Printed electronics on elastomer substrates have found wide applications in wearable devices and soft robotics. For everyday usage, additional requirements exist for the robustness of the printed ...flexible electrodes, such as the ability to resist scratching and damage. Therefore, highly robust electrodes with self‐healing, and good mechanical strength and stretchability are highly required and challenging. In this paper, a cross‐linking polyurea using polydimethylsiloxane as the soft segment and dynamic urea bonds is prepared and serves as a self‐healing elastomer substrate for coating and printing of silver nanowires (AgNWs). Due to the dynamic exchangeable urea bond at 60 °C, the elastomer exhibits dynamic exchange of the cross‐linking network while retaining the macroscopic shape. As a result, the AgNWs are partially embedded in the surface of the elastomer substrate when coated or printed at 60 °C, forming strong interfacial adhesion. As a result, the obtained stretchable electrode exhibits high mechanical strength and stretchability, the ability to resist scratching and sonication, and self‐healing. This strategy can be applied to a variety of different conducting electrode materials including AgNWs, silver particles, and liquid metal, which provides a new way to prepare robust and self‐healing printed electronics.
A concept involving preparing stretchable, robust, and self‐healing electrodes via a direct surface printing on a polyurea elastomer is developed in this work. Taking advantage of the dynamic polyurea's kinetic chain movement at an elevated temperature, variable conductive nano‐fillers can be self‐embedded into the elastomer's surface without shape changing, exhibiting high significance in designing both robust and self‐healing electrodes.
As a critical part of flexible electronics, flexible circuits inevitably work in a dynamic state, which causes electrical deterioration of brittle conductive materials (i.e., Cu, Ag, ITO). Recently, ...gallium‐based liquid metal particles (LMPs) with electrical stability and self‐repairing have been studied to replace brittle materials owing to their low modulus and excellent conductivity. However, LMP‐coated Ga2O3 needs to activate by external sintering, which makes it more complicated to fabricate and gives it a larger short‐circuit risk. Core–shell structural particles (Ag@LMPs) that exhibit excellent initial conductivity(8.0 Ω sq−1) without extra sintering are successfully prepared by coating nanosilver on the surface of LMPs through in situ chemical reduction. The critical stress at which rigid Ag shells rupture can be controlled by adjusting the Ag shell thickness so that LM cores with low moduli can release, achieving real‐time self‐repairing (within 200 ms) under external destruction. Furthermore, a flexible circuit utilizing Ag@LMPs is fabricated by screen printing, and exhibits outstanding stability and durability (R/R0 < 1.65 after 10 000 bending cycles in a radius of 0.5 mm) because of the functional core–shell structure. The self‐repairable Ag@LMPs prepared in this study are a candidate filler for flexible circuit design through multiple processing methods.
A novel core–shell conductive particle based on liquid metal (Ag@LMPs) is developed. This particle exhibits excellent conductivity without external sintering, while simultaneously exhibiting long‐term durability and real‐time self‐repairing in flexible circuits owing to the release of the liquid metal core. These Ag@LMPs are a candidate filler for self‐repairing flexible circuit design.
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•Pruney fingers-inspired highly stretchable and conductive fibers are developed.•Robust and isotropic wrinkles are constructed on fiber surfaces in a scalable strategy.•Robust ...interfaces between core-sheath are developed via an in-situ polymerization.•Isotropic surface wrinkles are conducive for high sensitivities in piezoresistive fibers.•Smart gloves fabricated by the piezoresistive fibers have a good application prospect.
Scalable construction of robust and isotropic wrinkles on fiber surface is crucial for the development of highly sensitive piezoresistive fibers, which still remains a challenge. Herein, inspired by the typical morphology and formation of pruney fingers, we develop a novel core–shell “pruney fiber” with both isotropic wrinkles and robust interfaces via a scalable and facile fabrication strategy. Briefly, the robust isotropic wrinkles are constructed through the core thermoplastic polyurethane (TPU) molecular chain’s constriction and the sheath pyrrole monomer’ synergistic interfacial polymerization. As a result, the robust interfaces enable the pruney fiber high stabilities under a remark stretchability (200%). Two as-prepared pruney fibers are overlapped vertically for piezoresistive sensing. Owe to the interlocking of the surface isotropic wrinkles, the piezoresistive fibers show high sensitivity (0.15 kPa−1), fast response time (47 ms), low detection limit (0.2 g), and high stability. For practical applications, the piezoresistive fibers can be easily weaved and integrated into a smart glove for wearable sensors and human–machine interfaces (HMI). At last, the novel structure and its unique scalable developing process would pave a new way in stable surface structure engineering on variable surface in the future.
