Construction of sensitive strain sensing nanofibrous membrane with polydopamine-modified MXene/CNT dual conductive network

The flexible mechanical sensors that can detect body parameters in real time have been applied in many fields of soft robots, human activity monitoring and health diagnosis. High sensitivity and durable stably signal output are two key factors in strain sensors. The MXene-based materials received extensive attention recently owing to their high conductivity and sense performance, however, poor inherent oxidation resistance properties and weak binding force of MXene-based composite materials always hinder the signal stability. Herein, we propose a facile strategy to prepare polydopamine-modified MXene nanosheets (PMXene) with good oxidation resistance through in situ polymerization, and then it was uniformly loaded on thermoplastic polyurethanes-carbon nanotube (TPUCNT) nanofibers. Due to the adhesion and interaction between PMXene, CNTs and doped Ni ion, an effective 1D/ 2D double conductive network is realized in as-prepared flexible sensors. The resultant sensor shows high sensitivity of 9.25, a tunable detection range at 100% strain, and reliable signal ability over 900 cycles. Furthermore, the adhesive dopamine layer effectively isolates oxygen and ensures the stability of the devices. Notably, the sensor can be employed to recognize various human joint motions and detect the physiological signal of swallowing and vocalization, exhibiting the promising potential of the strain sensor in wearable electronics.