Conductivity Of Carbon Nanotubes Research Articles

Scalable, roll-to-roll manufacturing of multiscale nanoparticle/fiber composites using electrophoretic deposition: Novel multifunctional in situ sensing applications

Multiscale composites, where traditional fiber reinforcements are combined with nanoscale reinforcements, have emerged as multifunctional materials and have found potential for in situ strain and damage sensing, and energy harvesting/storage applications. Critical to the advancement of future applications is the development of manufacturing techniques that are industrially scalable. Electrophoretic deposition (EPD) can uniformly coat functionalized nanoparticles, such as carbon nanotubes (CNT), on conductive and non-conductive fiber substrates, producing multiscale composites with controlled microstructures and functional properties. In this research, a pilot-scale roll-to-roll EPD system is developed to continuously manufacture CNT-integrated fabrics for in situ sensing applications. Based on fundamental knowledge of CNT deposition mechanisms, key experiments are conducted to determine electrode configurations to optimize deposition yield in the roll-to-roll process. Functionalized CNTs are then deposited on 4–6 m long continuous rolls of randomly oriented non-woven glass fiber veil with different areal weights, and the CNTs form a continuous, conductive fiber-level coating. The thin and open fabric microstructure allows embedded sensors that are minimally invasive to the composite structure and allow ultraviolet (UV) light transmittance for use with UV-curable resins. The electrically conductive CNT network created on the fabric allows for the integration of sensing functionality. Short beam specimens with the CNT sensors embedded at the midplane showed no deterioration in strength. Multiple functionalities, including strain sensing and flow/UV cure monitoring during vacuum infusion are demonstrated. Sensors tested under flexural loading demonstrated sensitivity in tension and compression, and during resin infusion, the sensors could track resin flow and cure progression.

Nanoscale Dispersion of Carbon Nanotubes in a Metal Matrix to Boost Thermal and Electrical Conductivity via Facile Ball Milling Techniques.

Carbon nanotube (CNT)/metal composites have attracted much attention due to their enhanced electrical and thermal performance. How to achieve the scalable fabrication of composites with efficient dispersion of CNTs to boost their performance remains a challenge for their wide realistic applications. Herein, the nanoscale dispersion of CNTs in the Stannum (Sn) matrix to boost thermal and electrical conductivity via facile ball milling techniques was demonstrated. The results revealed that CNTs were tightly attached to metal Sn, resulting in a much lower resistivity than that of bare Sn. The resistivity of Sn with 1 wt.% and 2 wt.% CNTs was 0.087 mΩ·cm and 0.056 mΩ·cm, respectively. The theoretical calculation showed that there was an electronic state near the Fermi level, suggesting its electrical conductivity had been improved to a certain extent. In addition, the thermal conductivity of Sn with 2 wt.% CNTs was 1.255 W·m-1·K-1. Moreover, Young's modulus of the composites with CNTs mass fraction of 10 wt.% had low values (0.933 MPa) under low strain conditions, indicating the composite shows good potential for various applications with different flexible requirements. The good electrical and thermal conductive CNT networks were formed in the metal matrix via facile ball milling techniques. This strategy can provide guidance for designing high-performance metal samples and holds a broad application potential in electronic packaging and other fields.

Ultrathin, Large‐Area, and Multifunctional Polarizer Based on Highly Ordered Carbon Nanotubes Produced by Simple Shear Flow

AbstractAligning carbon nanotubes (CNTs) with high orientational ordering in a 2D array is essential for realizing optical polarizers with high polarization efficiency over a wide spectral range. Two methods are reported: dispersing CNTs in a polymer matrix followed by stretching, and mechanical stretching of a vertically grown CNT forest and then transferring it onto a substrate. However, neither can realize nanometer‐thin or large polarizers. Herein, a novel approach is demonstrated to construct a large and thin (150 nm) conductive CNT polarizer by achieving liquid crystal (LC) phase of size‐controlled CNTs in chlorosulfonic acid, unidirectional shearing, and then drying. The polarizer exhibits an excellent polarization efficiency of 98.4% for ultraviolet (365 nm) and 96.0% for visible light (550 nm). This performance is maintained even at 400 °C, while the conventional iodine‐type polarizer starts to lose efficiency over 100 °C. The CNT polarizer with high polarization efficiency for UV can replace the costly nano‐patterned wire‐grid polarizers currently used for photoaligning LCs and also its multifunction playing role of polarizer, electrode, and LC alignment is confirmed with switching of LC device. This study provides a new paradigm for realizing ultrathin and large CNT polarizers for broadband applications with outstanding heat resistance.

