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Flexible triboelectric generators present a wide range of prospective applications owing to their small size, light weight, and wearability; in addition, they can convert external mechanical energy into electrical energy to provide an energy supply for wearable electronic products. In this study, a wearable textile triboelectric generator was developed by weaving polyurethane (PU) nanofiber core-spun yarn and Si 3 N 4 -electret-doped polyvinylidene fluoride (PVDF) nanofiber core-spun yarn into a double-layer fabric. Within the double-layer fabric, one layer was Si 3 N 4 -doped PVDF (denoted as Si 3 N 4 @PVDF) nanofiber fabric, and the other was PU nanofiber fabric. When subjected to an external mechanical force, PU nanofiber fabric and Si 3 N 4 @PVDF nanofiber fabric came into contact and were able to convert external mechanical energy into electrical energy. The most notable instantaneous electrical performance of this triboelectric nanogenerator was open circuit voltage of 71 V, short-circuit current of 0.7 μA, and output power of 56 μW. Additionally, the wearable textile triboelectric generator exhibited superior washability, stability, and cycle durability. More significantly, it was capable of driving some low-consumption electronic products, including capacitors, LED bulbs, and digital meters, thereby exhibiting a strong potential for flexible self-powered electronic devices and intelligent textiles., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Antibacterial textiles, which effectively inhibit bacterial breeding and resist pathogenic diseases, have wide applications in medicine, hygiene, and related fields. However, traditional antibacterial textiles exhibit significant limitations, such as poor antibacterial durability and contamination during preparation. In this work, nanofiber yarn loaded with a high-efficiency antibacterial agent was prepared using electrospinning technology. Polyethyleneimine (PEI) was introduced as a solubilizing material to functionalize graphene oxide (GO) to form GO-PEI composites. A facile microwave heating method was used to synthesize GO-PEI and silver nanoparticles (AgNPs). A multi-needle conjugated electrospinning device was used to blend the nanofibers with the GO-PEI-Ag composite to form a nanofiber core-spun yarn. The antibacterial agent was firmly fixed on the fiber to prevent easy removal. A uniformly oriented yarn structure and internal morphology were observed, and the antibacterial activity of the fabric was measured. The antibacterial rate of the fabric was over 99.99%for both Escherichia coli and Staphylococcus aureus. After ten washes, the antibacterial rate remained above 99.99%. Thus, nanofiber fabric from electrospinning displays high antibacterial activity and excellent durability, thereby providing a feasible methodology for future production of antibacterial textiles., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Highly sensitive wearable textile pressure sensors represent the key components of smart textiles and personalized electronics, with potential applications in biomedical monitoring, electronic skin, and human-machine interfacing. Here, we present a simple and low-cost strategy to fabricate highly sensitive wearable textile pressure sensors for non-invasive human motion and physiological signal monitoring and the detection of dynamic tactile stimuli. The wearable textile sensor was woven using a one-dimensional (1D) weavable core-sheath nanofiber yarn, which was obtained by coating a Ni-coated cotton yarn electrode with carbon nanotube (CNT)-embedded polyurethane (PU) nanofibers using a simple electrospinning technique. In our design, the three-dimensional elastic porous nanofiber structure of the force-sensing layer and hierarchical fiber-bundled structure of the conductive Ni-coated electrode provide the sensor with a relatively large surface area, and a sufficient surface roughness and elasticity. This leads to rapid and sharp increases in the contact area under stimuli with low external pressure. As a result, the textile pressure sensor exhibits the advantages of a high sensitivity (16.52 N -1 ), wide sensing range (0.003-5 N), and short response time (~0.03 s). Owing to these merits, our textile-based sensor can be directly attached to the skin as usual and conformally fit the shape deformations of the body's complex flexible curved surfaces. This contributes to the reliable real-time monitoring of human movements, ranging from subtle physiological signals to vigorous movements. Moreover, a large-area textile sensing matrix is successfully fabricated for tactile mapping of spatial pressure by being worn on the surface of wrist, highlighting the tremendous potential for applications in smart textiles and wearable electronics., (Copyright © 2019. Published by Elsevier Inc.)

