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Developing multimodal wearable textile sensors to simulate the complex human skin characteristics is central for healthcare, electronic skins, artificial intelligence and biomedical electronic applications. In this paper, stretchable piezoresistive carbon nanotubes-embedded nanofiber sensing yarns are successfully produced and mechanically robust enough to be woven to a wearable textile sensor that can detect and differentiate the multiple mechanical stimuli of pressure, stretching and bending. The smart nanofiber sensing yarn is obtained by wrapping piezoresistive elastic nanofibers onto a stretchable fiber-shaped core electrode with a facile electrospinning technique. The delicate hierarchical structure of this textile sensor ranges from the 1D macroscopic yarns to the submicron elastic nanofibers and internal nanoscale CNT percolation networks. This type of sensor offers a relatively larger contact area, multiple contact sites and larger deformation space for multimodal sensing various mechanical stimuli with improved sensitivity and broad sensing range. The textile-based sensor can be conformally attached to complex surfaces or integrated into a textile, demonstrating an excellent capability of continuous transient detection and differentiation of dynamic human movements. Moreover, a textile sensing platform is successfully integrated for spatially mapping the pressure and strain distribution, which makes it a promising candidate for electronic textiles and wearable devices.

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.

The battery separator is an important component of the battery which is related to the safety of the battery. However, there are many flaws of traditional lithium ion battery separator made by polyolefin , especially thermal stability and wettability . It was necessary, therefore, to invent a battery that heat resistance and electrolyte wettability. Here, we use the polyimide (PI) as a base material and graphene oxide (GO) as a reinforcing material, and get the nanofiber membrane through electrospinning technology, with the feature of three dimensional porous. Results show that as prepared PI nanofiber membrane possesses excellent thermal stability (no shrinkage even up to 200 °C), and admirable electrolyte absorption rate (2200%), which further significantly improves the ionic conductivity (2.04041 mS/cm). In addition, cells assembled with PI nanofiber membrane deliver outstanding cycling performance and C-rate discharge capability compared with 2400 separator in the same conditions. It is indicates that as-fabricated PI nanofiber separator has the potential of becoming a more mature technology offering better performance.

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 Si3N4-electret-doped polyvinylidene fluoride (PVDF) nanofiber core-spun yarn into a double-layer fabric. Within the double-layer fabric, one layer was Si3N4-doped PVDF (denoted as Si3N4@PVDF) nanofiber fabric, and the other was PU nanofiber fabric. When subjected to an external mechanical force, PU nanofiber fabric and Si3N4@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.

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%.

Electrospinning is a simple and cost-effective method to prepare fiber with nanometer scale. More importantly, 3D flexible nanofiber yarns that fabricated by electrospinning have shown excellent application prospects in smart textiles, wearable sensors, energy storage devices, tissue engineering, and so on. However, current methods for preparing electrospinning nanofiber yarns had some limitations, including low yarn yield and poor yarn structure. In this paper, a stepped airflow-assisted electrospinning method was designed to prepare continuously twisted nanofiber yarn through introducing stepped airflow into traditional electrospinning system. The stepped airflow could not only help to improve nanofiber yield, but also good for controlling the formed nanofibers to be deposited in a small area. In addition, the experimental methods of single factor variables were used to study the effects of stepped airflow pressure, applied voltage, spinning distance, solution flow rate, air pumping volume and friction roller speed on nanofiber yarn yield, nanofiber diameter, yarn twist and mechanical property. The results showed that prepared nanofiber yarns exhibited perfect morphologies and the yield of nanofiber yarn could reach to a maximum of 4.207 g/h. The breaking strength and elongation at break of the prepared yarn could reach to 23.52 MPa and 30.61 %, respectively.

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.

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.