Design of efficient thermal conductive epoxy resin composites via highspeed transport pathways of heterogeneous compatible carbon framework

Thermal interface materials are crucial for addressing the hot issues of a rapid increase in thermal density in narrow and limited service spaces. Flexible and designable epoxy resin (EP) based composites are competitive choice yet lacks desirable thermal conductivity (∼0.2 W m−1 K−1) and mechanical properties (tensile strength: ∼19.6 MPa). Herein, EP-based composites with a reinforced three-dimensional (3D) interconnected carbon material architecture were prepared by in-situ growing 1D carbon nanotubes (CNTs) on the surface of 2D carbon fiber braid (CFB) and infiltrating matrix EP. CNTs not only promote the wettability between carbon fibers inside CFB and EP but also observably bridge the adjacent carbon fibers. The analysis of numerical models reveals the prominent contribution of 3D CFB/CNTs network to a significant increase in thermal conductivity. Non-equilibrium molecular dynamics (NEMD) indicates the high intrinsic thermal conductivity of CNTs in both systems: single CNT model and CNT/Ni model. The coupling behavior of high-frequency phonons at the interface contributes to the in-plane thermal transport. The in-plane thermal conductivity of 7.86 W m−1 K−1 and the through-plane thermal conductivity of 5.85 W m−1 K−1 are obtained in the composites with 23.2 wt% hybrid fillers, increased by 3830 % compared to neat EP. The tensile (58.93 MPa) and compressive strength (138.83 MPa) are also enhanced, meeting practical demands. These properties even perform no obvious changes after 100 cycles of bending. The stable and reliable EP-based composites with outstanding comprehensive performance designed by this work have enormous application potential in the advanced heat dissipation system.

Preparation of an Activated Carbon Composite with High Thermal Conductivity Based on Emulsified Asphalt and Carbon Nanotubes and its Adsorption Performance for n‐Hexane

AbstractActivated carbon, as the main adsorption material for treating VOCs, has been widely used. To solve the problem of safety hazards in activated carbon adsorption process due to the large amount of heat released, highly thermally conductive composite activated carbon (A‐AC/CNTs) was prepared using asphalt and highly thermally conductive carbon nanotubes (CNTs) for thermal conductivity improvement. Uniform dispersion and firm loading of CNTs in the carbon production material were achieved by dispersing carbon nanotubes (CNTs) in the asphalt‐in‐water emulsion. Experimental results showed that the specific surface area of A‐AC/CNTs reached a maximum when the loading of CNTs was 0.5 wt %. Meanwhile, the thermal conductivity increased by 1.5 times compared with the original activated carbon. The adsorption capacity of n‐hexane reached the maximum of 2868 mmol ⋅ g−1, and the adsorption capacity increased by 21.41 %. It also maintained good regeneration performance after dynamic adsorption experiments.

Role of non-covalent interactions in 2,5-di-Me-pyrazine-di-N-oxide - tertiary butyl alcohol - single-walled and multi-walled carbon nanotubes electrocatalytic systems

Oxidation of tert-butyl alcohol (tert-BuOH, Me3COH), a compound with a high C-H bond breaking energy in the absence of precious metals or their oxides as catalysts and using metal-free electrodes, is an inexpensive process and is of interest for practical applications in electrocatalysis and sensors. In this work, electrocatalytic systems 2,5-di-Me-pyrazine-di-N-oxide (Pyr1) - tert-BuOH – single - walled (SWCNT) and multi-walled (MWCNT) carbon nanotube paper electrodes in 0.1 M Bu4NClO4 solution in acetonitrile (MeCN) were studied by the methods of cyclic voltammetry, quantum chemical modeling and electron paramagnetic resonance (EPR) electrolysis. Calculaition of energies of non-covalent interactions between the components of the electrocatalytic system in complexes Me3COH*Me3COH, Me3COH*MeCN, Pyr1*Me3COH and the adsorption energy of Me3COH and complexes of Pyr1*Bu4NClO4, Pyr1*Me3COH, Pyr1*MeCN and Me3COH *Bu4NClO4 on CNTs surface using a cluster model describing the surface of conducting carbon nanotubes (10, 10) was performed. The study made it possible to reveal the regularities characteristic of aromatic-di-N-oxide – CNT electrocatalytic systems and to propose a mechanism of tert-BuOH oxidation in the presence of electrochemically generated radical cation Pyr1. The data will be useful at using CNT electrodes in electrocatalytic processes, as well as aromatic di-N-oxide-CNT catalytic systems in electrocatalysis and sensors.