Dual-network conductive hydrogels have drawn wide attention in epidemic electronics such as epidemic sensors and electrodes because of their inherent low Young’s modulus, high skin-compliance, and ...tunable mechanical strength. However, it is still full of challenges to gain a dual-network hydrogel with high stretchability, low hysteresis, and skin-adhesive performance simultaneously. Herein, to address this issue, a novel dual-network hydrogel (denoted as PAa hydrogel) with polyacrylamide as the first network and topologically entangled polydopamine as the secondary network was prepared through a facile gel-phase in situ self-polymerization and soaking treatment. Benefiting from the topological enhancement as well as the synergetic effects of hydrogen bonds and metal coordination bonds, low modulus (∼10 kPa), excellent stretchability (1090.8%), high compression (90%), negligible hysteresis (η = 0.019, energy loss coefficient), rapid recovery in seconds, and self-adhesion are obtained in the PAa hydrogels. To demonstrate their practical use, a states-independent and skin-adhesive epidemic sensor was successfully attached on human skin for motion detection. What is more, by using the hydrogel as an epidemic electrode, electromyogram signals were accurately detected and wirelessly transmitted to a smart phone. This work offers a new insight to understand the strengthening mechanism of dual network hydrogels and a design strategy for both epidemic sensors and electrodes.
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•Fibers with variable microstructure and module are fabricated by adjusting the diffusion coefficient.•The uniform-porous piezoresistive fibers exhibit a record high pressure ...sensitivity.•The high sensitivity is obtained by the synergic optimization of micropore and elastic modulus.•The piezoresistive fiber exhibits multifunctional sensing capabilities.
Although different kinds of microengineering have been developed in piezoresistive fibers recently, it is still challenging to achieve a high-pressure sensitivity in these fibers. This is because these microstructures can only geometrically increase the conducting paths under pressure. In this work, via the theoretical calculation and practical experiments, we firstly demonstrated that not only the conducting paths but also the fibers’ elastic moduli of compression exhibit key roles in improving the sensitivities in fibers. Typically, by adjusting the kinetic diffusion coefficient between the spinning dope and the coagulation solution in wet-spinning, various structured (solid, hollow, porous, and hollow-porous) thermoplastic polyurethane (TPU) fibers with variable elastic moduli of compression were developed in this work. As a result, the piezoresistive fiber with a uniform and through porous structure (porous in both the core and the surface) exhibited the highest sensitivity of 0.67 kPa−1 due to its synergic improvement in conducting paths and contact area (with a low elastic modulus of compression of 6.98 kPa) under pressure. To the best of our knowledge, it is the recorded highest sensitivity in the piezoresistive fibers. Beyond the pressure sensing, we also proved the as-prepared porous fibers with an ultra-high stretchability of 2110%, a high performance in strain sensing, and a good candidate in humidity and gas sensing. At last, we successfully applied the piezoresistive fibers in our daily life for wearable sensing, demonstrating its high potential in practical application.
