Carbon fibers (CFs) demonstrate a range of excellent properties including (but not limited to) microscale diameter, high hardness, high strength, light weight, high chemical resistance, and high temperature resistance. Therefore, it is necessary to summarize the application market of CFs. CFs with good physical and chemical properties stand out among many materials. It is believed that highly fibrotic CFs will play a crucial role. This review first introduces the precursors of CFs, such as polyacrylonitrile, bitumen, and lignin. Then this review introduces CFs used in BESs, such as electrode materials and modification strategies of MFC, MEC, MDC, and other cells in a large space. Then, CFs in biosensors including enzyme sensor, DNA sensor, immune sensor and implantable sensor are summarized. Finally, we discuss briefly the challenges and research directions of CFs application in BESs, biosensors and more fields.
| • | CF is a new-generation reinforced fiber with high hardness and strength. |
| • | Summary precursors from different sources of CFs and their preparation processes. |
| • | Introduction of the application and modification methods of CFs in BESs and biosensor. |
| • | Suggest the challenges in the application of CFs in the field of bio-electrochemistry. |
| • | Propose the prospective research directions for CFs. |
Fabrics with durable flame retardancy are of great importance for preventing potential fire threats in daily life. This review presents a comprehensive discussion of advances in durable flame-retardant fabrics by finishing over the decade. The environmentally sustainable and toxicologically acceptable strategies for improving the durable flame retardancy of fabrics are classified into six types:. (i) the formation of covalent bonds, (ii) the formation of crosslinking networks, (iii) the formation of water-insoluble products, (iv) the use of adhesive layers, (v) the construction of hydrophobic layers, and (vi) the intercalation of flame-retardants into fibres. The design principles, methodologies, and existing problems of different fabrication strategies for imparting durable flame retardancy are summarized and reviewed. The advantages and disadvantages of each strategy are critically discussed. The current challenges and future opportunities are also proposed based on the current market requirements and state-of-the-art technologies. Many recent methodologies have great potential for replacing the conventional durable flame-retardant processes of cellulosic textiles.
Long-term continuous health care monitoring, using wearable technologies has received considerable interest due to the significant contribution of wearables to the diagnosis of diseases and identification of health conditions. Fibers have been widely applied in human societies due to their unique advantages, including stretchability, small diameters, high dynamic bending elasticity, high length-to-width ratios, and mechanical strength. A new generation of fiber-based electrodes is being integrated into smart textiles and wearables for continuous long-term biosignal monitoring. Dry fiber-based electrodes are breathable, flexible, and durable, unlike conventional disposable gel electrodes, which are difficult to employ for long-term applications because of skin irritation and allergic responses caused by their moist and adhesive interface with the skin. In this review, we provide a concise summary of recent breakthroughs in the design, and manufacturing of dry fiber-based electrodes for electrophysiology applications, with a particular emphasis on applications in electrocardiography, electromyography, and electroencephalography. Focusing on numerous features of electroactive fiber materials, fiber processing, electrode fabrication, scaled-up manufacturing, standardization of testing and performance criteria, we discuss current limitations and provide an outlook for the future development of this field.
As mechanical devices for moving or controlling mechanisms or systems, actuators have attracted increasing attention in various fields. Compared to traditional actuators with rigid structures, soft actuators made up of stimulus-responsive soft materials are more adaptable to complex working conditions due to soft bodies and diverse control styles. Different from plate-shaped soft actuators, which have the limited deformations between two dimensional (2D) and 3D-configurations such as bending and twisting, fiber-shaped soft actuators (FSAs) own intriguing deformation modes to satisfy diverse practical applications. In this mini review, the recent progress on the controlled fabrication of the FSAs is presented. The advantages and disadvantages of each fabrication method are also demonstrated. Subsequently, the as-developed actuation mechanisms of the FSAs are displayed. Additionally, typical examples of the related applications of the FSAs in different fields have been discussed. Finally, an outlook on the development tendency of the FSAs is put forward as well.