Nano GeSe2/C anchored in carbon sponge skeleton for free-standing flexible lithium-ion battery electrodes

As a typical conversion alloyed anode material, Germanium selenide (GeSe2) exhibits isotropic lithiation behavior and high theoretical charge-discharge specific capacity. However, pure GeSe2 anode faces significant volume expansion (∼250 %−360 %) and further exploration is needed in the preparation of flexible electrode materials and structural design. Herein, a simple strategy is designed to load GeSe2/C-2 nanoparticles with porous carbon-coated structure on a flexible cross-networking substrate. The 3D network substrate is composed of highly conductive carbon nanotubes and adhesive cotton cellulose fibers. A two-step method involving coating and cross-linking is designed to achieve the fabrication of self-supporting flexible electrodes. As an anode for LIBs, the one layer GeSe2 discs with ∼0.65 mm thickness manifest capacities of 827.1, 744.4, 676.3, and 472.9 mAh g−1 at 0.1, 0.2, 0.5, and 1 A g−1, respectively. This superior Li+ storage performance can be attributed to the positive collective impact from the integration of nano-scale material, low crystalline properties, and carbon sponge skeleton. Furthermore, the GITT tests indicate that the diffusion coefficient of Li+ in the GeSe2-based electrodes ranged from 10−15 to 10−12 cm2/s, and the thickness of the flexible electrode (including two layers) has a negligible impact on its electrochemical performance.

Single Ru Sites on Covalent Organic Framework-Coated Carbon Nanotubes for Highly Efficient Electrocatalytic Hydrogen Evolution.

Covalent organic frameworks (COFs) with precisely controllable structures and highly ordered porosity possess great potential as electrocatalysts for hydrogen evolution reaction (HER). However, the catalytic performance of pristine COFs is limited by the poor active sites and low electron transfer. Herein, to address these issues, the conductive carbon nanotubes (CNTs) are coated by a defined structure RuBpy(H2 O)(OH)Cl2 in bipyridine-based COF (TpBpy). And this composite with single site Ru incorporated can be used as HER electrocatalyst in alkaline conditions. A series of crucial issues are carefully discussed through experiments and density functional theory (DFT) calculations, such as the coordination structure of the atomically dispersion Ru ions, the catalytic mechanism of the embedded catalytic site, and the effect of COF and CNTs on the electrocatalytic properties. According to DFT calculations, the embedded single sites Ru act as catalytic sites for H2 generation. Benefitting from increasing the catalyst conductivity and the charge transfer, the as-prepared c-CNT-0.68@TpBpy-Ru shows an excellent HER overpotential of 112mV at 10mA cm-2 under alkaline conditions as well as an excellent durability up to 12h, which is superior to that of most of the reported COFs electrocatalysts in alkaline solution.

Synthesis of highly thermal conductive carbon nanotubes on cellulose nanofiber film-loaded polyethylene glycol phase change material with flame retardancy by layered double hydroxide

The nitrogen-doped carbon nanotubes (CNTs) were obtained by using methyl orange as a soft template and high temperature treatment, on which the layered double hydroxide (LDH) was grown in situ by hydrothermal method, and finally mixed with the phase change materials (PCM) by vacuum filtration to obtain a series of novel composite films with great flame retardancy and thermal conductivity. The use of cellulose nanofiber (CNF), polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as PCM increased the film-forming properties, and the CNTs could improve the thermal conductivity of composites, while reducing the agglomeration of LDH nanolayers and improving the flame retardancy of the composite films. The results showed that the LDH grown on the nanotubes had a typical hexagonal lamellar structure, and its uniform distribution was the fundamental reason for the flame retardancy of the films which was verified by defined combustion experiments, the shortest self-extinguishing time and the least unburned area were achieved at a mass ratio of 7.14 % of LDH material. The melt and crystallization enthalpies of the thermally conductive flame-retardant films were 74.65 J/g−1 and 74.82 J/g−1, and the thermal conductivity of the material was increased to 0.04129 W/(m·K) after the use of 2.5 % thermally conductive filler. It can reduce the temperature of LED by up to 5.9 °C during the LED opening process and up to 5.2 °C during the LED closing process.

