Wearable strain sensors with excellent stretchability and sensitivity have emerged as a very promising field which could be used for human motion detection and biomechanical systems, etc. ...Three-dimensional (3D) graphene foam (GF) has been reported before for high-performance strain sensors, however, some problems such as high cost preparation, low sensitivity, and stretchability still remain. In this paper, we report a highly stretchable and sensitive strain sensor based on 3D GF and polydimethylsiloxane (PDMS) composite. The GF is prepared by assembly process from graphene oxide via a facile and scalable method and possesses excellent mechanical property which facilitates the infiltration of PDMS prepolymer into the graphene framework. The as-prepared strain sensor can be stretched as high as 30% of its original length and the gauge factor of this sensor is as high as 98.66 under 5% of applied strain. Moreover, the strain sensor shows long-term stability in 200 cycles of stretching-relaxing. Implementation of the device for monitoring the bending of elbow and finger results in reproducibility and various responses in the form of resistance change. Thus, the developed strain sensors exhibit great application potential in fields of biomechanical systems and human-interactive applications.
Copper nanowires (CuNWs) are attracting a myriad of attention due to their preponderant electric conductivity, optoelectronic and mechanical properties, high electrocatalytic efficiency, and large ...abundance. Recently, great endeavors are undertaken to develop controllable and facile approaches to synthesize CuNWs with high dispersibility, oxidation resistance, and zero defects for future large‐scale nano‐enabled materials. Herein, this work provides a comprehensive review of current remarkable advancements in CuNWs. The Review starts with a thorough overview of recently developed synthetic strategies and growth mechanisms to achieve single‐crystalline CuNWs and fivefold twinned CuNWs by the reduction of Cu(I) and Cu(II) ions, respectively. Following is a discussion of CuNW purification and multidimensional assemblies comprising films, aerogels, and arrays. Next, several effective approaches to protect CuNWs from oxidation are highlighted. The emerging applications of CuNWs in diverse fields are then focused on, with particular emphasis on optoelectronics, energy storage/conversion, catalysis, wearable electronics, and thermal management, followed by a brief comment on the current challenges and future research directions. The central theme of the Review is to provide an intimate correlation among the synthesis, structure, properties, and applications of CuNWs.
Copper nanowires (CuNWs) are highly attractive in a myriad of fields for their admirable structure, optoelectronic and mechanical properties, high electrocatalytic efficiency, and large abundance. This Review focuses on the latest advancements in structure, growth mechanism, purification, multidimensional assemblies, surface modifications, and emerging applications of CuNWs, aiming to realize the industrial applications of CuNWs.
Three-dimensional (3D) compressible carbon-based foams with ultralow density, high porosity and excellent electrical conductivity have aroused considerable interest especially as pressure sensors, ...recyclable absorbents and for other advanced applications. Herein, highly compressible 3D graphene/carbon nanotube foams (GCFs) were prepared by a facile self-assembly process under mild conditions. The incorporation of CNTs into graphene resulted in great improvement of their mechanical and compressible properties compared with the graphene-only foam (under a high strain of 80% and a higher stress of 25.64 kPa). Besides, the GCFs exhibited excellent piezoresistive properties with high sensitivity (with a high gauge factor of 8.4 at a strain of 10%) and great stability during the compression cycles which was quite important for the pressure sensors. In addition, the compressible GCFs also possessed excellent adsorption capacity for organic solvents with great reusability. With unique electrical features and high sensitivity as well as robust mechanical strength, the as-fabricated 3D GCFs possess great potential as elastic pressure sensor materials, absorbents and beyond.
