Multilayer Fiber Research Articles

Flexible pressure sensor based on multi-layer with gradient structure P(VDF-HFP)/MXene/BaTiO3 composite film for human motion monitoring

In recent years, flexible pressure sensors have been widely used in fields such as human health monitoring, flexible energy storage, wearable electronic devices, and flexible sensing due to their advantages of simple and efficient preparation process, highly sensitive, fast response, and strong piezoelectric performance. In this paper, we studied a kind of polyvinylidene fluoride hexafluoropropylene (P(VDF-HFP))/MXene/BaTiO3 nanofiber prepared by electrospinning technology, and designed a multi-layer structure system with gradient to prepare a flexible pressure sensor. The piezoelectric properties, mechanical properties and dielectric properties are obviously improved. At the same time, the addition of nano fillers and structural design have increased the sensitivity of multi-layer composite fiber membrane-based sensors by 16.5 times compared to pure P(VDF-HFP) in the low-pressure range (<1 kPa), and by 1.5 times compared to PFP-0.5M5BT nanofiber-based sensors, reaching 0.23 kPa−1. When pressed by the palm of the hand, the output voltage of the three-layer gradient structure thin film sensor can be up to about 100 V. Compared with the output voltage of 5 V when the P(VDF-HFP) thin film is pressed by the palm, the output voltage of the flexible pressure sensor of the three-layer gradient structure thin film after adding the filler is 20 times higher. The flexible pressure sensor can analyze and recognize the form of human motion based on the peak, frequency, and shape characteristics of the voltage signals generated by different forms of human motion. This makes it possible for flexible pressure sensors to be used in pressure detection, flexible sensing, electronic skin sensors and other fields.

Investigation on Composites Reinforced with Multi-Layer Carbon Fiber and Silicone Rubber Against Impact test and Shoot Strength.

The aim of this study is to examine the durability of composite materials reinforced with carbon fiber and the effects of silicone rubber on the composites' tensile strength, bending, firing, impact, and density. The silicon fiber was mixed with resin using a magnetic stirrer at 250 rpm, with a temperature of 40o C for 30 minutes. Furthermore, the composite production process was carried out using a vacuum infusion method with carbon fiber sheet variations of 6, 8, and 10. Tensile strength shows a proportional increase with the number of carbon fiber layers. Flexural strength indicates the opposite. The impact test was conducted in accordance with the ASTM E 23 standard, the firing test was performed using a 9x19 mm caliber bullet with a distance of 10 m, and the density was found by employing ASTM 792-13. The greatest density was 1,274 grams/cm3, and it was gotten from the sample with 10 fiber layers. Following this, the results of the impact test (Izod) showed that the specimen with 6 layers of carbon fiber had the highest impact strength of 0.040 Joule/mm. While the shoot test results indicated that the composite with 6 layers of carbon had smaller shot holes. There was no significant absorption in the water absorption test.

Synergetic effect of MXene/MoS2 heterostructure and gradient multilayer for highly sensitive flexible piezoelectric sensor

In this study, we proposed a flexible piezoelectric sensor made of gradient multilayer polyacrylonitrile (PAN) MXene/Molybdenum disulfide (MoS2) nanocomposites prepared by layer-by-layer electrospinning technology. Each layer of the composite film was formed by adding different mass ratios of MXene and MoS2 (MXene: MoS2 = 4:1, 2:1, 1:1) as filler materials, with a constant content of MXene (2% of the PAN matrix), and the concentration of MoS2 increases progressively from the inner layer to the outer layer. In addition, a heterojunction structure was formed using MXene and MoS2, which formed hydrogen bonds with –CN on PAN, thereby enhancing their interaction. By employing this novel concept of gradient multilayer and 2D/2D heterostructure, the interface coupling effect could be effectively promoted, and more 31−helical conformations could be transformed into planar zigzag conformations, significantly improving the dielectric, ferroelectric, and piezoelectric properties of the multilayer composite fiber films, thereby enhancing its output performance. With the gradient multilayer structure, the piezoelectric sensor exhibited excellent voltage sensitivity (14.9 V/N). The piezoelectric sensor detected body movement during basketball shooting and offered excellent breathability for enhanced comfort. It shows promise for use in health monitoring, electronic skin, and human-computer interaction.

