Wet-spinning Strategy Research Articles

Automated Microfluidics-Assisted Hydrogel-Based Wet-Spinning for the Biofabrication of Biomimetic Engineered Myotendinous Junction.

The muscle-tendon junction (MTJ) plays a pivotal role in efficiently converting the muscular contraction into a controlled skeletal movement through the tendon. Given its complex biomechanical intricacy, the biofabrication of such tissue interface represents a significant challenge in the field of musculoskeletal tissue engineering. Herein, a novel method to produce MTJ-like hydrogel yarns using a microfluidics-assisted 3D rotary wet-spinning strategy is developed. Optimization of flow rates, rotational speed, and delivery time of bioinks enables the production of highly compartmentalized scaffolds that recapitulate the muscle, tendon, and the transient MTJ-like region. Additionally, such biofabrication parameters are validated in terms of cellular response by promoting an optimal uniaxial alignment for both muscle and tendon precursor cells. By sequentially wet-spinning C2C12 myoblasts and NIH 3T3 fibroblasts, a gradient-patterned cellular arrangement mirroring the intrinsic biological heterogeneity of the MTJ is successfully obtained. The immunofluorescence assessment further reveals the localized expression of tissue-specific markers, including myosin heavy chain and collagen type I/III, which demonstrate muscle and tenogenic tissue maturation, respectively. Remarkably, the muscle-tendon transition zone exhibits finger-like projection of the multinucleated myotubes in the tenogenic compartment, epitomizing the MTJ signature architecture.

Design, application, and recycling of zinc alginate/guar gum hydrogel-based fibers

Extreme cold events are quite common, highlighting the urgent need for flexible wearable electronic devices capable of diagnosing human health in low-temperature environments. Using a wet spinning strategy, we successfully developed sodium zinc alginate/guar gum(SZA/GG) hydrogel fibers with excellent environmental resistance, antimicrobial properties, and electrical conductivity. Building on this, we developed a flexible wearable sensing device that operates stably at low temperatures and exhibits a sensitivity of 0.585 within the range of −20 °C to −40 °C, demonstrating excellent response performance. When evaluating the physical state of outdoor athletes, the amplitude and fluctuation range of electrical resistance provide valuable information about the monitored environment and the risk of frostbite for the individual. However, like any device, it eventually reaches its usage limit. To address the issue of recycling hydrogel fiber waste, we propose recycling and carbonizing the discarded devices to use as a biomass carbon source for fabricating button-type supercapacitors. After 10,000 charge-discharge cycles, the capacitance retention rate reached 92.53 %, demonstrating the potential of these supercapacitors and offering a new approach to reducing resource waste.

Durable and Wearable Self-powered Temperature Sensor Based on Self-healing Thermoelectric Fiber by Coaxial Wet Spinning Strategy for Fire Safety of Firefighting Clothing

Durable and Wearable Self-powered Temperature Sensor Based on Self-healing Thermoelectric Fiber by Coaxial Wet Spinning Strategy for Fire Safety of Firefighting Clothing

Aramid nanofiber-reinforced MXene/PEDOT:PSS hybrid fibers for high-performance fiber-shaped supercapacitors

In recent years, a great deal attention has been paid to one-dimensional fiber-shaped wearable energy storage devices, but further exploration is still needed to obtain fiber-shaped devices with high mechanical and electrochemical performance to meet the requirements of stretching, twisting and squeezing deformation in daily use. Herein, high-performance aramid nanofiber-reinforced (ANF) MXene/PEDOT:PSS hybrid fibers were fabricated by a simple and tractable wet spinning strategy. In this strategy, ANF played the role of fiber reinforcement and barrier for the MXene layer, not only greatly enhancing the mechanical properties of fibers, but also effectively preventing the re-stacking of MXene layers. As a kind of spinnable conductive polymer, PEDOT:PSS can effectively improve the spinnability of fibers. The obtained hybrid fiber exhibited high tensile strength and high conductivity. Meanwhile, the assembled all solid-state fiber-shaped supercapacitor (FSC) showed a high energy density of 9.8 mWh cm−3 at the power density of 250.7 mW cm−3. Besides, the assembled FSC displayed outstanding cycle performance (86.9% capacitance retention after 10 000 cycles) and excellent flexibility. It is worth noting that the FSC could be extended in series to meet the needs of different equipment. This work provides a good reference for the manufacture of wearable high-performance fiber-shaped devices by facile wet spinning.

