Modified Carbon Fiber Research Articles

Influence of Interfacial Interaction and Composition on Fracture Toughness and Impact Properties of Carbon Fiber-Reinforced Polyethersulfone.

In this study, the interlaminar fracture toughness and impact strength of polyethersulfone reinforced with continuous carbon fibers were studied. Interlaminar fracture toughness tests were performed using the double cantilever beam method. It was shown that surface modification using the thermal oxidation method of the carbon fibers can strongly increase the interlaminar fracture toughness of the obtained composites. Thus, the maximum value reached 1.72 kJ/m2, which was 40% higher than the fracture toughness of the composites reinforced with initial carbon fibers. Moreover, fractographic analysis using a scanning electron microscope allowed us to highlight the main reasons for the dependence of fracture toughness on fiber content and surface modification conditions of the carbon fibers. It was shown that the main factor that allowed for an increase in fracture toughness was the enhanced interfacial interaction between the fibers and polymer matrix. Additionally, it was found that expectedly, there was a good correlation between interlaminar fracture toughness and interlaminar shear strength results. However, a negative influence of surface modification on the impact properties of composites was found. Such behavior occurred because of higher structural stability and lower exposure to delamination in multiple layers of the composites reinforced with the modified carbon fibers. It was found that impact energy reached ~150 kJ/m2 for the polyethersulfone-based composites reinforced with initial fibers, while the composites reinforced with modified carbon fibers showed impact energy values of only ~80 kJ/m2. Nevertheless, surface modification of carbon fibers using the thermal oxidation method can be an effective method for improving the performance properties of polyethersulfone-based composite materials.

Nanocomposites of Nanocarbon Functionalized Carbon Fibers—Manufacturing to Methodological Applications

Abstract Carbon fibers have been technically applied in high performance materials and industrial scale applications. Importantly, carbon fiber reinforced composite materials have found applications in aerospace industries. These properties of carbon fiber reinforced composites depend upon the carbon fiber features such as length, orientation, surface properties, adhesion with matrices, etc. To improve the surface properties of carbon fibers and adhesion and interactions with polymers, fiber modification has been suggested as an efficient approach. Carbon nanoparticle or nanocarbon functionalized carbon fibers have been manufactured using various facile physical and chemical approaches such as electrospraying, electrophoretic deposition, chemical vapor deposition, etc. Consequently, the modified carbon fibers have nanocarbon nanoparticles such as graphene, carbon nanotube, nanodiamond, fullerene, and other nanocarbons deposited on the fiber surface. These nanocarbon nanoparticles have fine capability to improve interfacial linking of carbon fibers with the polymer matrices. The chemical vapor deposition has been adopted for uniform deposition of nanocarbon on carbon fibers and chemical methods involving physical or chemical modification have also been frequently used. The resulting advanced epoxy/carbon fiber/nanocarbon composites revealed improved tensile and physical profiles. This review basically aims manufacturing and technical aspects of polymer/fiber/nanofiller nanocomposites toward the development of high performance structures. The resulting morphology, strength, modulus, toughness, thermal stability, and other physical features of the nanocarbon functionalized carbon fibers have been enhanced. In addition, the fabricated polymer/fiber/nanofiller nanocomposites have fine interfacial adhesion, matrix-nanofiller-filler compatibility, and other characteristics. The application areas of these nanomaterials have been found wide ranging including the strengthened engineering structures, supercapacitors, shape memory materials, and several others.