Fabrication of Multi-Layered Paper-Based Supercapacitor Anode by Growing Cu(OH)2 Nanorods on Oxygen Functional Groups-Rich Sponge-Like Carbon Fibers.

This work addresses the challenges in developing carbon fiber paper-based supercapacitors (SCs) with high energy density by focusing on the limited capacity of carbon fiber. To overcome this limitation, a sponge-like porous carbon fiber paper enriched with oxygen functional groups (OFGs) is prepared, and Cu(OH)2 nanorods are grown on its surface to construct the SC anode. This design results in a multi-layered carbon fiber paper-based electrode with a specific structure and enhanced capacitance. The Cu(OH)2 @PCFP anode exhibits an areal capacitance of 547.83 mF cm-2 at a current density of 1mA cm-2 and demonstrates excellent capacitance retention of 99.8% after 10 000 cycles. Theoretical calculations further confirm that the Cu(OH)2 /OFGs-graphite heterostructure exhibits higher conductivity, facilitating faster charge transfer. A solid-state SC is successfully assembled using Ketjen Black@PCFP as the cathode and KOH/PVA as the gel electrolyte. The resulting device exhibits an energy density of 0.21Wh cm-2 at 1.50mW cm-2 , surpassing the performance of reported Cu(OH)2 SCs. This approach, combining materials design with an understanding of underlying mechanisms, not only expands the range of electrode materials but also provides valuable insights for the development of high-capacity energy storage devices.

A Novel Multilayer Fiber Mesh Electrode for Ammonia Nitrogen Removal from Wastewater

A Novel Multilayer Fiber Mesh Electrode for Ammonia Nitrogen Removal from Wastewater

Bio-inspired gradient multilayer ceramic fiber aerogel loaded with TaSi2 and WSi2: Fabrication, anti-oxidation and thermal insulation

Aerogel is widely used in the field of thermal insulation. However, aerogel exhibits brittleness and infrared radiation transparency at high temperatures. Fiber composite aerogel achieved great progress, but the homogeneous structure hardly allowed heat convection, heat conduction, and heat radiation to be controlled simultaneously. In this paper, inspired by bamboo’s multilayer and gradient structure, SiC fiber loaded with TaSi2 and WSi2 antioxidant particles was prepared by electrostatic spinning. The fiber was incorporated into the silicoboron carbonitride (SiBCN) aerogel to prepare gradient multilayer SiC/SiBCN ceramic fiber aerogel. The fiber network enhanced the mechanical properties. Antioxidant particles improved antioxidant performance. Heat radiation was reduced through the fiber, while heat conduction and heat convection were decreased by the aerogel. The results showed that the ceramic fiber aerogel exhibited ultra-low thermal conductivity, excellent infrared radiation shielding, and antioxidation performance. This study is expected to provide new ideas for constructing high-temperature thermal insulation ceramic fiber aerogel.

Recent developments in the use of centrifugal spinning and pressurized gyration for biomedical applications.

Centrifugal spinning is a technology used to generate small diameter fibers and has been extensively studied for its vast applications in biomedical engineering. Centrifugal spinning is known for its rapid production rate and has inspired the creation of other technologies which leverage the high-speed rotation, namely Pressurized Gyration. Pressurized gyration incorporates a unique applied gas pressure which serves to provide additional control over the fiber production process. The resulting fibers are uniquely suitable for a range of healthcare-related applications that are thoroughly discussed in this work, which involve scaffolds for tissue engineering, solid dispersions for drug delivery, antimicrobial meshes for filtration and bandage-like fibrous coverings for wound healing. In this review, the notable recent developments in centrifugal spinning and pressurized gyration are presented and how these technologies are being used to further the range of uses of biomaterials engineering, for example the development of core-sheath fabrication techniques for multi-layered fibers and the combination with electrospinning to produce advanced fiber mats. The enormous potential of these technologies and their future advancements highlights how important they are in the biomedical discipline. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Lipid-Based Structures.