Development and characterization of edible plant-based fibers using a wet-spinning technique

Analogous to those of natural animal muscle fibers is considered to be a major challenge in improving the texture of meat analog foods. Herein, in this current work, a facile and effective wet-spinning strategy is introduced for edible fibers fabrication based on sodium alginate/soybean protein isolate composite, which, to a large extent, significantly regulated by the interactions between polysaccharides and proteins. As illustrated, the ratio of polysaccharide/protein and pH values tailored the solution behavior of composite solutions, suggesting an influence of the spinning medium on the spinnability outcomes. The FTIR result after Gaussian multi-peaks-fitting additionally proved the types and relative strengths of hydrogen bonds in composite fibers, modulated by varying the preparation parameters. The SEM images of fibers showed that it could easily lead to the generation of porous structure inside the fiber in higher protein content or in alkaline pH condition. Importantly, increasing protein content could improve the water holding capacity, also impacting the stronger tensile strength of the composite fiber under neutral condition. In general, the facile preparation of edible fibers and the use of naturally abundant components in their synthesis provide a novel subassembly for the industrialized production of plant-based meat analogue. • A facile and effective wet-spinning strategy is introduced for meat analog fibers fabrication. • Regulating ratio of reactants and pH could tailor the spinnability and other physicochemical property. • Different from other types of meat analog fibers, the mechanical property of single fiber could be measured.

Reliable coaxial wet spinning strategy to fabricate flexible MnO2-based fiber supercapacitors

With the rapid development of electronic technique, wearable energy conversion and storage devices are facing huge challenges. Particularly, fiber supercapacitors have advantages of small size, light weight, high flexibility, fast charge/discharge process, high power density, long cycle life and wide operating temperature, showing considerable application prospect in the smart wearable field. This work proposes a strategy to fabricate MnO2, MnO2/PANI and MnO2/GN fiber electrodes via coaxial wet spinning technology, in which the electrochemical active materials could be wrapped into CMC layer perfectly, ensuring the structure stability of fiber electrodes effectively. And a series of MnO2-based parallel fiber supercapacitors are further assembled. After optimization of mixing ratios, the MnO2/PANI fiber supercapacitor with mixing-ratio of 1:1 exhibits specific capacitance of 0.68 μF·cm−1 at 0.25 μA·cm−1, and the MnO2/GN fiber supercapacitor with mixing-ratio of 9:1 presents 1.23 μF·cm−1at the same current density, which are both higher than that of pure MnO2 fiber supercapacitor (0.59 μF·cm−1), proving significant enhancement of electrochemical performance due to the introduced PANI or GN. Therefore, this work provides a reliable guidance for design and application of wearable fiber supercapacitors.

Carbon nanotubes boosts the toughness and conductivity of wet-spun MXene fibers for fiber-shaped super capacitors

