Silver nanowire (AgNW) films have been studied as the most promising flexible transparent electrodes for flexible photoelectronics. The wire–wire junction resistance in the AgNW film is a critical ...parameter to the electrical performance, and several techniques of nanowelding or soldering have been reported to reduce the wire–wire junction resistance. However, these methods require either specific facilities, or additional materials as the “solder”, and often have adverse effects to the AgNW film or substrate. In this study, we show that at the nanoscale, capillary force is a powerful driving force that can effectively cause self-limited cold welding of the wire–wire junction for AgNWs. The capillary-force-induced welding can be simply achieved by applying moisture on the AgNW film, without any technical support like the addition of materials or the use of specific facilities. The moisture-treated AgNW films exhibit a significant decrease in sheet resistance, but negligible changes in transparency. We have also demonstrated that this method is effective to heal damaged AgNW films of wearable electronics and can be conveniently performed not only indoors but also outdoors where technical support is often unavailable. The capillary-force-based method may also be useful in the welding of other metal NWs, the fabrication of nanostructures, and smart assemblies for versatile flexible optoelectronic applications.
Phase measuring deflectometry (PMD) stands as an extremely important technique for specular surface measurement. However, the parasitic reflection from the rear surface poses a challenge for PMD. To ...solve this problem, this paper proposes an effective method based on multi-frequency and phase-shifting to search for the correct phase. Firstly, the relationship between the phase error and fringe frequency is adequately investigated. Subsequently, an auxiliary function is established to find the special frequency at which the phase error is zero theoretically and the unwrapped phase is the phase of the top surface exactly. Then, the shape of the top surface can be reconstructed correctly. A standard plane element with a thickness of 40 mm and a flat glass with 19 mm were measured. The experimental results verify the feasibility of the proposed method. Considering the result of the interferometer as a reference, the RMSE of the error map is up to 20 nm for the standard plane element. The experimental results demonstrate that the proposed method can successfully untangle the superposed reflections and reliably reconstruct the top surface of the object under test.
Flexible pressure sensors are essential components for soft electronics by providing physiological monitoring capability for wearables and tactile perceptions for soft robotics. Flexible pressure ...sensors with reliable performance are highly desired yet challenging to construct to meet the requirements of practical applications in daily activities and even harsh environments, such as high temperatures. This work describes a highly sensitive and reliable capacitive pressure sensor based on flexible ceramic nanofibrous networks with high structural elasticity, which minimizes performance degradation commonly seen in polymer‐based sensors because of the viscoelastic behavior of polymers. Such ceramic pressure sensors exhibit high sensitivity (≈4.4 kPa−1), ultralow limit of detection (<0.8 Pa), fast response speed (<16 ms) as well as low fatigue over 50 000 loading/unloading cycles. The high stability is attributed to the excellent mechanical stability of the ceramic nanofibrous network. By employing textile‐based electrodes, a fully breathable and wearable ceramic pressure sensor is demonstrated for real‐time health monitoring and motion detection. Owing to the high‐temperature resistance of ceramics, the ceramic nanofibrous network sensor can function properly at temperatures up to 370 °C, showing great promise for harsh environment applications.
A highly sensitive and reliable pressure sensor based on flexible ceramic nanofibrous networks is designed in an extra lightweight, compliant, and breathable form, which is demonstrated to be suitable for continuous health monitoring and motion detection during long‐term wearing. Moreover, the sensor can function properly under high temperatures, showing great promise for applications under extreme conditions.
In this paper, a nanocomposite electrodeposition method is proposed to prepare hydrophobic surfaces. After further surface modification of a layer of FAS-17,11(heptadecafluorodecyl)-trimethoxysilane, ...CF3(CF2)7CH2CH2Si(OCH3)3. superhydrophobic surfaces were obtained. The electrodeposited composite coatings exhibited thorn-like hierarchical structures with high roughness. Moreover, this binary geometric morphology could be controlled by adjusting current density and electrodeposition time, resulting in a contact angle (CA) as high as 174.9°. Importantly, this method can be easily extended to other materials as long as they are electrically conductive. Since this approach is quite time-saving and cost-effective, it is supposed to have a promising future in industrial fields.
► Ni–TiO2 nanocomposite coatings with FAS-17 show superhydrophobicity. ► Coatings exhibit thorn-like hierarchical structures with high roughness. ► TiO2 nanoparticles confine the growth of nickel grains. ► High current density leads to rough morphology and large contact angle. ► Long deposition time leads to hierarchical structures with high contact angle.
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► BaTiO3 nanofibers were fabricated by a facile electrospinning method. ► The BaTiO3 nanofibers calcined at temperatures below 650°C are amorphous. ► Intense visible photoluminescence ...was detected in amorphous BaTiO3 nanofibers. ► PL performance exhibited a strong dependence on the calcination temperature. ► Highly disordered structure may be responsible for the intense photoluminescence.
Broad visible emission at the wavelength range of 400–800nm was obtained at room temperature in amorphous barium titanate (BaTiO3) nanofibers, which were prepared by electrospinning and calcined at low temperatures. Structure and morphology of the BaTiO3 nanofibers were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), thermo-analysis and Raman spectroscopy. XRD data shows that the BaTiO3 nanofibers calcined at temperatures below 650°C are amorphous, in which intense photoluminescence (PL) emission bands at 600nm have been detected. More importantly, PL performance of the BaTiO3 nanofibers exhibited a strong dependence on the calcination temperature. Observable emission was only found in the low-temperature treated fibers. Mechanism of the observed photoluminescence has been discussed. The achievements shown herein may be help to find new light-emitting materials.
