Flexible fiber-shaped supercapacitors (FSSCs) are recently of extensive interest for portable and wearable electronic gadgets. Yet the lack of industrial-scale flexible fibers with high conductivity and capacitance and low cost greatly limits its practical engineering applications. To this end, we here present pristine twisted carbon fibers (CFs) coated with a thin metallic layer via electroless deposition route, which exhibits exceptional conductivity with ∼300% enhancement and superior mechanical strength (∼1.8 GPa). Subsequently, the commercially available conductive pen ink modified high conductive composite fibers, on which uniformly covered ultrathin nickel-cobalt double hydroxides (Ni-Co DHs) were introduced to fabricate flexible FSSCs. The synthesized functionalized hierarchical flexible fibers exhibit high specific capacitance up to 1.39 F·cm in KOH aqueous electrolyte. The asymmetric solid-state FSSCs show maximum specific capacitance of 28.67 mF·cm and energy density of 9.57 μWh·cm at corresponding power density as high as 492.17 μW·cm in PVA/KOH gel electrolyte, with demonstrated high flexibility during stretching, demonstrating their potential in flexible electronic devices and wearable energy systems.

Multifunctional skin-like sensors play an important role in next-generation healthcare, robotics, and bioelectronics. Here, we report a skin-like wearable optical sensor (SLWOS) enabled by a stretchable, flexible, and attachable patch...

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Multifunctional electronic skins (e-skins), which mimic the somatosensory system of human skin, have been widely employed in wearable devices for intelligent robotics, prosthetics, and human health monitoring. Relatively low sensitivity and severe mutual interferences of multiple stimuli detection have limited the applications of the existing e-skins. To address these challenges, inspired by the physical texture of the natural fingerprint, a novel fully elastomeric e-skin is developed herein for highly sensitive pressure and temperature sensing. A region-partition strategy is utilized to construct the multifunctional fingerprint-shaped sensing elements, where strain isolation structure of indurated film patterns are further embedded to enhance the sensitivity and effectively reduce mutual interferences between the differentiated units. The fully elastomeric graphene/silver/silicone rubber nanocomposites are synthesized with tunable properties including conductivity and sensitivity to satisfy the requirements of highly sensitive pressure and temperature sensing as well as stretchable electrodes. Remarkable progress in sensitivities for both pressure and temperature, up to 5.53 kPa–1 in a wide range of 0.5–120 kPa and 0.42% °C–1 in 25–60 °C, respectively, are achieved with the inappreciable mutual interferences. Further studies demonstrate the great potential of the proposed e-skin in the next-generation of wearable electronics for human–machine interfaces.

Layered molybdenum disulfide (MoS) exhibits rich electronic and optical properties and possesses vastly differing characteristic dimensions. A multi-layer MoS membrane represents the critical hierarchical structure which bridges the length-scale of monolayer and bulk material architectures. In this study, the in-plane mechanical properties of MoS membranes were investigated by in situ SEM tensile testing. Under the uniaxial tensile loading, brittle fracture caused failure in a highly localized region of the MoS membranes and their mechanical properties showed a thickness effect: the strengths of the relatively thicker MoS membranes (thickness around hundreds of nanometers) distribute from ∼100 to ∼250 MPa, while the corresponding values of the MoS nanosheets (thickness around tens of nanometers) increase significantly to more than 1 GPa. Upon molecular dynamics (MD) simulations on the fractures of MoS with various thicknesses/layers, the thicker MoS membranes show interplanar fracture, and the typical MoS nanosheets demonstrate the transition from interplanar to intraplanar fractures, while monolayer and few-layer MoS are dominated by intraplanar fracture. Our study provides some critical insights into the mechanical properties and fracture behavior of layered MoS 2D materials, which could be of value for their flexible electronic, optoelectronic and nano-electro-mechanical system (NEMS) applications.

Magnetic nanoparticle superstructures with controlled magnetic alignment and desired structural anisotropy hold promise for applications in data storage and energy storage. Assembly of monodisperse magnetic nanoparticles under a magnetic field could lead to highly ordered superstructures, providing distinctive magnetic properties. In this work, a low-cost fabrication technique was demonstrated to assemble sub-20-nm iron oxide nanoparticles into crystalline superstructures under an in-plane magnetic field. The gradient of the applied magnetic field contributes to the anisotropic formation of micron-sized superstructures. The magnitude of the applied magnetic field promotes the alignment of magnetic moments of the nanoparticles. The strong dipole-dipole interactions between the neighboring nanoparticles lead to a close-packed pattern as an energetically favorable configuration. Rod-shaped and spindle-shaped superstructures with uniform size and controlled spacing were obtained using spherical and polyhedral nanoparticles, respectively. The arrangement and alignment of the superstructures can be tuned by changing the experimental conditions. The two types of superstructures both show enhancement of coercivity and saturation magnetization along the applied field direction, which is presumably associated with the magnetic anisotropy and magnetic dipole interactions of the constituent nanoparticles and the increased shape anisotropy of the superstructures. Our results show that the magnetic-field-assisted assembly technique could be used for fabricating nanomaterial-based structures with controlled geometric dimensions and enhanced magnetic properties for magnetic and energy storage applications.

Tactile sensors are of great significance for robotic perception improvement to realize stable object manipulation and accurate object identification. To date, it remains a critical challenge to develop a broad-range...

Brain-inspired electronics require artificial synapses that have ultra-low energy consumption, high operating speed, and stable flexibility. Here, we demonstrate a flexible artificial synapse that uses a rapidly crystallized perovskite layer at room temperature. The device achieves a series of synaptic functions, including logical operations, temporal and spatial rules, and associative learning. Passivation using phenethyl-ammonium iodide eliminated defects and charge traps to reduce the energy consumption to 13.5 aJ per synaptic event, which is the world record for two-terminal artificial synapses. At this ultralow energy consumption, the device achieves ultrafast response frequency of up to 4.17 MHz; which is orders of magnitude magnitudes higher than previous perovskite artificial synapses. A multi-stimulus accumulative artificial neuromuscular system was then fabricated using the perovskite synapse as a key processing unit to control electrochemical artificial muscles, and realized muscular-fatigue warning. This artificial synapse will have applications in future bio-inspired electronics and neurorobots.