doped Carbon@Sn Composite on High-Curvature Surface of Zinc Foam for Dendrite-Free 3D Zinc Anode.

Commercial 3D zinc foam anodes with high deposition space and ion permeation have shown great potential in aqueous ion batteries. However, the local accumulated stress from its high-curvature surface exacerbates the Zn dendrite issue, leading to poor reversibility. Herein, we have employed zincophilic N-doped carbon@Sn composites (N-C@Sn) as nano-fillings to effectively release the local stress of high curvature surface of 3D Zn foams toward dendrite-free anode in aqueous zinc ion battery (AZIB). These electronegative and conductive N-C@Sn nano-fillings as supporters can provide a highly zincophilic channel for initial Zn nucleation and reduce local current density for regulating Zn deposition. Uniform Zn deposition further assists homogenous stress distribution on the platting surface, which gives a positive feedback loop to improve anode reversibility. As a result, zinc foam with N-C@Sn composite (ZCSn Foam) symmetric cell achieves a long cycle lifespan of 1100h at 0.5mA cm-2, much more than that of Zn Foam (∼80h lifespan). The full cell ZCSn Foam||MnO2 exhibits remarkable reversibility with 67% retention after 1000 cycles at 0.8 A g-1 and 76% after 1600 cycles at 2 Ag-1. This 3D-constructing strategy may offer a promising and practical pathway for metal anode application.

Novel approaches of charging and compounding a single-cylinder diesel engine

Conventionally, charging the single-cylinder engine by turbocharging or supercharging has always been technically challenging. Turbocharging the single-cylinder engine reduces performance due to higher pumping losses and the phase lag between the intake and exhaust valves. Although employing a supercharger enhances the potential for extracting higher power output, the higher brake specific fuel consumption is a disadvantage due to the power consumed by the supercharger. Furthermore, the energy in the exhaust gases is inevitably discharged into the atmosphere. Hence, single-cylinder engines have been significantly underpowered and under-utilized for several decades. The work explores three novel approaches to charge and compound a commercial single-cylinder diesel engine. Firstly, a novel concept of turbocharging the single-cylinder engine using an exhaust plenum was studied. Then, a novel supercharging and turbo-compounding of the test engine is explored, followed by an impulse turbine compounding. All three novel approaches were simulated with a 1D model developed using the commercial 1D simulation software AVL BOOST. Experiments were carried out on the naturally aspirated, supercharged, and turbocharged single-cylinder engine, while simulated results were used on the impulse turbine. Results showed that with the first novel approach, the turbocharged single-cylinder engine delivered 33% higher brake power output with a 345 basis points (3.45% points) improvement in brake thermal efficiency compared to the base naturally aspirated (NA) engine. With the second approach, the supercharged and impulse turbine compounded engine generated 15 kW of power, 47% higher, with 700 basis points (7% points) of improved brake thermal efficiency compared to the base naturally aspirated (NA) engine. The third novel approach delivered 11% higher engine brake power output with 354 basis points improvement (3.54% points) in brake thermal efficiency compared to the base naturally aspirated (NA) engine. All three novel approaches also delivered reduced emissions levels except for oxides of nitrogen (NOx) emissions.

Effects of Recovery and Phase Transformation on the Recrystallization Kinetics of Ti-6Al-4V During β-Processing

This work unifies the description of microstructure evolution during dynamic and static recrystallization of Ti-6Al-4V in a single model. The developed model incorporates the role of dislocation interactions on the phenomenological concepts of dynamic and static recovery, continuous dynamic and static recrystallization, nucleation rate, and grain growth. The β-grain elongation during hot compression and the role of the deformed prior β-grain size on the number of potential nucleation sites are considered to visualize the influence of the initial grain size before deformation on the kinetics of static recrystallization. The model is calibrated and validated with experimental data from Ti-6Al-4V samples thermomechanically treated in the β-domain. Finally, the model is implemented as subroutines into the commercial FEM-based software DEFORM™ 2D. The proposed model accurately predicts I) the flow behavior and grain refinement during supertransus deformation, II) the influence of initial grain size, temperature, and deformation rate on the static recrystallization kinetics, and III) the grain growth kinetics. Simulations of hot forming followed by isothermal heat treatment and continuous cooling show that the Zener drag effect due to the formation of the α-phase has a greater influence on the kinetics of β-recrystallization than the cooling rate itself.

