Fiber Diameter Research Articles

Awafung Emmanuel Adie

The exploration of electrospun nanofibers has gained significant attention in wound healing due to their unique structural properties and potential to enhance therapeutic efficacy. This review examines the development and application of electrospun nanofibers, focusing on their antibacterial properties and biocompatibility, which are essential for effective wound management. Electrospinning techniques enable the production of nanofibers with high surface-area-to-volume ratios, tunable porosity, and controlled release profiles of therapeutic agents, making them ideal for wound dressings. We explore various biopolymers and synthetic polymers used in electrospun nanofiber fabrication, emphasizing their contributions to antibacterial effects and biocompatibility. The incorporation of antimicrobial agents, such as silver nanoparticles and essential oils, enhances infection prevention and promotes healing. Additionally, challenges related to the scalability of electrospinning processes and the need for standardized evaluation methods are discussed. The review also highlights the influence of nanofiber architecture such as fiber diameter, alignment, and surface modifications on cellular response and tissue integration. The findings underscore the potential of electrospun nanofibers to not only serve as passive wound dressings but also actively facilitate healing through antibacterial action and favorable biological interactions. Future research should focus on optimizing fabrication techniques, enhancing functional properties, and conducting in vivo studies to fully realize the clinical potential of these materials in wound care applications. Keywords: Electrospun, nanofibers, wound healing, antibacterial and biocompatibility

Evaluation of mechanical properties for Ricinus communis L plant fiber/epoxy composite

AbstractThis research explores the mechanical properties of castor oil plant (Ricinus communis L) natural fiber‐reinforced epoxy composites, addressing the need for sustainable materials. Cortex and xylem fibers extracted from castor oil plant residue using a standardized method were used to fabricate unidirectional long fiber and short random fiber composites. Various fiber volume fractions (10 %, 20 %, 30 %, 40 %) and fiber lengths (5 mm to 40 mm) of cortex fibers were tested according to ASTM standards and results showed that fibers of diameters 275 μm to 325 μm, have superior tensile strength (290 MPa to 346 MPa) compared to xylem fibers (90 MPa to 140 MPa). Composites of 40 % volume fraction cortex fibers aligned longitudinally exhibited the highest tensile (76.35 MPa), flexural (121.45 MPa), and impact strength (6.99 kJ/m2) significantly improved compared to the epoxy matrix. For short random cortex fiber composites, the optimal mechanical performance was achieved with 20 mm fibers and a 40 % volume fraction, resulting in the highest tensile strength (32.12 MPa), flexural strength (84.31 MPa), and impact energy (40 J/m). These results highlight the potential of castor oil cortex fibers to enhance the mechanical properties of epoxy composites for various engineering applications.

Simulation-based high-speed elongational rheometer for Carreau-type materials

Abstract For the simulation-based design of fiber melt spinning processes, the accurate modeling of the processed polymer with regard to its material behavior is crucial. In this work, we develop a high-speed elongational rheometer for Carreau-type materials, making use of process simulations and fiber diameter measurements. The procedure is based on a unified formulation of the fiber spinning model for all material types (Newtonian and quasi-Newtonian), whose material laws are strictly monotone in the strain rate. The parametrically described material law for the elongational viscosity implies a nonlinear optimization problem for the parameter identification, for which we propose an efficient, robust gradient-based method. The work can be understood as a proof of concept, a generalization to other, more complex materials is possible.

Effect of blown air temperature on morphology, phase structure and filtration efficiency of PVDF nanofibrous mats produced via electro‐blowing

