Highly compressible, breathable, and waterproof piezoresistive sensors based on commercial three-dimensional air-laid nonwovens

There have been ample three-dimensional (3D) wearable piezoresistive sensors with high sensitivity, fast response, and outstanding long-term stability. Nevertheless, less consideration is given to simple fabrication, economical materials, and comfort. Herein, a simple and cost-effective strategy for fabricating piezoresistive sensors is presented based on commercial 3D air-laid nonwovens (NW), poly(tetrafluoroethylene- co -hexafluoropropylene- co -vinylidene fluoride) (THV), and carbon nanotubes (CNTs) via one-step dip-coating method. CNTs without functionalization are dispersed homogenously in the solvent and coated uniformly on the substrate with the help of THV as dispersant and adhesive. This highly compressible 3D NW-THV-CNTs piezoresistive sensor showcases splendent air permeability (2682.33 mm·s −1 ), water–vapor permeability (1625.50 g·m −2 ·d −1 ) and super-hydrophobicity (water contact angle = 158.5°), and is characterized by remarkable photothermal performance. Furthermore, the NW-THV-CNTs sensor has a sensitivity of 1.26 kPa −1 with good linearity ( r 2 = 0.99833) in wide detecting range (0–100 kPa), moderate response time (0.45 s) and release time (0.25 s), and good cyclic stability. Additionally, the sensor excels in monitoring human activities, and the array sensor composed of 4 × 4 pixels is capable of plotting distribution and shape of pressure.