Responsive 3D Printed Microstructures Based on Collagen Folding and Unfolding.

Mimicking extracellular matrices holds great potential for tissue engineering in biological and biomedical applications. A key compound for the mechanical stability of these matrices is collagen, which also plays an important role in many intra- and intercellular processes. Two-photon 3D laser printing offers structuring of these matrices with subcellular resolution. So far, efforts on 3D microprinting of collagen have been limited to simple geometries and customized set-ups. Herein, an easily accessible approach is presented using a collagen type I methacrylamide (ColMA) ink system which can be stored at room temperature and be precisely printed using a commercial two-photon 3D laser printer. The formulation and printing parameters are carefully optimized enabling the manufacturing of defined 3D microstructures. Furthermore, these printed microstructures show a fully reversible response upon heating and cooling in multiple cycles, indicating successful collagen folding and unfolding. This experimental observation has been supported by molecular dynamics simulations. Thus, the study opens new perspectives for designing new responsive biomaterials for 4D (micro)printing.

Fabrication of Patterned TiO2 Nanotube Layers Utilizing 3D Printer Platform and Their Electrochromic Properties

An anodization method can easily fabricate nanostructured oxide layers by controlling electrochemical parameters such as the types of electrolyte solutions, the electrolyte composition, applied voltage/current, temperature and pH. In the anodization process, it is common to form an oxide on the surface of a metal substrate with an area of several to several hundred cm2. However, several approaches have been attempted to form oxide layers on a local area or manufacture a certain oxide layer pattern using the anodization process. For this purpose, partial oxidation can be achieved through the masks and patterned metal substrates can be employed for local anodization. However, these methods are disadvantageous in process-complexity and time-consumption. Therefore, this study realizes complicated patterns composed of anodized TiO2 nanostructures using a 3D printer and apply them to the electrochromic displays. A commercial 3D printer was modified to enable a direct anodization and TiO2 nanotube was anodized on the Ti substrate with the desired pattern designed by a digital code (G-code). High speed anodization was performed at a speed of 1 mm/s. Furthermore, the surface of the patterned TiO2 nanotube was modified by adsorption of the viologen molecules and the electrochromic properties of the viologen-anchored TiO2 (V-TiO2) nanotube layers were investigated.

3D Printed Stent from Graphene-Polyethylene Glycol Diacrylate Using Digital Light Processing Technique

Abstract This paper presents the development of the photocurable resin material based on the graphene reinforced polyethylene glycol diacrylate (gPEGDA) for vascular stent fabrication using a commercial 3D printer. 3D printing with digital light processing (DLP) technique is an attractive alternative for low-cost fast fabrication with high accuracy. Four photocurable resin compositions were prepared by mixing PEGDA and varied composition of graphene and the photoinitiator according to the design of experiment of 22 full factorial design. The diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator was adopted to meet the required 405 nm UV-light source wavelength of the 3D printer for stent fabrication. Material characterization of the UV-absorbance and viscosity tests were conducted and optimized to obtain resin printability. Mechanical characteristics tests were conducted to obtain the best resin composition for stent application. For this purpose, the tensile tests were conducted according to the ASTM D638 standard using the type-V specimen size. The test specimens were 3D printed with varied UV exposure time 20 and 30 seconds. Finally, the stents were successfully fabricated using a commercial 3D printer DLP with the bottom parameter time setting of 60 seconds, and the UV exposure time of 30 seconds. The resin material was applicable for 3D printing of the stent. The result has shown that 3D printer with DLP technique is suitable for stent fabrication with excellent surface quality. Moreover, the innovative bioresorbable stent materials and fabrication approach could open up new possibilities in the development of medical devices, particularly in the treatment of vascular diseases.

Efficient Cross-Linking through C-H Bond Insertion of Unfunctionalized Commodity Materials Using Diazirine-Containing Polymers.

The synthesis and application of multifunctional diazirine-containing polymers for on-demand cross-linking of unfunctionalized commodity polymers through C-H bond insertion is demonstrated. While small-molecule diazirine cross-linkers have seen important applications such as plastic compatibilization and photopatterning, the high degree of functionalization of polymer-based diazirine cross-linkers offers promise for enhanced compatibility based on polymer blending and increased efficiency due to controllable multivalency. As a demonstrative example, unfunctionalized linear poly(n-butyl acrylate) (PnBA) can be cross-linked using various polymeric cross-linkers with diazirine contents as low as 0.8 wt % in 1 min under photochemical conditions. With gel fractions up to 95%, tunable rheological behavior is observed with increasing cross-linker loadings, consistent with a transition from entangled branched polymers to a cross-linked network. Moreover, the synthetic stability of the diazirine units can be exploited to prepare diazirine-containing polymers based on a variety of different backbones, from vinyl copolymers to poly(dimethylsiloxane) (PDMS), which allows successful photopatterning using a commercial 3D printer.

