Ultrastretchable, Multihealable, and Highly Sensitive Strain Sensor Based on a Double Cross-Linked MXene Hydrogel

The ability of a flexible strain sensor to directly adapt the complicated human biological motion or combined gestures and remotely control the artificial intelligence robotics could benefit the wearable electronics such as intelligent robotics and patient healthcare. However, it is a challenge for the flexible strain sensor to simultaneously achieve high sensing performances and stretchability and long sustainability under various deformation stress or damage. Herein, a dual-cross-linked poly(acrylic acid-stearyl methacrylate)/MXene [P(AA-SMA)M] hydrogel with enhanced mechanical stretchability and self-healability is fabricated by importing reversible coordination and hydrophobic interaction into polymer networks. As a result, the hydrogel film not only exhibits high tensile strength (525 kPa) and stretchability (∼2600%) but also achieves repetitive healable property with 843% elongation even after the 20th broken/self-healing cycle. More importantly, the resultant strain sensor delivers a low detection limit, wide sensing range, fast response time, and repeatability of 1000 cycles even after repeated self-healing. So, the sensor can monitor subtle human motions and recognize different handwriting and gestures, which reveals potential applications toward health-care devices, flexible electronics, and human-machine interfacing.