Flexible Fiber Research Articles

Uniform Li‐deposition induced by Ni‐catalyzing graphitization of natural carbon materials in lithium metal batteries

AbstractLithium metal batteries are known as the most prospecting recyclable accumulation system owing to the high specific capacity of 3860 mAh g−1. Nevertheless, Li‐dendrites formed by the charge‐discharge process would lead to poor performances and severe safety problems. In this work, we proposed a new silk‐film with a composite network that was full of the Ni‐containing functionalized nanoparticles to induce the uniform Li‐deposition and prevent the wanton growth of lithium dendrite. As a result, the as‐designed flexible fiber materials (Ni‐silks) were successfully prepared by utilizing degradable silks as the substrates and Ni‐particles as the catalyzer for graphitization of carbon materials. The Ni‐silk‐Li (NSL) as anodes were constructed by Ni‐silk and Li metals, which exhibited the long‐term cycle of 800 h and high coulombic efficiency of 98.35% for the half cells. In addition, the NSL anodes also showed outstanding electrochemical performances in full cells using LiFePO4 as the cathode with an outstanding specific capacity of 155 mAh g−1. To further explore the working mechanism of the NSL electrode, Density functional theory (DFT) computations were analyzed. Our findings provide a new idea for evoking uniform Li‐nucleation by introducing graphitization of flexible Ni‐silks, which is not to be ignored for reducing Li‐dendrite formation.

Novel polymer optical fibers with high mass-loading g-C3N4 embedded metamaterial porous structures achieve rapid micropollutant degradation in water

The performance of conventional photocatalytic reactors suffers from low photocatalyst mass-loading densities affixed to surfaces and light scattering losses or light attenuation in slurry reactors. These limitations are overcome by fabrication of high mass-loading g-C3N4 embedded metamaterial porous structures on flexible polymeric optical fibers (g-C3N4-POFs). In this study, the fabricated g-C3N4-POFs contain g-C3N4 with mass-loading 100−1000x higher than previouly reported, enabling efficient light delivery to g-C3N4 and improved pollutant mass transport within metamaterial porous structures. The key fabrication step involved using acetone, based on its high saturated vapor pressure and low dielectric constant, making roll-to-roll mass production of high mass-loading photocatalyst-embedded metamaterial POFs possible at room-temperature within seconds. Using bundles of 150 individual g-C3N4-POFs in the reactors, we achieved 4x higher degradation rates for micropollutants under visible light irradiation at 420 nm compared with equivalent mass-to-volume ratios of photocatalysts in a slurry suspension reactor. The bundled g-C3N4-POF reactor showed no degradation in the structural integrity or loss of pollutant degradation using deionized or model drinking water under accumulated HO• exposures of ∼4.5 × 10−9 M•s after 20 cycles of treatment. It operates continuously at g-C3N4 dosages equivalent to 100−1000 g/L and a water depth over 40 cm, making it a feasible alternative to conventional photocatalytic reactors.

Exploring the role of nasal hair in inhaled airflow and coarse dust particle dynamics in a nasal cavity: A CFD-DEM study

This study presents a novel coupled computational fluid dynamics-discrete element method (CFD-DEM) model for simulating airflow and inhaled particle dynamics in the nasal cavity, considering the fluid-structure interactions between nasal hair and airflow, which are often overlooked in existing CFD simulations. The CFD-DEM model, based on a virtual nasal cavity geometry, represents nasal hairs as flexible fibers implanted on the inner wall of the nasal cavity. Inhaled air-particle transport dynamics were simulated in the presence of nasal hairs with three different diameters (40, 95, and 120 μm), and the results were compared with simulations without nasal hairs. Polydisperse particles with diameters ranging from 5 to 15 μm, aligning with global coarse dust statistics, were inhaled at flow rates between 216 mL/s and 630 mL/s, representing human nose breathing conditions from rest to exercise. The CFD-DEM simulation results indicate that the differences in deposition fraction predictions between cases with and without nasal hairs exceed 20% for particle size ranges corresponding to impaction parameter values between 3E+3 and 2E+4 μm2cm3/s. This emphasizes the importance of accounting for nasal hair interactions in accurately simulating inhaled particle transport dynamics within the nasal cavity. Thinner nasal hairs, more flexible than thicker ones, lead to more significant deformation and allow more particles to penetrate the nasal vestibule without being trapped. Additionally, thinner hairs occupy a smaller cross-section area in the nasal vestibule, resulting in lower filtration capability due to decreased particle deposition from interception and inertial impaction. Thicker nasal hairs trap more coarse dust particles (> 5 μm) effectively than thinner nasal hairs. Moreover, as the nasal hair diameter increases, particle deposition on the nasal cavity wall decreases. Nasal hairs demonstrate higher efficiency in trapping smaller particles. In conclusion, the CFD-DEM model, capable of modeling nasal hair motion, can serve as a next-generation in silico tool for investigating biofluid dynamics in the nasal cavity.

