Silk is one of the most favourable fabrics with cooling sensation. The nanoprocessing of silk through a molecular bonding design and scalable coupling reagent-assisted method can achieve subambient daytime radiative cooling, opening up a new pathway to realizing thermoregulatory materials for sustainable energy.
Acoustic fabrics have traditionally been served as sound absorbers, dissipating sound signals into unusable heat. An innovative electronic fiber woven into an elaborately designed fabric enables an unprecedented acoustic fabric. Demonstrated useful applications in sound direction identification, acoustic communications and heart sound auscultation illustrate a wide spectrum of unforeseen opportunities of the considerable technology.
Conventional electronic devices with bulky and rigid features cannot fully meet the requirements of flexibility and wearability in wearable applications. Fiber-shaped electronic devices have been intensively pursued in the past decade attributed to their excellent flexibility, weavability and wearability. The innovation of novel functions has been widely recognized as an emerging direction of fiber-shaped electronic devices, pursuing a better adaptability and longer lifetime in practical applications. In this Review, we summarize the recent advances of functional fiber devices, focusing on the preparation of functional fiber electrodes and electrolytes, as well as the formed interfaces. Fiber devices with a variety of novel functions are systematically introduced, including but not limited to stretchability, healability, shape memory and electrochromism. The remaining challenges and opportunities are also discussed to propose future directions for functionalization of fiber electronics.
Photocatalysis is an effective means to solve the greenhouse effect caused by the large amount of carbon dioxide (CO2) emissions from fossil fuel consumption. Graphitic carbon nitride (g-C3N4) has the advantages of suitable band gap, easy preparation, low price, and good stability, making it a promising semiconductor photocatalyst. However, bulk g-C3N4 also has disadvantages such as low gas adsorption, low photocatalytic efficiency, narrow spectral response, and easy recombination of electron–hole pairs. The modification method based on g-C3N4 photocatalyst helps to improve the above-mentioned problems. This review summarizes the research progress in recent years from four aspects: morphology adjustment, co-catalysts, heterostructures and doping. Each aspect includes the pros and cons of different improvement methods, the comparison of theoretical calculations and experimental results, the application of different characterization methods, and the detailed listing of product yield and selectivity. Prior to this, there was an explanation of the basic theory of semiconductor photocatalytic CO2 reduction. Finally, the future challenges and development prospects are also briefly prospected.
With the rapid development of smart products, flexible and stretchable smart wearable electronic devices gradually play an important role, and they are considered as the pioneers of the new generation of flexible electronic devices. Among these intelligent devices, flexible and stretchable strain sensors have been widely studied for their good flexibility, high sensitivity, high repeatability and huge potential for application in personal healthcare and motion detection. Moreover, unlike traditional rigid bulky sensors, the high-performance flexible strain sensors are lightweight portable devices with excellent mechanical and electrical performance, which can meet personalized needs and become more popular. Herein, the research progress of flexible strain sensors in recent years are reviewed, which mainly introducing the sensing principles and key parameters of strain sensors, commonly used conductive materials and flexible substrates and common preparation methods, and finally proposes the future application and prospects of strain sensors.
The Bombyx mori silk fibers are regarded as one of the most fascinating flexible materials in the twenty-first century and have shown great potential in areas including fiber sensors, fiber actuators, optical fibers, energy harvester, etc. The regenerated silk fibroin (SF) molecules taken from B. mori cocoon fibers have been verified to be capable of mesoscopically reconstructing during the SF molecules refolding process. The key concern of this review is to summarize recent engineering applying principles of meso reconstruction, meso hybridization and meso doping to synthesize artificial regenerated SF fibers with enhanced or even novel functions, especially based on rerouting the refolding process of SF molecules via controlling nucleation pathway. In general, the knowledge of the meso reconstruction of silk fibre shed light on the design and fabrication of other ultra-performance SF materials from the crystallization and meso structural point of view.