The development of highly sensitive, stretchable, and wearable textile-based electronic skin is of great value for application in human health monitoring, robot skin, and intelligent electronic devices. Here, we construct a highly sensitive and stretchable electronic fabric with a simple and low-cost electrospinning technology that enables us to simultaneously map and quantify the mechanical stresses induced by normal pressure, lateral strain, and flexion and to detect the noncontact finger proximity. The fabric is woven from composite yarns that are formed by a core-spun yarn wound helically around the surface of the elastic thread, wherein the core-spun yarn is obtained by coating a graphene (GO)-doped polyurethane (PU) nanofiber on the surface of a Ni-coated cotton yarn. The Ni-coated cotton yarn serves as conductive electrodes, and the nanofiber coating provides a dielectric layer. The three-dimensional elastic porous nanofiber structure of the dielectric layer, the fiber aggregate structure of the conductive electrode, and the helical structure of the elastic composite yarn play key roles in allowing the sensor unit of the electronic fabric to improve sensitivity, realize multiple-force sensitivities and realize stretchable and woven wearability. The sensor unit that can induce a large contact-area accumulation of the nanofiber dielectric layers under low external force exhibits excellent sensitivity (1.59 N−1

To better mimic natural bone, a graphene oxide-hydroxyapatite/silk fibroin (cGO-HA/SF) scaffold was fabricated by biomineralizing carboxylated GO sheets, blending with SF, and freeze-drying. The material has increasing porosity and decreasing density from outside to inside. Analysis of GO mineralization in simulated body fluid indicated that carboxylation and Chitosan may synergistically regulate HA growth along the c-axis of weakly crystalline, rod-like GO-HA particles. Compared with HA/SF gradient composites, a cGO-HA gradient scaffold with cGO:HA mass ratio 1:4 has 5-fold and 2.5-fold higher compressive strength and compressive modulus, respectively. Additionally, the cGO-HA/SF composite stimulated mouse mesenchymal stem cell adhesion and proliferation, alkaline phosphatase secretion, and mineral deposition more strongly than HA/SF and pure HA scaffolds. Hence, the material may prove to be an excellent and versatile scaffold for bone tissue engineering.

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

Polyvinylidene fluoride (PVDF) nanofiber fabric, polyvinylidene fluoride/polyethylene glycol (PVDF/PEG) nanofiber fabric and polyvinylidene fluoride/polyethylene glycol/silicon dioxide (PVDF/PEG/SiO2) nanofiber fabrics are fabricated through a combination of electrospinning and weaving technology, inspired by the “lotus effect”. Nanofiber surfaces with a hierarchical nanofiber structure in the PVDF/PEG and PVDF/PEG/SiO2 nanofiber fabrics are formed by hydrolyzing PEG and doping with SiO2 nanoparticles, which is similar to the surface structure of a lotus leaf. The structures of these three fabrics are characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) and the mechanical properties and wettability are analyzed. The results show that the fiber structure of the PVDF/PEG composite nanofiber doped with SiO2 nanoparticles after water scrubbing is composed of many balls, which are formed by the embedding of the SiO2 nanoparticles in the polymer. Moreover, the “ball” is not only similar to the “hill” of a lotus leaf surface, but also similar to the “small thorn” on the “hill” because of the embossment of SiO2 nanoparticles on the “ball” surface. The ultimate tensile strength and failure strain of the PVDF/PEG/SiO2 nanofiber fabric are 92.12 MPa and 18.98%, respectively. The PVDF/PEG/SiO2 nanofiber fabric exhibits superhydrophobicity with a water contact angle of 173.2°.

One-dimensional, flexible yarn-shaped supercapacitors for woven cloth have the potential for use in different kinds of wearable devices. Nevertheless, the challenge that supercapacitors face is low energy density. In this paper, we present a low-cost and large-scale manufacturing method to construct a supercapacitor yarn with high power and high energy density. To construct the novel and flexible poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)&ndash, polyacrylonitrile (PDEOT: PSS-PAN)/Ni cotton (PNF/NiC) capacitor yarn, an electrospinning technique was initially used to wrap the polyacrylonitrile (PAN) nanofibers around the core Ni-coated yarn. The PEDOT: PSS&ndash, PAN nanofiber composite electrode was created using in situ deposition and H3PO4/PVA was used as a gel electrolyte. This electrode material has a yarn/nanofiber/PEDOT: PSS nanoparticle hierarchical structure, providing a high specific area and enhanced pseudocapacitance. The electrode demonstrated a high volumetric capacitance of 26.88 F&middot, cm&minus, 3 (at 0.08 A&middot, 3), an energy density of 9.56 mWh&middot, 3, and a power density of 830 mW&middot, 3. In addition, the PNF/NiC capacitor yarns are lightweight, highly flexible, resistant to bending fatigue, can be connected in series or parallel, and may be suitable for a variety of wearable electronic products.