Carbon nanotubes and hexagonal boron nitride nanosheets co‐filled ethylene propylene diene monomer composites: Improved electrical property for cable accessory applications

AbstractRubber‐based composites based on ethylene propylene diene monomer (EPDM) with excellent non‐linear electrical conductivity are preferred to serve as reinforced insulation in cable accessories, which can self‐adaptively regulate electric field distribution and avoid electric field concentration due to the non‐linear conductivity. The conductive carbon nanotubes (CNT) are filled into EPDM to improve the non‐linear conductivity, while the insulating hexagonal boron nitride nanosheets (h‐BN) are used to reconcile the electric breakdown strength. The results show that with the increase of CNT loading content, the non‐linear conductivity of CNT/h‐BN/EPDM composites becomes more prominent, accompanying the decrease of threshold field strength and increase of non‐linear coefficient. However, the electric breakdown strength of CNT/h‐BN/EPDM composites seriously deteriorates due to the increase of CNT content and temperature. By incorporating 10 wt.% h‐BN into the composites, the reduction percentage of breakdown strength can be significantly lowered, which is 19.95% of neat EPDM and 13.74% of CNT/h‐BN/EPDM composites at 70°C, respectively. The COMSOL Multiphysics simulation results demonstrate that using the CNT/h‐BN/EPDM composite as the reinforced insulation can eliminate the electric field concentration of the cable accessory as well as enable the cable accessory with good lightning shock resistance.

In-situ damage self-sensing and strength recovery activated by self-electricity in carbon fibrous composites embedded with multi-functional interleaves

It is challenging to simultaneously in-situ monitor and then repair the delamination crack of carbon fiber reinforced plastics (CFRPs) without sacrificing the initial mechanical properties. Herein, two sandwich interleaves are prepared by using healable poly (ethylene-co-methacrylic acid), reinforced and conductive carbon nanotubes (CNTs), and shear-resistant epoxy columns, to achieve self-sensing and self-healing functionalities. The results reveal that both interleaves show significant self-resistance changes to damage initiation and tensile strength of the interleaves themselves can be restored to 67.9–69.1%. Also, the interleaved CFRP exhibits obvious resistance change features during the progressive damage process after multiple healings. Moreover, a self-healing efficiency of more than 90% to interlaminar shear strength after two damage-healing cycles can be obtained. Furthermore, the interleaf with more CNTs possesses higher initial and healed strength. Therefore, the proposed interleaves can be used to prepare CFRP structure with self-sensing and self-healing functions, thereby with improved service reliability and service life.

Liquid oxygen compatibility study: carbon nano-tubes based CFRP composite

This study focuses on developing a LOX-compatible PMC material by enhancing its thermal conductivity. An innovative technique involving the integration of high thermally conductive carbon nanotubes (CNTs) onto carbon fibers (CF) was employed, followed by impregnation with cyanate ester (CE) resin. The LOX compatibility of CE resin-only, CF impregnated with CE resin (CF/CE), and the proposed CNT-modified CF composite (CNTs-CF/CE) was investigated according to ASTM D2512 guidelines. While the CE resin-only samples exhibited no reaction, CF/CE and CNTs-CF/CE composites reacted with a flash event during the LOX compatibility test. Further investigation revealed that the introduction of CNTs in the CF/CE composite increased the LOX reaction probability. Notably, the study identified the influence of the damage level on the ignition rate, emphasizing the importance of damage assessment. These findings underscore the potential of CNTs in enhancing LOX compatibility and contribute valuable insights toward the development of efficient LOX storage tank applications.

Conductance of Metallic Carbon Nanotubes Network

The conductance of the carbon nanotubes (CNTs) network incorporates intertube and intratube conductance. Using the Anderson and tight-binding models, we calculate both conductances in the armchair and chiral metallic CNTs. We found that, at room temperature, the intertube conductance dominates in CNTs with larger localization lengths. Intertube conductance includes electronic and phonon-assisted junction conductance. We have revealed that the electronic conductance of a relaxed structure is around an order of magnitude larger than an unrelaxed structure. We found that the phonon-assisted conductance of armchair CNTs is comparable with their electronic conductance. However, the phonon-assisted conductance of chiral CNTs is around seven times smaller than the electronic conductance due to the large momentum needed for momentum relaxation. Furthermore, we address the dependence of junction conductance on the angle between the CNTs, the twist angle and sliding shift of the CNTs, the Fermi energy, and the applied bias voltage between CNTs. Our calculations perfectly match the experimentally measured temperature-dependent conductance using a single geometrical fitting parameter.