Epidermal electrodes for long-term electrophysiological signals monitoring have great potentials in bioelectronics such as health monitoring, disease diagnosis, and human-machine interaction. ...However, it still remains challenges for epidermal electrodes with simultaneously high breathability, surface self-cleaning, and robust skin-adhesion, which may cause skin discomfort, loosing adhesion, and misleading signals during long-term using. In this work, based on the soft and wet-adhesive silk fibroin nanofibers membrane, we report a novel three-layer all-nanofiber-based polytetrafluoroethylene (PTFE)/silver nanowires (Ag NWs)/silk fibroin nanofibers membrane (Silk NFs) fabric electrode. This hierarchical porous structure endows the fabric with thinness (∼10 μm), high conductivity (∼3.58 Ω/sq), high breathability (51.5 mm/s, water vapor transmission rate (WVTR) = 2553 g m−2 d−1 at 35 °C), wet skin-adhesion (13 N/m on wet skin), and surface hydrophobicity (contact angle of 142.3°). As a result, it can be conformally attached to the skin with no skin irritation and prevent sweat accumulation and immersion. Furthermore, compared to the commercial Ag/AgCl gel electrodes, the as-prepared fabric electrode in this work provides a better skin-electrode interface, so that the obtained electrochemical signals in exercise have higher signal qualities with equivalent signal strength and lower signal noise. Therefore, this fabric electrode may further promote the development of epidermal electrode in real-time long-term use.
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The 2 D assembly of polymers to form free‐standing and large crystalline films is quite appealing but very challenging. Although there have been some works using interface templates, reports of in ...situ assembly in solution are still rare. Herein, a simple strategy is developed for the creation of a free‐standing and centimeter‐sized 2 D crystalline polymer film through crystallization of an amphiphilic brush polydiacetylene (PDA) in solution. The film exhibits good shape memory, a low dielectric constant, and good carrier mobility. This strategy may be applied extensively to produce a variety of other macroscopic 2 D crystalline polymer films for applications in electronics, catalysis, and so on.
Crystallizing polymers: An amphiphilic brush polydiacetylene is crystallized in solution, yielding a free‐standing and centimeter‐sized 2 D crystalline polymer film (see figure), which exhibits good flexibility, shape‐memory properties, an ultra‐low dielectric constant, and good carrier mobility.
The 2 D assembly of polymers to form free‐standing and large crystalline films is quite appealing but very challenging. Although there have been some works using interface templates, reports of in ...situ assembly in solution are still rare. Herein, a simple strategy is developed for the creation of a free‐standing and centimeter‐sized 2 D crystalline polymer film through crystallization of an amphiphilic brush polydiacetylene (PDA) in solution. The film exhibits good shape memory, a low dielectric constant, and good carrier mobility. This strategy may be applied extensively to produce a variety of other macroscopic 2 D crystalline polymer films for applications in electronics, catalysis, and so on.
In many 2D materials reported thus far, the forces confining atoms in a 2D plane are often strong interactions, such as covalent bonding. Herein, the first demonstration that hydrogen (H)‐bonding can ...be utilized to assemble polydiacetylene (a conductive polymer) toward a 2D material, which is stable enough to be free‐standing, is shown. The 2D material is well characterized by a large number of techniques (mainly different microscopy techniques). The H‐bonding allows splitting of the material into ribbons, which can reassemble, similar to a zipper, leading to the first example of a healable 2D material. Moreover, such technology can easily create 2D, organic, conductive nanowire arrays with sub‐2‐nm resolution. This material may have potential applications in stretchable electronics and nanowire cross‐bar arrays.
Hydrogen (H)‐bonding can be utilized to construct a free‐standing 2D material. The H‐bonding allows splitting of the material into ribbons, which can re‐assemble (self‐heal), similar to a zipper. Such a strategy can easily create 2D, organic, conductive nanowire arrays with sub‐2‐nm resolution. This material may have applications in stretchable electronics and cross‐bar arrays.
Pulmonary hydatid disease is a helminthic zoonotic disease caused by Echinococcus infection. The symptoms may appear several years after infection. Chest computed tomography (CT) is the preferred ...examination method and plays an important role in early diagnosis, treatment, and prognosis evaluation. CT can be used to diagnose simple cystic lesions. However, when the cysts are infected or ruptured, atypical imaging findings such as increased cyst density, blurring of the cyst wall, and surrounding exudation may lead to misdiagnosis of lung infection or lung abscess, hindering the therapeutic effect. We analyzed and compared the atypical imaging manifestations of pulmonary simple hydatid disease and hydatid cyst rupture. The aims of this report are to improve clinicians' understanding of these diseases, promote early diagnosis and treatment, and reduce the occurrence of complications.
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