Fiber Diameter Research Articles

(Invited) Novel Brush Design for Post CMP Cleans

Chemical Mechanical Polishing (CMP) process is one of the key processes in semiconductor wafer processing. A sub 10nm wafer fabrication process may require more than 40 dielectric and metal CMP steps. As CMP process requirements get more stringent, CMP slurries are formulated with smaller and smaller metal oxide abrasive particles. The abrasive particles may also be surface modified or doped with other metal oxides. Post CMP cleaning chemistry formulations are designed to remove polish byproducts, pad residues and abrasive particles from wafer surface. Chemical composition and PH are tuned for modulating wafer surface-particle interactions so brushes can mechanically “sweep” them off the surface. PVA brushes, used of post CMP cleans, are a highly porous network of crosslinked polyvinyl acetate with pore size in the range of 30 – 100 um and 80% - 90% porosity, depending on the type of brush being used. While PVA brushes have largely met the process capability requirements, they have limitations for advanced cleans such as nano-particle removal. As CMP process continues to expand to new dielectric and metal films for different process steps in wafer fabrication, there is a need for customized brush material and surface design for optimal cleaning efficiency.We discuss a new engineered post CMP brush design that shows high efficiency in nano-particle cleans and allows high level of material tunability. New brush design is an engineered composite with an open cell microporous core, overlaid with engineered fibers in form of loops. Brush design is compatible with existing post CMP cleans. Figure 1(a) shows the new design, where in DIW enters the brush through the center of microporous core and flows outwards to the surface. As water exits the surface, it flows over and across the loops and contacts the wafer surface. Flow resistance through core and loops can be independently tuned, which allows better fluid distribution and more effective cleans. Figure 1(b) show a close-up schematic of interaction between loop and particle. Flexing of the loops on brush surface provides improved contact as well as cleaning ability Brush design can be optimized for chemical and mechanical properties with choice of fiber material, fiber diameter and loop height. Figure 2 shows the Zeta potential of PVA and different loop materials. The fiber material maybe selected such that zeta potential of the loops can enhance mechanical action in removing particle. Mechanical action of the Loops can be modeled as a cantilever and force on the particle is exerted by flexing of the loops.Deflection of loops can be approximated with flexure stiffness of rods with point load at free end. For initial purposed loop is approximated as single element. The equation can be rewritten to calculate cleaning force P at the free end for given loop deflection (Y), P = 3EIY/L3 (1)Where E is elastic modulus, I = moment, L = length of fiber and for rod shapes; I = Pi*(r4/4)The adhesion of particles on the surface is due to the effect of van der Waals and electrostatic forces. The total adhesion force on the surface can be written as: F=F vdw + F edl (2) where Ft is total adhesion force, Fvdw is the van der Waals force, and Fedl is the electrostatic force.Fvdw = AR/6r2 (3)Where A is the Hamaker constant, R is particle radius, r is the separation distanceFor effective removal of particles, P >/= F (4)Flex force and adhesion force were modeled based on equation (1) and (3) and are shown in Figure 3. New brush design was used for post CMP cleaning of silicon dioxide wafers polished with ceria slurry. Two different brush designs were tested for cleaning efficiency. Modeling data and comparison with experimental results is presented. Figure 1

(Invited) Microwires Based on Carbon Nanotubes for Medicine and Biology

Flexible and biocompatible microwires are generally employed for biomedical implants in medicine, more specifically in neuroscience. These microwires used as electrodes need to be chemically inert and electrically conducting in order to record and stimulate the electrical activity of neurons in the nervous system. The electrodes available today are made of metals and silicon that lack the required flexibility resulting in a mechanical mismatch between soft tissues and rigid metals which induces faster biofouling and inconsistent performance for long-term implants. Biofouling triggered by inflammatory responses dramatically affects the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical applications require electrically conducting flexible electrode materials with reduced dimensions and antibiofouling properties. These characteristics reduce the degree of inflammatory reactions and increase the lifetime of implanted neural electrodes. Carbon nanotubes (CNTs) are well known for their flexibility, electrical conductivity, and chemical inertness. This talk will report the fabrication of CNT fibers and subsequent coating using a biocompatible flexible polymer hydrogenated nitrile butadiene rubber (HNBR). Unlike the gold standard parylene-C coating that requires processing under vacuum, dissolved elastomer HNBR polymer can deposit uniform coating in solutions. Polymer dip-coating has been employed for uniform and continuous coating of meters-long CNT fibers of multiple diameters (26 to 66 mm) to evaluate the robustness of the approach. The polymer was able to provide uniform thickness and pinhole-free coating along the CNT fiber. Furthermore, the polymer has been shown to be biocompatible when tested with in vitro elusions and culturing neurons. The covalent functionalization of CNT microwire cross-section interfacing with the neurons using hydrophilic, anti-biofouling phosphorylcholine molecules displays reduced impedance and increased hydrophilicity. These CNT microwire assemblies are promising for the development of low-impedance neural electrodes with higher hydrophilicity and protein-fouling resistance to inhibit inflammatory responses.

