Engineering Applications Research Articles

Exploring the Biological Applications of TiO2 and AgNPs: Innovations and Impacts

The foundation for crucial industrial applications and rapid expansion is now nanotechnology. The nanoparticles are synthesized by various methods that are classified into bottom-up or top-down method Ag NPs show antimicrobial effect and are possibly useful in the areas of food preservation, antibacterial surfaces and tissues, nanomedicine, and dentistry, TiO2 NPs are one of the most widely generated metal oxide NPs, which is typically because of its adaptable and acceptable qualities that come from the optical, electrical, chemical properties, and physical. Its various kinds of minerals include anatase, rutile, and brookite; generally, the former has more TiO2 due to increased photocatalytic activity. Despite TiO2 NPs' relevance, very little work has been done to generate them sustainably. Nanoparticles have many applications likes engineering of tissue antimicrobial applications, and regenerative medicine, carrier for drug delivery, cancer Treatment, the major aim of the essay to provide overview about silver and titanium nanoparticles their application in medicine especially how the penetration occur

The Effects of Different Developmental Stages on Bone Regeneration of Periodontal Ligament Stem Cells and Periodontal Ligament Cell Sheets In Vitro and Vivo.

Periodontal ligament stem cells (PDLSCs) have broad applications in tissue engineering and regeneration. However, the function of PDLSCs changes in different microenvironments. This study aimed to explore the effects of different developmental stages on the biological characteristics of PDLSCs. Here, PDLSCs were successfully cultured from the periodontal tissues of various groups, including a group with immature roots, a young group with mature roots, and an aging group with mature roots. By comparing the results of the three experimental groups, we found that the donors with immature roots exhibited the best proliferative ability and osteogenic differentiation, while the aging group demonstrated the worst proliferation. The trend for adipogenic differentiation was the opposite to that for osteogenic differentiation. The cell sheet and in vivo experiments revealed that in the immature root group, the cells produced more extracellular matrix (ECM) and new bone and better absorbed the implant materials. These results indicate that PDLSCs perform various functions at different stages of development. In clinical applications of PDLSCs for periodontal regeneration, donors with incompletely developed roots have stronger biological characteristics.

Molecular Interactions Between Hexanal Schiff Bases and Boron Nanocages: A DFT Approach

This study explores the interactions between hexanal Schiff bases and a B12N12 nanocage, employing density functional theory (DFT) calculations to deepen our understanding of noncovalent bonds. Hexanal, a key component in tea, plays a vital role in prolonging the shelf-life of various plant-based products by inhibiting phospholipase-D. Our research initially focused on synthesizing Schiff bases through the condensation of hexanal with nucleobases and an amino acid. We then conducted a series of DFT calculations, including geometry optimizations, frontier molecular orbital (FMO), natural bond orbital (NBO) and noncovalent interactions (NCI) assays, using Gaussian 16 and ORCA 5.0.2 software packages. This study reveals that hexanal Schiff bases form stable complexes with the B12N12 nanocage, exhibiting notable dative coordinate bonding. The FMO analysis indicates a significant energy gap variation among the complexes, with CSB2 showing the lowest energy gap, hinting at its high reactivity. In the LED assay, CSB2 demonstrates the lowest decomposition energy, highlighting its potential stability. The AIMD simulations provide insights into the electronic motions of these complexes, underscoring their dynamic nature. Our NBO analysis offers a comprehensive view of the electron distribution within these complexes, emphasizing the significance of nitrogen and boron atoms in the bonding process. The NCI assay sheds light on the predominant van der Waals and steric interactions contributing to the stability of the complexes. This investigation provides a detailed account of the NCI between hexanal Schiff bases and the B12N12 nanocage. The findings not only contribute to the field of noncovalent bonding in inorganic- fullerene structures but also open avenues for future applications in material science and molecular engineering.

