Flexible Strain Sensor Based on TPU/CNTs/rGO Conductive Membrane with Dual-Microcrack Structure for High-Performance Wearable Sensing

Flexible strain sensors are crucial for wearable electronics and human–machine interaction, yet simultaneously achieving high sensitivity and a broad working range remains challenging. Here, a high-performance strain sensor is developed by integrating carbon nanotubes (CNTs)/reduced graphene oxide (rGO) hybrid conductive networks with electrospun thermoplastic polyurethane (TPU) nanofibers, followed by pre-stretching to engineer a dual-microcrack architecture. The synergistic interplay between 1D CNTs and 2D rGO stabilizes conductive pathways, while strain-regulated microcrack evolution amplifies resistance variation. The sensor delivers a wide strain range of up to 100%, with gauge factors of 75.2, 1600.5, and 7484.5 across 0–32%, 32–60%, and 60–100% strain, respectively. It further exhibits a rapid response/recovery time of 30/40 ms, a low detection limit of 0.01%, and excellent durability over 1000 cycles. Benefiting from these comprehensive superior sensing performances, the sensor can reliably monitor both subtle human physiological signals and large-amplitude human motions, demonstrating great application potential in wearable health monitoring, intelligent motion perception and human–machine interaction fields.