Fabrication of patterned TiO2 nanotube layers utilizing a 3D printer platform and their electrochromic properties

Anodization enables nano-structure fabrication through electrochemical parameter control. While various approaches exist for creating localized or patterned oxide layers, many are complex and time-consuming. This study adopted a commercial 3D printer for high-speed (1 mm/s) anodization, forming TiO2 nanotube layers on Ti substrates in G-code-designed patterns. Comprehensive characterization using XRD, SEM, XPS, and simulated electric field distribution analysis revealed well-defined nanostructures and provided insights into the formation mechanism. Furthermore, viologen-anchored TiO2 showed significantly improved electrochromic performance compared to pristine TiO2, with a higher reflectance difference (46.2% vs. 6.85%). This 3D printing-anodization hybrid method offers a rapid approach to fabricating patterned TiO2 nanostructures, showing promise for electrochromic devices with enhanced optical modulation capabilities.

Sustainable and Recyclable Acrylate Resins for Liquid-Crystal Display 3D Printing Based on Lipoic Acid.

The development of renewable vinyl-based photopolymer resins offers a promising solution to reducing the environmental impact associated with 3D printed materials. This study introduces a bifunctional lipoate cross-linker containing a dynamic disulfide bond, which is combined with acrylic monomers (n-butyl acrylate) and conventional photoinitiators to develop photopolymer resins that are compatible with commercial stereolithography 3D printing. The incorporation of disulfide bonds within the polymer network's backbone imparts the 3D printed objects with self-healing capabilities and complete degradability. Remarkably, the degraded resin can be fully recycled and reused for high-resolution reprinting of complex structures while preserving mechanical properties that are comparable to the original material. This proof-of-concept study not only presents a sustainable strategy for advancing acrylate-based 3D printing materials, but also introduces a novel approach for fabricating fully recyclable 3D-printed structures. This method paves the way for reducing the environmental impact while enhancing material reusability, offering significant potential for the development of eco-friendly additive manufacturing.

Photonic crystal fibers based on Dirac point-guiding

—In this work photonic crystal fibers of different cross-sectional patterns are studied. Dirac points of these various lattices are explored, propagation diagrams showing positions of the Dirac spectrums are obtained, and their application in fiber guiding is discussed. A quasi-3D FDTD simulation method, which is simpler and more efficient than a commercial 3D FDTD simulation software, is developed for photonic crystal fiber. This method is then applied to the new photonic crystal fiber proposed in [Fiber guiding at the Dirac frequency beyond photonic bandgaps, Light Sci. & App. 4 (2015) e304.]. Dirac-point guidance, which is based on Dirac localization of photons, is verified for these fibers.

Surface‐Functionalization of Oleate‐Capped Nano‐Emitters for Stable Dispersion in 3D‐Printable Polymers

AbstractTwo‐photon polymerization 3D‐printing is a well‐known technique for fabricating passive micro/nanoscale structures, such as microlenses and inversely designed polarization splitters. The integration of light emitting nanoparticle (NP) dopants, such as quantum dots (QDs) and rare‐earth doped nanoparticles (RENPs), into a polymer resist would enable 3D printing of active polymer micro‐photonic devices, including sensors, lasers, and solid‐state displays. Many NPs contain oleic acid ligands to prevent degradation, but oleate‐capped NPs (oc‐NPs) tend to agglomerate in nonpolar media despite the hydrophobicity of the ligand. This results in an uneven nanoparticle distribution and increased optical extinction. In this work, a general approach is proposed for dispersing oc‐NPs in commercial 3D printable polymers. Controlled growth of small carbon chains around the oc‐NPs is achieved by functionalizing them with methyl‐methacrylate monomers. The proposed approach is validated on RENPs (≈65 nm) and CdSe/ZnS quantum dots (≈12 nm) using commercial polymer resists (IP‐Dip and IP‐Visio). Dispersions of functionalized NPs (f‐NPs) have improved the NP density by an order of magnitude and are shown to be stable for several weeks with minimal impact on printing quality. The approach is generalizable to other oc‐NPs, enabling synthesis of functional resins for high‐quality polymer‐based optical and electronic devices.