Detection of barely visible impact damage in composite plates using non-linear pump-probe technique

In the last decades, composite materials have been increasingly used in aircraft structures as a mean to reduce the weight. For safety reasons, periodic checks of impact-induced damage need to be performed. In that framework, ultrasound non destructive testing has proven its ability to detect macro-defects such as delamination. However, at early stages, Barely Visible Impact Damage (BVID) may not be detected via linear ultrasound techniques. In recent years, non-linear ultrasound has gained traction for the inspection of such defects. However, detection of the weak non-linear defect signature buried in ambient noise remains challenging, and depends on an empirical choice of excitation frequencies. This study focuses on the evaluation of a non-linear pump probe ultrasound inspection technique applied to BVID in multilayer carbon fibre reinforced composites used in aeronautics. In particular, the influence of various experimental parameters on the measured non-linear response is studied. A low frequency pump wave (via a shaker) and a high frequency wave (via a piezoelectric transducer) are transmitted to the medium while a second transducer records the ultrasonic response. Both pump and probe waves are sent in the form of a few secondslong frequency sweep, in the audible and ultrasonic range respectively. Appropriate post processing is then applied to the recorded signals to retrieve the non-linear response of the defect. The procedure is repeated on several composite plates with and without impact damages. The nonlinear response appears in the form of modulation sidebands in the frequency spectrum of the post-processed signals. The relative amplitudes of the side bands obtained for the various samples with various defect sizes and excitation amplitude or frequency content are studied. Optimal experimental parameters were obtained and led to a good detection of defects. The limits of the method are also discussed.

Developing Thick Cardiac Tissue with a Multilayer Fiber Sheet for Treating Myocardial Infarction

Human-induced pluripotent stem cell (hiPSC)-derived cardiac patches have been extensively used for treating myocardial infarction and have shown potential for clinical application. However, the limited patch thickness can hamper its therapeutic effect. We previously developed a fibrous scaffold that allowed the formation of well-organized cardiac tissue constructs. In the present study, based on the above technology, we developed a three-dimensional multilayer fibrous scaffold with dynamic perfusion, on which approximately 20 million hiPSC-derived cardiomyocytes (CMs) could be seeded in a single step and organized into 1 mm thick and viable tissue. The multilayer cardiac tissue demonstrated enhanced contractile properties and upregulated cytokine secretion compared with the control group. Notably, when used on the myocardial infarction model, the multilayer group showed improved functional recovery and less fibrosis. These results indicated that the appropriate hiPSC-CM dose requires careful evaluation in developing clinical therapy. The multilayer cardiac tissue group demonstrated significant improvement than the control group, indicating that higher doses of transplanted cells may have improved therapeutic effects in treating myocardial infarction.

Design and Study of a Novel Regular Decagon Multilayer Photonic Crystal Fiber

This study introduces a unique regular decagon multilayer photonic crystal fiber and investigates its design and properties. Through extensive utilization of COMSOL Multiphysics optical module, the fiber's optical characteristics were thoroughly examined. The simulation outcomes indicate that, within the wavelength range of 1000-1500 nm, the photonic crystal fiber exhibits an effective mode field area ranging from 2.33*10-11 to 2.55*10-11 m2, a nonlinear coefficient between 4.96*10-3 and 8.08*10-3 s³/(kg·m³), a dispersion spanning from 1.46 to 1.54, and a loss varying from 3.76*10-3 to 1.29*10-2. This research presents novel approaches and concepts for the calculation, optimization, and design of photonic crystal fibers, ultimately fostering advancements in optical communication, optical sensing, and related domains. Furthermore, it bears significant implications for the practical implementation of innovative photonic crystal fibers in optical sensing and detection applications.

