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Flexible wearable sensors are of interest for underwater applications such as aquatic robots and marine exploration. Non‐swelling hydrogels would be a preferable candidate for underwater sensing with stable sensing performance. Herein, hydrogels comprised of MXene and polyhydroxyethyl methacrylate (PHEMA) are designed and manufactured. Owing to the synergistic effect of phase separation zones and hydrophilic/hydrophobic interaction, MXene/PHEMA hydrogels exhibit non‐swelling performance in various liquid media (e.g., water, seawater) and effectively avoid the adhesion of proteins and bacteria. In addition, MXene/PHEMA hydrogels exhibit a large sensing range (more than 400%), high tensile strength (0.54 MPa), and skin‐compliance modulus (120 kPa). Furthermore, the resulted hydrogel‐based sensors possess superior sensibility (4.42 at 150–450% strain), fast responsiveness (200 ms), and durable sensing ability (over 1000 cycles). The hydrogel‐based sensors can accurately monitor human motions (both large and subtle motions) in air and in various liquid media. Benefiting from the non‐swelling and anti‐fouling ability, the hydrogels could maintain high mechanical strength and cyclic stability after being immersed in water for 30 days, and precisely detect the movement of human and shark models underwater. It is conceivable that non‐swelling and anti‐fouling MXene/PHEMA hydrogels provide a feasible material to construct electronic skins for various harsh liquid environments. [ABSTRACT FROM AUTHOR]

Skin‐attachable conductive hydrogels are ideal candidates for the design of flexible and wearable electronics, and tremendous efforts are devoted to preparing multifunctional hydrogels. However, antibacterial ability and ultraviolet (UV)‐blocking property are still essential yet rarely reported. In this study, a novel ionically conductive multifunctional polyacrylamide (PAAm)/chitosan (CS)/tannic acid (TA) hydrogel (PCT hydrogel) with transparency, adhesiveness, antibacterial activity, and UV‐blocking ability simultaneously is fabricated via a facile one‐pot strategy. In the hydrogel, PAAm chains form the backbone of PCT hydrogel, CS and TA endow hydrogel with antibacterial activity (>97%) and UV‐blocking ability (>96%), respectively. More importantly, existing free ions also endue PCT hydrogel with conductivity (0.256 ± 0.005 S m−1) and strain sensitivity (GF > 3). The prepared PCT hydrogel‐based strain sensors can effectively monitor various human movements, indicating their huge potential in soft robotics, human–machine interaction, and health‐monitoring systems. [ABSTRACT FROM AUTHOR]

Flow sensing exhibits significant potential for monitoring, controlling, and optimizing processes in industries, resource management, and environmental protection. However, achieving wireless real‐time and omnidirectional sensing of gas/liquid flow on a simple, self‐contained device without external power support has remained a formidable challenge. In this study, a compact‐sized, fully self‐powered wireless sensing flowmeter (CSWF) is introduced with a small size diameter of down to less than 50 mm, which can transmit real‐time and omnidirectional wireless signals, as driven by a rotating triboelectric nanogenerator (R‐TENG). The R‐TENG triggers the breakdown discharge of a gas discharge tube (GDT), which enables flow rate wireless sensing through emitted electromagnetic waves. Importantly, the performance of the CSWF is not affected by the R‐TENG's varied output, while the transmission distance is greater than 10 m. Real‐time wireless remote monitoring of wind speed and water flow rate is successfully demonstrated. This research introduces an approach to achieve a wireless, self‐powered environmental monitoring system with a diverse range of potential applications, including prolonged meteorological observations, marine environment monitoring, early warning systems for natural disasters, and remote ecosystem monitoring. [ABSTRACT FROM AUTHOR]

Multimodal haptic perception is essential for enhancing perceptual experiences in augmented reality applications. To date, several artificial tactile interfaces have been developed to perceive pressure and precontact signals, while simultaneously detecting object type and softness with quantified modulus still remains challenging. Here, inspired by the campaniform sensilla on insect antennae, we proposed a hemispherical bimodal intelligent tactile sensor (BITS) array using the triboelectric effect. The system is capable of softness identification, modulus quantification, and material type recognition. In principle, due to the varied deformability of materials, the BITS generates unique triboelectric output fingerprints when in contact with the tested object. Furthermore, owing to the different electron affinities, the BITS array can accurately recognize material type (99.4% accuracy), facilitating softness recognition (100% accuracy) and modulus quantification. It is promising that the BITS based on the triboelectric effect has the potential to be miniaturized to provide real-time accurate haptic information as an artificial antenna toward applications of human-machine integration.