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 t...

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.

This paper presents a new approach for the mass production of nanofiber yarns, which involves the use of a multinozzle air-jet electrospinning system and airflow twisting. In this system, the aggregation, orientation, and continuous bundling of nanofibers are first achieved by applying the principle of conjugate electrospinning. Three-dimensional highspeed rotating airflow is then applied to continuously twist and spin the nanofibers into yarn. In this study, the mechanisms for formation and aggregation of nanofibers using the new air-jet electrospinning system were analyzed. In addition, numerical simulations of the airflow field within the nozzle were performed to understand the airflow characteristics and to study the effects of airflow twisting on nanofiber spinning. The obtained results indicated that the output of nanofiber bundles for the proposed multinozzle air-jet electrospinning system was able to reach 6.642 g/h. The application of three-dimensional rotating airflow enabled continuous production of twisted nanofiber yarns with favorable orientation and uniform twist distribution. Under an air pressure of 0.3 MPa and at a spinning speed of 132.1 m/s, the twist angle, tensile strength, and elongation of the nanofiber yarn were 65.2 °, 74.23 MPa, and 85.55 %, respectively. Thus, it can be concluded that the proposed spinning tenique is practical and efficient for high-speed and large-scale production of nanofiber yarn.

The paper proposes a new air-jet spinning method for the preparation of continuous twisted nanofiber yarns. The nozzle-twisting device is designed to create the 3-D rotating airflow to twist nanofiber bundles. The airflow characteristics inside the twisting chamber are studied numerically. The airflow field distribution and its effect on nanofiber yarn spinning at different pressures are also discussed.

Continuously twisted polyacrylonitrile/viscose nanofiber core-spun yarns were fabricated through novel self-designed multi-nozzle air jet electrospinning set-up. The effect of voltage, solution flow rate, air flow rate and funnel rotating speed on coating rate of core-spun yarn, nanofiber diameter, twist level and mechanical property were discussed. The results showed that polyacrylonitrile/viscose nanofiber core-spun yarns with perfect nanofiber orientation and uniform twist distribution could be obtained at voltage of 32 KV, solution flow rate of 32 ml/min and air flow rate of 1000 ml/min, and the spinning speed could reach to 235.5 cm/min. The diameters of outer coated nanofiber distributed from 100 nm to 300 nm, and nanofiber coating rate could reach to 70.4 %. In addition, the strength and elongation at break increased from 30.82 MPa to 69.65 MPa and from 28.34 % to 43.29 % at the twist angle of 46.6 °, respectively.

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.

A novel multi-nozzle bubble electrospinning apparatus, including spinning unit, metering pump, constant flow pump, metal funnel and yarn winder, was designed for the preparation of continuous twisted polyacrylonitrile nanofiber yarns, and the principle of nanofiber yarn spinning was studied. An innovative spinning unit consisting of nozzle and air chamber was used to improve the production of nanofibers. Double conjugate electrospinning was developed using two pairs of oppositely charged spinning units to neutralize the charges. The effects of applied voltage, air flow rate, overall solution flow rate and funnel rotary speed on the fiber diameter, production rate and mechanical properties of the nanofiber yarns were analyzed. Nanofibers could be aggregated stably and bundled continuously, then twisted into nanofiber yarns uniformly at an applied voltage of 34 kV, air flow rate of 1200 mL min−1 and overall solution flow rate of 32 mL h−1. With an increase in the funnel rotary speed, the twist angle of the nanofiber yarns gradually increased when the take-up speed was constant. The yarn tensile strength and elongation at break showed an increasing trend with increasing twist angle. Nanofiber yarns obtained using this novel method could be produced at a rate from 2.189 to 3.227 g h−1 with yarn diameters ranging from 200 to 386 µm. Nanofiber yarns with a twist angle of 49.7° showed a tensile strength of 0.592 cN dtex−1 and an elongation at break of 65.7%. © 2013 Society of Chemical Industry

A new method is proposed to fabricate continuous twisted nanofiber yarns. Nanofibers are bunched by a double conjugate electrospinning, and then twisted through a three-dimensional high-speed swirling airflow. Its principle and process are analyzed theoretically, and the airflow field inside the nozzle chamber is studied numerically, and mechanical properties of nanofiber yarns at different spinning conditions are systematically discussed.