Guar gum-based multilayer fiber membranes inspired by plant transpiration for enhancing the functionality of dry facial masks

As more eco-friendly and economical choice for wet facial masks, dry facial masks have always had the problem of cumbersome application process and poor water retention property. In this study, based on the mechanism of directional water transport of Janus membrane and plant transpiration, the hydrophobic polylactic acid (PLA) nanofiber layer and the superhydrophilic guar gum (GG) nanofiber layer were prepared on both sides of the silk facial mask (SM) by electrospinning to obtain the guar gum-based bionic Janus directional water transport facial mask (G-DFM). The results showed that the directional water transport function improved the facial mask's water retention by 37 %, and the nicotinamide (NAM) encapsulated in the GG layer gave the facial mask excellent whitening and antibacterial properties. The GG layer could be directed to swell after absorbing water to form the “gel-like”, which ensured that the G-DFM could continue to release NAM during its work and would enhance the attachment between the G-DFM and the skin. G-DFM not only retained the advantages of SM but also expanded the functions that SM did not have, providing an idea for designing more practical and ideal facial masks in the future.

Design of Multilayered Ring-Core Fiber With Low-Level Inter-Group Crosstalk

We propose a novel ring-core fiber (RCF) with multilayered ring core and modulated refractive index profile (RIP). The simulated results indicate that such a special fiber design is able to support 5 orbital angular momentum (OAM) mode groups (18 OAM modes) with crosstalk between any two high-order adjacent mode groups (MGs) less than -28 dB/km over the whole C and L band. At the wavelength of 1550 nm, crosstalk between the two highest-order MGs is below -36 dB/km. Besides, with the limitation of the existing manufacturing restriction, the geometric size and doping concentration of the designed fiber are allowable and reasonable, which is promising for practical manufacturing. The designed RCF also shows good bending characteristics. Moreover, ultra-broadband performance is analyzed over the whole C + L band ranging from 1530 nm to 1625 nm. This kind of fiber design could be employed in small-scale multiple-input multiple-output digital signal processing (MIMO-DSP) assisted intra-group modes multiplexing transmission or MIMO-free inter-group modes multiplexing transmission combined with the mature wavelength-division multiplexing technique.

Progressive conductivity modular assembled fiber reinforced polymer composites for absorption dominated ultraefficient electromagnetic interference shielding

Mechanical strong and durable fiber reinforced polymer composites (FRPC) with adjustable electromagnetic interference (EMI) shielding performance are urgently needed due to the rapid growing of electronics in civil and military fields. However, regulating the electromagnetic feature of fiber reinforced resin composites for tunable and absorption-dominated EMI shielding performance is still a great challenge due to the fixed electromagnetic properties of the continuous fabrics. Herein, an ultraefficient fiber reinforced epoxy resin EMI shielding composite with extremely low reflection, adjustable electromagnetic shielding feature and strong mechanical properties is fabricated through a facile progressively conductive fabric modular assembly. By decorating electromagnetic particles to obtain customized electromagnetic functional fiber cloths and progressively conductive modular design, this multi-layered fiber reinforced epoxy resin composites enable the arbitrary regulation of the electromagnetic wave reflection and absorption capabilities, leading to an excellent average EMI shielding effectiveness of 78.6 dB and extremely low reflectivity (R) of 0.05 in X-band frequency range. In addition, benefitting from the reasonable fabric arrangement and asymmetric layered structure, the composite also exhibits excellent mechanical properties. The tensile strength is 283.1 MPa, and the energy absorption reached 15.9 J under the impact of 20 J. Our work demonstrated that this progressive conductivity modular assembly is a reliable and efficient strategy to develop highly efficient EMI shielding FRPC composites with adjustable and absorption-dominated shielding feature, and is highly promising for applications in next-generation electronic devices.

