Mechanically flexible ceramic fiber-based electronic skins are attractive materials ascribed to the features of monitoring signals of various physical parameters in a harsh environment, but the inherent brittleness of the ceramic fibers has limited their wide applications in emerging fields, such as fire-protecting clothing. Herein, a strategy to fabricate the flexible stannum(IV)-doped SrTiO3 (SSTO) nanofiber membranes by a facile sol-gel electrospinning method is reported. The calcination temperature and Sn4+ doping content play vital roles in regulating the crystalline and pore structures that are closely relevant to the flexibility and mechanical properties of the resultant SSTO nanofiber membranes. The as-prepared SSTO nanofiber membranes exhibited exceptional flexibility with an optimum tensile strength of 0.22 MPa, an elongation rate of 1.8%, and a Young's modulus of 13.3 MPa. Significantly, the flexible SSTO nanofiber-based piezoresistive sensors exhibited intriguing sensing performance toward pressure involving high sensitivity (2.24 kPa-1) in a low-pressure range (<400 Pa), fast response time (12 ms) and recovery time (32 ms), good durability (>1000 cycles), and excellent stability at different humidity levels and elevated temperatures. Furthermore, the sensor can also accurately monitor the signals of human motion such as finger bending, throat swallowing, and radial pulse. The fabrication of flexible ceramic nanofiber-based piezoresistive sensors would pave the way to fabricate wearable devices for fire-protecting clothing, personal healthcare, real-time human activity detection.
Keywords: electronic skin; flexible stannum-doped SrTiO3 nanofiber; high sensitivity; human motion monitoring; piezoresistive pressure sensor.