In bone tissue engineering, the fabrication of a scaffold with a hierarchical architecture, excellent mechanical properties, and good biocompatibility remains a challenge. Here, a solution of polylactic acid (PLA) and Tussah silk fibroin (TSF) was electrospun into nanofiber yarns and woven into multilayer fabrics. Then, composite scaffolds were obtained by mineralization in simulated body fluid (SBF) using the multilayer fabrics as a template. The structure and related properties of the composite scaffolds were characterized using different techniques. PLA/TSF (mass ratio, 9:1) nanofiber yarns with uniform diameters of 72±9μm were obtained by conjugated electrospinning; the presence of 10wt% TSF accelerated the nucleation and growth of hydroxyapatite on the surface of the composite scaffolds in SBF. Furthermore, the compressive mechanical properties of the PLA/TSF multilayer nanofiber fabrics were improved after mineralization; the compressive modulus and stress of the mineralized composite scaffolds were 32.8 and 3.0 times higher than that of the composite scaffolds without mineralization, respectively. Interestingly, these values were higher than those of scaffolds containing random nanofibers. Biological assay results showed that the mineralization and multilayer fabric structure of the composite nanofiber scaffolds significantly increased cell adhesion and proliferation and enhanced the mesenchymal stem cell differentiation toward osteoblasts. Our results indicated that the mineralized nanofiber scaffolds with multilayer fabrics possessed excellent cytocompatibility and good osteogenic activity, making them versatile biocompatible scaffolds for bone tissue engineering., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The development of flexible and stretchable electronic skins that can mimic the complex characteristics of natural skin is of great value for applications in human motion detection, healthcare, speech recognition, and robotics. In this work, we propose an efficient and low-cost fabrication strategy to construct a highly sensitive and stretchable electronic skin that enables the detection of dynamic and static pressure, strain, and flexion based on an elastic graphene oxide (GO)-doped polyurethane (PU) nanofiber membrane with an ultrathin conductive poly(3,4-ethylenedioxythiophene) (PEDOT) coating layer. The three-dimensional porous elastic GO-doped PU@PEDOT composite nanofibrous substrate and the continuous self-assembled conductive pathway in the nanofiber-based electronic skin offer more contact sites, a larger deformation space, and a reversible capacity for pressure and strain sensing, which provide multimodal mechanical sensing capabilities with high sensitivity and a wide sensing range. The nanofiber-based electronic skin sensor demonstrates a high pressure sensitivity (up to 20.6 kPa -1 ), a broad sensing range (1 Pa to 20 kPa), excellent cycling stability and repeatability (over 10,000 cycles), and a high strain sensitivity over a wide range (up to approximately 550%). We confirmed the applicability of the nanofiber-based electronic skin to pulse monitoring, expression, voice recognition, and the full range of human motion, demonstrating its potential use in wearable human-health monitoring systems.

The wearable electronic skin with high sensitivity and self-power has shown increasing prospects for applications such as human health monitoring, robotic skin, and intelligent electronic products. In this work, we introduced and demonstrated a design of highly sensitive, self-powered, and wearable electronic skin based on a pressure-sensitive nanofiber woven fabric sensor fabricated by weaving PVDF electrospun yarns of nanofibers coated with PEDOT. Particularly, the nanofiber woven fabric sensor with multi-leveled hierarchical structure, which significantly induced the change in contact area under ultra-low load, showed combined superiority of high sensitivity (18.376 kPa -1 , at ~100 Pa), wide pressure range (0.002-10 kPa), fast response time (15 ms) and better durability (7500 cycles). More importantly, an open-circuit voltage signal of the PPNWF pressure sensor was obtained through applying periodic pressure of 10 kPa, and the output open-circuit voltage exhibited a distinct switching behavior to the applied pressure, indicating the wearable nanofiber woven fabric sensor could be self-powered under an applied pressure. Furthermore, we demonstrated the potential application of this wearable nanofiber woven fabric sensor in electronic skin for health monitoring, human motion detection, and muscle tremor detection.

Highlights • A novel airflow-electrospinning method to prepare nanofiber-coated hybrid yarn. • Prepared nanofiber-coated hybrid yarn had a uniform and close-knit out-of-plane wavy structure. • The hybrid yarn possessed a high strain of 531.98%. • The method was suitable for the preparation of highly elastic hybrid yarn with low-elastic polymer nanofiber layer. Abstract Nanofiber-coated hybrid yarn not only exhibited the performance advantages of coating nanofiber-layer, but also possessed the structural feature of core layer, which could endow it excellent application prospect. Previous studies for fabricating nanofiber-coated hybrid yarn had limitations of poor yarn structure and discontinuity, and obtained hybrid yarns with a small strain. Herein, a novel stepped airflow-electrospinning method, in which stepped airflow field could effectively control the movement of nanofibers, was proposed to spin continuous nanofiber-coated hybrid yarn. Interestingly, a highly stretchable nanofiber-coated hybrid yarn with uniform wavy structure was obtained by our designed method, achieving an ultra-high strain of 531.98%. [ABSTRACT FROM AUTHOR]

