Stretchable electronics are attracting intensive attention due to their promising applications in many areas where electronic devices undergo large deformation and/or form intimate contact with ...curvilinear surfaces. On the other hand, a plethora of nanomaterials with outstanding properties have emerged over the past decades. The understanding of nanoscale phenomena, materials, and devices has progressed to a point where substantial strides in nanomaterial‐enabled applications become realistic. This review summarizes recent advances in one such application, nanomaterial‐enabled stretchable conductors (one of the most important components for stretchable electronics) and related stretchable devices (e.g., capacitive sensors, supercapacitors and electroactive polymer actuators), over the past five years. Focusing on bottom‐up synthesized carbon nanomaterials (e.g., carbon nanotubes and graphene) and metal nanomaterials (e.g., metal nanowires and nanoparticles), this review provides fundamental insights into the strategies for developing nanomaterial‐enabled highly conductive and stretchable conductors. Finally, some of the challenges and important directions in the area of nanomaterial‐enabled stretchable conductors and devices are discussed.
Recent progress with regard to nanomaterial‐enabled stretchable conductors and related stretchable devices is reviewed (e.g., capacitive sensors, supercapacitors and electroactive polymer actuators). Focusing on carbon nanomaterials (e.g., carbon nanotubes and graphene) and metal nanomaterials (e.g., metal nanowires and nanoparticles), this review provides fundamental insights into the strategies for developing nanomaterial‐enabled highly conductive and stretchable conductors.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop ...highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ∼1.2 MPa) and finger touch with high sensitivity, fast response time (∼40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels.
Highly sensitive wearable sensors that can be conformably attached to human skin or integrated with textiles to monitor the physiological parameters of human body or the surrounding environment have ...garnered tremendous interest. Owing to the large surface area and outstanding material properties, nanomaterials are promising building blocks for wearable sensors. Recent advances in the nanomaterial‐enabled wearable sensors including temperature, electrophysiological, strain, tactile, electrochemical, and environmental sensors are presented in this review. Integration of multiple sensors for multimodal sensing and integration with other components into wearable systems are summarized. Representative applications of nanomaterial‐enabled wearable sensors for healthcare, including continuous health monitoring, daily and sports activity tracking, and multifunctional electronic skin are highlighted. Finally, challenges, opportunities, and future perspectives in the field of nanomaterial‐enabled wearable sensors are discussed.
The development of nanomaterial‐enabled wearable sensors, including temperature, electrophysiological, strain, tactile, and electrochemical sensors is summarized in this review including challenges and opportunities. The integration of multiple sensors and components into wearable systems is also reviewed. The applications of wearable sensors in health monitoring, activity tracking, and electronic skin are presented.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Long-term, continuous, and unsupervised tracking of physiological data is becoming increasingly attractive for health/wellness monitoring and ailment treatment. Nanomaterials have recently attracted ...extensive attention as building blocks for flexible/stretchable conductors and are thus promising candidates for electrophysiological electrodes. Here we provide a review on nanomaterial-enabled dry electrodes for electrophysiological sensing, focusing on electrocardiography (ECG). The dry electrodes can be classified into contact surface electrodes, contact-penetrating electrodes, and noncontact capacitive electrodes. Different types of electrodes including their corresponding equivalent electrode–skin interface models and the sources of the noise are first introduced, followed by a review on recent developments of dry ECG electrodes based on various nanomaterials, including metallic nanowires, metallic nanoparticles, carbon nanotubes, and graphene. Their fabrication processes and performances in terms of electrode–skin impedance, signal-to-noise ratio, resistance to motion artifacts, skin compatibility, and long-term stability are discussed.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
Lithium‐sulfur (Li‐S) battery based on sulfur cathodes is of great interest because of high capacity and abundant sulfur source. But the shuttling effect of polysulfides caused by ...charge‐discharge process results in low sulfur utilization and poor reversibility. Here, we demonstrate a good approach to improve the utility of sulfur and cycle life by synthesizing carbon nanofibers decorated with MoO2 nanoparticles (MoO2‐CNFs membrane), which plays a role of multiinterlayer inserting between the separator and the cathode for Li‐S battery. The S/MoO2‐CNFs/Li battery showed a discharge capacity of 6.93 mAh cm−2 (1366 mAh g−1) in the first cycle at a current density of 0.42 mA cm−2 and 1006 mAh g−1 over 150 cycles. Moreover, even at the highest current density (8.4 mA cm−2), the battery achieved 865 mAh g−1. The stable electrochemical behaviors of the battery has achieved because of the mesoporous and interconnecting structure of MoO2‐CNFs, proving high effect for ion transfer and electron conductive. Furthermore, this MoO2‐CNFs interlayer could trap the polysulfides through strong polar surface interaction and increases the utilization of sulfur by confining the redox reaction to the cathode.