Multi-scale modeling of fog harvesting using thin-fiber grids – Towards new design rubrics

Fog collectors with fibers thinner than 1 mm harvest fog droplets more effectively at a low airflow velocity around 1 m s-1 than thicker fibers. However, existing models and design rubrics are restricted to thick fibers at higher velocity. This paper reports a multi-scale numerical model for fog harvesting at airflow velocity of 1 m s-1 using thin-fiber grids with different fiber spacing and diameter. The numerical model can simulate fog harvesting at two extreme length scales that are comparable to collector scale at the large end and fiber scale at the small end. The results confirm two new and important effects of fiber grid geometries on water collection efficiency, which are not included in existing theories and design rubrics. First, dense thin-fiber grids negatively influence the collection efficiency because of wall effect caused by viscous boundary layers. Second, the sparse thin-fiber grids can benefit from isolated clogging waterdrops and maintain relatively high efficiency when clogging blocks multiple grid openings. The two identified effects are then included to develop a new performance map for fog collectors, thereby shaping new design rubrics for fog harvesting. This work extends the existing theories of fog harvesting and sheds light on the design of novel fog collectors.

Metabolic and Biochemical Performances of Abaca (<i>Musa textilis</i> Née) under Intermediate and Advanced Phase Agroforestry System

Abaca, one of the potential fiber crops with high-quality fiber and promising economic value, is mainly established under the agroforestry system, for it is considered a non-primary crop. The study aims to observe the metabolic and biochemical performance as well as the fiber quality of abaca under the agroforestry system. The experimental design used in this study was nested with two types of agroforestry systems, i.e., intermediate phase (Fase Tengah, FT) and advanced phase (Fase Lanjutan, FL) and was conducted during the rainy season. Parameters observed in this study were divided into edaphic and climatic parameters, oxidative response parameters, foliage macro- and micronutrient, and fiber quality. Despite poor soil quality compared to FL, higher relative humidity (4.35%), lower temperature (2.73%), and lower shading intensity were observed in FT. Improved soil characteristics in FL, viz. soil water content (19.64%), organic carbon (72.89%), porosity (4.29%), cation exchange capacity (13.77%), and pH (35.13%), were unable to compensate plant stress induced by the high shading intensity at 83.99%. Consequently, it contributed to higher levels of malondialdehyde, superoxide anion, hydrogen peroxide, superoxide dismutase, peroxidase, and phenol by 0.07%, 1.86%, 32.66%, 0.08%, 14.63%, and 35.08%, respectively, due to shading stress. Nevertheless, ascorbic acid content in FL was lower (18.90%) compared to FT. Higher fiber diameter (23.53%) and tensile strength (18.77%) of abaca in FT were observed compared to FL. The improved microclimatic conditions under FT promoted the high adaptability of abaca to poor soil quality. Therefore, it contributed to enhanced growth and fiber quality compared to FL. Pruning is pivotal to managing shading intensity.

Antibacterial, Mechanical, and Thermal Properties of Ag, ZnO, TiO2 Reinforced PVA Nanocomposite Fibers