Electrochemical detection of nitrite in medical and environmental samples with oxidation modified carbon fiber electrode

The potential toxicity of nitrite to organisms and the environment makes it necessary to build a sensitive and accurate nitrite detection platform. The oxidation-modified carbon fiber electrode (OMCF) with a rougher surface and oxygen-containing functional groups is constructed by a simple high-temperature calcined treatment at 400 °C for 2 h for sensitive detection of nitrite. The amperometric test results exhibit that OMCF has two linear ranges of 1–1000 µM and 1000–6000 µM. Besides, its corresponding sensitivities are 988.57 and 668.51 µA mM−1 cm−2, respectively. The low detection limit is 0.1 µM. Importantly, the OMCF can be used to detect nitrite in a drop of water or medical samples. In addition, the OMCF with a length of 150 cm was successfully synthesized. The nine sections of the above OMCF are randomly selected to detect nitrite, which shows good reproducibility. Therefore, this work provides a facile method for preparing OMCFs with high sensitivity and wide linear range for the electrochemical detection of nitrite in urine and enables large-scale electrode production for medical applications.

Effect of Low-Temperature Plasma-Modified Carbon Fibers on Impact Load Damage of Low-Density Oil-Well Cement.

After large-scale exploitation of conventional oil and gas resources, most remaining resources are in highly depleted zones, where the fracture pressure of the formations is greatly reduced. Low-density oil-well cement prevents wellbore and formation fractures by reducing annular liquid column pressure and is one of the most commonly used cements in the oil and gas industry. However, cement sheaths made of low-density oil-well cement can be easily damaged due to the impact load generated during the well completion process. Incorporating carbon fibers into the cement matrix can effectively enhance the performance of cement sheaths. To ensure that carbon fibers can be closely combined with the cement matrix, low-temperature plasma modification technology was used in this study to pretreat the fibers. The mechanical properties of low-density oil-well cement incorporated with unmodified or modified carbon fibers were studied in detail under an impact load. The results of X-ray photoelectron spectroscopy revealed that the content of hydrophilic groups on the surface increased from 18.3 to 60.3% after the plasma treatment. The impact test results showed that the peak strengths of the cements cured at 60 °C for 14 days with 0.3% unmodified and modified carbon fibers could reach 37.01 ± 1.7 and 62.27 ± 1.7 MPa, respectively, under the impact load, i.e., an increase of 68.25% after the carbon fibers were treated with low-temperature plasma. Similarly, the absorbed energy increased from 15.59 to 44.31 J, and the energy absorption rate increased from 25.98 to 73.85%. Low-temperature plasma modification provided hydrophilic functional groups on the surface, significantly improving the interfacial bonding between the carbon fibers and cement matrix. The strengthened interaction was beneficial to extending the bearing time under the impact load and demonstrated a positive influence on the mechanical properties related to the impact resistance.

One-step prepared of e-Gelatin-CNTs nano-composite fiber modified carbon fiber microelectrode for continuous dopamine monitoring: Characterization, biocompatibility evaluation and in vivo experiment

Fabricating electrochemical sensor capable of stable sensing in complex organism's environment will undoubtedly underpin key in the development of implanted electrochemical sensor. However, nonspecific protein adsorption can greatly reduce sensing sensitivity of electrode due to the abundance of protein in vivo. Herein, we aim to fabricating a modified layer of good protein adsorption resistance. The nano-composite fibers from gelatin with good hydrophily and multiwall carbon nanotubes (CNTs) for constructing on the surface of carbon fiber microelectrode using one-step electrospinning technology (e-Gelatin-CNTs/CFME). A comprehensive discussing on the protein adsorption resistance of e-Gelatin-CNTs/CFME that are, through the use of SEM, AFM, water contact angle, UV–vis, cyclic voltammetry and I-T. The resulting electrochemical sensor revealed stable sensing sensitivity in protein solution, a slightly decrease (0.02nA/μM). Furthermore, the sensor was successfully used for the detection of DA in human blood. More remarkable, e-Gelatin-CNTs nano-composite fibers presented excellent biocompatibility, which could meet the biosafety as implantation materials in vivo. This work provided a platform for the development of implantable electrochemical sensor.

