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Flexible materials with favorable electromagnetic wave interference (EMI) shielding performance are highly desirable to response to the fast-growing wireless technologies and flexible electronic devices. However, next-generation of wireless techniques or electronic devices should withstand multiple deformation forms such as bending, folding, wrinkling and stretching. Among them, it is rather difficult for shielding materials to achieve high performance at a dynamic stretching process due to the gradually dropdown of electrical conductivities when increasing tensile deformation. Herein, for the first time, we report a highly flexible and stretchable electrospun polyurethane (PU) nanofibers fabric covered by MXene (Ti3C2Tx) with delicate wrinkle structure design to meet this demand. The as-prepared MXene/PU fabric with sandwich structure exhibits stable mechanical properties and can keep EMI shielding values (SE) (>~20 dB) at a stretching process within 30% deformation. These amazing properties of the composite fabrics make them promising candidates for EMI shielding applications in wireless technologies, robots joints and flexible electronic devices.

Emerging wearable electronics pose urgent needs for high-performance, wearable gas sensors. However, the state-of-the-art gas sensors based on planer interdigited electrodes (IE) are commonly flexible yet not stretchable, which is not desirable for integration with human skin or clothing. Here, we report the fabrication of a stretchable and wearable gas sensor by using MXene/polyurethane (PU) core-sheath fibers. The synergetic effects of charge transfer and swelling-induced stretching offer the MXene/PU fiber sensor with high sensitivity to acetone (5–325 fold higher than planer MXene sensor deposited on an IE), wide sensing range (from ppb level to saturated vapor), and high signal-to-noise ratio (SNR, 160 % higher than planer MXene sensor). To further improve the sensing performance of the MXene/PU fiber, microstructures including microcracks and microwrinkles were developed into the fiber sheath. The microcracks can amplify the swelling-induced resistance variation of the conductive sheath; and therefore, leading to an enhanced sensing response 40 % higher than the flat core-sheath fiber. Furthermore, by developing microwrinkles onto the conductive sheath, a highly stretchable fiber-based gas sensor has been successfully demonstrated, which can accommodate human skin deformation (30 %) with a minimal sensing interference from tensile strain. The as-reported MXene/PU fibers can be knitted into clothing and serve as wearable gas sensors with good sensing reliability and gas permeability. Our results provide insight in utilizing microstructure engineering to tailor the sensing performance of gas sensors.

The rational design of artificial electronic skin has attracted considerable attention due to its potential applications in wearable electronics and human–machine interfaces. Flexible and highly sensitive pressure sensing is one of the primary abilities of electronic skin. In this paper, we present a simple, energy-saving and large-scale capable process to fabricate flexible skin-like pressure sensors based on graphene/polyamide interlocking fabric. The microstructure of the interlocking fabric endows the obtained pressure sensors with a high sensitivity (2.34 kPa−1), a low detection limit (

Flexible and multifunctional strain sensors with superior properties including high sensitivity, low detection limits, and a wide sensing range are always in high demand for wearable electronics. However, it remains a big challenge to fully satisfy the aforementioned requirements. In particular, there is always a trade-off between high sensitivity and wide sensing range. Here, we developed a multifunctional strain sensor based on a network-structured MXene/polyurethane mat (network-M/P mat) and well balanced the relationship between the sensitivity and sensing range by rationally designing the morphology and microstructures of the sensing device. The network-structured polyurethane mat (network-P mat) was fabricated through a facile and scalable electrospinning technique. The highly conductive MXene sheets were decorated onto the network-P mat through hydrogen bonding or electrostatic interactions. The obtained highly flexible and stretchable network-M/P mat exhibited a superior comprehensive sensing performance that was characterized by high sensitivity (gauge factor up to 228), a low limit of detection (0.1%), a large and tunable sensing range (up to 150%), excellent stability (over 3200 cycles), and multiple functions (lateral strain, vertical pressure, bending and subtle vibration). Based on its superior performance, the network-M/P mat-based strain sensor can detect a full range of body actions and subtle physiological signals (e.g. respirations and pulse waves), demonstrating great potential for applications in artificial electronic skin and wearable health detectors.

