Abstract
Fibers that harvest mechanical energy via the triboelectric effect are excellent candidates as power sources for wearable electronics and functional textiles. Thus far however, their ...fabrication remains complex, and exhibited performances are below the state-of-the-art of 2D planar configurations, making them impractical. Here, we demonstrate the scalable fabrication of micro-structured stretchable triboelectric fibers with efficiencies on par with planar systems. We use the thermal drawing process to fabricate advanced elastomer fibers that combine a micro-textured surface with the integration of several liquid metal electrodes. Such fibers exhibit high electrical outputs regardless of repeated large deformations, and can sustain strains up to 560%. They can also be woven into deformable machine-washable textiles with high electrical outputs up to 490 V, 175 nC. In addition to energy harvesting, we demonstrate self-powered breathing monitoring and gesture sensing capabilities, making this triboelectric fiber platform an exciting avenue for multi-functional wearable systems and smart textiles.
The ability to integrate complex electronic and optoelectronic functionalities within soft and thin fibers is one of today's key advanced manufacturing challenges. Multifunctional and connected fiber ...devices will be at the heart of the development of smart textiles and wearable devices. These devices also offer novel opportunities for surgical probes and tools, robotics and prostheses, communication systems, and portable energy harvesters. Among the various fiber‐processing methods, the preform‐to‐fiber thermal drawing technique is a very promising process that is used to fabricate multimaterial fibers with complex architectures at micro‐ and nanoscale feature sizes. Recently, a series of scientific and technological breakthroughs have significantly advanced the field of multimaterial fibers, allowing a wider range of functionalities, better performance, and novel applications. Here, these breakthroughs, in the fundamental understanding of the fluid dynamics, rheology, and tailoring of materials microstructures at play in the thermal drawing process, are presented and critically discussed. The impact of these advances on the research landscape in this field and how they offer significant new opportunities for this rapidly growing scientific and technological platform are also discussed.
The preform‐to‐fiber thermal‐drawing technique is emerging as a versatile platform to fabricate advanced electronic and optoelectronic fibers and textiles in a simple and scalable way. Recent breakthroughs in fundamental and applied research along with future perspectives are critically discussed. Potential applications in a variety of technological fields including sensing, energy harvesting, robotics, smart textiles, and bioengineering are highlighted.
Due to the two-dimensional character of graphene, the plasmons sustained by this material have been invariably studied in supported samples so far. The substrate provides stability for graphene but ...often causes undesired interactions (such as dielectric losses, phonon hybridization, and impurity scattering) that compromise the quality and limit the intrinsic flexibility of graphene plasmons. Here, we demonstrate the visualization of plasmons in suspended graphene at room temperature, exhibiting high-quality factor Q~33 and long propagation length > 3 μm. We introduce the graphene suspension height as an effective plasmonic tuning knob that enables in situ change of the dielectric environment and substantially modulates the plasmon wavelength, propagation length, and group velocity. Such active control of micrometer plasmon propagation facilitates near-unity-order modulation of nanoscale energy flow that serves as a plasmonic switch with an on-off ratio above 14. The suspended graphene plasmons possess long propagation length, high tunability, and controllable energy transmission simultaneously, opening up broad horizons for application in nano-photonic devices.
The effect of bilayer structure on high-k and low loss in graphene/polyvinylidene fluoride (GR/PVDF) composites, and the bilayer structured composites consist of negative-k and positive-k layers.
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•Synergistic effect of negative and positive-k leads to a good dielectric property.•The permittivity 559 and tanδ 0.053 were observed in bilayer structure composites.•Negative-k response can be obtained and tailored in the resulting composites.
Polymer matrix composites (PMCs) with high-k and low loss (tanδ) have aroused extensive research due to their significant applications in energy-storage capacitors and novel printed circuit board. In this work, the single layer structured graphene/polyvinylidene fluoride (GR/PVDF) composites were synthesized by hot pressing process, in which the fascinating permittivity transition from positive to negative was attributed to plasma oscillation. Meanwhile, the alternating current conductivity (σac) and reactance behavior were well consistent with Jonscher’s power law and equivalent circuit model. More importantly, the GR/PVDF composites consisted of negative-k layer that led to high-k and low tanδ performances. When the GR content of the negative-k layer was 10 wt% and positive-k layer was 2 wt%, the permittivity reached up to 559 and tanδ was just 0.053 at 100 kHz in bilayer structured composite, respectively. Theoretically, the high-k performance originated from strong interfacial polarization between positive-k and negative-k layers, which is beneficial to the synergistic effect of capacitive and inductive characters. Additionally, the low tanδ was attributed to the effectiveness restriction of electron transfer in capacitive layer. Therefore, the multilayer structured GR/PVDF composites by introducing negative-k layer can achieve high-k and low loss that supply a novel strategy for preparing dielectric materials.