Multifunctionality of MWCNT modified carbon fiber reinforced thermoplastic composite, and reclaiming composite in the pursuit of sustainable energy storage applications: An experimental and numerical analysis

The functionalized multi-walled carbon nanotubes (MWCNTs) carbon fiber reinforced polycarbonate with multifaceted intrinsic features have been fabricated to explore its structural and sustainable reliability in diverse industrial applications. A technologically simple air spray deposition method was used to modify the carbon fiber with various concentrations (0.1, 0.3, 0.5, and 0.7 wt%) of amine-MWCNTs. The fiber/film stacked composites were fabricated using the hot stamping technique. The interlaminar shear strength of the 0.7 % MWCNT reinforced composite is 50.77 MPa, which is 65.90 % higher than the neat composite. The interlaminar properties predicted through the integrated micromechanical modeling (Digimat-FE) and Abaqus FEA agree well with the experimental results. The 0.1 % CNT reinforcement possesses higher storage (2593 MPa) and loss (457.5 MPa) modulus compared to the neat sample. The continuous conducting network structure enables the maximum shielding effectiveness (SE) of 45.77 dB with 99.995 % efficiency for 0.7 % MWCNT-CF reinforced sample. The electrochemical performance of a symmetric pouch-type supercapacitor device developed from reclaimed carbon fiber (RCF) was investigated. The device has an areal energy density of 102 μWh/cm2 and an areal power density of 2.96 mW/cm2 at 1.5 mA/cm2.

Constructing a new multiscale “soft-rigid-soft” interfacial structure at the interphase to improve the interfacial performance of carbon fiber reinforced polymer composites

The high strength and toughness of Carbon Fiber-Reinforced Polymers (CFRPs) are the main requirements for their properties in various fields. Herein, the “soft-rigid-soft” structure has been designed by us to achieve the aim of the improvement for the CFRP strength and toughness simultaneously. The soft-rigid-soft structural interface layer of CF was firstly constructed by carbon nanotubes (CNT) and Tannin/Aminopropyl isobutyl POSS (TA/NH2-POSS). The interfacial shear strength (IFSS) of the modified carbon fiber composite was 111.94 MPa, which was 84.08 % higher than that of the untreated fiber (60.81 MPa). Moreover the interlaminar shear strength(ILSS) and impact strength were increased by 50.43 % and 80.37 %. Enhancement of interface performance is mainly ascribed to CNT and TA/NH2-POSS, because they can effectively which is more effective to consume energy and decentralize stress. In this paper, the strength and toughness of CFRPs ware effectively improved by the in-depth and detailed design of the “soft-rigid-soft” multi-scale structure.

Simultaneous detection of norepinephrine and 5-hydroxytryptophan using poly-alizarin/multi-walled carbon nanotubes-graphene modified carbon fiber microelectrode array sensor

Multi-walled carbon nanotubes, graphene and alizarin polymer composites coated carbon fiber microelectrode array sensor (p-AZ/MWCNT-GR/CFMEA) was constructed and used for the simultaneous detection of norepinephrine (NE) and 5-hydroxytryptophan (5-HT). The morphology and structural characteristics of sensor are characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Its electrochemical behavior has been studied with cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrochemical activity for the oxidation of NE and 5-HT, two well separated oxidation peaks with the peak potential difference of 220 mV are observed on the cyclic voltammogram. NE and 5-HT both show two electrons and two protons electrochemical reaction on the p-AZ/MWCNT-GR/CFMEA. Under the optimized experiment conditions, the linear ranges of the sensor for NE and 5-HT are 0. 08- 8 μM and 0. 1–20 μM with detection limits of 4. 22 nM and 14. 2 nM (S/N = 3), respectively. In addition, the microsensor array show good reproducibility, stability and selectivity for the determination of NE and 5-HT. Finally, the p-AZ/MWCNT-GR/CFMEA is applied to the simultaneous detection of NE and 5-HT in human serum samples and macrophages.

