A hierarchical carbon nanotube/SiO2 nanoparticle network induced superhydrophobic and conductive coating for wearable strain sensors with superior sensitivity and ultra-low detection limit

It is desirable to develop strain sensors with large stretchability, high sensitivity, and good anti-corrosive properties, due to their promising applications in wearable electronics. Here, a facile spraying method is used to prepare superhydrophobic and conductive coatings on elastic tape with a hierarchical fluorinated carbon nanotube (FCNT)/SiO2 nanoparticle structure. The uniformly distributed FCNTs construct a conductive network, while hydrophobic SiO2 nanoparticles enhance the surface roughness, contributing to the superhydrophobicity. The superhydrophobic coating possesses excellent stability and durability when subjected to external forces such as repeated stretching and abrasion, and it also exhibits superior anti-corrosive properties. The superhydrophobic coating based strain sensors display an extremely low detection limit of strain (<0.1%) with a large strain sensing range (>80%), high sensitivity with a gauge factor as high as 1766, and excellent reliability and recyclability. The strain sensor could realize the full range monitoring of human motion including large and subtle body movements even in a harsh environment.