Hydrogels usually suffer from low mechanical strength, which largely limit their application in many fields. In this Research Article, we prepared a dual physically cross-linked hydrogel composed of ...poly(acrylamide-co-acrylic acid) (PAM-co-PAA) and poly(vinyl alcohol) (PVA) by simple two-steps methods of copolymerization and freezing/thawing. The hydrogen bond-associated entanglement of copolymer chains formed as cross-linking points to construct the first network. After being subjected to the freezing/thawing treatment, PVA crystalline domains were formed to serve as knots of the second network. The hydrogels were demonstrated to integrate strength and toughness (1230 ± 90 kPa and 1250 ± 50 kJ/m3) by the introduction of second physically cross-linked network. What̀s more, the hydrogels exhibited rapid recovery, excellent fatigue resistance, and self-healing property. The dynamic property of the dual physically cross-linked network contributes to the excellent energy dissipation and self-healing property. Therefore, this work provides a new route to understand the toughness mechanism of dual physically cross-linked hydrogels, hopefully promoting current hydrogel research and expanding their applications.
Stretchable strain sensors, as crucial components in wearable intelligent devices, have become one of the recent research hotspots with promising potential in human-interactive, personal health ...monitoring, and flexible smartphones. Graphene-based materials have been reported for high-performance strain sensors. However, there still remain some limitations such as their high production cost and low sensitivity and stretchability. Herein, a highly stretchable and ultra-sensitive strain sensor based on nickel nanoparticles and a graphene-coated polyurethane sponge (Ni@GPUS) ternary hybrid material has been reported. Herein, Ni@GPUS was fabricated via a series of techniques including preparation of a graphene-coated polyurethane sponge, electrodeposition of nickel nanoparticles, and encapsulation by polydimethylsiloxane. The obtained sensors can be stretched up to 65% and exhibit a remarkable gauge factor of up to 3360.09. Furthermore, a fast signal response (<100 ms) and 1000 cycles of stretching and bending prove the rapid steady state response and long-term durability of the sensor, respectively. In addition, the working mechanisms of the sensor have been proposed. Moreover, the strain sensor was used as a bodily motion sensor to monitor finger bending and facial muscle tension, showing great potential in the fields of flexible, stretchable, and wearable electronics.
Conductive elastomers, an irreplaceable component of stretchable electronics, have recently gained significant attention. Herein, we report highly conductive, sensitive, stretchable, and fully ...printed hybrid composites comprising carbon nanotubes (CNTs), silver nanoparticles (Ag NPs) and hydroxyl-poly(styrene- block -butadiene- block -styrene) (OH-SBS) polymers. The electrically conductive composites are fabricated via direct evaporation of CNT-dispersed OH-SBS suspension under mild heating conditions, followed via an iterative process of silver precursor absorption and reduction, generating large amounts of Ag NPs on both the surface and inner regions of the CNT-embedded composites. The obtained CNT–Ag NP embedded composites possess a superior electrical conductivity of 1228 S cm −1 , a high break elongation of 540%, and a high gauge factor of 26 500. The unique hierarchical multiscale hybrid architecture of CNT–Ag NPs and the utilization of OH-SBS enable the as-prepared composites to exhibit huge piezoresistive behavior with a broad range of tensile strains. Moreover, handwritten electric circuits with diverse geometries are designed, and the printed strain gauge sensor could successfully detect sign language via its strain-sensing behavior. We believe that our hierarchical multiscale hybrid design could pave the way for the simple fabrication of stretchable circuits for wearable electronics.
In previous work, we have developed a dual physically cross-linked hydrogel composed of poly (acrylamide-co-acrylic acid) (PAM-co-PAA) and polyvinyl alcohol (PVA), named as PVA/CP DN gel, by facile ...copolymerization and freezing/thawing. The PVA/CP DN gel is featuring both excellent mechanical properties and self-healing ability. Additionally, we have preliminarily found that the comonomer ratio for PVA/CP DN gel have great influence on the self-healing efficiency. In this research article, we will further discuss the mechanical and self-healing properties of the PVA/CP DN gel by varying the comonomer ratio of PAM-co-PAA. The results proved that the structure of DN will be loosen when the number of PAA segments exceed that of PAM. More PAA segments in copolymer make the PVA/CP DN gel have better elongation at break but weak in tensile strength and young’s modulus because of less PVA crystalline domains formed in the gel. The energy dissipation value for the double-network hydrogel decrease with the addition of PAA segments, whereas self-healing efficiency of PVA/CP DN gel increased. Anyway, this work provides more information to further understand the effects of composition on the properties of dual physically cross-linked PVA/CP DN hydrogel.