A Bioreactor for Celullarised Membrane Culture and Delivery under Sterile Conditions

A novel, user-friendly bioreactor for the cultivation of cellularised membranes for tissue engineering has been successfully designed, manufactured, and validated. This bioreactor features a culture vessel and a cover, the latter equipped with one or more sidewalls to ensure airtightness in two distinct zones, thereby maintaining sterile conditions. The cover, designed to integrate seamlessly with the culture vessel, includes several ports compatible with commercial connectors. This design allows the introduction of cells and culture medium without requiring the opening of the cover, thus preserving sterility. Additionally, the cover is equipped with flanges that effectively press the membrane against the bottom surface of the culture vessel, preventing it from shrinking or shifting. This ensures that cells can properly adhere to the membrane and proliferate. Manufactured under Good Manufacturing Practice (GMP) conditions, the bioreactor supports cultivation in optimal aseptic environments, thereby preventing external contamination. This feature is critical for the safe transportation of cultivated tissue to clinical settings. Validation tests have confirmed the bioreactor’s excellent performance, endorsing its suitability for intended applications in tissue engineering.

Comprehensive experimental thermal analysis of single bubble nucleation in vertical flow boiling: Whole field temperature and microlayer dynamics

Nucleate boiling, an important heat transfer phenomenon, holds significance in the thermal management of numerous engineering applications. Understanding and predicting its heat transfer characteristics are vital for system optimization. The formation of a microlayer, resulting from rapid bubble growth on a heater substrate, subsequently facilitates further bubble growth through evaporation playing a critical role in overall bubble dynamics. This study examines the intricate relationship between bubble and microlayer dynamics and their impact on heat transfer rates. Experimental work is conducted for varying heat fluxes using rainbow schlieren deflectometry (RSD) and thin-film interferometry (TFI) in tandem for simultaneous mapping of key parameters: bubble dynamics, microlayer dynamics, and two-dimensional temperature field in vertical flow boiling. The analysis of these parameters has provided significant insights into some fundamental aspects of boiling. Firstly, this study emphasizes that the bubble growth rate models need to take into initial microlayer thickness in accurately predicting bubble growth dynamics. The iteratively obtained constant Ceff (describing the initial microlayer thickness) for bubble growth models matches well the value of Ceff obtained experimentally from thin film interferograms. Additionally, this study also validates the applicability of the kinetic theory-based model in predicting the evaporative heat transfer coefficient during the initial stage of flow boiling, while demonstrating that the accommodation coefficient is ∼0.04 for the investigated range of heat fluxes. Subsequently, using the experimentally obtained evaporative heat transfer coefficient, further insights are provided into the dry patch dynamics. Experimental dry patch dynamics were in good agreement with theoretical predictions up to the rewetting phase. The results also indicate a substantial contribution of microlayer evaporation, constituting approximately 34 % of the total heat flux.

A hybrid FEM-IBM-level set algorithm for water entry of deformable body

Water entry of deformable bodies has been investigated extensively despite the major challenges in precise simulations of the whole physical process. Inspired by the basic idea of immersed boundary method (IBM), a hybrid FEM-IBM-level set algorithm is proposed where structural compliance is considered. The flow is described by Navier-Stokes equations with an added body force while the drastically moving object of arbitrary geometry is represented by several Lagrangian points on solid boundary. The direct forcing IBM is enhanced and coupled with finite element method (FEM) to facilitate simulation of severe fluid-structure interactions. Consequently, the added body force is calculated implicitly based on the exact velocity boundary condition with divergence-free condition ensured simultaneously. The improved conservative level set technique is adopted for accurate depiction of instantaneously distorted water surface, and the strongly coupled system is resolved iteratively through a partitioned scheme. Examples including sedimentation of a disk, water entry of deformable wedge and cylindrical shell are performed for validation. Specifically, hydroelastic impact of a three-dimensional conical shell is investigated, and the influence factors of entry dynamics are discussed. The results demonstrate the reliability and great potential of present algorithm for practical applications in ocean engineering, naval architecture and military engineering, etc.