Meshing pair geometry of the intersecting-axis internally geared screw compressor

The Intersecting-Axis Internally Geared Screw Compressor (IISC) is an emerging advanced positive displacement machine showing the potential to greatly broaden the application of screw compressor technology. The core component of the IISC is an internally geared meshing pair with the intersecting-axis gearing, while its design methodology has not been disclosed yet. To fill the gap, this paper established the geometry model for the meshing pair and discussed the influence of its core parameters on geometric performance. First, the generation model of meshing pairs was presented, and the complete parameters set of meshing pairs was defined. The established model was verified by a meshing pair manufactured by 3D printing and CNC techniques. Next, the geometric analysis model of IISCs was established such as working volume and leakage channels, which was verified by commercial 3D software. Using the analysis model, the mesh pair parameters (rotor profile, cone angle, wrap angle, and L/D ratio) were discussed to reveal the design methodology of IISCs. Finally, the variable-pitch technology was discussed, and a novel variable-pitch method was proposed to further enhance the performance of IISCs. This paper could effectively guide the design of IISCs to further promote the development of the screw compressor technology.

A practical approach to build an ultrasonic immersion test setup

Ultrasonic evaluation enables nondestructive defect detection and material characterization in situ and ex situ. Contact ultrasound is used for field inspections due to its portability, although it lacks resolution. Immersion testing offers higher resolution: however, these systems are more expensive and tend to be bulky. The need to balance higher resolution with portability and accessibility presents a significant gap for field testing and academic research. Our project introduces an economical and practical immersion setup. We modified a commercial 3D printer kit by incorporating plexiglass into the aluminum rails and sealing it with silicone paste to ensure watertight integrity. The original servo motors from the printer were repurposed to maneuver a custom transducer holder for precise transducer movement control. This setup achieved a resolution of 500 µm in step size for pulse-echo data collection. Constructed for about $2000 in less than a couple of days, this system exemplifies frugal engineering by delivering ultrasonic evaluations at a fraction of the cost and complexity of conventional systems. This portable setup can serve as an additional step for on-field inspections, providing greater resolution. Beyond industrial applications, it holds potential for enhancing ultrasonic education and workforce development in NDE.

Verification of mean dose in a tumor using 3D-printed tumor-model scintillators in anthropomorphic phantoms and a spherical phantom

To enhance treatment outcomes of radiotherapy, accurate verification of dosimetric parameters such as the mean, minimum, and maximum doses is essential. This study aimed to measure the mean absorbed dose in a tumor-shaped target and compare the results with the calculated value of the treatment planning system. Tumor model scintillators (TMSs) mimicking brain tumors were fabricated with a commercial 3D printer based on stereolithography files of tumors. The TMSs were irradiated following treatment plans made with the Leksell Gamma Plan® (Elekta AB, Stockholm, Sweden), and the mean dose in each TMS was measured three times and compared with the calculated value. Eleven TMSs were set at the center of a spherical solid water phantom. Two additional TMSs were fabricated according to images of vestibular schwannomas and were set at the tumor location in head model phantoms following each patient's head shape. The mean relative differences between the measured and calculated mean doses were less than one percent. This method provides an independent parameter for evaluating the accuracy of the treatment planning system.

Green ink revolution: Pioneering eco‐friendly 3D printing with vegetable oil‐derived inks

AbstractSustainability in additive manufacturing (AM) (3D printing) could play a pivotal role for manufacturers and producers in the next‐generation manufacturing framework. The market for 3D printing is expanding rapidly, and it is expected to do so in the foreseeable years to come. As ecologically, responsible manufacturing gains more attention, renewable substitutes for regular commercial 3D printable inks must be developed for lower environmental carbon footprints (less CO2 emissions, recycling, bio‐compatibility, and zero waste). Herein, we review the recent literature on using vegetable oil (VO) as bio‐based inks for sustainable formulations for digital light processing or stereolithography additive printing. The feedstock selections (VO, terpenes, and waste cooking oil), and the chemistry of the VO‐based synthons toward sustainability in the field of photopolymerization‐based 3D printing are discussed. These renewable materials can mitigate the detrimental environmental effects of AM while remaining competitive with the existing fossil‐based resins produced by industrial manufacturers. The current challenges and limitations of AM in terms of surface finish, material properties, photo‐curing time, and end‐of‐use recycling options from biomass‐derived photocurable monomers are also identified. Overall, this development promotes the bio‐based economy and allows for the on‐demand production of a variety of sustainable inks for AM and sustainable end‐of‐use products.Highlights The significance of vegetable oils (VOs) as photopolymerizable monomers is explored. The necessity for 3D printing, specifically recycling and end‐of‐use, for the industrial revolution is provided. Green developments in stereolithography/digital light processing 3D printing utilizing VOs are covered.