Flexible and conductive core-sheath fiber using multifunctional merocyanine as a smart electrolyte for a high-performance fibrous visible light sensor

Flexible conductive fibers have attracted significant attention in the wearable electronics field because of light weight, small size, and easy shape morphing. To date, there are few reports on multifunctional flexible conductive fibers. Finding a facile and effective solution for large-scale production of flexible conductive fibers is still a challenge. In this work, a flexible core-sheath fiber with excellent electrical conductivity (24.71 Ω·m) and visible light sensing is fabricated, which contains a merocyanine diol (MC(OH)2)/CrCl3·6H2O/ethanol aqueous solution core layer and a silicon rubber outer layer. The synthesized MC(OH)2 is an intelligent molecular switch with a visible light response that can reversibly convert from open-form MC(OH)2 to closed-form spiropyran diol (SP(OH)2) after short visible light irradiation. In the reverse process, the transition from SP(OH)2 to MC(OH)2 can occur gradually in the dark. This can be used to sense visible light in addition to electrical conductivity. The reversible change in the electrical resistance of the MC(OH)2/CrCl3·6H2O/ethanol aqueous solution reaches 15.59%. This fiber shows excellent electrical conductivity, good flexibility, a sensitive visible light response, good photochromism, a simple structure, low cost, easy preparation, and suitability for industrial large-scale production, offering promise for applications in the fields of flexible and wearable electronics.

An Implantable Fiber Biosupercapacitor with High Power Density by Multi‐Strand Twisting Functionalized Fibers

AbstractBiosupercapacitors (BSCs) that can harvest and store chemical energy show great promise for power delivery of biological applications. However, low power density still limits their applications, especially as miniaturized implants. Here, we report an implantable fiber BSC with maximal power density of 22.6 mW cm−2, superior to the previous reports. The fiber BSC was fabricated by integrating anode and cathode fibers of biofuel cell with supercapacitor fibers through multi‐strand twisting. This twisting structure endowed many channels inside and high electrochemical active area for efficient mass diffusion and charge transfer among different fibers, benefiting high power output. The obtained thin and flexible fiber BSC operated stably under deformations and performed high biocompatibility after implantation. Eventually, the fiber BSC was implanted subcutaneously in rats and successfully realized electrical stimulation of sciatic nerve, showing promise as a power source in vivo.

An Implantable Fiber Biosupercapacitor with High Power Density by Multi-Strand Twisting Functionalized Fibers.

Biosupercapacitors (BSCs) that can harvest and store chemical energy show great promise for power delivery of biological applications. However, low power density still limits their applications, especially as miniaturized implants.Here, we report an implantable fiber BSC with maximal power density of 22.6 mW‧cm-2, superior to the previous reports. The fiber BSC was fabricated by integrating anode and cathode fibers of biofuel cell with supercapacitor fibers through multi-strand twisting. This twisting structure endowed many channels inside and high electrochemical active area for efficient mass diffusion and charge transfer among different fibers, benefiting high power output. The obtained thin and flexible fiber BSC operated stably under deformations and performed high biocompatibility after implantation. Eventually, the fiber BSC was implanted subcutaneously in rats and successfully realized electrical stimulation of sciatic nerve, showing promiseas a power source in vivo.

Simple Mixed-Acid-Treated Carbon Fiber Electrodes with Oxygen-Containing Functional Groups for Flexible Supercapacitors

Flexible supercapacitors are demanded for energy storage of wearable electronics. In this paper, a simple strategy for preparing flexible carbon fibers (CFs) with good energy storage capacity using a mixed acid treatment process is reported. When the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1, the carbon fiber electrodes have the best electrochemical performance with a high capacitance of 27.83 F g−1 at 15 mA g−1 and extremely high capacitance retention of 79.9% after 500 cycles at 100 mA g−1. Furthermore, their energy density can reach 3.86 Wh kg−1 with a power density of 7.5 W kg−1. Such an excellent electrochemical performance of carbon fiber electrodes is attributed to their surface rich oxygen-containing functional groups, rough surface, and a certain number of graphene quantum dots (GQDs). Importantly, the all-solid-state flexible supercapacitor performs excellent bending stability performance with a capacitance retention of almost 100% after 500 times of bending at 180°, showing good prospects and applications in the field of flexible energy storage devices.