Electrospun nanofibers (NFs) are directly produced by electrospinning technology. They are useful in a series of applications such as excellent performance in biosensing and environmental monitoring, due to their large specific surface area and high porosity. The wide range of materials used provide a solid foundation and core guarantee for electrospun NFs to sense, which are used in a variety of polymers, small molecules, colloidal particles, and composites. Biosensing primarily aims at small biomolecules, biomacromolecules, wearable human motion monitoring, and food safety testing. Environmental monitoring encompasses the detection of gases, humidity, volatile organic compounds, and monitoring the degradation of heavy metal ions. We aim to sort out some recent research for electrospun NFs in the sensing area, which may inspire emerging smart sensing devices and bring a novel approach for biomedical development and environmental remediation. We highlight the powerful applications of electrospun NFs in the rapidly growing field of wearable electronic devices, which may spur the industry’s novel perspectives on the development of wearables. Finally, we point out some unresolved difficulties in the sensing field for electrospun NFs and propose possible and novel ideas for this development.
Silkworm silk and spider silk have been attracting numerous interests. Rapid solvation of silkworm silk protein and spider silk protein without hydrolysis of peptide bonds is highly desirable. Microwave irradiation has been proposed for facile extraction of water-soluble silk protein by various liquid media. However, microwave exposure can cause hydrolysis of peptide bonds, leading to irreversible degradation of silk protein. In this study, a series of representative dipeptides and a rationally designed recombinant protein derived from silk protein is employed to investigate the effect of microwave on the stability of the peptide bonds during a long time dissolution process, i.e., heating at 60 ℃ in a CaCl2:CH3CH2OH:H2O (1:2:8) solution. Results demonstrate that microwave irradiation imposes a minor damage and a negligible cleavage of the peptide bonds, compared with the conventional heating method. The microwave irradiation treatment suggested in this is suitable for dissolution of silk protein. It is anticipated that this approach can be developed to a commercial level commercially.
Cable/fiber-shaped Zn-ion batteries are designed to power wearable electronics that require high flexibility to operate on human body. However, one of technical challenges of these devices is the complexity and high cost for manufacturing fibered cathode. In this work, we demonstrated gamma manganese oxide (ɣ-MnO2)/reduced graphene oxide (rGO) fibered cathode fabrication using facile and cost-effective fiber production and active material coating techniques. Specifically, rGO fibers were fabricated via wet spinning, followed by chemical reduction with hydroiodic acid (HI). The synthesized rGO fiber bundle was then dip-coated with a mixture of ɣ-MnO2, carbon black or multi-walled carbon nanotubes, and xanthan gum or polyvinylidene fluoride binder to obtain ɣ-MnO2/rGO fibered cathode. We studied the effect of binders and conductive materials on physical properties and electrochemical performance of the fibered cathode. It was found that hydrophobic binder had more benefits than hydrophilic binder by providing higher active material loading, better coating layer homogeneity, and more stable electrochemical performance. Cable-shaped Zn-ion batteries (CSZIBs) were then assembled by using the ɣ-MnO2/rGO fibered cathode, Zn wire anode, and xanthan gum polymeric gel electrolyte with 2 M ZnSO4 and 0.2 M MnSO4 salts without a separator. We investigated the battery assembling procedure on a glass slide (prototype ZIB) and in a plastic tube (cable-shaped ZIB), and evaluated their electrochemical performance. The CSZIB showed promising maximum capacity of ~ 230 mAh/g with moderate cycling stability (80% capacity retention after 200 cycles) and high flexibility by maintaining the potential after consecutive pressing for 200 times under controlled pressing distance, duration, and testing speed. Finally, we explored ion intercalation behaviours and proposed a H+/Zn2+ co-intercalation mechanism in ZIB with ɣ-MnO2 active material.
Continuous pulse wave signals monitoring is the essential basis for clinical cardiovascular diagnosis and treatment. Recent researches show the majority of current electronic pulse sensors usually face challenges in electrical safety concern, poor durability and demanding precision in position alignment. Thus, a highly sensitive, inherently electrical safe, robust and alignment-free device is highly desired. Here, we present a wearable alignment-free microfiber-based sensor chip (AFMSC) for precise vital signs monitoring and cardiovascular health assessment. The AFMSC comprises an optical micro/nano fiber sensor (MNF) and a flexible soft liquid sac while the MNF sensor is used to perceive the physiological signals and the liquid sac is used to eliminate the misalignment. The real-time and accurate monitoring of the pulse signals was realized by tracking the optical power variation of transmitted light from MNF. Then, the cardiovascular vital signs extracted from radial artery pulse signals were used to evaluate cardiovascular health condition and the results were in accordance with human physiological characteristics. Moreover, the pulse signals from different arterial area, the respiration signals from chest and the radial pulse signals before and after exercise were detected and analyzed. The non-invasive, continuous and accurate monitoring of cardiovascular health based on the reported wearable and alignment-free device is promising in both fitness monitoring and medical diagnostics for cardiovascular disease prevention and diagnosis.