AbstractThis study investigates the effects of temperature of pressurized blown air on fiber morphology, porosity, phase structure, and filtration performance of PVDF nanofibers produced via the electro‐blowing method for the first time. The blown air heated to 20, 40, 60, and 80°C was utilized during production. Increasing air temperature resulted in more homogeneous distribution of fibers and defect‐free fibrous mats, accompanied by a significant reduction in fiber diameter. A linear relationship between fiber diameter and pore size was observed; as fiber diameter decreased, reducing air permeability due to smaller pore sizes. FTIR measurements revealed the highest β‐phase content (82%) in the PVDF‐80C sample produced at 80°C. The rise in temperature lowered solution viscosity and surface tension, contributing to improved drawing effect and therefore higher β‐phase content in the PVDF polymer. Corona discharge treatment further enhanced the surface potential, with the finest fibers exhibiting the highest surface charge. The PVDF‐80C sample demonstrated the best performance during filtration tests against NaCl aerosols (PM0.3) at a flow rate of 95 L/min, achieving a filtration efficiency of 98.68% with a pressure drop of 153 Pa. These findings highlight the critical role of temperature in influencing nanofiber properties and filtration performance.Highlights Finer fibers and defect‐free mats achieved with increased air temperature. PVDF‐80C showed 82% β‐phase content, the highest among all samples. Smaller fiber diameter led to reduced pore size and lower air permeability. Corona discharge enhanced surface potential, boosting fiber charge. PVDF‐80C achieved 98.68% filtration efficiency with 153 Pa pressure drop.

Study on Deposition of Coaxial Electrospinning Fibers by Coaxial Auxiliary Flow Field

Gas-assisted coaxial electrospinning (GACES) is a simple and general method for the mass preparation of coaxial nanofiber membranes, which has great industrial potential. However, in the manufacturing process, due to the bending instability of the jet in the electric field and the pulling effect of the gas flow field, the deposition uniformity of the fiber is still a big problem. Through finite element simulation analysis of the flow field in the manufacturing process and the construction of the jet mechanics model after adding the flow field, the influence mechanism of coaxial auxiliary flow on the fiber deposition area and its uniformity was successfully revealed in this research. Finally, the deposition area and thickness uniformity of coaxial fibers are increased by 3 times (the deposition area: 19.63 cm2 → 78.50 cm2) and 2.34 times (the standard variance: 3 μm2 → 10 μm2) by gas-assisted coaxial electrospinning. At the same time, the coaxial auxiliary gas flow also reduces the coaxial fiber diameter by 36.9% (the average fiber diameter: 241 nm ± 5 nm → 152 nm ± 23 nm) and the distribution range by 66% (the standard variance: 1.5 × 102 nm2 → 51 nm2). This research provides a reliable idea and experimental basis for homogeneous preparation of coaxial nanofiber membranes.

Pulmonary inflammatory responses and retention dynamics of cellulose nanofibrils.

Cellulose nanofibrils (CNFs) are advanced biomaterials valued for their strength, lightweight nature, and low thermal expansion, making them suitable for diverse industrial applications. However, their potential inhalation risks necessitate thorough safety evaluations. This study investigates the pulmonary inflammatory effects and retention of CNFs following intratracheal instillation in rats. TEMPO-oxidized CNF (CNF1; 11.5 nm × 1.8 μm), mechanically fibrillated CNF (CNF2; 23.9 nm × 2.4 μm), and shorter-fibrillated CNF (CNF3; 21.6 nm × 1.2 μm) were administered at 2.0 mg/kg body weight. Endotoxin contamination was assessed using lipopolysaccharide (LPS) controls. Pulmonary inflammation was evaluated 28 days post-instillation, and lung retention of chemically stained CNFs was tracked for 90 days. Results indicated: (1) CNFs were taken up by alveolar macrophages, but no significant acute inflammation was observed; (2) CNF characteristics, particularly fiber diameter and length, play a key role in influencing lung inflammation responses and determining inflammation sites; (3) endotoxin levels in the CNF dispersions may have limited effects on inflammatory responses; and (4) CNFs persist in lung tissue for extended periods, indicating slow clearance. While immediate inflammatory responses were minimal, the prolonged retention of CNFs in the lungs could contribute to chronic low-grade inflammation. Given the variability in CNF properties influenced by raw materials and manufacturing processes, it is essential to test each CNF type individually, including toxicological endpoints beyond inflammation, to accurately assess their potential health risks.

Several variants on chromosome 10 are associated with coarse hair diameter in Dazu black goats (Capra hircus).