A mini review concerns the recent progress of fiber-shaped soft actuators (FSAs) on the fabrication technology, actuation principle and application. In addition, an outlook on the development tendency of the FSAs is made.
High-performance fiber-shaped power sources are anticipated to considerably contribute to the continuous development of smart wearable devices. As one-/two-dimensional (1D/2D) frameworks constructed from graphene sheets, graphene fibers and fabrics inherit the merits of graphene, including its lightweight nature, high electrical conductivity, and exceptional mechanical strength. The as-fabricated graphene fiber/fabric flexible supercapacitor (FSC) is, therefore, regarded as a promising candidate for next-generation wearable energy storage devices owing to its high energy/power density, adequate safety, satisfactory flexibility, and extended cycle life. The gap between practical applications and experimental demonstrations of FSC is drastically reduced as a result of technological advancements. To this end, herein, recent advancements of FSCs in fiber element regulation, fiber/fabric construction, and practical applications are methodically reviewed and a forecast of their growth is presented.
Natural structural materials, such as spider silk, wood, and bone, are universally acknowledged as the gold standard for the ideal combinations of strength and toughness. The exceptional integrated performance of these biological materials can be ascribed to their multiscale hierarchical architectures and components. Mimicking the hierarchical assembly feature of natural materials, artificial fibers, which are generated through the one-dimensional (1D) assembly of nanowires, have been widely reported with remarkable flexibility and functionality. Furthermore, the distinguishing feature of nanowires’ 1D assembly can bridge the unique properties of nanowires with their potential functional applications. This tutorial review summarizes the recent developments in the assembly of nanowires into macroscopic 1D fibers in the liquid state. We begin by introducing the general strategies and mechanisms for assembling nanowires in one direction and then, illustrate their potential applications in energy storage, sensors, biomedical engineering, etc. Finally, a brief summary and some personal perspectives on the future research directions of nanowires’ 1D assembly are also proposed.
A large of energy consumption is required for indoor and outdoor personal heating to ameliorate the comfortable and healthy conditions. Main personal thermal management strategy is to reflect mid-infrared human body radiation for human surface temperature (THS) regulation. We demonstrate a visible Janus light absorbent/reflective air-layer fabric (Janus A/R fabric) that can passively reflect radiative heating meanwhile can actively capture the solar energy. A series of azobenzene derivatives functionalized with alkyl tails are reported to co-harvest the solar and phase-change energy. The THS covered by Janus A/R fabric can be heated up to ~ 3.7 °C higher than that covered by air-layer fabric in cold environment (5 °C). Besides, integrating the thermo- and photo-chromic properties is capable of monitoring comfort THS and residue energy storage enthalpy, respectively. According to the colour monitors, intermittent irradiation approach is proposed to prolong comfortable-THS holding time for managing energy efficiently.
For the personal thermal management, we fabricate a visible Janus light absorbent/reflective fabric, which can actively capture solar energy and passively reflect the human radiation reflection (MIR). The solar energy can be released as heat to actively warm human surface temperature up, and the reflective MIR can passively heat the human body. The surface temperature and residue energy storage can be monitored by distinct colour change.
With the rise of optogenetic manipulation of neurons, the effects of optogenetic heating on temperature-sensitive physiological processes, and the damage to surrounding tissues have been neglected. This manuscript reports the fabrication of a highly temperature-sensitive semi-interpenetrating optical hydrogel fiber (TSOHF) using the integrated dynamic wet-spinning technique. TSOHF exhibits a structural tunable diameter, clear core/sheath structure, tunable temperature-sensitivity, excellent light propagation property (0.35 dB cm− 1, 650 nm laser light), and good biocompatibility (including tissue-like Young’s modulus, stable dimensional stability, and low cytotoxicity). Based on these properties, a potential application of optogenetic regulation of neural tissue (hypoglossal nerve), with controllable temperature using TSOHF was designed and performed. Further, this work provides new insight into molecular design and a practical approach to continually manufacture a temperature-sensitive hydrogel optical fiber for applications in intelligent photomedicine.