Enhanced electrochemical hydrogen storage performance of Co9S8 material by doping with cobalt nanoparticles embedded hollow porous carbon nanofibers

Co-axial electrospinning has been regarded as an effective technology to fabricate hollow or core/shell nanofibers. Herein, co-axial electrospinning was carried out employing polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN) as the core and shell components. Cobalt acetate was used as the cobalt source. The cobalt nanoparticles embedded hollow porous carbon fibers (Co/HCNF) were obtained after electrospinning and subsequent carbonization process. For comparison, the conventional carbon fibers (CNF), hollow carbon fibers (HCNF), and cobalt nanoparticles modified carbon fibers (Co/CNF) were also synthesized. Co9S8 material was manufactured via mechanical alloying. By adjusting the types of carbon fibers, a series of carbon fibers modified Co9S8 composites were obtained by ball milling and their electrochemical hydrogen storage properties were studied. As a result, the Co9S8 + Co/HCNF electrode showed the higher discharge capacity of 603.3 mAh/g than CNF, HCNF, Co/CNF modified Co9S8 and conventional Co9S8 electrodes. The Co nanoparticles within Co/HCNF provided high electrocatalytic activity. The special hollow porous structure and high specific surface area of Co/HCNF increased the conductivity, offered more electrochemical active sites and rapid channel for charge transfer. Moreover, Co9S8 + Co/HCNF also demonstrated improved high-rate dischargeability (HRD), capacity retention and kinetics properties. An advantageous solid-solid interface may be generated between Co9S8 and Co/HCNF, serving as a beneficial electron conduction path and facilitating the hydrogen diffusion, thereby enhancing the electrode performance of Co9S8 material.

In Situ Ratiometric Determination of Cerebral Ascorbic Acid after Ischemia Reperfusion.

Ascorbic acid (AA) is significant in protecting the brain from further damage and maintaining brain homeostasis after ischemia stroke (IS); however, the dynamic change of cerebral AA content after different degrees of ischemic stroke is still unclear. Herein, carboxylated single-walled carbon nanotube (CNT-COOH)- and polyethylenedioxythiophene (PEDOT)-modified carbon fiber microelectrodes (CFEs) were proposed to detect in situ cerebral AA with sensitivity, selectivity, and stability. Under differential pulse voltammetry scanning, the CFE/CNT-COOH/PEDOT gave a ratiometric, electrochemically responsive signal. The internal standard peak at -310 mV was from the reversible peak of O2 reduction and the deprotonation and protonation of quinone groups, while AA was oxidized at -70 mV. In vivo experimental results indicated that the cerebral AA level gradually increased with the ischemic time increasing in different middle cerebral artery occlusion (MCAO) model mice. This work implies that the increasing cerebral AA level may be highly related to the glutamate excitotoxicity and ROS-led cell apoptosis and paves a new way for further understanding the release and metabolic mechanisms of AA during ischemia reperfusion and IS.

Surface functionalization of carbon fiber by hydrothermally synthesized ZnO nanostructures for mechanical strengthening of polymer composites

AbstractIn this work, the effects of ZnO nanostructure‐surface functionalized carbon fibers has been examined along with their impacts on mechanical attributes of resulting hybrid carbon fiber reinforced polymer (CFRP) composites. The procedure involves hydrothermally generating ZnO nanostructures on carbon fibers. To generate hybrid composites, the modified carbon fiber fabric is then utilized as reinforcement in a matrix made of bisphenol‐A epoxy resin and polymer. The electron microscopy technique was employed to study development phenomenon of nanostructures on the fiber. According to the findings, lengthening the growth treatment and increasing seeding cycles improves the rate of ZnO formation. However, the results are not significantly impacted by the growth solution's concentration. The weight change analysis, X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐spectroscopy, and energy dispersive spectroscopy all provide additional support for these conclusions. In comparison to plain CFRP composites, the developed hybrid CFRP composites tensile properties and impact resistance are significantly better. The ZnO‐modified CFRP composites exhibit improvements in elastic modulus, tensile strength, and in‐plane shear strength of up to 46.44%, 48.63%, and 20.79%, respectively. The hybrid composites' capacity to absorb impact energy also rises by 76%. Based on these results, the developed hybrid composites exhibit promising properties for applications in industries such as aircraft and automobile manufacturing. They offer high impact strength, high modulus, lightweight characteristics, and low void content, making them desirable materials for these industries.Highlights Controlled growth of vertically aligned ZnO nanostructures on fiber surface has been accomplished using hydrothermal method. Characteristics of CFRP composites such as tensile strength, elastic modulus, in‐plane shear strength, and impact energy absorption, were significantly enhanced on inclusion of ZnO. The developed hybrid composites offer cost‐effective solutions with improved mechanical properties. High impact strength and modulus make them suitable for applications in aircraft and automobile industries. Achieved exceptional morphological structure and enhanced surface‐to‐volume ratio.