Mechanically strong and electrically conducting fibers, particularly those with high specific capacitances, are promising fiber-shaped electrodes for fiber- and textile-based energy storage devices like fiber-shaped supercapacitors (FSCs). However, a high loading of fillers or bridging agents is commonly required to fabricate fiber electrodes with good mechanical strength, which compromises electrical conductivity and energy storage performance. Herein, an easily scalable wet-spinning strategy is reported to fabricate multifunctional Ti3C2Tx MXene/carbon nanotubes (MXene/CNT) hybrid fibers from a harmonious mixture of MXene and CNT in water and using acetic acid as a coagulation bath. The hybrid fiber achieved high strength (61 ± 7 MPa), good conductivity (1142.08 ± 40.04 S cm−1) and excellent energy storage performance (∼295 F g−1 at 5 mV s−1) at a very low CNT content of ∼1 wt%. When CNT loading increased to ∼9 wt%, the maximum strain at broken reached 161 ± 19 MPa and conductivity further increased to 1715 ± 22 S cm−1. The excellent mechanical performance allows hybrid fibers to be knitted into textiles for energy storage textiles. The assembled FSCs exhibit energy and power densities of ∼6.08 mW h cm−3 and ∼6440 mW cm−3, respectively. The excellent performance of MXene/CNT fiber and good feasibility for scalable production will open up new opportunities for the development of wearable and textile-based devices in the near future.

Wet spinning of hollow graphene fibers with high capacitance

Herein, we report a facile coaxial wet-spinning strategy to continuously produce hollow graphene fibers (HGF) with the merits of high conductivity, excellent flexibility, and enhanced electrode–electrolyte contact. The hollow structure is achieved by introducing reductant-containing coagulant solution into the fiber core with a composition identical to the spinning bath. The produced fibers were assembled into a supercapacitor device with an ultra-high specific capacitance of 711 mF/cm2 (i.e. 33.5 mF/cm or 190F/cm3). The combination of outstanding electrochemical and mechanical properties makes this HGF a promising candidate for use in wearable supercapacitors and electronics.

Mechanically strong all-chitin filaments: Wet-spinning of β-chitin nanofibers in aqueous NaOH

Herein, a facile wet-spinning strategy was used for the fabrication of mechanically strong all-chitin filaments from an aqueous NaOH solution using β-chitin nanofibers (β-ChNFs). It is hypothesized that to reach high mechanical performance it is important to preserve the crystalline structure of chitin during fabrication. To explore this possibility, β-ChNFs were disintegrated from squid pens by a mild procedure and showed a uniform diameter of 10–25 nm, length of a few microns, and a high aspect ratio of more than 200. An interesting finding was that gel-like β-ChNF filaments were directly formed in aqueous NaOH without using any organic or ionic agents. The gelation of β-ChNFS under alkali treatments contributed to the construction of strong nanonetworks and thus facilitated the formation of high-strength filaments. The resulting all-chitin filaments showed a high tensile strength and Young's modulus of 251.3 ± 12.45 MPa and 12.1 ± 0.72 GPa, respectively, which were further investigated for utilization as flexible sensors. The advantages of this strategy included the lack of use of any toxic solvents and the achievement of high mechanical performance for the all-chitin filaments. We believe that this wet-spinning approach may promote the functional utilization of chitin to develop high-strength filaments in smart textiles, biosensors, and structural reinforcements.

Direct Wet-Spun Single-Walled Carbon Nanotubes-Based p-n Segmented Filaments toward Wearable Thermoelectric Textiles.

Three-dimensional thermoelectric (TE) textiles (TETs) fabricated with TE filaments (TEFs) possess merits over other types such as thickness-direction thermal energy harvesting and excellent conformability with dynamic body curves, revealing the prospect of generating electricity for on-body application. Nonetheless, there is still a lack of a costless but scalable method to automatically and seamlessly produce in-series interconnected p-n segmented TEFs with high TE properties via conventional fiber spinning processes. Here, we developed an alternate wet-spinning strategy to continuously manufacture single-walled carbon nanotube-based p-n segmented TEFs at large scale. The TEF with high electrical conductivity (400-800 S cm-1) displays a low contact resistivity of 189.8 μΩ cm2 between the segments and interelectrode, showing 2 orders of magnitude smaller than that reported in the literature. More importantly, the power factors of p-type and n-type segments are 26.25 and 17.14 μW m-1 K-2, respectively, which are 3 and 4 orders of magnitude higher than those of advanced studies. We finally embroidered it into spacer fabric to fabricate a wearable TET, demonstrating an output power density of 501 nW m-2 at ΔT = 27.7 K. The methodology can inspire the development of fiber-based electronics such as wearable TEs and diodes and so forth.