Highly sensitive, selective, and room-temperature-performing gas sensors have always been the pursuit in the sensing field for practical applications. However, the existing gas sensors can seldom satisfy the aforementioned requirements. Here, we integrate zero-dimensional Ag nanoparticles (AgNPs), one-dimensional polymer fibers, and two-dimensional aminoanthroquinone-functionalized reduced graphene oxide (AQRGO) sheets into a three-dimensional sensing scaffold (AgNP-3D-AQRGO) for high-performance NO

Emerging electronic skin (e-skin) poses urgent needs for high-performance pressure sensors. However, the state-of-the-art pressure sensing electronics require further advances to simultaneously satisfy the multiple parameters including high sensitivity, wide sensing range, good stretchability and selectivity. Especially, selective pressure detection without interference from lateral strain is highly demanded for a pressure sensor to mimic skin touch sensation. Here, high-performance pressure sensors were fabricated through developing periodic wrinkles and fibrous network geometries into the piezoresistive layer. The obtained wrinkled conductive fibrous mat (wrinkled-CFM) sensor showed high pressure sensitivity (186.5 kPa−1) accompanied by an ultra-wide working window (0–550 kPa) and good mechanical stability. To tackle the intrinsic instability of MXene nanosheets, CFM was treated with fluoroalkylsilane to achieve a hydrophobic surface, enabling long-term reliable sensing with minimal conductance variation ( 100%), pressure-sensitive and lateral strain insensitive (with a low gauge factor of ~0.25) sensor that can be stretched for thousands of cycles without sensing function degradation, demonstrating great potential for the future e-skin application.

Fiber-based architectures exhibit remarkable advantages in wearable electronics. Despite the various techniques to achieve strain sensitive fibers, important factors concerning the sensing performance, e.g. fiber arrangement, have been rarely explored. Herein, various fiber sensing patterns with anisotropic and isotropic microstructures were fabricated, and their localized strain distribution and conductive pathway configuration were tailored through fiber alignment. The sensing performance and mechanisms were investigated based on experimental characterization and theoretical modeling. We find out that the fibers arrangement strongly determines their strain sensitive behavior including sensitivity and sensing range. Additionally, by introducing a mechanical-guided step to realize a constant microcrack density in the fiber patterns, strain sensitivity and stability can be further improved. As a proof of concept, we integrated two fiber array sensors into a strain sensing system to simultaneously achieve an ultrahigh sensitivity (gauge factor up to 9540) and a wide sensing range (0.01–110%) as well as fast response.

Stretchable strain sensors have exhibited emerging prospects in bioelectronics due to the ubiquitous health-related strain in biosystems. However, most of the existing stretchable strain sensors are plagued by their sensitivity and sensing range trade-off. In this study, we designed a microstructured MXene/polyurethane fibrous membrane (m-MXene FM) with porous network structures and tunable micropatterns (including microcracks and microwrinkles), and demonstrated its superior strain sensing properties. The microcracks can serve as stable mechanical weak points to enhance the sensitivity, while the highly porous network as well as the microwrinkle patterns can cushion the strain loading on individual fibers under large deformations, thus offering wide sensing range. The as-prepared m-MXene FM is highly stretchable and conductive and shows extremely high gauge factor of 1000 and wide sensing range up to 120%. Furthermore, both the sensitivity and sensing range can be facilely tailored through adjusting the micropatterns. This work provides a scalable strategy to fabricate highly sensitive strain sensors with customizable sensing properties suitable for a range of applications in health monitoring.

The development of skinlike strain sensors that are integrated with multiple sensing functions has attracted tremendous attention in recent years. To mimic human skin, strain sensors should have the abilities to detect various deformations such as pressing, stretching, bending, and even subtle vibrations. Here, we developed a facile, cost-effective, and scalable method for fabrication of high-performance strain sensors based on a graphene-coated springlike mesh network. This composite-based sensor exhibits an incorporation of low detection limit (LOD) for minute deformation (LOD of 1.38 Pa for pressure, 0.1% for tensile strain, and 10 μm for vibration), multiple sensing functions, long-term stability, and wide maximal sensing range (up to 80 kPa for pressure and 110% for tensile strain). On the basis of its superior performance, it can be applied for in situ monitoring of human motions ranging from subtle physiological signals (e.g., pulse, respiration, and phonation) to substantial movements (e.g., finger bending).