Zinc phosphate glass microspheres promoted mineralization and expression of BMP2 in MC3T3-E1 cells.

Degradable phosphate glasses have shown favorable properties for tissue engineering. By changing the composition of the glasses, the degradation rate, and ion release are controllable. Zinc oxide can function as a glass network modifier and has been shown to play a positive role in bone formation. Also, phosphate glasses can easily be processed into microspheres, which can be used as microcarriers. This study aims to develop zinc phosphate glasses microspheres and explore the optimized size and composition for applications in bone tissue engineering. Zinc-titanium-calcium-sodium phosphate glasses with 0, 1, 3, 5, or 10 mol % zinc oxide were prepared and processed into microspheres. The smaller microspheres ranged in size from 50 to 106 μm, while the larger ones ranged from 106 to 150 μm. The characteristics of glasses were examined. The osteoblastic cell line MC3T3-E1 was cultured on the surface of microspheres and the cell viability was examined. To evaluate osteogenic differentiation, Alizarin Red S staining, quantitative reverse transcription polymerase chain reaction, and western blot analysis were performed after 14 days. Different sizes of zinc phosphate glass microspheres were successfully made. The glass microspheres with <10 mol % zinc oxide were able to support the adhesion and proliferation of MC3T3-E1 cell lines. The relative gene expression of BMP2 was significantly upregulated in the smaller glass microspheres containing 3 mol % zinc oxide (26-fold, p < .001) and both sizes of microspheres containing 5 mol % zinc oxide (smaller: 27-fold, p < .001; larger: 35-fold, p < .001). Additionally, cluster formation was observed in glass microspheres after 14 days, and the mineralization of MC3T3-E1 cell lines was promoted. Based on these findings, the glass microspheres containing 3-5 mol % of zinc oxide can promote osteogenic differentiation for MC3T3-E1 cells.

Microfluidic Synthesis of Multifunctional Micro-/Nanomaterials from Process Intensification: Structural Engineering to High Electrochemical Energy Storage.

Multifunctional micro-/nanomaterials featuring functional superiority and high value-added physicochemical nature have received immense attention in electrochemical energy storage. Microfluidic synthesis has become an emergent technology for massively producing multifunctional micro-/nanomaterials with tunable microstructure and morphology due to its rapid mass/heat transfer and precise fluid controllability. In this review, the latest progresses and achievements in microfluidic-synthesized multifunctional micro-/nanomaterials are summarized via reaction process intensification, multifunctional micro-/nanostructural engineering and electrochemical energy storage applications. The reaction process intensification mechanisms of various micro-/nanomaterials, including quantum dots (QDs), metal materials, conducting polymers, metallic oxides, polyanionic compounds, metal-organic frameworks (MOFs) and two-dimensional (2D) materials, are discussed. Especially, the multifunctional structural engineering principles of as-fabricated micro-/nanomaterials, such as vertically aligned structure, heterostructure, core-shell structure, and tunable microsphere, are introduced. Subsequently, the electrochemical energy storage application of as-prepared multifunctional micro-/nanomaterials is clarified in supercapacitors, lithium-ion batteries, sodium-ion batteries, all-vanadium redox flow batteries, and dielectric capacitors. Finally, the current problems and future forecasts are illustrated.