Ta3N5/CdS core–shell S-scheme heterojunction nanofibers are fabricated by in situ growing CdS nanodots on Ta3N5 nanofibers via a simple wet-chemical method. These Ta3N5/CdS nanofibers not only affords superior photocatalytic tetracycline degradation and mineralization performance, but also cause an efficient photocatalytic Cr(VI) reduction performance. The creation of favorable core–shell fiber-shaped S-scheme hetero-structure with tightly contacted interface and the maximum interface contact area promises the effective photo-carrier disintegration and the optimal photo-redox capacity synchronously, thus leading to the preeminent photo-redox ability. Some critical environmental factors on the photo-behavior of Ta3N5/CdS are also evaluated in view of the complexity of the authentic aquatic environment. The degradation products of tetracycline were confirmed by HPLC–MS analyses. Furthermore, the effective decline in eco-toxicity of TC intermediates is confirmed by QSAR calculation. This work provides cutting-edge guidelines for the design of high-performance Ta3N5-based S-scheme heterojunction nanofibers for environment restoration.
Tissue engineering provides a promising approach for regenerative medicine. The ideal engineered tissue should have the desired structure and functional properties suitable for uniform cell distribution and stable shape fidelity in the full period of in vitro culture and in vivo implantation. However, due to insufficient cell infiltration and inadequate mechanical properties, engineered tissue made from porous scaffolds may have an inconsistent cellular composition and a poor shape retainability, which seriously hinders their further clinical application. In this study, silk fibroin was integrated with silk short fibers with a physical and chemical double-crosslinking network to fabricate fiber-reinforced silk fibroin super elastic absorbent sponges (Fr-SF-SEAs). The Fr-SF-SEAs exhibited the desirable synergistic properties of a honeycomb structure, hygroscopicity and elasticity, which allowed them to undergo an unconventional cyclic compression inoculation method to significantly promote cell diffusion and achieve a uniform cell distribution at a high-density. Furthermore, the regenerated cartilage of the Fr-SF-SEAs scaffold withstood a dynamic pressure environment after subcutaneous implantation and maintained its precise original structure, ultimately achieving human-scale ear-shaped cartilage regeneration. Importantly, the SF-SEAs preparation showed valuable universality in combining chemicals with other bioactive materials or drugs with reactive groups to construct microenvironment bionic scaffolds. The established novel cell inoculation method is highly versatile and can be readily applied to various cells. Based on the design concept of dual-network Fr-SF-SEAs scaffolds, homogenous and mature cartilage was successfully regenerated with precise and complicated shapes, which hopefully provides a platform strategy for tissue engineering for various cartilage defect repairs.
Advanced fabric electronics for long-term personal physiological monitoring, with a self-sufficient energy source, high integrity, sensitivity, wearing comfort, and homogeneous components are urgently desired. Instead of assembling a self-powered biosensor, comprising a variety of materials with different levels of hardness, and supplementing with a booster or energy storage device, herein, an all-fiber integrated thermoelectrically powered physiological monitoring device (FPMD), is proposed and evaluated for production at an industrial scale. For the first time, an organic electrochemical transistor (OECT) biosensor is enabled by thermoelectric fabrics (TEFs) adaptively, sustainably and steadily without any additional accessories. Moreover, both the OECT and TEFs are constructed using a cotton/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/dimethylsulfoxide/(3-glycidyloxypropyl) trimethoxysilane (PDG) yarn, which is lightweight, robust (90° bending for 1000 cycles) and sweat-resistant (ΔR/R0 = 1.9%). A small temperature gradient (ΔT = 2.2 K) between the environment and the human body can drive the high-gain OECT (71.08 mS) with high fidelity, and a good signal to noise ratio. For practical applications, the on-body FPMD produced an enduring and steady output signal and demonstrated a linear monitoring region (sensitivity of 30.4 NCR (normalized current response)/dec, 10 nM ~ 50 µM) for glucose in artificial sweat with reliable performance regarding anti-interference and reproducibility. This device can be expanded to the monitoring of various biomarkers and provides a new strategy for constructing wearable, comfortable, highly integrated and self-powered biosensors.