AbstractThis study investigated the effects of concentration and electrospinning parameters on the production of poly (vinyl alcohol) (PVA) nanofibers and examined the impact of reinforcing additives like nano‐sized silver (Ag), titanium oxide (TiO2), and zinc oxide (ZnO) on these nanofibers. The PVA concentration was varied between 3 % and 10 % wt./v, while the flow rate was adjusted to 0.5, 1, and 5 ml/h. The optimal conditions for producing PVA nanofibers are a concentration of 10 % wt./v at a flow rate of 0.5 ml/h and an applied voltage of 9 kV, resulting in nanofibers with an average diameter of 502±0.10 nm. PVA nanofibers reinforced with nano‐sized 3 % wt. Ag, TiO2, and ZnO and electrospun at optimum conditions. The morphological properties were determined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and the average fiber diameter was measured with the Image J program. The presence of nanoparticles within the nanofibers was confirmed through Energy Dispersive Spectrometry (EDS) and X‐ray diffraction (XRD). Chemical interactions of functional groups between PVA and ZnO, TiO2, and Ag NPs were analyzed with Fourier Transform Infrared Spectroscopy (FTIR), and thermal behaviors were studied with Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Among the water absorption, Ag‐reinforced PVA nanofibers showed maximum absorbance. Mechanical properties, evaluated through tensile testing, showed the elastic modulus of the nanocomposite fibers to be 38.07±12.01 MPa for PVA/Ag, 88.98±27.5 MPa for PVA/TiO2, and 30.56±9.77 MPa for PVA/ZnO. The antimicrobial activity of the nanoparticle‐reinforced PVA nanofibers was tested using the agar disc diffusion method. The results showed that both Ag and TiO2 reinforced PVA nanocomposite fibers exhibited significant antimicrobial activity (gram–(Escherichia coli) and gram+(Staphylococcus aureus)), with inhibition zones of 8.48±0.08 cm against E. coli and 9.98±0.47 cm against S. aureus for Ag, and 4.32±0.02 cm against E. coli and 3.56±0.05 cm against S. aureus for TiO2.

Cascaded geometric parametric process in a tapered air-silica graded-like multimode microstructure fiber.

We experimentally study the spatial beam profile and the spectral broadening at the output of a multimode air-silica microstructure fiber taper, used along the direction of an increasing fiber diameter. By using a laser pump at 1064 nm emitting 60 ps Gaussian beam pulses, we observed a competition between Raman beam cleanup and Kerr beam self-cleaning: the multimode frequency conversion process permits to generate spectral sidebands with frequency detuning from the pump that are difficult to obtain in standard graded-index multimode fibers. The generated supercontinuum spans from 500 nm up to 2.5 µm.

Development of Cerium Oxide-Laden GelMA/PCL Scaffolds for Periodontal Tissue Engineering.

This study investigated gelatin methacryloyl (GelMA) and polycaprolactone (PCL) blend scaffolds incorporating cerium oxide (CeO) nanoparticles at concentrations of 0%, 5%, and 10% w/w via electrospinning for periodontal tissue engineering. The impact of photocrosslinking on these scaffolds was evaluated by comparing crosslinked (C) and non-crosslinked (NC) versions. Methods included Fourier transform infrared spectroscopy (FTIR) for chemical analysis, scanning electron microscopy (SEM) for fiber morphology/diameters, and assessments of swelling capacity, degradation profile, and biomechanical properties. Biological evaluations with alveolar bone-derived mesenchymal stem cells (aBMSCs) and human gingival fibroblasts (HGFs) encompassed tests for cell viability, mineralized nodule deposition (MND), and collagen production (CP). Statistical analysis was performed using Kruskal-Wallis or ANOVA/post-hoc tests (α = 5%). Results indicate that C scaffolds had larger fiber diameters (~250 nm) compared with NC scaffolds (~150 nm). NC scaffolds exhibited higher swelling capacities than C scaffolds, while both types demonstrated significant mass loss (~50%) after 60 days (p < 0.05). C scaffolds containing CeO showed increased Young's modulus and tensile strength than NC scaffolds. Cells cultured on C scaffolds with 10% CeO exhibited significantly higher metabolic activity (>400%, p < 0.05) after 7 days among all groups. Furthermore, CeO-containing scaffolds promoted enhanced MND by aBMSCs (>120%, p < 0.05) and increased CP in 5% CeO scaffolds for both variants (>180%, p < 0.05). These findings underscore the promising biomechanical properties, biodegradability, cytocompatibility, and enhanced tissue regenerative potential of CeO-loaded GelMA/PCL scaffolds for periodontal applications.

