Electronic skin is driving the next generation of cutting-edge wearable electronic products due to its good wearability and high accuracy of information acquisition.However,it remains a challenge to fulfill the requirements on detecting full-range human activities with existing flexible strain sensors.Herein,highly stretchable,sensitive,and multifunctional flexible strain sensors based on MXene-(Ti3C2Tx-)composited poly(vinyl alcohol)/polyvinyl pyrrolidone double-network hydrogels were prepared.The uniformly distributed hydrophilic MXene nanosheets formed a three-dimensional conductive network throughout the hydrogel,endowing the flexible sensor with high sensitivity.The strong interaction between the double-network hydrogel matrix and MXene greatly improved the mechanical properties of the hydrogels.The resulting nanocomposited hydrogels featured great tensile performance(2400％),toughness,and resilience.Particularly,the as-prepared flexible pressure sensor revealed ultrahigh sensitivity(10.75 kPa")with a wide response range(0-61.5 kPa),fast response(33.5 ms),and low limit of detection(0.87 Pa).Moreover,the hydrogel-based flexible sensors,with high sensitivity and durability,could be employed to monitor full-range human motions and assembled into some aligned devices for subtle pressure detection,providing enormous potential in facial expression and phonation recognition,handwriting verification,healthy diagnosis,and wearable electronics.
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