Derivation and numerical resolution of 2D shallow water equations for multi-regime flows of Herschel–Bulkley fluids

This paper presents mathematical modelling and simulation of thin free-surface flows of viscoplastic fluids with a Herschel–Bulkley rheology over complex topographies with basal perturbations. Using the asymptotic expansion method, depth-averaged models (lubrication and shallow water type models) are derived for 3D (three-dimensional) multi-regime flows on non-flat inclined topographies with varying basal slipperiness. Starting from the Navier–Stokes equations, two flow regimes corresponding to different balances between shear and pressure forces are presented. Flow models corresponding to these regimes are calculated as perturbations of the zeroth-order solutions. The classical reference models in the literature are recovered by considering their respective cases on a flat-inclined surface. In the second regime case, a pressure term is non-negligible. Mathematically, it leads to a corrective term to the classical regime equations. Flow solutions of the two regimes are compared; the difference appears in particular in the vicinity of sharp changes of slopes. Nonetheless, both regime models are compared with experiments and are found to be in good agreement. Furthermore, numerical examples are shown to illustrate the robustness of the present shallow water models to simulate viscoplastic flows in 3D and over an inclined topography with local perturbations in basal elevation and basal slipperiness. The derived models are adequate for direct (engineering and geophysical) applications to real-world flow problems presenting Herschel–Bulkley rheology like lava and mud flows.

Electron-phonon interaction, magnetic phase transition, charge density waves, and resistive switching in VS2 and VSe2 revealed by Yanson point-contact spectroscopy

VS2 and VSe2 have attracted particular attention among the transition metals dichalcogenides because of their promising physical properties concerning magnetic ordering, charge density wave (CDW), emergent superconductivity, etc., which are very sensitive to stoichiometry and dimensionality reduction. Yanson point-contact (PC) spectroscopic study reveals metallic and nonmetallic states in VS2 PCs, as well as a magnetic phase transition, was detected near 20 K. The rare PC spectra, where the magnetic phase transition was not visible, show a broad maximum of around 20 mV, likely connected with electron-phonon interaction (EPI). The PC spectra of VSe2 demonstrate metallic behavior, which allowed us to detect features associated with EPI and CDW transition. The Kondo effect appeared for both compounds, apparently due to interlayer vanadium ions. Besides, the resistive switching was observed in PCs on VSe2 between a low resistive, mainly metallic-type state, and a high resistive nonmetallic-type state by applying bias voltage (about 0.4 V). Reverse switching occurs by applying a voltage of opposite polarity (about 0.4 V). The reason may be the alteration of stoichiometry in the PC core due to the displacement of V ions to interlayer under a high electric field. The observed resistive switching characterizes VSe2 as a potential material, e.g., for non-volatile resistive RAM, neuromorphic engineering, and other nanoelectronic applications. Per contra, VS2 attracts attention as a rare layered van der Waals compound with magnetic transition.

Study of Engineering Developing Decagonal-like Rational Approximant Structure of Al-Ni-Cu-Fe-Mn-Cr Senary System in Aluminum Alloy through Additive Manufacturing

Quasi-periodic materials hold unique properties, but mass-producing bulk materials with such structures remains challenging. The rational approximant phase belongs to the Bravais crystal system but exhibits irrational cut features and diffraction symmetries, which are similar to quasicrystals. This study uses additive manufacturing (AM) and prolonged annealing to create an aluminum-based alloy featuring a quasicrystal-like rational approximant phase, Al6(Cu, Ni)1(Cr, Mn, Fe)1, overcoming the production limitations of reproducible quasi-periodic materials. This phase transformation occurs at the Al-Al9FeNi interface, resulting in a monoclinic periodic structure with long-range translational symmetry. The structure comprises sublattices of stars and compressed hexagons, forming tile mode coverings with pseudo-five-fold decagonal shield-like tiles (SLTs) through transition-element atoms. Furthermore, HAADF imaging reveals clear dark monoclinic rhombic patterns with long-range ordered translational symmetry, free from atomic defects. The rational approximant phase has been verified crystallography through X-ray diffraction, confirming its translational symmetry. Additionally, the Al3(Zr, Sc) phase facilitates the phase transformation process through lattice interactions. These findings introduce a novel perspective on the phase transformation in decagonal-like rational approximants and broaden the realm for future engineering applications.