Underwater sensing and warming E-textiles with reversible liquid metal electronics

Emerging underwater exploration suggests the need for subaqueous E-textiles. Large-deformation signal feedback for swimming motions and body thermal protection against hypothermia are urgently desirable. Here, underwater-usable E-textiles with remarkable sensing and electrothermal behaviors are introduced, which are composed of stretchable core-sheath fibers based on liquid metal fabricated via a coaxial wet-spinning strategy. The fibers possess outstanding specific resistance (∼0.05 Ω·cm−1) and robust sensing detection range for both strain (∼600% elongation) and pressure (∼30 MPa), as well as a quick response time (30 ms). Meanwhile, the fabricated E-textiles present excellent low-power-driving electrothermal performance (1.5 W, ∼50 °C) even at underwater conditions. Remarkably, the conducting liquid metal circuit can be well reversed even after being entirely broken out of the sensing ranges. For proof of concept, an underwater glove integrating motion sensing, visual danger warning and hypothermia prevention is exhibited, which has potential for application in underwater exploration.

Acid-catalyzed in-situ cross-linking of polyol on sodium alginate to improve its strength and hydrophobic properties

To simultaneously improve the strength and hydrophobicity of alginate-based fibers, a new wet spinning strategy for preparing alginate ester fibers (AE) based on esterification reaction with polyols as in-situ crosslinking agents through acid catalysis is proposed. The esterification was confirmed by FTIR and NMR. XRD analysis showed that the crystallinity of AE fiber increased by 235%. The test results of mechanical properties showed that the modulus has seen an increase of 41.18% and strength an increase of 78.4%. Interestingly, the contact angle was found to increase from 54.6° to 121.9°. Moreover, the influences of polyol types (Ethylene glycol, Glycerol, Pentaerythritol) on the properties of AE fiber are also investigated, the types of polyol have obvious influences on the mechanical properties, crystallinity, and hydrophobicity in AE fibers. These results indicate that this strategy provides a broad application space for alginate-based materials.

Wet-spun PVDF nanofiber separator for direct fabrication of coaxial fiber-shaped supercapacitors

Coaxial graphene fiber-based supercapacitors have many enticing advantages in terms of large electrode/electrolyte contact interface area, short ion-transport path and high stability, but the polymer electrolyte separators upon which these supercapacitors are based typically lead to high resistance and the risk of short circuit upon severe deformations. To address these challenges, we have developed an efficient and controllable wet-spinning strategy for making poly(vinylidene fluoride) (PVDF) nanofiber separator with modulated thickness to directly fabricate high-performance coaxial fiber-shaped supercapacitors. The porous PVDF nanofiber separator tightly sandwiched in between graphene fiber electrodes featured an interconnected, thin and highly wrinkled network architecture, thereby enabling sufficient chemical reduction of electrode without concomitant destruction of the separator structure, good contact interface, and rapid infiltration and transport of electrolyte ions to the electrode without risk of short circuit. The coaxial fiber supercapacitor made using the wet-spun PVDF nanofiber separator delivered a remarkable specific capacitance of 346.5 mF cm−2 and energy density of 30.8 µWh cm−2, while maintaining high structural toughness and long cycling life (94% retention after 10,000 cycles). This coaxial architectural design with PVDF nanofiber as separator represents a promising strategy to fabricate high-performance fiber supercapacitors for flexible energy storage.