EFFICIENCY OF GROWING MEAT-WOOL FIELDS DEPENDING ON THE TONNAGE OF WOOL

In the article, based on the conducted research, considers the expediency of using wool fineness indicators in the selection process when growing meat-wool breeds. Due to the lack of a comparative analysis of animal husbandry, experimental groups were formed conditionally and distributed according to the total number of herds. The first group of experimental animals included yaks with the thickness of wool fibers – 23.1–25.0 μm or 60th quality; to the II group with an average fiber diameter of 25.1–27.0 μm or 58th good quality;The III group consisted of ditches with a greater thickness of wool fibers – 27.1–29.0 μm or 56th good quality. In order to study the effectiveness of using fodder in production, three model groups of 10 head each at the age of 12 months were formed. It was established that during the 60-day growing period, the indicators of absolute, average daily and relative growth in pits of II and III groups were higher. Feed costs per 1 kg of body weight gain amounted to 11.4 units in the first group and 1282 g of digestible protein, in the II and III groups, respectively, 10.3 units. and 1166 g and 10.4 k. units. and 1169 g of digestible protein. Conducted studies have shown that the yaks with the tone of wool of the 56th quality are characterized by higher indicators in terms of live weight, development and wool productivity, which indicates their better adaptation to the natural and climatic conditions in which the farm is located.

Analysis of the genetic variance of fibre diameter measured along the wool staple for use as a potential indicator of resilience in sheep

BackgroundThe effects of environmental disturbances on livestock are often observed indirectly through the variability patterns of repeated performance records over time. Sheep are frequently exposed to diverse extensive environments but currently lack appropriate measures of resilience (or sensitivity) towards environmental disturbance. In this study, random regression models were used to analyse repeated records of the fibre diameter of wool taken along the wool staple (bundle of wool fibres) to investigate how the genetic and environmental variance of fibre diameter changes with different growing environments.ResultsA model containing a fifth, fourth and second-order Legendre polynomial applied to the fixed, additive and permanent environmental effects, respectively, was optimal for modelling fibre diameter along the wool staple. The additive genetic and permanent environmental variance both showed variability across the staple length trajectory. The ranking of sire estimated breeding values (EBV) for fibre diameter was shown to change along the staple and the genetic correlations decreased as the distance between measurements along the staple increased. This result suggests that some genotypes were potentially more resilient towards the changes in the growing environment compared to others. In addition, the eigenfunctions of the random regression model implied the ability to change the fibre diameter trajectory to reduce its variability along the wool staple.ConclusionsThese results show that genetic variation in fibre diameter measured along the wool staple exists and this could be used to provide greater insight into the ability to select for resilience in extensively raised sheep populations.

Can the diameter of nerve fibers be effectively utilized to enhance the accuracy of determining the length of the aganglionic segment compared to intraoperative biopsy in patients with Hirschsprung’s disease?

ObjectiveThe aim of this study is to investigate the accuracy of utilizing neural fiber trunk diameter in accurately diagnosing the length of the aganglionic segment in patients definitively diagnosed with Hirschsprung’s disease.ResultsIn this study, 40 patients (19 males, 21 females; mean age 2.5 ± 2.2646 years) were assessed for Hirschsprung’s disease. Constipation was the main symptom (75%), followed by abdominal issues. All underwent contrast enema and rectal suction biopsy for diagnosis, followed by surgery (predominantly Soave and Swensen techniques). Majority (85%) had rectosigmoid involvement. Neural fiber diameter was measured, with 52.5% ≤40 μm and 47.5% >40 μm. Statistical analysis showed 40% sensitivity(CI:95%) and 47% specificity(CI:95%) with a cutoff of 40.5 μm. Cohen’s kappa index for aganglionic segment size was 0.7.

Response Surface Methodology to Explore the Influence Mechanism of Fiber Diameter in a New Multi-Needle Electrospinning Spinneret.

Multi-needle electrospinning is an efficient method for producing nanofiber membranes. However, fluctuations in the fluid flow rate during the process affect membrane quality and cause instability, an issue that remains unresolved. To address this, a multi-stage flow runner spinneret needs to be developed for large-scale nanofiber membrane production. This paper uses COMSOL finite element software to simulate polymer flow in the spinneret runner. From this, the velocity field distribution and velocity instability coefficient were obtained, providing theoretical guidance for optimal spinneret design. In addition, response surface analysis (RSM) was used to experimentally explore the process parameters, and then residual probability plots were used for reliability verification to evaluate the effect of each process parameter on fiber diameter. These process parameters can guide the controlled production of nanofibers during multi-needle electrospinning.

