Preparation and Application of Hydrophobic and Breathable Carbon Nanocoils/Thermoplastic Polyurethane Flexible Strain Sensors

The emphasis on physical activity and health monitoring has increased the demand for developing multifunctional, flexible sensors through straightforward methods. A hydrophobic, breathable, and flexible strain sensor was prepared using a filtration method, employing thermoplastic polyurethane (TPU) as a substrate, carbon nanocoils (CNCs) as conductive fillers, and polydimethylsiloxane (PDMS) as a binder. The sensing layer, prepared using the unique three-dimensional helical structure of carbon nanocoils, achieved a hydrophobic angle of 143° and rapidly changed the color of the pH test paper in 5 s. The sensor had a strain range of 40% and a gauge factor of 34, and achieved a linear fit of R² = 0.98 in the 5-35% strain range. The CNCs/TPU sensor exhibits high reliability and stability after 1000 tensile cycle tests. These favorable features ensure that the sensors are comfortable to wear and respond quickly and accurately to movements in all body parts, meeting the need for human motion detection.