Differential multi-probe thermal transport measurements of multi-walled carbon nanotubes grown by chemical vapor deposition

Carbon nanotubes (CNTs) are quasi-one dimensional nanostructures that display both high thermal conductivity for potential thermal management applications and intriguing low-dimensional phonon transport phenomena. In comparison to the advances made in the theoretical calculation of the lattice thermal conductivity of CNTs, thermal transport measurements of CNTs have been limited by either the poor temperature sensitivity of Raman thermometry technique or the presence of contact thermal resistance errors in sensitive two-probe resistance thermometry measurements. Here we report advances in a multi-probe measurement of the intrinsic thermal conductivity of individual multi-walled CNT samples that are transferred from the growth substrate onto the measurement device. The sample-thermometer thermal interface resistance is directly measured by this multi-probe method and used to model the temperature distribution along the contacted sample segment. The detailed temperature profile helps to eliminate the contact thermal resistance error in the obtained thermal conductivity of the suspended sample segment. A differential electro-thermal bridge measurement method is established to enhance the signal-to-noise ratio and reduce the measurement uncertainty by over 40%. The obtained thermal resistances of multiple suspended segments of the same MWCNT samples increase nearly linearly with increasing length, revealing diffusive phonon transport as a result of phonon-defect scattering in these MWCNT samples. The measured thermal conductivity increases with temperature and reaches up to 390 ± 20 W m−1 K−1 at room temperature for a 9-walled MWCNT. Theoretical analysis of the measurement results suggests submicron phonon mean free paths due to extrinsic phonon scattering by extended defects such as grain boundaries. The obtained thermal conductivity is decreased by a factor of 3 upon electron beam damage and surface contamination of the CNT sample.

LiBH4 hydrogen storage system with low dehydrogenation temperature and favorable reversibility promoted by metallocene additives

LiBH4 is of great potential as hydrogen storage material due to its high theoretical hydrogen storage capacity. However, it suffers from high thermal stability, sluggish dehydrogenation/hydrogenation kinetics and poor reversibility. Introduction of catalysts is an effective way to improve the hydrogen storage properties of LiBH4. In the present study, chromocene and nickelocene are used as catalytic additives to LiBH4 by a simple ball-milling. Nickelocene is mostly decomposed, forming CNTs (carbon nanotubes) cross-linking the LiBH4 particles, while chromocene maintains stable during the ball-milling process. But they are fully decomposed to Cr and Ni nanoparticles after the initial dehydrogenation and further transferred to CrB2 and Ni2B nanoparticles after initial hydrogenation. The in situ formed CrB2 and Ni2B show superfine nanoparticles and are uniformly dispersed in the matrix, acting as highly active catalysts. The dehydrogenation temperature of the combined system is evidently reduced, and the hydrogen storage kinetics and reversibility are significantly improved. The highly thermal conductive CNTs are considered helpful in heat transfer during dehydrogenation and hydrogenation. The method for the introduction of the catalysts is facile and low cost. The present work provides a new insight into the design of novel catalysts for LiBH4.

Flexible thermoelectric energy harvesting system based on polymer composites

Flexible and easy processing lightweight thermoelectric materials for energy harvesting applications have shown an increasing interest. Thermoplastic polyvinylidene fluoride (PVDF) and elastomer styrene-ethylene/butylene-styrene (SEBS) polymers reinforced with thermoelectric ceramics, including bismuth sulfide (Bi2S3), bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3), and electrically conductive carbon nanotubes (CNT) have been developed, tailoring their thermal and electrical properties for thermoelectric device applications. The Seebeck coefficient of the composites increases with thermoelectric ceramic filler content for semicrystalline PVDF composites, slightly decreasing for amorphous SEBS composite. Thermoelectric power factor and figure-of-merit in the polymer composites increases up to 9 orders of magnitude with respect to the pristine polymer, up to a maximum value of 10−3 µW/(m·K2) and 10−6, respectively, for the PVDF/CNT/Bi2Te3 composite. A device composed by 2 printable p-n thermocouples based on PVDF/50Bi2S3 and PVDF/50Bi2Te3 can generate power in the order of the nW and charge a capacitor with 5 V. Theoretical modeling allows to evaluate different thermoelectric configurations, the effect of the number of thermocouples and the influence of the temperature gradient on device performance.