Large-scale wet-spinning of highly electroconductive MXene fibers

Ti3C2Tx MXene is an emerging class of two-dimensional nanomaterials with exceptional electroconductivity and electrochemical properties, and is promising in the manufacturing of multifunctional macroscopic materials and nanomaterials. Herein, we develop a straightforward, continuously controlled, additive/binder-free method to fabricate pure MXene fibers via a large-scale wet-spinning assembly. Our MXene sheets (with an average lateral size of 5.11 μm2) are highly concentrated in water and do not form aggregates or undergo phase separation. Introducing ammonium ions during the coagulation process successfully assembles MXene sheets into flexible, meter-long fibers with very high electrical conductivity (7,713 S cm−1). The fabricated MXene fibers are comprehensively integrated by using them in electrical wires to switch on a light-emitting diode light and transmit electrical signals to earphones to demonstrate their application in electrical devices. Our wet-spinning strategy provides an approach for continuous mass production of MXene fibers for high-performance, next-generation, and wearable electronic devices.

Simultaneously electrochemical exfoliation and functionalization of graphene nanosheets: Multifunctional reinforcements in thermal, flame‐retardant, and mechanical properties of polyacrylonitrile composite fibers

AbstractFunctionalized graphene has a promising prospect in improving the thermal, mechanical, and flame‐retardant properties of polymer composites, which was unfortunately limited by the low yield and high pollution during graphene production. In this study, we reported a facile and eco‐friendly electrochemical approach to prepare ferric diethylenetriaminepentakis (methylphosphonic acid) functionalized graphene nanosheets (FGNS), which were subsequently used to fabricate polyacrylonitrile (PAN) composite fibers by a wet spinning strategy. Composite fibers showed better thermal stability above 350°C in contrast to pure PAN. Furthermore, a significant improvement on flame‐retardant properties of PAN fibers in the case of peak heat release rate (decreased by 36.7%) was caused by the inclusion of FGNS. The analysis results of condensed phase revealed that FGNS facilitated the formation of the compact and graphitic char residues, protecting underlying composite fibers during combustion. With adding 3.0 wt% FGNS, the tensile strength and breaking elongation of PAN composite fibers achieved 67.6% and 126.5% increment, respectively. This electrochemical method provides an eco‐friendly approach for scale production of functional graphene.

Facile scalable one-step wet-spinning of surgical sutures with shape memory function and antibacterial activity for wound healing

Surgical suture is commonly used in clinic due to its action in accelerating the process of wound healing. However, difficultly handling in minimally invasive surgery and bacteria-induced infection usually limit its use in a wide range of applications. Here, we report a facile scalable strategy to fabricate surgical sutures with shape memory function and antibacterial activity for wound healing. Specifically, a shape memory polyurethane (SMPU) with a transition temperature (Ttrans) at 41.3 °C was synthesized by adjusting the mole ratio of the hard/soft segment, and then the shape memory surgical sutures containing polyhexamethylene biguanide hydrochloride (PHMB) as a model drug for antibacterial activity were fabricated by a facile scalable one-step wet-spinning approach, in which PHMB was directly dissolved in the coagulation bath that enable its loading into the sutures through the dual diffusion during the phase separation. The prepared sutures were characterized by their morphology, mechanical properties, shape memory, antibacterial activity, as well as biocompatibility before the wound healing capability was tested in a mouse skin suture-wound model. It was demonstrated that the optimized suture is capable of both shape memory function and antibacterial activity, and promote wound healing, suggesting that the facile scalable one-step wet-spinning strategy provides a promising tool to fabricate surgical sutures for wound healing.

Multifunctional Wet-Spun Filaments through Robust Nanocellulose Networks Wrapping to Single-Walled Carbon Nanotubes.

