Superhydrophobic and Stretchable Carbon Nanotube/Thermoplastic Urethane-Based Strain Sensor for Human Motion Detection

Challenges to developing new types of stretchable and flexible strain sensors with high sensitivity, good stability, and high antifouling properties still exist. Here, through a layer-by-layer self-assembly method, we successfully prepared a superhydrophobic carbon nanotube (CNT)/thermoplastic urethane (TPU) nanocomposite fibrous mat. CNT was used to construct the conductive layer, and polyhedral oligomeric silsesquioxane (POSS) and 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (FAS) were used to form the hydrophobic layer. The obtained CNT/F-TPU mat possessed good hydrophobicity and mechanical stability; meanwhile, it exhibited a remarkable tensile property up to 550% strain. The CNT/F-TPU-based strain sensor showed an excellent sensing performance, including stable sensitivity, fast responsivity, and excellent repeatability. It can successfully detect not only large deformation movements of the human body, such as the bending of fingers, wrists, elbows, and knees, but also output stable signals for small deformation, such as smiling, blinking, swallowing, and vocalizing. This superhydrophobic CNT/F-TPU nanocomposite fibrous mat shows great potential for developing high-performance strain sensors suitable for monitoring human health and designing wearable devices.