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Nanotechnology: Spinning continuous carbon nanotube yarns
Abstract
The creation of continuous yarns made out of carbon nanotubes would enable macroscopic nanotube devices and structures to be constructed. Here we show that carbon nanotubes can be self-assembled into yarns of up to 30 cm in length simply by being drawn out from superaligned arrays of carbon nanotubes, and that the strength and conductivity of these yarns can be enhanced by heating them at high temperatures. Our findings should help to translate the remarkable mechanical, electrical and thermal properties of carbon nanotubes to a macroscopic scale.
... In this process, the CNTs transition from a vertically oriented forest to a horizontally aligned state where mechanical coupling of adjacent bundles leads to interconnections at the top and bottom of the sidewall, fostering continuity of CNT in the sheet. [36][37][38] The SEM image of the CNT forest during air drawing process clearly shows the unidirectional alignment of CNT sheet, and the inter-fibrils between each set of parallel lines is also visible ( Figure S2, Supporting Information). The electrical anisotropy of the CNT sheet is significantly influenced by its anisotropic structure, [34] which consists of main nanotubes aligned along the longitudinal direction and laterally branched inter-fibrils. ...
... [39] The width and length of the CNT sheet could be controlled with relative ease by adjusting the initial teasing conditions (in our case, a few nm thickness, 2 cm width, and 10 cm length, Figure S3a,b, Supporting Information). [37] To regulate the application thickness, the sheet could be stacked in multiple layers, with the thickness of the overall CNT layer increasing from 8.0 ± 0.5 to 24.5 ± 1.1 μm as the number of CNT sheets stacked increased from one to five layers ( Figure S3c, Supporting Information). Concurrently, the optical absorption also visibly increased with the thickness ( Figure S3d, Supporting Information). ...
Neural probe engineering is a dynamic field, driving innovation in neuroscience and addressing scientific and medical demands. Recent advancements involve integrating nanomaterials to improve performance, aiming for sustained in vivo functionality. However, challenges persist due to size, stiffness, complexity, and manufacturing intricacies. To address these issues, we propose a neural interface utilizing freestanding CNT‐sheets drawn from CNT‐forests integrated onto thermally drawn functional polymer fibers. This approach yields a device with structural alignment, resulting in exceptional electrical, mechanical, and electrochemical properties while retaining biocompatibility for prolonged periods of implantation. This Structurally Aligned Multifunctional neural Probe (SAMP) employing forest‐drawn CNT sheets demonstrates in vivo capabilities in neural recording, neurotransmitter detection, and brain/spinal cord circuit manipulation via optogenetics, maintaining functionality for over a year post‐implantation. The straightforward fabrication method's versatility, coupled with the device's functional reliability, underscores the significance of this technique in the next‐generation carbon‐based implants. Moreover, the device's longevity and multifunctionality positions it as a promising platform for long‐term neuroscience research.
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... Sample preparation. SACNT array is synthesized on an 8-inch silicon substrate in a LPCVD furnace [11][12][13] . SACNT film can be directly drawn out from a SACNT array (Fig. 1a, 1g). ...
The high-temperature thermal insulation materials (TIM) are critical for aerospace technology. The more thermal insulation it is, the thinner TIM is needed. Here we show that, by stacking super-aligned carbon nanotube (SACNT) films together, SACNT-stacked films (SACNT-SF) can be obtained, which outperforms the traditional TIMs for a wide range of working temperatures. In vacuum, the effective thermal conductivity of SACNT-SF is only 0.004W/m·K at room temperature, and 0.03 W/m·K at 2600℃. Theoretical analysis indicates that the nanometer diameter of the carbon nanotube, the nanoporous and anisotropic structure and the ultra-low density of SACNT-SF, and the high extinction coefficient of sp2-carbon play critical roles in reducing heat conduction via solid skeletons, radiation, and gas medium. The SACNT-SF is nanometer thick and fully flexible, which can be continuously and freely winded on various shapes of surfaces, generating a conformal TIM for a broad spectrum of applications.
... CNT-based catalyst supports offer high surface area, uniform pore distribution, and corrosion resistance, leading to improved catalyst utilization and enhanced fuel cell efficiency . Moreover, carbon nanotubes can be functionalized with active catalytic sites or heteroatom dopants to enhance catalytic activity and selectivity for fuel oxidation and oxygen reduction reactions (Jiang et al, 2002). ...