Innovations in Flexible Electronic Skin: Material, Structural and Applications

Flexible electronic skin (e-skin) has emerged as a promising technology for advanced sensing capabilities in applications such as robotics, prosthetics, and human-machine interfaces. The properties of e-skin devices hinge on the selection of appropriate materials and structures, such as sensitivity, mechanical flexibility, and biocompatibility. This article provides an overview of the current state of e-skin research, focusing on the materials and structures used to create e-skin devices. Various materials were discussed in this paper, including conductive polymers, carbon nanotubes, graphene, bacterial cellulose, metal-organic frameworks, ionogels, and self-healing materials, highlighting their unique properties and potential applications in e-skin designs. Additionally, the structures and architectures of e-skin devices were examined, covering aspects such as multilayer designs, hybrid structures, and hierarchical configurations. This comprehensive review offers valuable insights into the development and optimization of e-skin materials and structures, paving the way for the creation of innovative, high-performance e-skin devices for various applications.

A metal-organic framework-based electrocatalytic membrane boosts redox kinetics of lithium‑sulfur batteries

The shuttle behavior and sluggish conversion kinetics of polysulfides significantly impede the commercialization of lithium‑sulfur (LiS) batteries. Herein, we report a membrane-based electrocatalytic interlayer that consists of metal-organic framework (MOF) Co-ZIF-9 sheets and carbon nanotubes (CNT) for these issues, which is facilely weaved by vacuum filtration. The fully exposed active sites of ZIF-9 sheets endow this interlayer an efficient anchoring ability towards polysulfides, therefore efficaciously suppressing the polysulfides shuttle, and, more importantly, a strong electrocatalytic effect to accelerate the redox kinetics. Meanwhile, the three-dimensional cross-linked network structured by the conductive CNT and MOF material favours a rapid ion and electron transport, and the full utilization of adsorption and catalytic sites. As a consequence, this interlayer exhibits an excellent rate performance (a capacity up to 817 mAh g−1 under 5 C), an exceptional cyclic stability (a tiny decay of 0.019% for 1000 cycles at 1 C) and a distinctive high‑sulfur loading performance (7.2 mg cm−2) under a reduced electrolyte content. This study provides inspirations for the rational design of MOF-based nanostructures that can validly anchor polysulfides and catalyze their conversion for high-powered LiS batteries.

Microneedles coated with composites of phenylboronic acid-containing polymer and carbon nanotubes for glucose measurements in interstitial fluids

A microneedle (MN) sensor coated with a sensing composite material was proposed for measuring glucose concentrations in interstitial fluid (ISF). The sensing composite material was prepared by blending a polymer containing glucose-responsive phenylboronic acid (PBA) moieties (i.e., polystyrene-block-poly(acrylic acid-co-acrylamidophenylboronic acid)) with conductive carbon nanotubes (CNTs). The polymer exhibited reversible swelling behavior in response to glucose concentrations, which influenced the distribution of the embedded CNTs, resulting in sensitive variations in electrical percolation, even when coated onto a confined surface of the MN in the sensor. We varied the ratio of PBA moieties and the loading amount of CNTs in the sensing composite material of the MN sensor and tested them in vitro using an ISF-mimicking gel with physiological glucose concentrations to determine the optimal sensitivity conditions. When tested in animal models with varying blood glucose concentrations, the MN sensor coated with the selected sensing material exhibited a strong correlation between the measured electrical currents and blood glucose concentrations, showing accuracy comparable to that of a glucometer in clinical use.

CNT/PDMS conductive foam-based piezoresistive sensors with low detection limits, excellent durability, and multifunctional sensing capability

In this paper, a carbon nanotube (CNT)/polydimethylsiloxane (PDMS) conductive composite foam (CCF) was fabricated via a dual-solvent ice template (DSIT) process, whose structure features the conductive filler CNT "embedded" in the cell wall surface, and this CCF was applied to the field of flexible piezoresistive sensing. Benefiting from the sensitive conductive network constructed by the DSIT process, the CNT/PDMS CCF-based piezoresistive sensor can effectively detect compression strains down to 0.1% and exhibits excellent and stable response at compression strains up to 90%. In addition, the CCF shows fast response and recovery times (54 ms and 65 ms), as well as excellent durability and stability (2000 cycles). An electronic skin assembled from the CCF into 5 × 5 pixels was applied to detect the magnitude and spatial distribution of forces and strains. The CCF was also applied for roughness recognition, optical and thermal sensing responses, which shows its potential applications in personalized medical monitoring, electronic smart skin fabrication, external environment monitoring and other fields.