Flexible Strain Sensors Based on Ag/CNT/TPU Multi‐Level Conductive Network With High Sensitivity and Wide Sensing Range

ABSTRACT Flexible strain sensors, owing to their stretchability, tunable mechanical properties, and biocompatibility, hold great promise for electronic skin and human‐machine interaction devices. However, material and structural limitations often preclude the simultaneous achievement of high sensitivity and a wide detection range, thereby constraining their practical application. In this study, we first used high‐frequency ultrasound to develop a Carbon Nanotube/Thermoplastic Polyurethane (CNT/TPU) composite fiber membrane on electrospun TPU, and then printed a conductive silver paste pattern onto its surface to fabricate an Ag/CNT/TPU strain sensor. This sensor features a hierarchical conductive network, comprising a densely packed silver paste layer overlying a CNT‐modified TPU fiber network. Benefiting from the synergistic interaction between these two levels, the sensor exhibits a maximum gauge factor of 2711.3, a broad working range of 0%–400%, ultrafast response and recovery times, and excellent long‐term stability. Finally, we demonstrated its utility in monitoring human motion, from small‐amplitude finger bending to large‐range knee flexion, and successfully employed it to drive a complex bionic hand, thereby advancing the use of flexible strain sensors in human‐machine interaction applications.