Laser-Induced Graphene Derived from Aramid Nanofiber Films as Flexible Strain Sensors

In recent years, laser-induced graphene (LIG) has emerged as a promising material for electronics applications, owing to its numerous advantages. Kevlar textile fabrics have also been developed as LIG precursors due to their exceptional mechanical properties. However, the inherent tendency of Kevlar textiles to exhibit discontinuous conductive paths during laser ablation has hindered the attainment of a consistent conductivity in the induced layer. To address this challenge, this study developed an aramid nanofiber film based on Kevlar as precursor materials. By maintaining the intrinsic mechanical robustness of Kevlar while adopting a high-density fibrous architecture, we successfully resolved the ablation-induced discontinuity issue, thereby ensuring the stability of the conductive layer’s performance. The resulting flexible strain sensor exhibited a gauge factor exceeding 190 within a strain range of less than 5%, demonstrating superior sensitivity compared to those of many conventional counterparts. Its flexible design also guarantees user comfort. Further validation revealed the sensor’s outstanding durability and repeatability, surviving 1800 cyclic strain tests while maintaining a real-time response with minor signal fluctuation. Notably, the sensor demonstrated the capability to monitor diverse human physiological signals (including pulse, respiration, swallowing, and coughing) and motion states (finger bending and knee flexion). These functionalities suggest great potential for applications in intelligent medical treatment and sports rehabilitation. This study underscores the promising potential of aramid nanofibers-based LIG strain sensors and provides valuable insights into their application in diverse scenarios.