Synthesis, Characterization, and Antibacterial Properties of ZnO Nanostructures Functionalized Flexible Carbon Fibers.

Studies on the surface functionalization of flexible carbon fibers without any substrate by using cost-effective, fast, and practical processes that may provide antibacterial properties to carbon fiber have received great importance recently. The objective of this patent study is to obtain zinc oxide nanostructures functionalized carbon fibers by a facile, cheap, fast, and repeatable method, and to show their effective antibacterial activity. Electroplating and electrochemical anodization were used to synthesize zinc oxide nanostructures on carbon fiber surfaces, respectively, and their antibacterial properties were studied by zone inhibition test against Staphylococcus aureus and Pseudomonas aeruginosa. The zinc oxide nanostructures on carbon fiber surfaces were successfully synthesized in minutes, and they exhibited effective antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa. The morphological properties of the nanocomposite were studied using scanning electron microscopy, which showed that ZnO on the CF surface exhibits a flake-like nanostructure. Fourier transform infrared spectrophotometer, x-ray diffraction spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy were used to analyze the composite's compositional, structural, crystallographic, and spectral characteristics. The results from all analyses were in a good agreement, indicating that the wurtzite crystalline ZnO nanostructure was successfully produced on the CF surface. As a consequence, a method for the surface functionalization of carbon fiber using zinc oxide nanostructures has been developed that is feasible, low-cost, rapid, and repeatable. The flexible nanocomposite structure has a significant potential to be employed as a scaffold in sensor technology, wearable devices, and particularly in medical textiles due to its antibacterial and woven-able properties.

Study on cutting performance of aramid fiber weaving material by linear shaped charge

In order to realize the precise fuze-warhead matching, the parachute belt needs to be cut to realize the separation of projectile and parachute. Combining experiment and numerical simulation, study on cutting different layers of aramid fiber weaving parachute belt with linear shaped charge are carried out. The results show that the copper linear shaped charge with linear density of 15 g/m can reliably cut 6 layers of aramid fiber weaving material, and the cross section of parachute belt are neat. EXPLO5 software is used to calculate the JWL equation of state parameters of bulk RDX with different densities. And orthogonal anisotropic softening model proves to be successful in numerical model to simulate the cutting process of aramid fiber weaving materials by linear shaped charge. The number of cutting layers is in good agreement with the experimental results. On this basis, simulations of the cutting performance of the explosive standoff and linear density are carried out. The results show that with charge density of 1.4 g/cm3, the cutting performance is the best with the explosive standoff of 1 mm, which can cut 7 layers aramid fiber weaving material. The maximum cutting depth increases almost linearly with the increase of charge density.The research in this paper can provide theoretical support for cutting flexible aramid fiber weaving materials by linear shaped charge.

The flexible space of public art creates multiple languages of Central Line, shape and color

This paper constructs a flexible space by using three basic design elements: line, shape and color, and creates a flexible space through flexible materials and fiber art. The coordination design of lines, forms and colors of works is worthy of in-depth exploration, because it is related to the design effect of works, and has a great impact on the functions and aesthetic characteristics of works. As for the relationship among line, shape and color, we should treat them dialectically. They can exist alone as a design element, but together they will achieve a more complementary effect. In the construction of flexible space, we should seek a comfortable space expression, increase vitality and attraction, and realize harmonious development. When the flexible space is combined with human activities, the activity place can be formed. When considering flexible space, a residence space with centripetal force and cohesion shall be provided. Most importantly, these spaces should be closely linked and interdependent with human daily activities. Only in this way can the flexible space have vitality and humanization. Flexible space meets people's diverse needs, perhaps short-term rest, or long-term leisure, etc. it is precisely because we carry out these activities in the city that we shorten the distance between the city and people. We will not just "stay" in the city, but feel the familiarity brought by the flexible space to the city.