High‐purity, large‐aspect‐ratio, and well‐dispersed copper nanowires (CuNWs) with an average diameter of 45 nm and length >100 μm were successfully synthesized by reducing a Cu(II) salt with glucose, ...with oleylamine (OM) and oleic acid (OA) serving as dual capping agents, through hydrothermal reduction. A systematic study of the effects of the copper salt, capping agents, reductant, and temperature on the morphology of CuNWs has been conducted. Our results indicate that CuNWs with different diameters can be obtained using different copper salts. The diameter of the as‐prepared CuNWs decreases with increasing amounts of OM/OA and glucose but increases with the increasing temperature of the reaction. By adjusting the experimental parameters, we could achieve controlled synthesis of CuNWs and obtain high‐quality CuNWs with different diameters of 45, 76, 85, 90, 100, 112, 135, and 175 nm.
High‐purity, large‐aspect‐ratio, and well‐dispersed copper nanowires (CuNWs) with an average diameter of 45 nm and length >100 μm were successfully synthesized by reducing a Cu(II) salt with glucose, with oleylamine (OM) and oleic acid (OA) serving as dual capping agents, through a simple hydrothermal reduction methods. By adjusting the experimental parameters, we could achieve controlled synthesis of CuNWs and obtain high‐quality CuNWs with different diameters of 45, 76, 85, 90, 100, 112, 135, and 175 nm respectively.
Three-dimensional (3D) compressible carbon-based foams with ultralow density, high porosity and excellent electrical conductivity have aroused considerable interest especially as pressure sensors, ...recyclable absorbents and for other advanced applications. Herein, highly compressible 3D graphene/carbon nanotube foams (GCFs) were prepared by a facile self-assembly process under mild conditions. The incorporation of CNTs into graphene resulted in great improvement of their mechanical and compressible properties compared with the graphene-only foam (under a high strain of 80% and a higher stress of 25.64 kPa). Besides, the GCFs exhibited excellent piezoresistive properties with high sensitivity (with a high gauge factor of 8.4 at a strain of 10%) and great stability during the compression cycles which was quite important for the pressure sensors. In addition, the compressible GCFs also possessed excellent adsorption capacity for organic solvents with great reusability. With unique electrical features and high sensitivity as well as robust mechanical strength, the as-fabricated 3D GCFs possess great potential as elastic pressure sensor materials, absorbents and beyond.
Highly compressible 3D graphene/carbon nanotube foams were prepared by a facile self-assembly process which possess great potential as elastic pressure sensor materials, absorbents and beyond.
Stretchable strain sensors, as crucial components in wearable intelligent devices, have become one of the recent research hotspots with promising potential in human-interactive, personal health ...monitoring, and flexible smartphones. Graphene-based materials have been reported for high-performance strain sensors. However, there still remain some limitations such as their high production cost and low sensitivity and stretchability. Herein, a highly stretchable and ultra-sensitive strain sensor based on nickel nanoparticles and a graphene-coated polyurethane sponge (Ni@GPUS) ternary hybrid material has been reported. Herein, Ni@GPUS was fabricated
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a series of techniques including preparation of a graphene-coated polyurethane sponge, electrodeposition of nickel nanoparticles, and encapsulation by polydimethylsiloxane. The obtained sensors can be stretched up to 65% and exhibit a remarkable gauge factor of up to 3360.09. Furthermore, a fast signal response (<100 ms) and 1000 cycles of stretching and bending prove the rapid steady state response and long-term durability of the sensor, respectively. In addition, the working mechanisms of the sensor have been proposed. Moreover, the strain sensor was used as a bodily motion sensor to monitor finger bending and facial muscle tension, showing great potential in the fields of flexible, stretchable, and wearable electronics.
A highly stretchable and ultra-sensitive strain sensor based on a nickel nanoparticle-coated graphene polyurethane sponge (Ni@GPUS) ternary hybrid material was fabricated.