Agarose-collagen composite microsphere implants: A biocompatible and robust approach for skin tissue regeneration

Photoaged skin, a consequence of UV radiation-induced collagen degradation, presents a significant challenge for skin rejuvenation. Synthetic polymer microspheres, while offering collagen regeneration potential, carry risks like granulomas. To overcome this, we developed a novel agarose-collagen composite microsphere implant for skin tissue regeneration. Fabricated using an emulsification-crosslinking method, these microspheres exhibited excellent uniformity and sphericity (with a diameter of ~38.5 μm), as well as attractive injectability. In vitro studies demonstrated their superior biocompatibility, promoting cell proliferation, adhesion, and migration. Further assessments revealed favorable biosafety and blood compatibility. In vivo experiments in photoaged mice showed that implantation of these microspheres effectively reduced wrinkles, increased skin density, and improved elasticity by stimulating fibroblast encapsulation and collagen regeneration. These findings highlight the potential of agarose-collagen microspheres in dermatological and tissue engineering applications, offering a safer alternative for skin rejuvenation.

Efficient predictive modeling of resilient modulus in stabilized clayey soil using automated machine learning

Pavement subgrade design relies on the resilient modulus (Mr) to analyze structural response to vehicle-like loading. Adding stabilizers to the soil subgrade makes estimating Mr difficult and resource-intensive. This study uses an automated machine learning (ML) strategy to predict the Mr of stabilized clayey soil using recycled plastic waste. The proposed method automates model selection and hyperparameter tuning, making it a feasible alternative to tedious ML modeling and costly laboratory testing. From extensive laboratory investigation involving 3285 experimental data points, the automated ML model using Bayesian optimization evaluates ensembles, support vector machine (SVM), neural network (NET), decision trees, (TREE), and Gaussian process (GP) regression models, identifying the best model based on cross-validation mean squared error (MSE). Bayesian optimization explores hyperparameter spaces to find optimal configurations, enhancing the accuracy, scalability, and reliability of the prediction model. The optimization process yielded the best results for the ensemble least square boost (LSBoost) model with a cross-validation mean squared error (MSE) value of 6.723×10−29. The optimized ML model’s performance is measured using R2 and adjusted R2. The LSboost model’s R2 and adjusted R2 values of 0.9999 suggested overfitting, prompting further investigations using performance metrics like root mean squared error (RMSE), mean absolute error (MSE), and probability density function (PDF) for normalized absolute error (NAE) for training and testing datasets for the predictive ML model. The small RMSE and MAE (0.0049 and 0.0005) values and symmetrical NAE distribution of the proposed ML model demonstrate its high accuracy and generalization capabilities. The proposed model was subsequently tested on the new, unseen data and achieved predictions with an error rate of 0.24 %. This confirms the proposed ML model’s superiority over conventional deformation models, making it ideal for reliable geotechnical engineering applications.

Effect of Cu upon recrystallization and mechanical properties of TRIP-assisted high entropy alloy

The face-centered cubic (FCC) high-entropy alloys (HEAs) have been hindered in their engineering applications due to their low yield strength. Combining multiple strengthening mechanisms with phase transformation-induced plasticity (TRIP) may serve as an effective approach to overcome the strength-ductility trade-off. In this study, (Co3Cr1.6FeNi)100-xCux (x=0,2) high entropy alloys (HEAs) were designed. A straightforward processing route, involving hot rolling followed by annealing, was utilized to produce single-phase FCC HEAs. The alloy doped with 2 at.% Cu achieved a perfect combination of strength and ductility. It was also found that the addition of Cu suppresses the recrystallization process during the hot rolling and annealing of the alloy. The increase in strength is attributed to the synergistic effects of various strengthening mechanisms dominated by dislocation strengthening and heterogeneous deformation induced strengthening, while the TRIP effect ensures continuous strain hardening capability of the alloy while maintaining high yield strength and ensuring good ductility. These results offer valuable insights into the design and development of high-performance HEAs with exceptional strength and ductility.