Electronic and photonic fiber devices that can sustain large elastic deformation are becoming key components in a variety of fields ranging from healthcare to robotics and wearable devices. The ...fabrication of highly elastic and functional fibers remains however challenging, which is limiting their technological developments. Simple and scalable fiber‐processing techniques to continuously codraw different materials within a polymeric structure constitute an ideal platform to realize functional fibers and devices. Despite decades of research however, elastomeric materials with the proper rheological attributes for multimaterial fiber processing cannot be identified. Here, the thermal drawing of hundreds‐of‐meters long multimaterial optical and electronic fibers and devices that can sustain up to 500% elastic deformation is demonstrated. From a rheological and microstructure analysis, thermoplastic elastomers that can be thermally drawn at high viscosities (above 103 Pa s), allowing the encapsulation of a variety of microstructured, soft, and rigid materials are identified. Using this scalable approach, fiber devices combining high performance, extreme elasticity, and unprecedented functionalities, allowing novel applications in smart textiles, robotics, or medical implants, are demonstrated.
Superelastic multimaterial electronic and photonic fibers are fabricated via thermal drawing. Thermoplastic elastomers with the proper rheological properties to be codrawn with a variety of functional materials, including liquid metals and nanocomposites, are identified. This provides a novel approach for the scalable fabrication of advanced stretchable electronic and photonic devices with unprecedented functionalities.
The recent ability to integrate semiconductor‐based optoelectronic functionalities within thin fibers is opening intriguing opportunities for flexible electronics and advanced textiles. The scalable ...integration of high‐quality semiconducting devices within functional fibers however remains a challenge. It is difficult with current strategies to combine high light absorption, good microstructure and efficient electrical contact. The growth of semiconducting nanowires is a great tool to control crystal orientation and ensure a combination of light absorption and charge extraction for efficient photodetection. Thus far, however, leveraging the attributes of nanowires has remained seemingly incompatible with fiber materials, geometry, and processing approaches. Here, the integration of semiconducting nanowire‐based devices at the tip and along the length of polymer fibers is demonstrated for the first time. The scalable thermal drawing process is combined with a simple sonochemical treatment to grow nanowires out of electrically addressed amorphous selenium domains. First principles density‐functional theory calculations show that this approach enables to tailor the surface energy of crystal facets and favors nanowire growth along a preferred orientation, resulting in fiber‐integrated devices of unprecedented performance. This novel platform is exploited to demonstrate an all‐fiber‐integrated fluorescence imaging system, highlighting novel opportunities in sensing, advanced optical probes, and smart textiles.
High‐quality monocrystalline semiconducting nanowire‐based optoelectronic devices, for the first time, are integrated into the tip of a polymer optical fiber and along the fiber length. The fiber‐integrated devices, fabricated via a combination of simple and scalable approaches, exhibit unprecedented optoelectronic properties. The opportunities of this approach in advanced fibers and textiles are highlighted via an all‐fiber‐integrated fluorescence imaging system.
Flexible pressure sensors offer a wide application range in health monitoring and human–machine interaction. However, their implementation in functional textiles and wearable electronics is limited ...because existing devices are usually small, 0D elements, and pressure localization is only achieved through arrays of numerous sensors. Fiber‐based solutions are easier to integrate and electrically address, yet still suffer from limited performance and functionality. An asymmetric cross‐sectional design of compressible multimaterial fibers is demonstrated for the detection, quantification, and localization of kPa‐scale pressures over m2‐size surfaces. The scalable thermal drawing technique is employed to coprocess polymer composite electrodes within a soft thermoplastic elastomer support into long fibers with customizable architectures. Thanks to advanced mechanical analysis, the fiber microstructure can be tailored to respond in a predictable and reversible fashion to different pressure ranges and locations. The functionalization of large, flexible surfaces with the 1D sensors is demonstrated by measuring pressures on a gymnastic mat for the monitoring of body position, posture, and motion.