Upper and Lower Bounds to Pull-Out Loading of Inclined Hooked End Steel Fibres Embedded in Concrete

Steel fibre-reinforced concrete (SFRC) consists of short, hooked steel fibres that are randomly distributed and oriented within the cementitious matrix. This paper presents a new analytical load-bounding approach that captures the tensile response of misaligned fibres embedded in the matrix. The contribution of fibres in bridging cracks to provide the required stress transfer relies on the orientation of the fibres in the concrete. Bridging fibres aligned with a crack are less effective than those inclined to it. Therefore, understanding the pull-out behaviour of misaligned fibres is a key factor in quantifying and optimising the design of SFRC in structural applications. In the laboratory, a single-oriented fibre embedded in a solid cylinder of concrete was subjected to a pull-out test, where the axis of the tensile force is aligned with the axis of the cylinder. Based on the observed behaviour, this paper presents a new analytical bounding approach to capture the pull-out response of misaligned hooked-end steel fibres embedded in a concrete matrix. The analysis was based on a transversely isotropic failure criterion assumed for the plasticity that occurs in the cold-drawn fibre. Lower and upper bounds to the loading failure were derived from fibre pull-out and fibre fracture, respectively. The division between bounds depended upon the fibre orientation, fibre diameter and the combined strengths of the steel and concrete. Bounding predictions were drawn from ratios between a fibre’s shear strength and its transverse and axial uniaxial strengths, as found from a novel testing proposal. The two bounds were compared with new data and other experimental results published in the literature. The results showed that the region between the bounds captured the failure loads of embedded fibres with effective load-bearing orientations. A critical orientation was observed at maximum strength. The present interpretation of the plasticity occurring within off-axis, hooked-end steel fibres suggests that it is possible to optimise the strength of concrete using this method of reinforcement.

Enhancing therapeutic potential: Human adipose-derived mesenchymal stem cells modified with recombinant adeno-associated virus expressing VEGF165 gene for peripheral nerve injury.

This study aimed to investigate the therapeutic potential of human adipose-derived mesenchymal stem cells (hADSCs) modified with recombinant adeno-associated virus (rAAV) carrying the vascular endothelial growth factor 165 (VEGF165) gene in peripheral nerve injury (PNI). The hADSCs were categorized into blank, control (transduced with rAAV control vector), and VEGF165 (transduced with rAAV VEGF165 vector) groups. Subsequently, Schwann cell differentiation was induced, and Schwann cell markers were assessed. The sciatic nerve injury mouse model received injections of phosphate-buffered saline (PBS group), PBS containing hADSCs (hADSCs group), rAAV control vector (control-hADSCs group), or rAAV VEGF165 vector (VEGF165-hADSCs group) into the nerve defect site. Motor function recovery, evaluated through the sciatic function index (SFI), and nerve regeneration, assessed via toluidine blue staining along with scrutiny of Schwann cell markers and neurotrophic factors, were conducted. Modified hADSCs exhibited enhanced Schwann cell differentiation and elevated expression of Schwann cell markers [S100 calcium-binding protein B (S100B), NGF receptor (NGFR), and glial fibrillary acidic protein (GFAP)]. Mice in the VEGF165-hADSCs group demonstrated improved motor function recovery compared to those in the other three groups, accompanied by increased fiber diameter, axon diameter, and myelin thickness, as well as elevated expression of Schwann cell markers (S100B, NGFR, and GFAP) and neurotrophic factors [mature brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor (GDNF)] in the distal nerve segment. rAAV-VEGF165 modification enhances hADSC potential in PNI, promoting motor recovery and nerve regeneration. Elevated Schwann cell markers and neurotrophic factors underscore therapy benefits, providing insights for nerve injury strategies.