Adaptive approach methodology of the Ib-value estimator calculation for acoustic emission analysis of carbon fibre reinforced plastics

The b-value analysis is closely connected mainly with research in the field of geosciences such as earthquakes and rock failure processes. However, the given approach can also be applied in conjunction with the acoustic emission method, which processes signals arising on a similar physical principle as in the case of geological events mentioned above. The b-value analysis, including its modification in the form of an improved b-value, was mainly used during its existence to characterize the state of structural damage in several industrial applications. A certain advantage and disadvantage at the same time in the case of the improved b-value approach is the possibility to specify the interval range on which the calculation of the Ib-value is performed. The aim of this publication is to introduce a methodology for autonomous determination of the interval range within the Ib-value calculation process, since the given functionality may cause certain errors for an inexperienced user. The proposed methodology is subsequently verified on a tensile test of a multilayer carbon fibre reinforced plastic composite material, which is supplemented by monitoring the deformation of individual laminae using the digital image correlation technique and compared with the conventional evaluation of the (I)b-value method. The results obtained point to a conclusion that the proposed methodology makes it possible to react more sensitively to possibly occurring violations in structural integrity and, at the same time, more accurately characterise the cumulative amplitude distribution itself.

The Fabrication and SERS Performance of Multi-layer Hollow Au-Ag Alloy Nano Urchins Structure-based SERS Fiber Probe

The Fabrication and SERS Performance of Multi-layer Hollow Au-Ag Alloy Nano Urchins Structure-based SERS Fiber Probe

Experimental and numerical investigation of large-scale effect on buckling and post-buckling behavior of tubular structures

In this paper, compressive behavior of tubular structures made of aluminum and multilayer carbon fiber reinforced plastic (CFRP) are studied experimentally and numerically. Results show that current evaluation of aluminum tubes using Johnson–Euler method overestimates the critical stress values of the tubular structure because local failure is ignored. A finite element analysis (FEA) model based on Riks method is proposed to re-evaluate compressive performance and failure modes of aluminum tubes. This model is modified for laminated composites by introducing damage model based on Hashin’s theory, such as matrix tensile/compressive failure, and fiber tensile/compressive failure. Simulation results of CFRP tubular structure show close agreement with experimental results, but also sensitive to geometric constants. Material failure is primarily the failure mode of tubes with slenderness ratios under 21. A mixed failure mode can be found for slenderness ratios of tubes between 21 and 35. For tubes with slenderness ratios above 35, buckling failure is the primary failure mode.

Numerical Simulation of Particle Filtration by Rectangular Fibres within a Parallel and Staggered Array

In this research, two-dimensional numerical simulation is used to examine the filtration performance of rectangular fiber filters. Ansys Fluent is employed to obtain the stable flow field distribution and the DPM model is used to calculate the particle trajectories in the flow field. The effect of pertinent factors such as fiber arrangement, particle-to-fiber diameter ratio, and Stokes number on the performance of rectangular fiber filters are analyzed. The simulation results indicate that both the parallel and staggered arrays of rectangular fibers have a significant influence on the capture efficiency and pressure drop. At the same flow velocity, the pressure drop of the fibers with a parallel array is lower than that of the staggered array fiber model. The capture efficiency of the staggered array model and the parallel array model increases with the increase of the ratio of particle to fiber diameter and the Stokes number. When the interception and inertial impaction mechanisms domiant, the filter with a staggered fiber array structure performs batter than the parallel array in terms of capture efficiency. The research results can provide a theoretical basis for the structure optimization and design of the air filter with multi-layer fiber.

One-pot in-situ deposition toward fabricating superhydrophobic fiberglass membranes with composite microstructure for fast water-in-oil emulsions separation