On-chip based power estimation for CMOS VLSI circuits using support vector machine

Power estimation has a major impact on the reliability of very-large-scale integration (VLSI) circuits. As a results power estimation is highly needed in VLSI circuits at the early stages. One of the evident challenges in integrated circuit (IC) industry is development and investigation of techniques for the reduction of design complexity due to the growing process variations and reduction of chip manufacturing turnaround time. Under these conditions, the higher design levels of average power estimation before the chip manufacturing process is highly essential for the calculation of power budget and to take the necessary steps for the reduction of power consumption. Over the years, most of the approaches were designed to estimate the power usage, however, most of the conventional techniques are time consuming, resource-intensive and largely manual. Machine learning techniques have received much attention in many of the engineering applications and are capable for modelling the complex systems through historical data. Hence, in this work on chip-based power estimation for complementary metal-oxide-semiconductor (CMOS) VLSI using support-vector machine (SVM) is presented to estimate the power. The SVM is employed to estimate the usage of power at runtime. The performance of this model is evaluated in terms of Power usage, delay, data accuracy and error rate.

Carbon sources influence on heterotrophic ammonia assimilation: Performance and mechanism

Different carbon contents of organic carbon sources can be used as the reaction substrates of heterotrophic ammonia assimilation (HAA), which effectively dominates the recovery of available nutrients in wastewater. However, the influences of organic carbon sources on nutrient metabolism, degradation kinetics, and functional microbes of HAA were largely unknown. Here, HAA bioreactors fed with acetate, glucose, sucrose, starch, methanol, and sludge alkaline fermentation liquid (SAFL) were constructed to compare the nitrogen recovery performance, kinetic analysis, sludge characteristics, and microbial community structure. Higher COD and NH4+-N removal efficiencies were found in bioreactors supplied with acetate, glucose, and SAFL. Kinetic analysis showed that the acetate-fed bioreactor had more efficient organic utilization for assimilation. Corynebacterium, Pseudohoeflea, and Methylophaga emerged as the primary assimilation bacteria for typical carbon sources of organic acids, sugars, and alcohols, whereas Halomonas, Corynebacterium, and Marinobacter dominated in SAFL. Acetate- and SAFL-supported sludge particles displayed enhanced internal and external oxygen mass transfer, along with heightened sedimentation performance and deconsolidation ability. High-quality assimilative gene expression, assimilative enzyme activity, and assimilated organic nitrogen product synthesis with direct effects were observed in a reactor supplied with acetate and SAFL. The cost-effectiveness of SAFL preparation positions it as a promising candidate for practical engineering applications. This research underscored the pivotal role of different carbon contents in the nutrient recovery process of the HAA reaction, providing essential insights for optimizing wastewater treatment strategies and enhancing environmental sustainability.

In-plane compressive behavior of cross-laminated bamboo and timber with variable heights

This paper investigates the in-plane compressive behavior of 5-layer cross-laminated bamboo and timber (CLBT) specimens with variable heights. Five different heights of CLBT specimens, ranging from 400 mm to 3800 mm, were designed for the experiment, with conventional 5-layer cross-laminated timber (CLT) specimens used as controls. Theoretical calculations based on timber structure design codes were employed to analyze the ultimate bearing capacity, complemented by finite element simulations based on Abaqus that also explored the failure characteristics. The results indicated that CLBT wall panels had a significantly higher ultimate bearing capacity compared to those of CLT wall panels. For wall panels of around 3.0 m and 6.0 m in height, the compressive strength of the CLBT panels was approximately 65% and 40% higher than that of the CLT panels, respectively. For specimens showing buckling instability, CLBT demonstrated more concentrated failure in the end regions, contrasting with CLT, which failed primarily in the central region. The outcomes of this study clearly delineate the superiority of CLBT over CLT when used as wall panels, providing valuable references for their potential engineering applications.