Carbon nanotubes (CNTs) are cylindrical nanostructures composed of carbon atoms arranged in a hexagonal lattice, resembling rolled-up sheets of graphene. Since, their discovery in 1991 by Sumio Iijima, CNTs have garnered significant attention due to their exceptional properties, including high mechanical strength, electrical conductivity and thermal stability. This review provides an overview of carbon nanotubes, delving into their structural insights, current applications and future prospects. The structural insights section discusses the atomic structure, chirality, synthesis methods and characterization techniques of CNTs. Current applications span various fields, including electronics, materials science, energy storage, biomedicine and environmental remediation, where CNTs offer enhanced performance and functionality. Challenges and limitations such as dispersion issues and toxicity concerns are also addressed. Finally, future prospects and emerging trends highlight advancements in synthesis techniques, tailored properties for specific applications and the potential for commercialization. Overall, this review underscores the significance of carbon nanotubes in modern science and technology, showcasing their potential to revolutionize industries and address pressing global challenges.
The modern textile industry is observing a constant demand for novel and sustainable fabrics resulting in huge improvements in mechanical strength, texture and durability by infusing elements of nanotechnology. In recent times the advent of smart textiles has resulted from the combination of conventional materials with smart nanomaterials. Smart textiles or fabrics can adapt to different environmental conditions by altering their characteristic features accordingly. Nanotechnology is being explored to design sustainable fabrics which are infused with different properties like microbial and ultraviolet resistance, hydrophobic, etc. This chapter aims to explore the recent advances in the field of textile designing via the conjugation of nanotechnology. The advances which are of great utility such as the introduction and functionalization of nanomaterials in textiles and the development of smart and cost-effective, efficient and wearable fibres for the fashion industry, personal and healthcare are summarized in the chapter. Along with the benefits, drawbacks like the nanotoxicity of the fabricated textiles and the remedial strategies are also discussed.
Alignment, functionalization and detection of carbon nanotube (CNT) bundles are vital processes for utilizing this one-dimensional nanomaterial in electronics. Here, we report a polymer-assisted wet shearing method to acquire super-aligned crater-patterned CNT arrays by nanobubble (NB) self-assembly with a “migrate and aggregation” mechanism and use craters to controllably mold even-sized nanodisks periodically along CNT bundles with tunable densities. This green, low-cost method can be extended to diverse substrates and fabricate different nanodisks. As an example, the Ag-nanodisk-patterned CNT arrays are utilized as substrates of surface-enhanced Raman scattering (SERS) for rhodamine 6G (R6G) and methylene blue (MB) in which a linear correlation is found between the SERS intensity and the CNT bundle density due to the periodic distribution of hot spots, enabling a spectral detection of CNT bundles and their densities by conventional dye molecules. Distinguishing from routine morphological characterization, this spectral method possesses an enhanced accuracy and a detection range of 0.1–2 µm−1, showing its uniqueness in the detection of CNT bundle density since the intensity of traditional spectral merely relates to the quantity of CNTs, exhibiting its potential in future CNT-bundle-based electronics.
Nanomaterial‐based yarns have been actively developed owing to their advantageous features, namely, high surface‐area‐to‐volume ratios, flexibility, and unusual material characteristics such as anisotropy in electrical/thermal conductivity. The superior properties of the nanomaterials can be directly imparted and scaled‐up to macro‐sized structures. However, most nanomaterial‐based yarns have thus far, been fabricated with only organic materials such as polymers, graphene, and carbon nanotubes. This paper presents a novel fabrication method for fully inorganic nanoribbon yarn, expanding its applicability by bundling highly aligned and suspended nanoribbons made from various inorganic materials (e.g., Au, Pd, Ni, Al, Pt, WO 3 , SnO 2 , NiO, In 2 O 3 , and CuO). The process involves depositing the target inorganic material on a nanoline mold, followed by suspension through plasma etching of the nanoline mold, and twisting using a custom‐built yarning machine. Nanoribbon yarn structures of various functional inorganic materials are utilized for chemical sensors (Pd‐based H 2 and metal oxides (MOx)‐based green gas sensors) and green energy transducers (water splitting electrodes/triboelectric nanogenerators). This method is expected to provide a comprehensive fabrication strategy for versatile inorganic nanomaterials‐based yarns.
