Conductive Thermoplastic Polyurethane Composites with Multicarbon Fillers for Flexible Resistive Strain Sensors for Handwriting Recognition

With the rapid development of portable electronic devices, smart wearable technology shows great potential in the fields of personalized motion tracking, health monitoring, and human-computer interaction. However, the complex preparation processes and stringent performance requirements pose challenges to the widespread applications of these technologies. To address this issue, we propose a straightforward and economical method for the preparation of flexible resistive strain sensors using thermoplastic polyurethane porous films. By a nonsolvent induced phase separation method, we prepared porous films incorporating varying ratios of carbon black (CB)/graphene and CB/carbon nanofibers to serve as conductive strain-sensitive layers for the strain sensors. This simple and efficient preparation method not only reduces the production cost but also improves the manufacturability and performance stability of the sensors, thereby providing important support for the future development of intelligent technologies. The resulting flexible resistive strain sensors exhibit excellent sensing performance, characterized by a maximum strain gauge factor of 9.822, a wide tensile range (ε = 0% to 30%), and commendable cyclic tensile reliability. The application results indicate that these strain sensors excel in the handwriting recognition classification task, establishing a solid foundation for diverse sensor technology applications in the fields of smart health monitoring and virtual reality interaction.