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Wearable strain sensors are widely used in bionic robots and wearable electronic devices. However, such devices inevitably work in degradative environments such as under wet conditions and contaminants, deteriorating the sensing performance and stability. In this work, a stretch‐tolerant superhydrophobic, self‐cleaning graphene‐based strain sensor with high sensitivity, is reported using prestretching strategy. The stretch‐tolerant superhydrophobic surface of the sensor is prepared by attaching carbon black nanoparticles to the Ecoflex substrate for constructing surface roughness and modifying with polydimethylsiloxane for achieving low surface energy under stretched condition (50% strain), which endow the sensors with an outstanding self‐cleaning performance for various contaminants. Moreover, the sensor retains excellent super‐hydrophobicity even under stretching. The sensor is also insensitive to common liquids in daily life including water, such as tea, milk, and coffee. Furthermore, the proposed strain sensor achieves wide sensing ranges (strain over 100%) and has a superior sensitivity (gauge factor up to 653.4 at 90% stretching), which shows great promising in accurate human motions monitoring both in the air and underwater. Besides, by placing the strain sensor on a bridge, the number of vehicles on the bridge can be detected, which exhibits an ideal platform for real‐time traffic flow monitoring. [ABSTRACT FROM AUTHOR]

Hydrogels are considered as promising materials in developing next‐generation wearable sensors due to their intrinsic biocompatibility and low Young's modulus. However, there are few reports on their breathability which is very important for wear comfortability of wearable sensors. Here graphene‐based hydrogel is presented with regular pores using microneedles as templates endowing them with excellent breathability (water vapor transmitting rate 2.8 kg d–1 m–2), which is near ten times that of human skin (water vapor transmitting rate less than 0.3 kg d–1 m–2). A high‐performance strain sensor based on this breathable hydrogel is developed. This sensor not only possesses high sensitivity but also has an excellent linearity with strain ranging from 0% to 110%. Based on these performances, this sensor can be applied in monitoring various joint movements and muscle movements. Moreover, it can achieve barrier‐free communication through Morse code. [ABSTRACT FROM AUTHOR]