Effects of CNT microstructural characteristics on the interfacial enhancement mechanism of carbon fiber reinforced epoxy composites via molecular dynamics simulations

Numerous studies have concentrated on improving the mechanical properties of carbon fiber reinforced polymer composite (CFRP) through the modification of carbon fiber (CF) with carbon nanotubes (CNTs). However, most of them were confined to describing experimental phenomena. In this study, molecular dynamics (MD) simulation was used to systematically reveal the effect of CNT nanostructures on the interfacial reinforcement of CF/epoxy. An all-atom modeling method was used to provide a quantitative description of the CF-CNT/polymer interface characteristic structure. Computational results indicate that nanotubes can protect the intra- and intermolecular interactions of epoxy segments from being destroyed, thereby preventing the initiation and propagation of micro-defects during interfacial deterioration. The mechanical competition between the interface and polymer bulk leads to different failure mechanisms, and the strengthened interface region has fewer atoms leaving the equilibrium state during tensile deformation. The insertion of CNTs on the fiber surface, specifically increasing their length, diameter, distribution density, or orientation, can improve interfacial tensile strength (up to +62.11 %) and delay the detachment of epoxy molecules from the CF. Additionally, MD outcomes were verified by synthesizing CNTs onto CF using an electric field-assisted flame synthesis approach, leading to improvement in IFSS (+62.67 %) and ILSS (+27.78 %).

Waterborne polyurethane sizing agent with excellent water resistance and thermal stability for improving the interfacial performance of carbon fibers/epoxy resin composites

In order to improve the water-resistance and thermal stability of waterborne polyurethane (WPU), a series of silane and maleimide co-modified waterborne polyurethane emulsions (WPU-M-S) were prepared. Because of the high bond energy of the Si-O bond in silane and the rigid ring in 4-HPM, the WPU-M-S sizing agent achieved better thermal stability. Meanwhile, the excellent hydrophobicity of silane enhances its water resistance. Then, the electrochemical anodic oxidation (EAO) treatment was used to activate the surface of the carbon fibers to introduce carboxyl and hydroxyl groups. Next, WPU-M-S was attached to the carbon fiber by the sizing process. For compound modified carbon fibers, the water contact angle increased, and the single filament tensile strength was also improved. The WPU-M-S sizing agent can react with both the active groups on the fiber surface and the amino groups in the epoxy resin system, thereby achieving a significant improvement in the composite interfacial bonding performance. The interlaminar shear strength (ILSS) of the sizing carbon fibers reinforced epoxy resin composite was promoted to 59.80 MPa, with an increase of 41.61% compared with unsized carbon fiber.

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

Hybridization of cellulose nanocrystals modified ZnO nanoparticles with bio-based hyperbranched waterborne polyurethane sizing agent for superior UV resistance and interfacial properties of CF/PA6 composites

The interface of carbon fiber (CF) reinforced composites has been a long challenging issue that restricts the full utilization of its excellent properties in industrial applications. In present work, a green solvent γ-valerolactone and biogenetic derived gallic acid and tartaric acid were used to prepare a hyperbranched waterborne polyurethane (HWPU) sizing agent. Meanwhile, cellulose nanocrystal modified zinc oxide (CNC–ZnO) nanohybrids were successfully synthesized using a facile one-pot method to improve the dispersibility and specific surface area of ZnO nanoparticles. The hybridization of CNC–ZnO substantially enhanced the thermostability and UV resistance of bio-based HWPU. The mechanical properties of the modified composites were thoroughly examined, revealing remarkable enhancements in flexural strength and interlaminar shear strength, with improvements of 46.5 % and 48.1 % compared to pristine CF. Additionally, the interfacial shear strength test demonstrated a significant increase of 63.6 %. Remarkably, the modified carbon fiber composites retained more than 97 % of their mechanical properties after being subjected to continuous xenon irradiation for a week, highlighting the exceptional ultroviolet resistance derived from the hybrid HWPU sizing agent.