An all fiber integrated thermoelectric powering-physiological monitoring device (FPMD) consisted of thermoelectric fabrics (TEFs) and fiber-assembled organic electrochemical transistor (FOECT) is constructed from a PDF/cotton yarn, which was lightweight, robust (90° bending for 1000 cycles), sweat-resist (ΔR/R0 = 1.9%) and highly conductive (247 S/cm). A FOECT gm reaching up to 71.08 mS was first reported which operated continuously and steadily under a small temperature gradient (ΔT = 2.2K).The FPMD showed excellent homogeneity and structural uniformity and the on-body applications (ΔT = 2.2K) demonstrate the FPMD is able to monitor glucose in the range of 10 nM ~ 50 µM (a sensitivity of 30.4 NCR/dec).
[graphic not available: see fulltext]
Graphene-aerogel-based flexible sensors have heat tolerances and electric-resistance sensitivities superior to those of polymer-based sensors. However, graphene sheets are prone to slips under repeated compression due to inadequate chemical connections. In addition, the heat-transfer performance of existing compression strain sensors under stress is unclear and lacks research, making it difficult to perform real-temperature detections. To address these issues, a hyperelastic polyimide fiber/graphene aerogel (PINF/GA) with a three-dimensional interconnected structure was fabricated by simple one-pot compounding and in-situ welding methods. The welding of fiber lap joints promotes in-suit formation of three-dimensional crosslinked networks of polyimide fibers, which can effectively avoid slidings between fibers to form reinforced ribs, preventing graphene from damage during compression. In particular, the inner core of the fiber maintains its macromolecular chain structure and toughness during welding. Thus, PINF/GA has good structural stabilities under a large strain compression (99%). Moreover, the thermal and electrical conductivities of PINF/GA could not only change with various stresses and strains but also keep the change steady at specific stresses and strains, with its thermal-conductivity change ratio reaching up to 9.8. Hyperelastic PINF/GA, with dynamically stable thermal and electrical conductivity, as well as high heat tolerance, shows broad application prospects as sensors in detecting the shapes and temperatures of unknown objects in extreme environments.
Polyimide fibers in graphene aerogel are in-suit welded to fabricate a composite with excellent hyperelasticity and adjustable thermal conductivity for artificial intelligence sensing over a wide temperature range.
Aerogels are of great interest in diverse fields including thermal insulation, environmental protection, liquid separation, electromagnetic shielding, etc. However, the development of renewable and recyclable aerogels, especially synthetic polymer-based ones, remains an enormous challenge, which seriously hinders the practical application of aerogels. Herein, utilizing Kevlar nanofibers (KNFs) as representative synthetic polymer building blocks, a destabilizing dynamic balance (DDB) strategy is proposed to fabricate recyclable aerogels with high reprocessing consistency. More specifically, aprotic esters (e.g., di-tert-butyl decarbonate, DiBoc) and alkalis (e.g., potassium tert-butoxide, t-BuOK) are introduced to trigger the destabilizing dynamic balance between deprotonation–protonation of KNFs, resulting in a reversible sol–gel transition. Meanwhile, the duration of sol–gel transition (i.e., gelation) time, adjustable from 10–2 to 103 min, is compatible with versatile processing methods, such as static mould casting, dynamic wet spinning, dynamic blade coating and dynamic 3D printing. These unique advantages enable the fabrication of various KNF aerogel products (i.e., continuous fibers, continuous films, large-sized monoliths and 3D-printed articles) with low density (33–165 mg/cm3), high compressive modulus (up to 52 MPa), high specific surface area (360–404 m2/g) and low thermal conductivity (0.027–0.050 W/m·K). Notably, these properties are comparable or superior to that of previously reported KNF aerogels and far superior to that of recyclable aerogels. Compared with direct fabrication from raw materials, the DDB strategy reduces the cost by 50.5% and 82.5% when products are made from recycled aerogels and wet gels, respectively. Such cost reduction further increases with the number of recycling cycles, which is calculated as $275 per kilogram KNF aerogel with 5 cycles. This work develops extraordinary KNF aerogels those can be recycled and reused, as well as provides a strategy that can be applied to design more recyclable aerogels.