Preparation and properties of PCL coaxial electrospinning films with shell loaded with CEO and core coated LEO nanoemulsions

During storage and transportation, the reduction of microbial contamination and management of the exudation of fluids from the fish can effectively mitigate spoilage and degradation of fish fillets. In this work, the coaxial electrospinning films loaded with natural plant preservatives, namely laurel essential oil (LEO) and clove essential oil (CEO), were prepared by the coaxial electrospinning method synergistic with nanoemulsion techniques, and the hydrophilic preservation pads were prepared. The morphology of the film fiber is clear, without beads or damage, with fiber diameters falling within the 230–260 nm range. It has a distinct core–shell structure, exceptional thermal stability, and strong antibacterial and antioxidant properties. The core–shell structure of the fiber subtly regulates the release of preservatives and significantly improves the utilization efficiency. At the same time, the synergistic use of two essential oils can reduce the amount while amplifying their effectiveness. The pads significantly slowed down the increase of key indicators of spoilage, such as total viable count (TVC), pH, thiobarbituric acid reactive substances (TBA), and total volatile base nitrogen (TVB-N), during the storage of the fish fillets. Furthermore, the pads effectively slowed down the decline in water-holding capacity, the deterioration of textural qualities, and the negative changes in the microstructure of the fish muscle. Ultimately, the pads notably delayed the spoilage of fish fillets, extending their shelf life from 5 d to 9 d. The efficient utilization of biological preservatives in this film can provide technical support for the development of food preservation materials.

Development of pectin/chitosan-based electrospun biomimetic nanofiber membranes loaded with dihydromyricetin inclusion complexes for wound healing application

Accidents and surgical procedures inevitably lead to wounds, presenting clinical challenges such as inflammation and microbial infections that impede the wound-healing process. This study aimed to address these challenges by developing a series of novel wound dressings known as electrospun biomimetic nanofiber membranes. These membranes were prepared using electrostatic spinning technique, incorporating hydroxypropyl-β-cyclodextrin/dihydromyricetin inclusion complexes. The prepared electrospun biomimetic nanofiber membranes exhibited randomly arranged fiber morphology with average fiber diameters ranging from 200 to 400 nm, resembling the collagen fibers in the native skin. These membranes demonstrated excellent biocompatibility, hemocompatibility, surface hydrophilicity, and wettability, while also releasing dihydromyricetin in a sustained manner. In vitro testing revealed that these membranes, loaded with hydroxypropyl-β-cyclodextrin/dihydromyricetin inclusion complexes, displayed higher antioxidant potential and inhibitory effects against Staphylococcus aureus and Escherichia coli. Furthermore, these membranes significantly reduced the M1 phenotypic transition in RAW264.7 cells, even when stimulated by lipopolysaccharides, effectively restoring M2 polarization, thereby shortening the inflammatory period. Additionally, the in vivo wound healing effects of these membranes were validated. In conclusion, this study introduces a promising nanofiber membrane with diverse biological properties that holds promise for addressing various crucial aspects of the wound-healing process.

Antibacterial cellulose solution-blown nonwovens modified with salicylic acid microcapsules using NMMO as solvent

Solution blowing process was used to prepare cellulose nonwovens, by using N-methyl morpholine-N-oxide (NMMO) as solvent, and salicylic acid (SA) microcapsules as antibacterial additives. The structure and properties of cellulose nonwovens modified with different SA microcapsules contents were compared and evaluated. The results showed that more uniform and denser web structure was formed with the increase of SA microcapsules content, the average fiber diameter of cellulose nonwoven increased from 1.99 μm to 2.65 μm. The air flow resistance and filtration efficiency of cellulose nonwovens increased with addition of SA microcapsules, whereas the mechanical properties, and wearing comfort including air permeability, moisture vapor transfer rate, and softness of cellulose nonwovens decreased slightly, under the same basis weight. SA microcapsules modified cellulose nonwovens exhibited good sustained-release behavior and antimicrobial activity against Escherichia coli. The higher SA microcapsules content in cellulose nonwovens, the faster release rate and the higher antimicrobial activity. The cellulose solution-blown nonwovens modified with SA microcapsules are expected to find applications in medical and healthcare fields due to its antibacterial activity and biodegradability.

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 ($2000) 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.

In vitro investigations on the effects of graphene and graphene oxide on polycaprolactone bone tissue engineering scaffolds