Surface modification of carbon fiber by vinyl functionalized silane to enhance the interfacial adhesion with rubber via co-vulcanization

The application of carbon fiber reinforced rubber composites was restricted by the poor interfacial combination. To construct an effective interfacial transition layer, vinyl polysiloxane was introduced to be a chemical bridge connecting carbon fiber and rubber in this study. A modification method was designed since silicon hydroxyl generated from hydrolysis vinyl siloxane could be connected with carbon fiber through ether bond while unsaturated vinyl groups could be used as crosslinking point to form interpenetrating network by following vulcanization. This mechanism was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterization for the surface of carbon fiber during modification. The immigration of sulfur from rubber matrix to the established interfacial layer was also verified by the distribution of sulfur element based on scanning electron microscopy-energy dispersive spectroscopy results. The contact angle and H-shape pull-out test was applied to evaluate the surficial activity of carbon fiber and the interfacial properties of carbon fiber reinforced rubber composites. The results showed that the interfacial performance was improved significantly since the H-shape pull-out force of modified carbon fiber reinforced rubber, which means the strength of the interfacial layer, could be more than 3 times as that of untreated samples.

COF-Coated Microelectrode for Space-Confined Electrochemical Sensing of Dopamine in Parkinson's Disease Model Mouse Brain.

Parkinson's disease (PD) is a progressive neurodegenerative disorder causing the loss of dopaminergic neurons in the substantia nigra and the drastic depletion of dopamine (DA) in the striatum; thus, DA can act as a marker for PD diagnosis and therapeutic evaluation. However, detecting DA in the brain is not easy because of its low concentration and difficulty in sampling. In this work, we report the fabrication of a covalent organic framework (COF)-modified carbon fiber microelectrode (cCFE) that enables the real-time detection of DA in the mouse brain thanks to the outstanding antibiofouling and antichemical fouling ability, excellent analytical selectivity, and sensitivity offered by the COF modification. In particular, the COF can inhibit the polymerization of DA on the electrode (namely, chemical fouling) by spatially confining the molecular conformation and electrochemical oxidation of DA. The cCFE can stably and continuously work in the mouse brain to detect DA and monitor the variation of its concentration. Furthermore, it was combined with levodopa administration to devise a closed-loop feedback mode for PD diagnosis and therapy, in which the cCFE real-time monitors the concentration of DA in the PD model mouse brain to instruct the dose and injection time of levodopa, allowing a customized medication to improve therapeutic efficacy and meanwhile avoid adverse side effects. This work demonstrates the fascinating properties of a COF in fabricating electrochemical sensors for in vivo bioanalysis. We believe that the COF with structural tunability and diversity will offer enormous promise for selective detection of neurotransmitters in the brain.

Flexible self-powered solar-blind UV photodetectors based on amorphous Ga2O3 modified carbon fiber cloth