Solar-driven seawater desalination has attracted much attention for alleviating global freshwater shortage, but the practical application is often limited by complicated fabrication processes, unsatisfactory seawater-transferring and severe salt accumulation on the photothermal membranes. To solve these problems, hydrophobic industrial-grade carbon fiber membrane (CFM) with good photoabsorption was surface-modified with polydopamine (PDA) to prepare superhydrophilic CFM@PDA for the construction of efficient hanging-model evaporators without salt accumulation. The coating of PDA on CFM is realized by simple self-polymerization of dopamine, and the as-prepared CFM@PDA exhibits high solar absorption efficiency of 96.7%, good photothermal effect and superhydrophilicity. Especially, when CFM@PDA is hanging between two water tanks (one contains seawater and the other is empty) in a flat hanging-model evaporator, it can transport seawater at a high rate (26.35 g/h) which is 3.6 times that (7.28 g/h) of commercial cotton fabric. Under simulated sunlight (1.0 kW m−2) irradiation, CFM@PDA shows a high evaporation rate of 1.79 kg m−2 h−1 with a solar evaporation efficiency of 92.6%. Even if NaCl solution with a high concentration (21.0 wt%) is used for the evaporation, the hanging CFM@PDA can retain a high evaporation rate (~ 1.80 kg m−2 h−1) without salt accumulation during the long-time test (8 h), which is significantly better than that of the tradition floating model. Therefore, this study not only demonstrates the simple preparation of superhydrophilic CFM@PDA, but also promotes the further practical applications of hanging-model evaporators for continuous salt-free desalination.
Due to fiber swelling, textile fabrics containing hygroscopic fibers tend to decrease pore size under wet or increasing humidity and moisture conditions, the reverse being true. Nevertheless, for personal thermal regulation and comfort, the opposite is desirable, namely, increasing the fabric pore size under increasing humid and sweating conditions for enhanced ventilation and cooling, and a decreased pore size under cold and dry conditions for heat retention. This paper describes a novel approach to create such an unconventional fabric by emulating the structure of the plant leaf stomata by designing a water responsive polymer system in which the fabric pores increase in size when wet and decrease in size when dry. The new fabric increases its moisture permeability over 50% under wet conditions. Such a water responsive fabric can find various applications including smart functional clothing and sportswear.
Air pollution containing particulate matter (PM) and volatile organic compounds has caused magnificent burdens on individual health and global economy. Although advances in highly efficient or multifunctional nanofiber filters have been achieved, many existing filters can only deal with one type of air pollutant, such as capturing PM or absorbing and detecting toxic gas. Here, highly efficient, dual-functional, self-assembled electrospun nanofiber (SAEN) filters were developed for simultaneous PM removal and onsite eye-readable formaldehyde sensing fabricated on a commercial fabric mask. With the use of an electrolyte solution containing a formaldehyde-sensitive colorimetric agent as a collector during electrospinning, the one-step fabrication of the dual-functional SAEN filter on commercial masks, such as a fabric mask and a daily disposable mask, was achieved. The electrolyte solution also allowed the uniform deposition of electrospun nanofibers, thereby achieving the high efficiency of PM filtration with an increased quality factor up to twice that of commercial masks. The SAEN filter enabled onsite and eye-readable formaldehyde gas detection by changing its color from yellow to red under a 5 ppm concentrated formaldehyde gas atmosphere. The repetitive fabrication and detachment of the SAEN filter on a fabric mask minimized the waste of the mask while maintaining high filtration efficiency by replenishing the SAEN filters and reusing the fabric mask. Given the dual functionality of SAEN filters, this process could provide new insights into designing and developing high performance and dual-functional electrospun nanofiber filters for various applications, including individual protection and indoor purification applications.