All-solid-state Li-SeS2 batteries (ASSLSs) are more attractive than traditional liquid Li-ion batteries due to superior thermal stability and higher energy density. However, various factors limit the practical application of all-solid-state Li-SeS2 batteries, such as the low ionic conductivity of the solid-state electrolyte and the poor kinetic property of the cathode composite, resulting in unsatisfactory rate capability. Here, we employed a traditional ball milling method to design a Li7P2.9W0.05S10.85 glass–ceramic electrolyte with high conductivity of 2.0 mS cm− 1 at room temperature. In order to improve the kinetic property, an interpenetrating network strategy is proposed for rational cathode composite design. Significantly, the disordered cathode composite with an interpenetrating network could promote electronic and ionic conduction and intimate contacts between the electrolyte–electrode particles. Moreover, the tortuosity factor of the carrier transport channel is considerably reduced in electrode architectures, leading to superior kinetic performance. Thus, assembled ASSLS exhibited higher capacity and better rate capability than its counterpart. This work demonstrates that an interpenetrating network is essential for improving carrier transport in cathode composite for high rate all-solid-state Li-SeS2 batteries.
Advanced biomaterial-based strategies for treatment of peripheral nerve injury require precise control over both topological and biological cues for facilitating rapid and directed nerve regeneration. As a highly bioactive and tissue-specific natural material, decellularized extracellular matrix (dECM) derived from peripheral nerves (decellularized nerve matrix, DNM) has drawn increasing attention in the field of regenerative medicine, due to its outstanding capabilities in facilitating neurite outgrowth and remyelination. To induce and maintain sufficient topological guidance, electrospinning was conducted for fabrication of axially aligned nanofibers consisting of DNM and poly(ε-caprolactone) (PCL). Core–shell structured fibers were prepared by coaxial electrospinning using DNM as the shell and PCL as the core. Compared to the aligned electrospun fibers using preblended DNM/PCL, the core–shell structured fibers exhibited lower tensile strength, faster degradation, but considerable toughness for nerve guidance conduit preparation and relatively intact fibrous structure after long-term degradation. More importantly, the full DNM surface coverage of the aligned core–shell fibers effectively promoted axonal extension and Schwann cells migration. The DNM contents further triggered neurite bundling and myelin formation toward nerve fiber maturation and functionalization. Herein, we not only pursue a multi-functional scaffold design for nerve regeneration, a detailed comparison between core–shell structured and preblended electrospinning of DNM/PCL composites was also provided as an applicable paradigm for advanced tissue-engineered strategies using dECM-based biomaterials.
Hybrid polymer membrane (TA-APTES), synthesized by tannic acid (TA) and aminopropyl trethoxysilane (APTES) based on the Schiff’s base and Michael addition reaction, is deposited on the surface of poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibers, and then grafted with epoxy-terminated polysesquisiloxane (POSS) to obtain POSS-g-PBO@TA-APTES fibers. The POSS-g-PBO@TA-APTES fibers reinforced bisphenol A dicyanate ester (BADCy) resins (POSS-g-PBO@TA-APTES fibers/BADCy) wave-transparent laminated composites are prepared. The interlaminar shear strength and flexural strength of POSS-g-PBO@TA-APTES fibers/BADCy composites are respectively enhanced from 36.7 and 587.4 MPa to 42.8 and 645.8 MPa, increased by 16.6% and 9.9% compared with those of PBO fibers/BADCy composites. At 1 MHz, the corresponding dielectric constant and dielectric loss are reduced to 2.85 and 0.0047, respectively, lower than those of PBO fibers/BADCy (3.06 and 0.006) composites. Meanwhile, the simulated wave transmittance rate of POSS-g-PBO@TA-APTES fibers/BADCy composites with the thicknesses of 1.5–3.5 mm is higher than 86.2% at 0.3–40 GHz. The volume resistivity and breakdown strength of POSS-g-PBO@TA-APTES fibers/BADCy composites are 2.8 × 1015 Ω·cm and 19.80 kV/mm, higher than PBO fibers/BADCy composites (2.2 × 1015 Ω·cm and 17.69 kV/mm), respectively. And the corresponding heat resistant index is 221.5 °C, lower than PBO fibers/BADCy composites (229.6 °C).