In recent years, wearable electrochemical biosensors have received increasing attention, benefiting from the growing demand for continuous monitoring for personalized medicine and point‐of‐care medical assistance. Incorporating electrochemical biosensing and corresponding power supply into everyday textiles could be a promising strategy for next‐generation non‐invasive and comfort interaction mode with healthcare. This review starts with the manufacturing and structural design of electrochemical biosensing textiles and discusses a series of wearable electrochemical biosensing textiles monitoring various biomarkers (e.g., pH, electrolytes, metabolite, and cytokines) at the molecular level. The fiber‐shaped or textile‐based solar cells and aqueous batteries as corresponding energy harvesting and storage devices are further introduced as a complete power supply for electrochemical biosensing textiles. Finally, we discuss the challenges and prospects relating to sensing textile systems from wearability, durability, washability, sample collection and analysis, and clinical validation.
Free-standing aligned carbon nanotubes have previously been grown above 700°C on mesoporous silica embedded with iron nanoparticles.
Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666°C by
plasma-enhanced hot filament chemical vapor deposition. Acetylene gas was used as the carbon source and ammonia gas was used
as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0.1 to 50
micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are
suitable for device fabrication.
A simple method was used to assemble single-walled carbon nanotubes into indefinitely long ribbons and fibers. The processing consists of dispersing the nanotubes in surfactant solutions, recondensing the nanotubes in the flow of a polymer solution to form a nanotube mesh, and then collating this mesh to a nanotube fiber. Flow-induced alignment may lead to a preferential orientation of the nanotubes in the mesh that has the form of a ribbon. Unlike classical carbon fibers, the nanotube fibers can be strongly bent without breaking. Their obtained elastic modulus is 10 times higher than the modulus of high-quality bucky paper.
We have characterized the fundamental photoluminescence (PL) properties of individual, isolated indium phosphide (InP) nanowires to define their potential for optoelectronics. Polarization-sensitive measurements reveal a striking anisotropy in the PL intensity recorded parallel and perpendicular to the long axis of a nanowire. The order-of-magnitude polarization anisotropy was quantitatively explained in terms of the large dielectric contrast between these free-standing nanowires and surrounding environment, as opposed to quantum confinement effects. This intrinsic anisotropy was used to create polarization-sensitive nanoscale photodetectors that may prove useful in integrated photonic circuits, optical switches and interconnects, near-field imaging, and high-resolution detectors.
We report the polarized optical absorption spectra of single-walled 4 A carbon nanotubes arrayed in the channels of an AlPO (4)-5 single crystal. When the light electric field (E) is polarized parallel to the tube direction (c), the spectra display a sharp peak at 1.37 eV, with two broadbands at 2.1 and 3.1 eV. In the E perpendicular c configuration, the tube is nearly transparent in the measured energy region 0.5-4.1 eV. The optical dipole selection rules are discussed, and the absorption bands are assigned to the dipole transitions between the Van Hove singularities. The measured absorption spectra agreed well with the ab initio calculations of band structure based on the local density function approximation.
Carbon nanotube material can now be produced in macroscopic quantities. However, the raw material has a disordered structure, which restricts investigations of both the properties and applications of the nanotubes. A method has been developed to produce thin films of aligned carbon nanotubes. The tubes can be aligned either parallel or perpendicular to the surface, as verified by scanning electron microscopy. The parallel aligned surfaces are birefringent, reflecting differences in the dielectric function along and normal to the tubes. The electrical resistivities are anisotropic as well, being smaller along the tubes than perpendicular to them, because of corresponding differences in the electronic transport properties.
A simple method was used to assemble single-walled carbon nanotubes into indefinitely long ribbons and fibers. The processing consists of dispersing the nanotubes in surfactant solutions, recondensing the nanotubes in the flow of a polymer solution to form a nanotube mesh, and then collating this mesh to a nanotube fiber. Flow-induced alignment may lead to a preferential orientation of the nanotubes in the mesh that has the form of a ribbon. Unlike classical carbon fibers, the nanotube fibers can be strongly bent without breaking. Their obtained elastic modulus is 10 times higher than the modulus of high-quality bucky paper.
Large-scale synthesis of aligned carbon nanotubes was achieved by using a method based on chemical vapor deposition catalyzed by iron nanoparticles embedded in mesoporous silica. Scanning electron microscope images show that the nanotubes are approximately perpendicular to the surface of the silica and form an aligned array of isolated tubes with spacings between the tubes of about 100 nanometers. The tubes are up to about 50 micrometers long and well graphitized. The growth direction of the nanotubes may be controlled by the pores from which the nanotubes grow.
The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain
silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate
design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth
and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up
of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development
of nanotube devices integrated into silicon technology.
In the early 1990s, a chance finding in a Japanese laboratory introduced the world to carbon nanotubes. Today, interest in the tubes is still growing. Philip Ball reports on a decade of discovery.