The molybdenum dioxide‐carbon nanofibers, inserting between the separator and the cathode, are synthesized by the electrospinning method and followed by subsequent thermal treatment, which is used as an interlayer of Lithium‐Sulfur batteries. The enhanced electrochemical performance can be ascribed to its network structure and high electrical conductivity, which facilitates electron‐ion transport and effectively suppresses the shuttle effect.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The transfer of synthesized 2D MoS2 films is important for fundamental and applied research. However, it is problematic to translate the well-established transfer processes for graphene to MoS2 due ...to different growth mechanisms and surface properties. Here we demonstrate a surface-energy-assisted process that can perfectly transfer centimeter-scale monolayer and few-layer MoS2 films from original growth substrates onto arbitrary substrates with no observable wrinkles, cracks, and polymer residues. The unique strategies used in this process include leveraging the penetration of water between hydrophobic MoS2 films and hydrophilic growth substrates to lift off the films and dry transferring the film after the lift off. This is in stark contrast with the previous transfer process for synthesized MoS2 films, which explores the etching of the growth substrate by hot base solutions to lift off the films. Our transfer process can effectively eliminate the mechanical force caused by bubble generations, the attacks from chemical etchants, and the capillary force induced when transferring the film outside solutions as in the previous transfer process, which consists of the major causes for the previous unsatisfactory transfer. Our transfer process also benefits from using polystyrene (PS), instead of poly(methyl methacrylate) (PMMA) that was widely used previously, as the carrier polymer. PS can form more intimate interaction with MoS2 films than PMMA and is important for maintaining the integrity of the film during the transfer process. This surface-energy-assisted approach can be generally applied to the transfer of other 2D materials, such as WS2.
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IJS, KILJ, NUK, PNG, UL, UM
Lithium-sulfur (Li-S) batteries have attracted many attentions due to their high energy density and low-cost. However, the insulation and volume change of sulfur and high solubility of polysulfides ...lead to the fast decay of capacity and short cycle life. In order to solve these issues, we synthesized a novel multifunctional TiO2@C composite nanofibers (TiO2@C CNs) interlayer by electrospinning technique and subsequent heat treatment. It can significantly improve the specific capacity and long cycling stability of Li-S batteries, attributed to the effective restriction of “shuttle effect” and high reutilization of trapped active materials. Using TiO2@C CNs as a multifunctional interlayer, the BP2000/sulfur cathode with a high sulfur content (70 wt %) shows an initial capacity of 852 mAh g−1 at a high current rate of 4C and cycled over 2000 cycles with a fade rate of only 0.028% per cycle. The combination of metal oxides and carbon materials is facile and feasible way to archive high performance Li-S batteries.
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•The TiO2@C CNs was fabricated by electrospinning technique.•The mesoporous structure of TiO2@C CNs was used as the interlayer in Li-S cell.•TiO2@C CNs acts as polysulfide reservoirs to alleviate the shuttle effect.•TiO2@C CNs accelerates the electrochemical reaction kinetic during cycle process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The image outpainting based on deep learning shows good performance and has a wide range of applications in many fields. The previous image outpainting methods mostly used a single image as input. In ...this paper, we use the left and right images as input images, and expand the unknown region in the middle to generate an image that connects the left and right images to form a complete semantically smooth image. A cascaded refinement residual attention model for image outpainting is proposed. The Residual Channel-Spatial Attention (RCSA) module is designed to effectively learn image information about known regions. The Cascaded Dilated-conv (CDC) module is used to capture deep features, and more semantic information is obtained through dilated convolutions of different rates. The Refine on Features Aggregation (RFA) module connects the encoder and decoder to refine the result image for generating it clearer and smoother. Experimental results show that the proposed model is able to hallucinate more meaningful structures and vivid textures and achieve satisfactory results.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Deficits in hand function are common in a majority of stroke survivors. Although hand performance can be routinely assessed during rehabilitation training, a lack of hand usage information during ...daily activities could prevent clinicians or therapists from making informative therapeutic decisions. In this paper, we demonstrated and validated the application of silver nanowire-based capacitive strain sensors for finger kinematic tracking. The fabricated strain sensors show high sensitivity (gauge factor close to one), low hysteresis, good linearity, large stretchability (150%), and skin-like mechanical property (Young's modulus of 96 kPa). All these features allow the sensors to be conformally attached onto the skin to track finger joint movement with minimal interference to daily activities. Recordings of the skin deformation from the strain sensors and joint angles from reflective markers are highly correlated (>93%) for different joint oscillation speeds in a stroke survivor and a control subject, indicating the high accuracy of the strain sensors in joint motion tracking. With the wearable silver nanowire-based strain sensors, accurate hand utility information on the impaired hand of stroke survivors can be acquired in a continuous and unobtrusive manner.
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