A novel flexible carbon fiber with carbon nanotubes growing in-situ via chemical vapor deposition to impregnate paraffin for thermal energy application

Aiming at solid waste resources reuse and energy saving issue, a novel flexible paraffin/carbon fiber@carbon nanotubes (Paraffin/CF@CNTs) composite PCM was prepared in this study. In the flexible composite PCM, CNTs grew in-situ surrounding by recycled CF trunk via chemical vapor deposition to construct the fiber net-structure utilized as the supporting material, and paraffin as a thermal energy storage material was absorbed into spongy CF@CNTs by vacuum impregnation methods. The prepared Paraffin/CF@CNTs composite has a best solid-liquid phase change latent heat of 81.94 Jg−1 after solid-solid phase transition with 15.28 Jg−1, and still keep the high latent heat retention of 99.4 % even after being subjected to 300 melting/freezing cycles. The thermal conductivity of Paraffin/CF@CNTs composite (1.551 Wm−1 K−1) is enhanced by up to 573 % than that of pure paraffin, while this composite exhibits the good thermal stability that it decomposes over 215.6 °C with totally 51.9 % mass loss. Overall, the novel flexible Paraffin/CF@CNTs composite PCM behaves very stable performances in structure, chemical component, thermal storage and thermal stability, looking promising for applications in electronic device temperature control, near-infrared stealth, smart wear and textile industries.

Endospore pili: Flexible, stiff, and sticky nanofibers

Species belonging to the Bacillus cereus group form endospores (spores) whose surface is decorated with micrometers-long and nanometers-wide endospore appendages (Enas). The Enas have recently been shown to represent a completely novel class of Gram-positive pili. They exhibit remarkable structural properties making them extremely resilient to proteolytic digestion and solubilization. However, little is known about their functional and biophysical properties. In this work, we apply optical tweezers to manipulate and assess how wild-type and Ena-depleted mutant spores immobilize on a glass surface. Furthermore, we utilize optical tweezers to extend S-Ena fibers to measure their flexibility and tensile stiffness. Finally, by oscillating single spores, we examine how the exosporium and Enas affect spores’ hydrodynamic properties. Our results show that S-Enas (μm-long pili) are not as effective as L-Enas in immobilizing spores to glass surfaces but are involved in forming spore-to-spore connections, holding the spores together in a gel-like state. The measurements also show that S-Enas are flexible but tensile stiff fibers, which support structural data suggesting that the quaternary structure is composed of subunits arranged in a complex to produce a bendable fiber (helical turns can tilt against each other) with limited axial fiber extensibility. Finally, the results show that the hydrodynamic drag is 1.5 times higher for wild-type spores expressing S- and L-Enas compared with mutant spores expressing only L-Enas or “bald spores” lacking Ena, and 2 times higher compared with spores of the exosporium-deficient strain. This study unveils novel findings on the biophysics of S- and L-Enas, their role in spore aggregation, binding of spores to glass, and their mechanical behavior upon exposure to drag forces.

Swept-source multimode fiber imaging

High-resolution compressive imaging via a flexible multimode fiber is demonstrated using a swept-laser source and wavelength dependent speckle illumination. An in-house built swept-source allowing for independent control of bandwidth and scanning range is used to explore and demonstrate a mechanically scan-free approach for high-resolution imaging through an ultrathin and flexible fiber probe. The computational image reconstruction is shown by utilizing a narrow sweeping bandwidth of < 10 nm while acquisition time is decreased by 95% compared to conventional raster scanning endoscopy. Demonstrated narrow-band illumination in the visible spectrum is vital for the detection of fluorescence biomarkers in neuroimaging applications. The proposed approach yields device simplicity and flexibility for minimally invasive endoscopy.

Acquisition of insoluble soybean fiber with high gelation performance based on structural modifications through pH-shifting during steam-cooking treatment

Utilization of by-products remains a critical technical challenge in the food industry. This work aimed to improve the gelation performance of insoluble soybean fiber (ISF) from okara based on structural modifications via pH-shifting during steam-cooking treatment. Okara was intrinsically compact and tightly aggregated. Its amorphous region was degraded by steam-cooking at pH 3 and inter-molecular H-bonds were reduced, resulting in increased content of cellulose from 37.86 wt% to 43.32 wt% and crystallinity degree from 7.79% to 40.10%. The compact structure of okara was dissociated into flexible fibers by steam-cooking at pH 11, allowing for higher porosity with a specific surface area reaching 1.4428 m2/g. However, there were no significant changes in microstructure except for a decreased particle size as pH approached neutral. The outstanding structure and adsorption capacity of ISF supported the higher gelatin performance. The hydrogels with a self-supporting and dense network structure were observed after continuous stirring from ISF steam-cooked at pH 3, 4, and 11, which was attributed to H-bonds between ISFs, while okara and other ISF suspensions exhibited good fluidity. These findings provide a new method for ISF treated by steam-cooking to enable hydrogel formation for potential applications in reconstituted foods and low-calorie gel systems.

