Flexible and hydrophobic nanofiber composites with self-enhanced interfacial adhesion for high performance strain sensing and body motion detection

Flexible and electrically conductive fibric (fiber) composite (CFC) strain sensors are promising in smart wearable electronics. Challenges remain to develop CFC with strong interfacial interaction and excellent durability. Here, a facile and cost-efficient method is proposed to fabricate flexible and hydrophobic CFCs with self-enhanced interfacial adhesion based on ultrasonication induced carbon black nanoparticles (CBNPs) embedded onto the swelled polyurethane (PU) nanofiber membranes immersed in a mixed solvent. CBNPs were tightly decorated onto the nanofiber surface, while the electrical conductivity keeps stable during cyclic durability tests. The CBNPs improve the Young's modulus and tensile strength while maintain the outstanding stretchability of PU membrane. The CBNPs also endow the CFCs with hydrophobicity and photo-thermal conversion property. The stretchable CFC strain sensors show controllable sensitivity and cyclic stability, and can monitor various body motions. This work provides a new route to fabricate low-cost and high-performance strain sensors without using interfacial bonding agents.