Cellulose nanofibrils (CNFs) and single-walled carbon nanotubes (SWNTs) hold potential for fabricating multifunctional composites with remarkable performance. However, it is technically tough to fabricate materials by CNFs and SWNTs with their intact properties, mainly because of the weakly synergistic interaction. Hence, constructing sturdy interfaces and sequential connectivity not only can enhance mechanical strength but also are capable of improving the electrical conductivity. In that way, we report CNF/SWNT filaments composed of axially oriented building blocks with robust CNF networks wrapping to SWNTs. The composite filaments obtained through the combination of three-mill-roll and wet-spinning strategy display high strength up to ∼472.17 MPa and a strain of ∼11.77%, exceeding most results of CNF/SWNT composites investigated in the previous literature. Meanwhile, the filaments possess an electrical conductivity of ∼86.43 S/cm, which is also positively dependent on temperature changes. The multifunctional filaments are further manufactured as a strain sensor to measure mass variation and survey muscular movements, leading to becoming optimistic incentives in the fields of portable gauge measuring and wearable bioelectronic therapeutics.

Wet-spinning assembly of cellulose nanofibers reinforced graphene/polypyrrole microfibers for high performance fiber-shaped supercapacitors

Fiber-shaped supercapacitors with remarkable flexibility and considerable energy-storage capacity have become the promising candidates in the field of wearable and portable electronic devices. In fact, both of the mechanical properties and electrochemical performance are in need of significant improvement to satisfy the practical applications of fiber-shaped supercapacitors. In this paper, a high-performance cellulose nanofibers reinforced graphene/polypyrrole microfiber is fabricated by a convenient wet-spinning strategy. The cellulose nanofibers act as both “enhancer” and “spacer”, which not only provide substantial hydrogen bonds to strengthen the interlaminar force but also prevent the restacking of the graphene sheets. This microfiber exhibits excellent tensile strength (364.3 MPa), which is superior to most of the reported fibers for supercapacitors. Meanwhile, the assembled fiber-shaped supercapacitors possess high specific capacitances of 334 mF cm−2 in liquid electrolyte and 218 mF cm−2 in solid electrolyte at the current density of 0.1 mA cm−2, which are also at the top level of fiber-shaped supercapacitors. The presented strategy combines the industrially viable wet-spinning technology and the well-designed structure for the fabrication of high-performance ternary fiber-shaped supercapacitors, providing a good reference for the development of wearable and portable energy storage devices.

Highly conductive porous graphene/sulfur composite ribbon electrodes for flexible lithium-sulfur batteries.

Flexible batteries have become an indispensable component of emerging devices, such as wearable, foldable electronics and sensors. Although various flexible batteries have been explored based on one-dimensional and two-dimensional platforms, developing a high energy density electrode with high structural integrity remains challenging. Herein, a scalable, one-pot wet spinning strategy is used to synthesize a flexible porous cathode for lithium-sulfur batteries (LSBs) for the first time, which consists of reduced graphene oxide (rGO), graphene crumples (GCs) and sulfur powders. The electrode structures are tailored using GCs with different dimensions and functional features that are critical to its robustness under mechanical deformation and electrolyte penetration into the battery components. The optimized rGO/GC/S composite ribbon cathodes deliver a high capacity of 524 mA h g-1 after 100 cycles at a current rate of 0.2 C. A shape-conformable battery prototype comprising an rGO/GC/S cathode and a lithium anode demonstrates a stable discharge characteristic under repeated bending/flattening cycles. The LSB prototype supported by an elastomer presents stable discharge behavior with high mechanical robustness against an extension of up to 50%. The above-mentioned findings shed new light on developing sulfur cathodes for flexible, high performance LSBs based on the rational design of graphene structures.

A novel nitrogen-doped graphene fiber microelectrode with ultrahigh sensitivity for the detection of dopamine

A novel nitrogen doped graphene fiber (NGF) was fabricated via a simple and facile wet-spinning strategy followed by annealing at high temperature, which can be applied as a remarkable electrode material. The NGF microelectrode shows good sensitivity and selectivity for the detection of dopamine with a wide linear response in the range of 0.1μM to 80μM, with the detection limit of 30nM and an ultrahigh sensitivity of 22.08μAμM−1cm−2. Such high performance enables the NGF to be a prominent material in the branch of electrochemical analysis.