Protective silicide coating fabricated on ductile VNbTa refractory complex concentrated alloy: Microstructure, high-temperature oxidation and wear behaviors

VNbTa refractory complex concentrated alloy (RCCA) possesses broad application prospects in a wide temperature window owing to its remarkable strength-ductility synergy and super rolling formability, whereas poor oxidation resistance will give rise to excessive wear above 800 ℃. In this contribution, we aim to fabricate a protective silicide coating on VNbTa RCCA for the purposes of enhancing high-temperature oxidation as well as wear resistance. Microstructural characterizations revealed that a uniform and intact coating was obtained under the optimized processing condition of pack cementation. The coating is mainly composed of single-phase (VNbTa)Si2, along with a thin M5Si3-type interdiffusion zone. Compared with bare alloy, the coated specimens exhibit remarkable oxidation resistance at 1000 ℃ due to the preferential formation of protective SiO2 scale. Meanwhile, the coated specimens maintain desirable wear resistance from 800 ℃ to 1000 ℃. The results of this study would offer a valuable reference to expedite the future engineering applications of RCCAs.

Geometry optimization of wall-jet collection device: A study of flow-field dynamics and particle motion

Wall-jet collection has been recognized as an advanced technique for mining polymetallic nodules that has significant potential for practical engineering applications. Optimizing the geometry of the collection device can improve collection efficiency and reduce environmental disturbance. In this study, 24 distinct structures of nodule-collection device were investigated using a computational fluid dynamics–discrete element method, which was validated by comparing with the experimental data. A key parameter, the wall-jet half-width coefficient Cc, was employed to examine the collection performance, including the collection efficiency, collection flow field, and particle trajectory. An assessment indicator derived from energy-consumption and substrate-disturbance metrics was proposed, and this allowed the identification of optimal device structures tailored to various requirements. The results showed that based on collection efficiency–jet flow rate (η–q) response curves, the collection performance can be categorized into two distinct patterns. When Cc ≤ 1.56, induced flow will occur, and η can reach 1.0; when Cc &amp;gt; 1.56, a moving vortex that disturbs the particle trajectories is generated, and the jet escapes rightward, resulting in a decrease in η. The influences of geometric parameters on Cc exhibit coupled relationships, which is particularly noticeable in the relationship between the tangential angle of the jet and its thickness. The optimal device geometry varies for different criteria, and maximum reductions in substrate disturbance and jet energy consumption of 48.46% and 19.64%, respectively, were obtained with different optimization criteria. This study is expected to provide data to support the optimization of the structure of wall-jet collection devices.

Accessible Melt Electrowriting Three-dimensional Printer for Fabricating High-precision Scaffolds

Melt electrowriting (MEW) is an established 3D printing technology for producing high-resolution scaffolds for tissue engineering. Commercial MEW devices are expensive while having limited processing capabilities, which limits their accessibility and widespread use. Herein, we report an easy-to-assemble and inexpensive ($2,000) MEW printer based on an off-the-shelf automated dispensing machine with user-friendly controls and a custom-designed MEW printhead capable of printing polymers with a melting point of up to 260°C. Using the gold standard printable material, poly(ε-caprolactone) (PCL), this printer can deposit 3 μm diameter fibers at 50 μm spacing, demonstrating that the highest quality of scaffolds can be produced on the low-cost MEW system. Stability in printing is improved by maintaining a relative humidity of 30-35%, ensuring nozzle conditions are optimal, and minimizing bubbles in the polymer melt. Key printing parameters such as a 3 kV applied voltage, 75 °C heating temperature, 100 kPa air pressure, and 30 G nozzle size are critical for high accuracy, achieving 100 μm fiber spacing and layer stacking up to 30 layers without fiber breakage. The printer effectively creates complex scaffold geometries, showcasing its precision and suitability for advanced tissue engineering applications. Overall, this study promotes low-cost MEW technology by establishing a guideline on building an accessible but capable MEW printer and providing a crucial experimental foundation toward achieving high-accuracy scaffolds.