Single-ion conducting polymer electrolytes (SIPEs) can be formed by anchoring charge delocalized anions on the side chains of a crosslinked polymer matrix, thereby eliminating the severe concentration polarization effect in conventional dual-ion polymer electrolytes. Addition of a plasticizer into the polymer matrix confers advantages of both liquid and solid electrolytes. However, plasticized SIPEs usually face a trade-off between conductivity and mechanical strength. With insufficient strength, potentially there is short-circuiting failure during cycling. To address this challenge, a simple and mechanically-robust SIPE was developed by crosslinking monomer lithium (4-styrenesulfonyl) (trifluoromethylsulfonyl) imide (LiSTFSI) and crosslinker poly(ethylene glycol) diacrylate (PEGDA), with plasticizer propylene carbonate (PC), on electrospun polyacrylonitrile nanofibers (PAN-NFs). The well-fabricated polymer matrix provided fast and effective Li+ conductive pathways with a remarkable ionic conductivity of 8.09 × 10–4 S cm−1 and a superior lithium-ion transference number close to unity (t Li+ = 0.92). The introduction of PAN-NFs not only improved the mechanical strength and flexibility but also endowed the plasticized SIPE with a wide electrochemical stability window (4.9 V vs. Li+/Li) and better cycling stability. Superior long-term lithium cycling stability and dynamic interfacial compatibility were demonstrated by lithium symmetric cell testing. Most importantly, the assembled all-solid-state Li metal batteries showed stable cycling performance and remarkable rate capability both in low and high current densities. Therefore, this straightforward and mechanically reinforced SIPE exhibits great potential in the development of advanced all-solid-state Li-metal batteries.
Silkworm silk fibers have been woven into textiles for thousands of years, because of their attractive luster, good mechanical properties, excellent biocompatibility, and large-scale production. With the development of human society, preparation of silk fibers with modified or enhanced properties are highly desirable for potential applications in structural materials and smart textiles. Herein, we realized the reinforcement of multiple properties of silk fibers by feeding silkworms with Ag nanowire (Ag NW) modified diets. The obtained silk fibers show obviously enhanced comprehensive mechanical properties, including improved tensile strength, elongation at break, tensile modulus, and toughness, which are increased by 37.2%, 37.6%, 68.3%, and 69.8%, respectively. Furthermore, compared with unmodified silk, the electrical conductivity and thermal conductivity of modified silk fibers are improved by 246.4% and 32.1%, respectively. The analysis on the components and structure shows that the incorporated Ag NWs lead to increased content of random coil/α-helix, improved orientation of crystallites, and increased content of Ag compared to pristine silk fibers, which may contribute to the enhanced mechanical, electrical, and thermal properties.
In this study, a novel copper ion (Cu2+) crosslinked composites beads with components of sodium alginate (SA) as gel matrix and UiO-66-(COOH)2 metal organic framework (MOF) nanoparticle as functional filler could effectively adsorb toxins in dialysate. The maximum adsorption capacity of the optimized composite beads (Cu-SA/U-4) for creatinine reached 125.0 mg/g with a positive synergistic effect based on Langmuir isotherm model and pseudo-second-order kinetic model, which was 1.75 times and 1.50 times that of single component beads (Cu-SA) and UiO-66-(COOH)2 nanoparticle respectively. Furthermore, when the dialysis performance using thin-film nanofibrous composite (TFNC) membrane was comparable, introduction of Cu-SA/U-4 beads into the dialysate allowed the volume of dialysate reduced to one-tenth of that without beads. Therefore, the coordination of such highly efficient adsorbent beads and TFNC dialysis membrane can economize the usage of the dialysate and contributes to realize lightweight hemodialysis. More importantly, we not only prepared a kind of composite bead via carefully designed strategy, but also proposed widely applicable idea of using adsorbents in combination with dialysis membrane to realize lightweight or miniaturized hemodialysis.