Flexible electronics, as an emerging and exciting research field, have brought great interest to the issue of how to make flexible electronic materials that offer both durability and high performance ...at strained states. With the advent of on‐body wearable and implantable electronics, as well as increasing demands for human‐friendly intelligent soft robots, enormous effort is being expended on highly flexible functional materials, especially stretchable electrodes, by both the academic and industrial communities. Among different deformation modes, stretchability is the most demanding and challenging. This review focuses on the latest advances in stretchable transparent electrodes based on a new design strategy known as kirigami (the art of paper cutting) and investigates the recent progress on novel applications, including skin‐like electronics, implantable biodegradable devices, and bioinspired soft robotics. By comparing the optoelectrical and mechanical properties of different electrode materials, some of the most important outcomes with comments on their merits and demerits are raised. Key design considerations in terms of geometries, substrates, and adhesion are also discussed, offering insights into the universal strategies for engineering stretchable electrodes regardless of the material. It is suggested that highly stretchable and biocompatible electrodes will greatly boost the development of next‐generation intelligent life‐like electronics.
Latest advances in stretchable transparent electrodes based on a new design strategy known as kirigami (the art of paper cutting) and their novel applications in skin‐like electronics, implantable biodegradable devices, and bioinspired soft robotics are comprehensively reviewed. Key design considerations in terms of geometries, substrates, and adhesion are discussed, offering insights into the universal strategies for engineering stretchable electrodes.
Dendritic silver nanostructured surface has been prepared on copper substrate by a simple replacement reaction. It was observed that morphology of the silver surface became much rough with reaction ...time, from initial nanosized clusters to nanostructured dendrites. The silver surface modified with dodecanethiol showed great superhydrophobicity. It was also found that the dendritic silver nanostructured surface demonstrated highly sensitive surface enhanced Raman scattering (SERS) character. It is expected that the dendritic silver surface may be applied as molecular probe and biological sensing.
Abstract Adaptive photonic films in response to external stimuli have broad applications in optical communications, sensing, and anticounterfeiting. Yet, it remains challenging to develop photonic ...structures with tailorable fine patterns that display broadband color changing under ambient conditions. Here a hydrogen‐bonded supramolecular cholesteric liquid crystalline polymer (CLCP) that is mediated by a binary solvent consisting of citric acid (CA) and water is presented. The incorporation of CA not only improves the long‐range order of CLCPs through evaporation‐induced self‐assembly but is also capable of tuning their helical pitch across the entire visible spectrum. The extent of hydration‐induced pitch expansion can be further manipulated by thermal crosslinking, enabling a unique patterning strategy based on mask‐free, programmable laser inscription. High‐precision photonic patterns are created onto CLCPs, which reveal themselves upon hydration in high visual contrast. The study offers a feasible and up‐scaling route toward tailoring environmentally adaptive CLCPs with tunable broadband coloration and highly programmable photonic patterns.
Natural materials are adaptive with intriguing mechanical properties such as strain‐stiffening, high damping, and stimuli‐responsive actuation under ambient conditions, which are evolutionarily ...derived to adapt to variable environments. Such adaptabilities are highly desirable for advanced smart materials in soft robots and bionic applications yet rarely achieved all in one synthetic material. Inspired by the molecular chemistry and structure of spider silk, a structurally heterogeneous supramolecular network with all‐round adaptabilities is developed by evaporation‐induced self‐assembly of hydrogen‐bonded macromolecules. The supramolecular network consists of both hard (crystallites) and soft (amorphous) phases with dynamic hydrogen bonds, exhibiting strong strain, time, and hydration dependency with adaptive mechanical and structural responses to varying strain, deformation rate as well as moisture. Through multifunctional crosslinking, the network exhibits silk‐like attributes with an extensibility of >130%, intense strain‐stiffening (sixfold modulus enhancement), high damping capacity (>80%) over a wide range of strain rate, and moisture‐triggered large supercontraction (contraction ratio of >50%). Artificial materials with such combined adaptiveness under bio‐benign conditions are promising for applications in biomimetic and biomedical fields.
A novel bioinspired synthetic strategy for constructing heterogeneous supramolecular networks from one macromolecule is developed, providing a neat solution to designing advanced smart materials with diverse mechanical and structural adaptability. The self‐assembled network exhibits spider‐silk‐like all‐round adaptability with strain‐stiffening, high damping, and supercontraction capabilities under bio‐benign conditions, offering unique advantages for emerging bionic soft robotics and biomedical applications.
Nature has long offered human beings with useful materials. Herein, plant materials including flowers and leaves have been directly used as the dielectric material in flexible capacitive electronic ...skin (e‐skin), which simply consists of a dried flower petal or leaf sandwiched by two flexible electrodes. The plant material is a 3D cell wall network which plays like a compressible metamaterial that elastically collapses upon pressing plus some specific surface structures, and thus the device can sensitively respond to pressure. The device works over a broad‐pressure range from 0.6 Pa to 115 kPa with a maximum sensitivity of 1.54 kPa−1, and shows high stability over 5000 cyclic pressings or bends. The natural‐material‐based e‐skin has been applied in touch sensing, motion monitoring, gas flow detection, and the spatial distribution of pressure. As the foam‐like structure is ubiquitous in plants, a general strategy for a green, cost‐effective, and scalable approach to make flexible e‐skins is offered here.
Natural plant materialsare directly used as dielectrics in flexible capacitive electronic skin (e‐skin). The fabricated e‐skin exhibits high sensitivity of up to 1.54 kPa−1, broad‐pressure sensing (0.6 Pa–115 kPa), and high stability over 5000 cyclic pressings or bends. The natural e‐skins are potentially useful in motion detection, spatial pressure identification, and artificial intelligence.
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