Goats typically have double coats, with the outermost coarse hairs providing protection against mechanical and radiation damage. While much attention has been paid to cashmere due to its status as a high-end textile material, there is limited information available on coarse hair. This study aimed to identify genomic variants, such as single nucleotide polymorphisms (SNPs) and insertion/deletions (indels), associated with coarse hair diameter using a genome-wide association study (GWAS). Coarse hairs and blood samples were collected from 263 adult female goats. The diameter of coarse hairs was measured using an inverted microscope, and whole genome sequencing was conducted on the blood samples. After reads mapping, variants calling, and quality control, totals of 11 322 006 SNPs and 863 734 indels were included for SNP-GWAS and indel-GWAS analyses. Eight significant SNPs (p < 8.98e-8) and three significant indels (p < 1.16e-6) were identified. Among those, one SNP was located on Chromosome 4 and near the genes COL28A1 and C1GALT1. Seven significant SNPs were found in the region chr10_96664101-96670958, with the genes CDO1 and TMED7 located upstream and downstream, respectively. Haplotype analysis revealed that the diverse haplotypes of these seven SNPs presented varying values for coarse hair diameter. Notably, the only consistently significant insertion (chr10_96665085, GTA>G) was also located within the region chr10_96664101-96670958, further highlighting the importance of this genomic region in influencing coarse hair diameter. These significant variants and genomic regions provide valuable insights for investigating the genetic mechanisms underlying the variation in fiber diameter.

Role of sulfated GAGs in shear mechanical properties of human and porcine cornea

The corneal extracellular matrix is mainly composed of collagen fibers, proteoglycans, and glycosaminoglycans (GAGs). The present work was done to investigate the effect of GAGs on linear viscoelastic shear properties of human and porcine cornea. A clear understanding of structural functions of GAGs could result in the development of new intervention methods for diseased conditions that involve changes to the expression of GAGs/PGs. Here, we used keratanase II enzyme to deplete sulfated GAGs from porcine and human donor corneal disks. After quantifying the GAG content, collagen fiber diameter, and interfibrillar spacings of control and GAG-depleted specimens using the Blyscan assay and transmission electron microscopy, we performed torsional rheometry to determine their shear properties at different levels of axial strain. We found that the GAG content of control human (52.35 ± 3.40 μg/mg dry tissue) and porcine cornea (48.59 ± 7.79 μg/mg dry tissue) significantly reduced following keratanase II enzyme treatment. Moreover, we observed that the diameter of collagen fibers (28.78 ± 2.33 nm) and interfibrillar spacing (45.93 ± 2.33 nm) of human specimens were significantly smaller than the collagen fiber diameter (34.77 ± 21.90 nm) and interfibrillar spacing (54.28 ± 3.99 nm) of porcine corneal samples. Although GAG depletion did not have any significant effect on the collagen fiber diameter, it significantly increased the interfibrillar spacing in both porcine and human samples. Within the range of linear viscoelastic behavior, the shear stiffness of human and porcine corneal samples did not depend on the shear strain but significantly increased with increasing the applied axial strain. The average complex shear modulus was found to be between 1.0 KPa and 6.5 KPa and between 8.5 KPa and 31 KPa for control porcine and human discs, respectively. The GAG removal caused significant reduction of shear stiffness in both human and porcine corneal samples. Based on these findings, we conclude that sulfated GAGs are important in defining shear properties of porcine and human corneas and significant GAG content variation adversely affects corneal shear modulus.

Environmentally friendly zein/ethylcellulose nanofiber air filtration materials with tunable hydrophobicity and high filtration efficiency.

Due to people's environmental awareness and the continuous improvement of the living environment requirements, the pollution problem of fine particles has attracted widespread attention and great importance. Therefore, the development of new green and environmentally friendly air filtration materials with high efficiency and low resistance is ongoing. In this work, eco-friendly zein/ethylcellulose blende nanofiber membranes with different fiber morphologies, diameter sizes, and hydrophobicity are prepared by electrospinning technology, and their performance in the field of air filtration and purification is investigated, to make them highly efficient for the adsorption of small pollutants of various polarities. The experiments showed that the hydrophobicity of the nanofiber membrane was adjusted by changing the ratio of zein and ethylcellulose, and the addition of ethylcellulose improved the thermal stability and use temperature of the composite nanofiber membrane. The filtration efficiency of the nanofiber membrane can reach more than 85% for small particle pollutants of different polarities, and both sides of the tested membrane have high filtration capacity, which can still be maintained after three times of reused. This gives it great potential and broad application prospects in the field of air filtration.