Polycaprolactone (PCL) scaffolds that are produced through additive manufacturing are one of the most researched bone tissue engineering structures in the field. Due to the intrinsic limitations of PCL, carbon nanomaterials are often investigated to reinforce the PCL scaffolds. Despite several studies that have been conducted on carbon nanomaterials, such as graphene (G) and graphene oxide (GO), certain challenges remain in terms of the precise design of the biological and nonbiological properties of the scaffolds. This paper addresses this limitation by investigating both the nonbiological (element composition, surface, degradation, and thermal and mechanical properties) and biological characteristics of carbon nanomaterial-reinforced PCL scaffolds for bone tissue engineering applications. Results showed that the incorporation of G and GO increased surface properties (reduced modulus and wettability), material crystallinity, crystallization temperature, and degradation rate. However, the variations in compressive modulus, strength, surface hardness, and cell metabolic activity strongly depended on the type of reinforcement. Finally, a series of phenomenological models were developed based on experimental results to describe the variations of scaffold’s weight, fiber diameter, porosity, and mechanical properties as functions of degradation time and carbon nanomaterial concentrations. The results presented in this paper enable the design of three-dimensional (3D) bone scaffolds with tuned properties by adjusting the type and concentration of different functional fillers.Graphic abstract

Abstract We036: Recapitulating Cardiac Microenvironment: Elucidating the Role of ECM Components and Architecture on Cardiac Differentiation

The discovery of iPSCs was revolutionary for regenerative medicine, especially as a source to replace a cell population with limited regeneration capability, like cardiomyocytes (CMs). However, the exact mechanism(s) governing how the microenvironment influences cardiac differentiation at a cellular scale is still widely unclear. To bridge this gap, we created an in vitro fibrous model from a decellularized porcine cardiac extracellular matrix. The aim is to assess the impact of the microenvironment, specifically the effects of protein composition and micro-architecture, on the cardiac differentiation of iPSCs. To study the role of protein composition, atrial and ventricular regions of the porcine heart are manually identified and separated as their protein composition is observed to be different. To test this, the material was subjected to proteomics analysis with LS-Mass Spectrometry where about 1000 proteins were identified in the ventricular region and only 300 proteins in atria. The decellularized tissue was tested for complete removal of nuclei by staining and further validated with DNA quantification. The dECM was blended with synthetic polymer (polycaprolactone) for electrospinning. The average collected fiber diameter was 14.8 ± 3.9 μm. The fibrous scaffolds were seeded with iPSCs and differentiated towards cardiac lineage. dECM samples show comparable signs of biocompatibility as laminin-521 coated TCPS, forming clusters throughout the differentiation process indicating that the scaffolds encourage cardiac differentiation. Further analysis is being conducted to compare the cellular expressions of differentiation markers including mesoderm formation, cardiac specification, and cardiomyocyte structural and functional markers. The effects of the ECM composition will be checked with myosin light and heavy chain expressions, as their expressions vary in the atrial and ventricular regions of the heart.

Achieving superior Laplace pressure in electrospun PVDF/PAN Janus membranes: A morphological approach

Janus membranes have asymmetric wettability on each side. This contrasting structure gives them an internal driving force for spontaneous fluid transport (caused by Laplace pressure). The objective of this research is to attain the maximum Laplace pressure for electrospun PVDF/PAN Janus membranes by adjusting the fiber diameter and, consequently, the pore size and contact angle in each layer of the membrane. To achieve this goal, the Taguchi method was employed, and the parameters of the electrospinning process were modified to determine the optimal conditions for obtaining the smallest and largest fiber diameters for PAN and PVDF polymers. Accordingly, four distinct types of Janus membranes with different morphologies in each layer were synthesized. SEM analysis was employed to characterize the structural and morphological properties of the fibers in each layer. Additionally, the contact angle (CA) was measured to assess the hydrophilicity of each layer and determine the droplet penetration rate across the membrane. According to the results, the maximum Laplace pressure (205.60 kPa calculated by the analysis of SEM images and 197.4 kPa calculated by the bubble point test) and highest droplet penetration rate (0.83 µL/s) were attributed to the Janus membrane with the lowest pore size in the hydrophilic layer (0.65 µm) and the highest pore size in the hydrophobic layer (3.44 µm). The performance of the optimized membrane was evaluated with respect to unidirectional water transport and water–oil mixture separation. The results showed a rectification ratio of3.92, a permeate flux of7.9 × 104 L·m−2·h−1·bar−1, and a separation efficiency of96.8 %. Finally, it was demonstrated that the Laplace pressure of the optimal Janus membrane in this study is 2.66 times superior to that of the best similar one in previous studies. The appropriate and allowable range for pore size and contact angle, necessary to attain a satisfactory Laplace pressure (exceeding 100 kPa), has been explored, determined, and recommended for future researchers to foster inspiration in the field of Janus membranes.