Compressible and conducting fibers for the measurement of kPa‐scale pressures over m2‐size surfaces are demonstrated. Pressure quantification and localization on the thermally drawn fibers are achieved through the selective and reversible contacting of composite electrodes within a thermoplastic elastomer support at distinct pressure levels. By functionalizing surfaces with the fibers, pressures are assessed for body position, posture, and motion monitoring.
Food engineering faces the difficult challenge of combining taste, i.e., tailoring texture and rheology of food matrices with the balanced intake of healthy nutrients. In materials science, fiber ...suspensions and composites have been developed as a versatile and successful approach to tailor rheology while imparting materials with added functionalities. Structures based on such types of physical (micro)fibers are however rare in food production mainly due to a lack of food‐grade materials and processes allowing for the fabrication of fibers with controlled sizes and microstructures. Here, the controlled fabrication of multi‐material microstructured edible fibers is demonstrated using a food compatible process based on preform‐to‐fiber thermal drawing. It is shown that different material systems based on gelatin or casein, with plasticizers such as glycerol, can be thermally drawn into fibers with various geometries and cross‐sectional structures. It is demonstrated that fibers can exhibit tailored mechanical properties post‐drawing, and can encapsulate nutrients to control their release. The versatility of fiber materials is also exploited to demonstrate the fabrication of food‐grade fabrics and scaffolds for food growth. The end results establish a new field in food production that relies on fiber‐based simple and eco‐friendly processes to realize enjoyable yet healthy and nutritious products.
A novel platform for the production of food is proposed, based on the thermal drawing of microstructured food‐grade polymer fibers. Fibers with different surface textures and microchannels are demonstrated, embedding nutrients that can be released during digestion. The fibers can be used in suspension or embedded within textile‐like constructs for innovative food processing approaches.
Purpose/significance Quality assurance is one of the most important procedures in web archiving, it runs throughout the whole web archiving work and affects the success odds of web archiving work. ...Method/process In this article, we made an analysis and comparative study for the quality assurance strategies of domestic and foreign web archiving organizations, and proposed a strategic theoretical framework for data quality assurance. Result/conclusion The framework in this article is a data-centered design, it includes a series of criteria and operating specifications, carries out data quality inspection throughout the collecting procedure by using semi-automatic auxiliary tools. Meanwhile, to ensure access to high quality archive data, the framework also takes team building, running environment maintenance and authorized backup to the websites as supplementary means.
Stretchable and conductive nanocomposites are emerging as important constituents of soft mechanical sensors for health monitoring, human–machine interactions, and soft robotics. However, tuning the ...materials’ properties and sensor structures to the targeted mode and range of mechanical stimulation is limited by current fabrication approaches, particularly in scalable polymer melt techniques. Here, thermoplastic elastomer‐based nanocomposites are engineered and novel rheological requirements are proposed for their compatibility with fiber processing technologies, yielding meters‐long, soft, and highly versatile stretchable fiber devices. Based on microstructural changes in the nanofiller arrangement, the resistivity of the nanocomposite is tailored in its final device architecture across an entire order of magnitude as well as its sensitivity to strain via tuning thermal drawing processing parameters alone. Moreover, the prescribed electrical properties are coupled with suitable device designs and several fiber‐based sensors are proposed aimed at specific types of deformations: i) a robotic fiber with an integrated bending mechanism where changes as small as 5° are monitored by piezoresistive nanocomposite elements, ii) a pressure‐sensing fiber based on a geometrically controlled resistive signal that responds with a sub‐newton resolution to changes in pressing forces, and iii) a strain‐sensing fiber that tracks changes in capacitance up to 100% elongation.
Thermoplastic elastomer‐based nanocomposites, with specifically engineered rheological, mechanical, and electrical characteristics, enable multimodal mechanical sensing in thermally drawn fibers. Taking advantage of the materials’ properties and the design freedom of the thermal drawing process, the fiber‐based strain sensors can be tailored toward specific modes of deformation as well as integrate additional functionalities, such as actuation and light delivery.
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