A combined tri-dimensional fiber Bragg grating accelerometer for multi-directional measurements

In this research, a novel combined tri-dimensional accelerometer designed for vibration measurement in conventional rotating machinery is reported. The sensor utilizes a flexible hinge and fiber Bragg gratings (FBGs) which operates in three dimensions (3-D), allowing measurement along the X-axis, Y-axis, and Z-axis. The working principle and theoretical models of the sensor have been introduced and established. And then, the design and optimization of the sensor were achieved through nonlinear programming in MATLAB. To validate the theoretical resonant frequencies, Finite Element Method (FEM) analysis was employed, resulting in an accuracy that yielded an error of less than 5%. Experimental testing confirmed resonant frequencies of approximately 330 Hz, 350 Hz, and 560 Hz in the X-axis, Y-axis, and Z-axis, respectively, with sensitivities of 285.2 pm/g, 325.3 pm/g, and 202.2 pm/g within a frequency range of 0 Hz to 100 Hz. The sensor demonstrated a lateral interference level of less than 5.8% in all three-dimensional orientations. The high sensitivity and adaptability of the sensor make it suitable for monitoring mechanical equipment conditions, providing valuable insights for assessing the health and performance of rotating machinery.

A review of wearable supercapacitors fabricated from highly flexible conductive fiber materials

A review of wearable supercapacitors fabricated from highly flexible conductive fiber materials

Fabrication and property of flexible macro fiber composites for vibration-based energy harvesting

Fabrication and property of flexible macro fiber composites for vibration-based energy harvesting

Biodegradable, scalable and flexible fiber membrane for green passive radiative cooling

Biodegradable, scalable and flexible fiber membrane for green passive radiative cooling

High temperature-resistant flexible inorganic coating for aluminium silicate fiber cloth with low solar absorption ratio and high emissivity

To prepare a coating with a high emissivity and low solar absorption ratio on the surface of aluminum silicate fiber cloth, the sol-gel method was used with silica sol as a binder. In this study, the effects of two white fillers, titanium oxide and zirconia, on the substrate and radiation properties of coatings were compared after heat treatment at 800–1200 °C. The ZrO2-based coating had good stability after heat treatment at 800–1200 °C, and maintained its white color, exhibiting solar absorption ratio of approximately 0.14 and emissivity of 0.84. ZrO2-based coatings prevented harmful cracking, as observed for the TiO2-based coatings after heat treatment, because of the ZrO2 phase transformation. The ZrO2-based coating did not have strong bonding with the substrate, and the substrate strength was improved by maintaining a weak bonding interface. Compared with the TiO2-based coatings, which exhibit reduced substrate strength above 1000 °C, the ZrO2-based coating was more suitable for the surface of flexible fiber cloths as a temperature-resistant coating with good development prospects.

The Development of Aptamer-Coupled Microelectrode Fiber Sensors (apta-μFS) for Highly Selective Neurochemical Sensing.

The selective and sensitive sensing of neurochemicals is essential to decipher in-brain chemistry underlying brain pathophysiology. The recent development of flexible and multifunctional polymer-based fibers has been shown useful in recording and modulating neural activities, primarily electrical ones. In this study, we were able to realize fiber-based neurochemical sensing with high sensitivity and selectivity. We achieved a generalizable method to couple aptamers, a type of synthetic receptors on the carbon composites within fibers, as microsensors for highly selective neurochemical detection. Such an aptamer-coupled microelectrode fiber sensor (apta-μFS) enables simple, label-free, and sensitive dopamine (DA) detection down to 5 nM with ultrahigh specificity across major interferents. We succeeded in monitoring DA selectively within the living brain using our apta-μFS. We further showed the proof-of-concept of using microelectronic fiber-based toolsets to target neural pathways across electrical and chemical modalities. In summary, such fiber-based toolsets hold great potential to advance multimodal mechanistic understanding of brain pathophysiology.