Novel mutations in exon 2 of follistatin (FST) gene associated with wool fiber diameter in sheep

Novel mutations in exon 2 of follistatin (FST) gene associated with wool fiber diameter in sheep

Designing sustained release from nanofiber patch for paclitaxel as prospective localized nanotherapeutic delivery in breast cancer.

The second most prevalent cause of mortality among women is breast cancer, and paclitaxel (PTX) is an effective drug for its treatment. The present work aims to develop patch-based poly(ε-caprolactone) (PCL) nanofibers incorporating PTX as a localized and sustained drug delivery system. The co-deposition of poly(vinyl alcohol) (PVA) fibers during electrospinning was allowed to improve water absorption by the scaffold, which in turn facilitated the release of drug molecules. To figure out optimized electrospinning parameters and predict the optimal formulation, the quality-by-design approach was utilized. The blank mat, i.e., without drug and optimized nanofiber formulation (Fo), was characterized physiochemically using FE-SEM, XRD, FT-IR, TGA and DSC techniques. The optimization yielded a 92.7% final product yield, indicating high process efficiency and minimum losses during electrospinning. FE-SEM studies have demonstrated that uniform nanofibers with bead-free morphology. The average fiber diameter and drug entrapment of the optimal formulation, Fo, were 547±6.6nm and 85±1.73%, respectively. Diffraction and calorimetric studies revealed a sharp decrease in the crystallinity of pure PTX and its subsequent amorphization within the nanofiber matrix. FT-IR studies showed no chemical interaction between the drug and polymers. A decrease in water contact angle from 120.4±0.9 to 81.0±0.8 in the Fo formulation was due to the co-spinning of PVA; this ensures proper wettability and adhesion ideal for localized delivery. The Fo nanofiber formulation demonstrated sustained PTX release for up to 17days. The MTT assay results confirm Fo nanofibers were cytotoxic to the breast cancer cell line, MDA-MB-231, than pristine nanofibers. These findings suggest that Fo nanofiber mats could be a potential localized delivery system for PTX in breast cancer treatment, pending further in-vivo validation.

Chemical composition and histological structure of the longest muscle of the back of Aberdeen-Angus cattle depending on genotype

The article discusses the possibility of using calpain 1 (CAPN1) and calpastatin (CAST) genes for the prediction of beef tenderness and selection of the most perspective in this property animals. The aim of the research was the study of the CAPN1 and CAST gene polymorphisms in association with the chemical composition and histological structure of the meat in cattle. Samples from the longest muscle of the back (M. longissimus dorsum) of Aberdeen-Angus bulls (n=9) with known genotypes for the CAPN1_316, CAPN1_4751, CAST_282 and CAST_2959 polymorphisms were collected after slaughter and analyzed for protein, fat, dry matter and mineral content, as well as muscle, connective and adipose tissue content and muscle fiber diameter. It was found that meat from bulls with the GG-CAPN1_316 and GG-CAST_2959 genotypes contained 14.5-15.8% more protein and 11.4-13.3% less fat compared to other genotypes, and meat from animals with the ST-CAPN1_4751 and AA-CAST_2959 genotypes had lower connective tissue content (by 7.5-7.7 and 9.6-10.2%, respectively). The largest myofibril diameter was observed in samples from steers with genotypes CC-CAPN1_316 (111.2 μm), TT-CAPN1_4751 (116.2 μm) and AA-CAST_2959 (111.7 μm). With respect to the CAST_282 polymorphism, animals with the GC genotype showed advantages in all studied parameters.