Electrospinning nanofiber yarn with large surface area, excellent aligned degree, perfect anisotropy and secondary process-ability has shown good prospects in the application of functional textiles, flexible and wearable electronic devices, tissue engineering, and carbon nanofiber yarn formation. However, the current methods for preparing the electrospinning nanofiber yarn still have the problems of unstable spinning process and poor yarn properties caused by low nanofiber yield and improper twisting, which limits its functional application. In this paper, a novel electrospinning method controlled by stepped airflow field and negative pressure suction is designed to spin continuously twisted nanofiber yarn based on a combination of stepped airflow electrospinning and traditional friction spinning, improving the limitation of low nanofiber yield and poor yarn properties. Our designed method can perfectly match the collection and twisting of large-scale nanofibers with excellent alignment. Furthermore, we demonstrate that this method is suitable for many polymers to continuously spin yarn and that the prepared yarn shows perfect weave-ability. The successful fabrication of nanofiber yarn displays the importance for expanding the application of nanofiber materials. [ABSTRACT FROM AUTHOR]

Multi-nozzle air jet electrospinning was used to produce continuous viscose filament/polyvinylidenefluoride (PVDF) nanofiber hybrid yarns. The production of PVDF nanofibers using this method was based on the principle that the rupture of bubbles results in multiple jet flows. Nanofibers ejected from multiple nozzles were gathered and bundled by conjugate electrospinning and were then twisted on the surface of a filament yarn through the rotation of a metal funnel. The structures and properties of the hybrid yarn were characterized, and spinning mechanism of this novel method was analyzed. The experimental results obtained in this study showed that PVDF nanofibers were perfectly coated on the filament yarn surface with a good orientation and displayed uniform twist distribution with a twist angle of 24.3°, as well as PVDF nanofibers integrated with the core yarn well. After coating with twisted PVDF nanofibers, the mechanical properties of the yarn improved significantly. The stress and strain of the yarn at break increased from 19.39 MPa and 15.83% to 30.82 MPa and 19.81%, respectively. In addition, the hybrid yarn contact angle reached 150° after coating with the twisted PVDF nanofibers, indicating a transformation of the yarn from hydrophilic to hydrophobic. The nanofiber-coated hybrid yarn produced herein can possibly be used as a self-cleaning fabric. [ABSTRACT FROM AUTHOR]

Three different nanofiber yarns with various structures are first fabricated using a custom-made, coaxial, conjugate, electrospinning set-up. These yarns are then subjected to thermal stabilization and carbonization to obtain polyacrylonitrile-based carbon nanofiber yarns (PAN-based CNY), PAN/poly(methyl methacrylate)-based carbon nanofiber yarns (PAN/PMMA-based CNY), and C/Cu composite nanofiber yarns. The structures of the three CNYs are characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The electrical conductivity of the samples is measured using a four-point probe method. In the case of the PAN-based CNY, the fibers strongly adhere to each other and eventually fracture, making the individual fibers no longer distinguishable from each other. On the other hand, the PAN/PMMA-based CNY and C/Cu composite nanofiber yarns are composed of independent fibers that are well oriented. Moreover, for the C/Cu composite nanofiber yarn, a nanowire composed of Cu nanoparticles is observed along the central axis of these fibers. In addition, Cu nanoparticles uniformly adhere to the surfaces of these fibers. Compared to the PAN-based CNY, the electrical conductivity of the C/Cu composite nanofiber yarns is significantly higher. [ABSTRACT FROM AUTHOR]

• Degradable composite nanofibers of poly[(R)-3-hydroxybutyrate- co -(R)-3-hydroxyhexanoate]/cellulose acetate were prepared via electrospinning. • Preparation of fluorine-free superhydrophobic SiO 2 @PHBH/dCA composite nanofiber membrane. • The silane-modified composite nanofiber membrane exhibited a certain durability in various harsh environments. • The superhydrophobic nanofiber membrane showed excellent biodegradability in soil. A superhydrophobic, superoleophilic, and environmentally friendly composite membrane of poly[(R)-3-hydroxybutyrate- co -(R)-3-hydroxyhexanoate] and deacetylated cellulose acetate (SiO 2 @PHBH/dCA) was developed using electrospinning and surface silanization modification techniques. In this investigation, a simple strategy was proposed to prepare biodegradable PHBH/CA composite nanofiber membranes via electrospinning, followed by short-term alkali treatment to enhance the surface activity of the nanofibers. The sol-gel impregnation method of methyltrimethoxysilane (MTMS) and tetraethyl orthosilicate (TEOS) was used to in situ grow low surface energy silica particles on the surface of nanofibers. It demonstrated self-cleaning and anti-fouling capabilities against dust and dirty water droplets and maintained hydrophobicity even after soaking in strong acid and alkali solutions for 12 h, demonstrating its excellent durability. Furthermore, the oil-water separation efficiency for test liquids such as hexane, kerosene, and sunflower oil exceeded 98.29 %, indicating promising potential for oil-water separation. After 56 days of soil composting, the biodegradation rate of the SiO 2 @PHBH/dCA composite nanofiber membrane reached 73.68 %, showing good biodegradation performance. Therefore, this innovative work provides valuable insights into the silanization modification of single nanofibers and holds broad prospects in the field of hydrophobic and biodegradable membrane materials. [Display omitted] [ABSTRACT FROM AUTHOR]