Self-powered solar-blind ultraviolet (UV) photodetectors are gaining increasing recognition as green, efficient, and sustainable devices, representing a development trend in the evolution of next-generation optoelectronics. Much efforts have been devoted to carbon-based materials for their excellent conductivity. Among these materials, commercial carbon fiber sheets stand out due to their distinctive 3D structure, impressive conductivity, cost-effectiveness, and flexibility, rendering them highly suitable for a wide range of photosensitive applications. The realm of flexible optoelectronic devices has garnered substantial interest owing to its pivotal role in diverse domains. However, the utilization of carbon cloth (CC) as a substrate for photodetectors remains an area ripe for exploration. This study aims to fabricate self-powered solar-blind UV photodetectors based on amorphous Ga2O3 (a-Ga2O3) thin films modified CC using a concise and efficient physical vapor deposition technique (magnetron sputtering). The results show that the optimal responsivity of the a-Ga2O3/CC photodetector is 16.98 mA/W, with response times of 0.16/0.10 s (rise/decay time). Even after 300 cycles of bending treatment, this self-powered photodetector maintains excellent cyclic stability and repeatability. Furthermore, first-principles calculation reveals a significant built-in electric field around the interface between a-Ga2O3 and CC, which can effectively separate photogenerated electrons and holes and suppress carriers’ recombination. This inherent mechanism allows the a-Ga2O3/CC-based photodetector to exhibit remarkable self-powered characteristics and prominent solar-blind detection ability.

Amperometric bio-sensing of lactate and oxygen concurrently with local field potentials during status epilepticus

Epilepsy is a prevalent neurological disorder with a complex pathogenesis and unpredictable nature, presenting limited treatment options in >30 % of affected individuals. Neurometabolic abnormalities have been observed in epilepsy patients, suggesting a disruption in the coupling between neural activity and energy metabolism in the brain. In this study, we employed amperometric biosensors based on a modified carbon fiber microelectrode platform to directly and continuously measure lactate and oxygen dynamics in the brain extracellular space. These biosensors demonstrated high sensitivity, selectivity, and rapid response time, enabling in vivo measurements with high temporal and spatial resolution. In vivo recordings in the cortex of anaesthetized rats revealed rapid and multiphasic fluctuations in extracellular lactate and oxygen levels following neuronal stimulation with high potassium. Furthermore, real-time measurement of lactate and oxygen concentration dynamics concurrently with network electrical activity during status epilepticus induced by 4-aminopyridine (4-AP) demonstrated phasic changes in lactate levels that correlated with bursts of electrical activity, while tonic levels of lactate remained stable during seizures. This study highlights the complex interplay between lactate dynamics, electrical activity, and oxygen utilization in epileptic seizures.

A braided flexible Zn–MnO2 yarn battery based on cobweb-like carbonized polypyrrole modified carbon fiber electrodes

Flexible zinc ion batteries (ZIBs) are promising candidates for energy storage devices because of high safety and low cost. Carbon fibers (CFs) are ideal current collectors for ZIBs due to their good flexibility, electrical conductivity and corrosion resistance. Herein, a novel CFs-based current collector is proposed. At first, the inertness and non-polarity of CFs were significantly modified by activating and etching to obtain a multi-layered porous structure. Thereafter, carbonized polypyrrole (CPPy) nanowire conductive networks were built up on etched carbon fibers (ECFs) by electrochemical in situ growth and carbonization. Based on the CPPy network, MnO2 nanoflowers were grown firmly by the hydrothermal method to construct multi-layer MnO2@CPPy@ECFs composite electrode. The multi-layered 3D CPPy conductive network is rooted in MnO2, providing a dedicated transmission path for both electrons and ions during electrochemical redox reactions. The MnO2@CPPy@ECFs electrode had an initial capacity of 346.1 mA h·g−1 at 0.1 A g−1 and 252.8 mA h·g−1 after 800 cycles. In addition, the integrated flexible Zn–MnO2 2D fabric battery with MnO2@CPPy@ECFs fabric cathode shows a specific capacity of 254.7 mA h·g−1 at 0.1 A g−1. Finally, a flexible Zn–MnO2 yarn battery with high flexibility, shape adaptability, structural integrity and good mechanical stability was fabricated by the 2D braid method. The initial specific capacity of the flexible Zn–MnO2 yarn battery is 111.7 mA h·g−1 at 0.1C, which also presents a remarkable volumetric energy density of 30.5 mW h cm−3. This work opens up a new pathway for the rational design of flexible electrodes for wearable ZIBs.