Facile Strategy for Fabrication of Flexible, Breathable, and Washable Piezoelectric Sensors via Welding of Nanofibers with Multiwalled Carbon Nanotubes (MWCNTs)

Piezoelectric materials have been widely explored, due to their potential applications related to wearable sensors, energy harvesting, and electronics. However, the majority of previously reported flexible sensors cannot simultaneously possess the properties of conductivity, washability, and air permeability, which limits their further development in textile applications. Herein, we have processed a nanofibrous mat to successfully develop a textile, which acquired effective conductivity, while maintaining a soft and porous nature for comfortable wearing. Two steps were implemented in this strategy. First, the surface of poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) nanofibers was coated with multiwalled carbon nanotubes (MWCNTs) through electrospinning; second, for preventing the damage by washing, the MWCNTs were welded into the nanofibers to generate a strong connection with the nanofibers by a thermal welding process. With the incorporation of MWCNTs, the electrospun PVDF-HFP nanofibrous mat manifests good conductivity with a sheet resistance of 7.1 ± 2.8 kΩ and excellent mechanical properties (up to 35.4 ± 7.3 MPa). The as-prepared nanofibrous mat exhibits high stability, good bending stability over 10 000 bending cycles, and superior wearability in terms of washability and breathability. Besides, such a nanofibrous mat can be used in contact with the human skin or attached to textiles for body motion monitoring, displaying great potential for wearable devices.