Automated recognition and rebar dimensional assessment of prefabricated bridge components from low-cost 3D laser scanner

Dimension quality inspections for rebar spacing and length of prefabricated bridge components are critical for subsequent efficient assembly on-site. Currently, the traditional manual inspection method is time-consuming, labor-intensive, and error-prone. The existing commercial 3D LiDAR-based methods are difficult in making balances between inspection cost, efficiency, and accuracy. Thus, the automated recognition and segmentation method of 3D point clouds acquired by a self-developed low-cost LiDAR is proposed to evaluate the rebar spacing and length of bridge prefabricated components. Due to the high-cost commercial 3D laser scanner, a spinning 2D LiDAR-based low-cost 3D laser scanner device and geometric calibration model were developed to acquire the 3D spatial point cloud. Then, two-stage automated point cloud segmentation framework is proposed with coarse extraction of the point cloud in the interest region and fine recognition of point cloud using machine learning methods, including plane segmentation and circle fitting employing random sample consensus (RANSAC) algorithm, and rebars segmentation utilizing Gaussian mixture model (GMM) and density-based spatial clustering of applications with noise (DBSCAN) algorithm. The proposed system was evaluated in two prefabricated concrete columns and shows the potential for improving the quality inspection efficiency and accuracy.

Additive manufacturing of Diels-Alder self-healing polymers: Separate heating system to enhance mechanical, healing properties and assembly-free smart structures

Over the past decades, self-healing polymers have become increasingly popular due to their unique ability to recover mechanical and functional properties after sustaining structural damage, which significantly extends their lifespan compared to traditional polymers. Material Extrusion (MEX) 3D printing has recently emerged as a possible manufacturing approach for processing self-healing polymers; however, commercial MEX 3D printers lack of the flexibility to fabricate complex and functional structures based on such materials. In this work, an innovative MEX setup for extruding self-healing polymer networks based on a thermo-reversible reaction is presented. The proposed approach is based on the leverage of a separate heating system (SHS), enabling the degelation of the self-healing polymer network into a printable ink. This SHS regulates both the syringe-barrel, and nozzle temperatures during the processing (degelation and extrusion) of self-healing inks, leading to enhanced mechanical performance (Young modulus, tensile strength), and extrusion accuracy of 3D printed structures. The effectiveness of the SHS-based approach is demonstrated by an improved geometrical accuracy (filament deviation reduced by 26 %), which is directly correlated to the mitigation of the extrusion force (variability reduced by 77 %). Moreover, the SHS approach also improved both the mechanical properties and the self-healing performance of the printed parts. Finally, two different self-healing polymers a dielectric and an electrically conductive were extruded in a single manufacturing cycle to fabricate a self-sensing structure. This structure is capable of detecting bending with a sensitivity of 3.10 Ω/degree, even after healing. This paper aims to advance the role of MEX beyond its current limitations by enabling processing of high-quality self-healing structures with embedded sensors.

Surface profile inspection for large structures with laser scanning

Fringe projection profilometry is a powerful tool that is widely applied to shape measurement of objects in engineering. Limited by the light intensity of the projection unit, this technique is difficult to be applied to surface inspection of large structures, especially in outdoor applications. In this study, a line laser source is selected as the light projection unit. The line laser beam is controlled to scan the surface with the predefined angular speed while a stationary imaging unit captures images. An image fusion strategy has been proposed to construct grating images with a constant phase shift, which facilitates full-field phase shifting in determination of the structural profile. The accuracy of the measurement method is discussed and compared with a commercial 3D laser scanner. The proposed technique has also been applied to the surface topography of the wind turbine blades. The experimental results show that the bulging defects on the surface of the wind turbine blade model are detectable, which shows the feasibility of the proposed method in characterization of surface profile on large structures.