Characterization of motor nerve stimulation using sinusoidal low frequency alternating currents and cuff electrodes.

Direct electrical neurostimulation using continuous sinusoidal low frequency alternating currents (LFAC) is an emerging modality for neuromodulation. As opposed to the traditional rectangular pulse stimulation, there is limited background on the characteristics of peripheral nerves responses to sinusoidal LFAC stimulation; especially within the low frequency range (<50Hz). In this study, we demonstrate LFAC activation as a means to activate motor nerves by direct bipolar nerve stimulation via cuff electrodes, and characterize the factors of activation. We study and quantify the effects of sinusoidal frequency and electrode geometry on the motor nerve activation threshold in-vivo and in computational models, in-silico. Acute in-vivo experiments (N=34) were conducted on isoflurane-anaesthetized rats. A pure tone continuous sinusoidal current was applied to the rat sciatic nerve in bipolar configurations via bipolar or tripolar nerve cuff electrodes (different contact separations). LFAC activation thresholds were quantified by measuring the electromyogram (EMG) response of the triceps surae muscles and the induced twitch force to LFAC stimulation at six frequencies (1, 2, 3, 4, 8, and 20Hz). Computationally, we utilized a volume conductor model of a bipolar cuff electrode around a single rat-size fascicle and projected the potentials to the McIntyre-Richardson-Grill (MRG) models of myelinated motor nerve fibers. We compared the in-silico responses of a range of fiber diameters (5.7 to 16μm) to LFAC stimulation and their activation thresholds to the in-vivo findings. Sinusoidal LFAC stimulation elicited motor nerve activity in-vivo and in-silico, with a remarkable convergence of the in-silico predictions to the in-vivo observations. The EMG activity showed that muscle responses to LFAC stimulation were phase-locked to the sinusoidal cycle but exhibited two distinct activation modes. These modes were classified as burst and unitary, indicating the presence of two distinct patterns of muscle activation during LFAC stimulation. The LFAC motor activation threshold was significantly dependent on frequency and influenced by the contact separation of the cuff electrode, with a greater extent of reduction at a higher frequency or wider separation. Moreover, the order of fiber recruitment was found to be normal-physiological (small-to-large caliber) given the nature of the induced EMG activity and in-silico predictions. These findings provide significant insights into the nature of sinusoidal LFAC stimulation, at the explored range of frequency, and the expected mammalian peripheral motor nerve responses to LFAC. The characteristics of sinusoidal LFAC stimulation would facilitate selectivity approaches in a broader range of therapeutic and rehabilitative neuromodulation applications.

Optimizing solvent systems for electrospun PLGA scaffolds: effects on microstructure and mechanical properties for biomedical applications.

Electrospun scaffolds fabricated from poly(lactic-co-glycolic acid) (PLGA) have garnered widespread interest in biomedical applications due to their ability to mimic the extracellular matrix (ECM) structure with a tunable degradability profile. The properties of electrospun scaffolds are meticulously tailored for specific applications through the adjustment of polymer properties, solution parameters, and processing conditions. Solvent selection is crucial, influencing polymer spinnability and scaffold topographical, physical and mechanical features. Hansen solubility theory aids in predicting suitable solvent systems. The absence of specific data prompted a solubility experiment to determine Hansen solubility parameters for PLGA. Subsequently, various solvent systems were investigated for their impact on the microstructure of electrospun PLGA scaffolds. Optimizing the electrospinning process resulted in fibrous scaffolds with consistent average fibre diameter from different solvent systems, allowing a focused examination of the solvent's isolated influence on mechanical properties. PLGA samples electrospun using hexafluoro isopropanol (HFIP) displayed lower Young's modulus and ultimate tensile strength but higher failure strains than those created using binary solvent systems composed of tetrahydrofuran (THF), dichloromethane (DCM), and dimethylformamide (DMF). This research advances the understanding and optimization of electrospun PLGA scaffolds, enhancing their potential for biomedical applications.