The separation of oily wastewater, especially surfactant-stabilized water-in-oil emulsions, has become a pressing global challenge. Herein, to achieve ultrafast and efficient separation of water-in-oil emulsions, this work took advantage of the Dodecyltrimethoxysilane (DTMS)-modified TiO2 sol to prepare a superhydrophobic fiberglass (FG) membrane via a facile one-pot in-situ deposition technique. The unique composite microstructure: stalactite-shaped TiO2-SiO2 composite nanoparticles and multi-layer rough fibers were constructed on the fibrous membranes, which significantly increased the roughness and led to a water contact angle of 162.7°. As-prepared composite microstructures combined the capture, coalescence, and interception effects to achieve ultrafast gravity-driven separation of surfactant-stabilized emulsions, with a flux up to 3130.4 L m−2h−1 for surfactant stabilized water-in-hexane and high separation efficiency above 99% for various emulsions. Additionally, the prepared membrane exhibited an excellent cyclic adsorption capacity of 4.25–19.07 gg−1 and high stability. Such an easy, cost-efficient one-pot in-situ deposition method provides a brand-new solution to fabricate superhydrophobic membranes for efficient separation of water-in-oil emulsions, thus exhibiting great potential in applications of domestic wastewater treatment, oil spill treatment, and oil industry development.

Thin-Film Composite Matrimid-Based Hollow Fiber Membranes for Oxygen/Nitrogen Separation by Gas Permeation.

In recent years, the need to reduce energy consumption worldwide to move towards sustainable development has led many of the conventional technologies used in the industry to evolve or to be replaced by new alternatives. Oxygen is a compound with diverse industrial and medical applications. For this reason, obtaining it from air is one of the most interesting separations, traditionally performed by cryogenic distillation and pressure swing adsorption, two techniques which are very energetically expensive. In this sense, the implementation of membranes in a hollow fiber configuration is presented as a much more efficient alternative to carry out this separation. The aim of this work is to develop cost-effective multilayer hollow fiber composite membranes made of Matrimid and polydimethylsiloxane (PDMS) for the separation of oxygen and nitrogen from air. PDMS is used as a cover layer but can also enhance the performance of the membrane. In order to compare these two materials, three different configurations are studied. First, integral asymmetric Matrimid hollow fiber membranes were produced using the spinning method. Secondly, by using dip-coating method, a PDMS dense selective layer was deposited on a self-made polyvinylidene fluoride (PVDF) hollow fiber support. Finally, the performance of a dual-layer hollow fiber membrane of Matrimid and PDMS was studied. Membrane morphology was characterized by SEM and separation performance of the membranes was evaluated by mixed-gas permeation experiments. The novelty presented in this work is the manufacture of hollow fiber membranes and the way Matrimid is treated. This makes it possible to develop much thinner dense layers than in the case of flat-sheet membranes, which leads to higher permeance values. This is a key factor when implementing this technology on an industrial scale. Membranes prepared in this work were compared to the current state of the art, reporting quite good performance for the dual-layer membrane, reaching O2 permeance of 30.8 GPU and O2/N2 selectivity of 4.7, with a thickness of about 5-10 μm (counting both selective layers). In addition, the effect of operating temperature on the membrane permeances has been studied experimentally; we analyze its influence on the selectivity of the separation process.

Forming and Degradation Mechanism of Bowl Seedling Tray Based on Straw Lignin Conversion

In response to the problems of low straw utilization efficiency and poor returning effect in Northeast China, this paper takes rice straw containing cow dung as the experimental material, and according to the characteristics of lignin glass transformation of the material, proposes a new method to prepare biomass seedling trays. The seedling trays prepared by this method can meet the needs of corn seedling cultivation and transplantation. To study the molding mechanism, scanning electron microscopy and a universal testing machine were used to compare the changes in the internal structure and mechanical properties of the regularly- and hot-compressed seedling trays before and after seedling raising. The results show that the material with water content of 23% has the best hot-pressing effect. The forming mechanism is: that the strength of the molded seedling tray resulted from the mechanical setting force of the multilayered stem fibers with a mosaic structure within the seedling tray. The adhesion and wrapping by lignin prevented water penetration from damaging the multilayered stem fibers and slightly improved their strength. The seedling tray made of straw and manure was completely degraded over 40 days, and the straw degradation rate was improved. This method can increase the overall quality and benefits of straw, providing a foundational reference for high-quality and high-efficiency straw utilization.