Au/Graphene–CNT Crack-Based Strain Sensor for Wide-Range Motion Monitoring

Inspired by the remarkable sensitivity of spider slit organs, nanostructured strain sensors based on the controlled formation of micro/nanocracks offer promising solutions for applications in tactile sensing, electronic skin, and physiological monitoring. However, existing crack-based strain sensors often struggle to simultaneously achieve low detection limits, wide linear ranges, fast response, and long-term durability. This bottleneck arises from the fundamental trade-off between the large expansion of microcracks required for high signal modulation and the elastic recovery necessary for cyclic stability. Here, we developed a trinanomaterial Au/graphene–CNT (AGC) strain sensor by integrating a nanogold (Au) layer with a graphene–carbon nanotube (Gr–CNT) composite layer. The brittle Au nanolayer generates a dynamic microcrack network that enhances mechanical sensitivity during deformation, while the ductile Gr–CNT layer maintains electrical conductivity under large strains. Leveraging this strategy, the fabricated AGC strain sensor exhibits exceptional sensing performance: an ultralow detection limit (20,000 cycles). These combined capabilities make it highly versatile, enabling applications ranging from the real-time detection of subtle physiological signals and human joint movements to gesture recognition and high-frequency fatigue monitoring in structural materials.