Anisotropic hydrogel microelectrodes for intraspinal neural recordings in vivo

Creating durable, motion-compliant neural interfaces is crucial for accessing dynamic tissues under in vivo conditions and linking neural activity with behaviors. Utilizing the self-alignment of nano-fillers in a polymeric matrix under repetitive tension, here, we introduce conductive carbon nanotubes with high aspect ratios into semi-crystalline polyvinyl alcohol hydrogels, and create electrically anisotropic percolation pathways through cyclic stretching. The resulting anisotropic hydrogel fibers (diameter of 187 ± 13 µm) exhibit fatigue resistance (up to 20,000 cycles at 20% strain) with a stretchability of 64.5 ± 7.9% and low electrochemical impedance (33.20 ± 9.27 kΩ @ 1 kHz in 1 cm length). We observe the reconstructed nanofillers’ axial alignment and a corresponding anisotropic impedance decrease along the direction of cyclic stretching. We fabricate fiber-shaped hydrogels into bioelectronic devices and implant them into wild-type and transgenic Thy1::ChR2-EYFP mice to record electromyographic signals from muscles in anesthetized and freely moving conditions. These hydrogel fibers effectively enable the simultaneous recording of electrical signals from ventral spinal cord neurons and the tibialis anterior muscles during optogenetic stimulation. Importantly, the devices maintain functionality in intraspinal electrophysiology recordings over eight months after implantation, demonstrating their durability and potential for long-term monitoring in neurophysiological studies.

Photobiomodulation and aquatic training reduce TNF-α expression and enhance muscle fiber area in Wistar rats with compensatory hypertrophy.

This study aims to assess the effects of aquatic training (AT) and its combination with photobiomodulation (PBM) on cytokine synthesis and plantar muscle morphology during compensatory hypertrophy (H) in Wistar rats. H was induced by bilateral ablation of synergistic muscles, and PBM using a laser (780nm). AT involved 60min sessions, 5 times/week, for 7 and 14 days. Muscle weight relative to body weight did not differ significantly between groups. TNF-α synthesis levels decreased in the H + AT + PBM group at 7 days compared to H Control. IL-6 and IL-1β levels showed no significant changes. Cross-sectional area (CSA) was higher in H + AT + PBM at 7 days and 14 days compared to H + AT and H Control. Fiber diameter increased in H + AT and H + AT + PBM compared to H at 14 days. AT with PBM decreased TNF-α expression, increased CSA and fiber diameter, whereas AT alone increased fiber diameter. In conclusion, the combination of photobiomodulation (PBM) therapy and aquatic training (AT) effectively reduced TNF-α levels while increasing muscle fiber diameter and cross-sectional area (CSA). Furthermore, AT alone demonstrated the capacity to maintain fiber diameter.

Study on the influence of square fiber diameter quality on the optical characteristics of lobster eye X-ray micro pore optics

Background The lobster eye micro pore optics (MPO) plays a pivotal role in X-ray focusing, composed of thousands of hollow square microfibers. The channel error in MPO can profoundly impact its focusing performance. Due to the complex manufacturing process of MPO, there are numerous factors that can contribute to channel errors. Objective This paper investigates the impact of two key quality indicators of fiber, i.e., diameter precision and ovality, on the focusing performance of flat MPO. Methods During the actual production process of MPO, fibers with varying diameter precision and ovality are utilized, and point-to-point vacuum X-ray focusing equipment is used to assess MPO's focusing performance. Channel error models related to fiber diameter accuracy and ovality are established in the simulation. Results Experiments show that both the diameter precision and ovality of fiber influence MPO focusing abilities, with diameter precision primarily affecting the intensity and uniformity of the central point focus and the parallelism of the line foci, while ovality mainly affects the intensity and continuity of the line foci. Numerical simulation results reveal that tilt channel errors significantly affect the X-ray focusing effects. Conclusions These findings hold important guiding significance for the preparation process of square fibers and high quality X-ray focusing device.

Drop-off characteristics of film flow on inclined fibers

Abstract This paper presents an empirical analysis of a film flow dropping-off from an inclined fiber substrate, where the fiber diameter is on the order of the capillary length. The investigation aims to elucidate the dynamics of beads traveling down the inclined fibers. We explore the parameters influencing the bead’s final shape and their stability on the substrate (in terms of detaching or not detaching) in a flow driven by gravity and affected by surface tension and inertia. Three different growth modes and their connection to the two main existing drop-off mechanisms of beads on inclined fibers, namely drop-off due to unsaturated growth and drop-off due to coalescence events, are established and demonstrated. A new parameter, $$\Phi$$ Φ , is introduced, which includes information about the shape of the beads and its connection to the flow conditions. If $$\Phi &gt;1$$ Φ &gt; 1 , the bead exhibits a rather sinusoidal shape, indicating that its formation is predominantly influenced by surface tension. If $$\Phi &lt; 1$$ Φ &lt; 1 , the bead is subjected to front-steepening due to an inertia-dominated flow. If $$\Phi =1$$ Φ = 1 , the bead’s tail aligns with the direction of gravity, experiencing unsaturated growth until it drops off, which indicates a flow condition driven primarily by gravitational forces. Furthermore, this study offers a quantitative experimental basis for flow parameters on inclined fibers, including Nusselt film thickness, healing length within the unperturbed film and rate of growth of beads at the end of healing length, beads crest height, beads velocity, and parameter $$\Phi$$ Φ for future comparison to theoretical and numerical modelling.

Hybrid Nanofibrous Membrane with Durable Electret for Anti-Wetting Air Filtration.

Electrospun fibrous materials with fine fibers and small pores are fundamental for particulate matter (PM) filtration, addressing its harmful environmental and health impacts. However, the existing electrospun fibers are still limited to their sub-micron diameters and unstable surface electrostatic effect, leading to deteriorated filtration performance after prolonged storage or wetting. Herein, the study creates nanofibrous membranes with long-time stable electrostatics by electret-enhanced electrospinning. The phase separation and polarization of the charged jet are manipulated to achieve rapid stretch and strong electret. The obtained membrane exhibits nanosized structures with fiber diameters of ≈220 nm, pore size <1 µm, as well as robust surface potential of 0.4 kV. By virtue of the synergistic effects of sieving and adsorption, the nanofibrous membrane showed a remarkable PM0.3 filtration efficiency of 96.6% and pressure drop of 140 Pa, even reaching the N90 standard after five wetting cycles. The design of such durable membranes will offer a new sight in the functional filtration materials.

High-Performance Mechano-Sensitive Piezoelectric Nanogenerator from Post-Treated Nylon-11,11 Textiles for Energy Harvesting and Human Motion Monitoring.

Piezoelectric polymer textiles offer distinct advantages in the fabrication of wearable nanogenerators (NGs). One effective strategy to enhance the output capacity of NGs is to modulate the piezoelectric performance of the textiles. This paper focuses on further improving the piezoelectric properties of nylon-11,11 textiles through post-drawing and annealing treatments. We elucidate the evolution of morphology and the ferroelectric phase in the submicron/nanoscale fibers during post processing as well as the corresponding changes in performance. The drawing process primarily enhances the orientation of the crystalline phase and reduces the fiber diameter, while the annealing process more effectively promotes the crystal size and crystallinity. Afterward, we propose an optimal postdrawing and annealing assisted-electrostatic spinning process. Under the synergistic effects of these post-treatments, the remanent polarization (Pr) of nylon-11,11 textile increased to 4.7 times that of the untreated textile, resulting in amplified piezoelectric outputs. The output voltage, current, and power density of the prepared PENG reached 21.5 V, 800 nA, and 1.88 mW·m-2 (80 MΩ), respectively. Notably, at pressures exceeding 8 kPa, the mechano-voltage and current sensitivity reached as high as 266 mV/kPa and 13.99 nA/kPa, respectively, which is extraordinary compared to other piezoelectric NGs and comparable to the performance of nylon-based triboelectric NGs. Furthermore, we investigated the potential application of the prepared PENG in biomechanical energy harvesting and human movement monitoring. Experiments demonstrated its effectiveness in powering light bulbs, tracking walking status, and monitoring finger/hand/wrist gestures.