Polyvinyl Alcohol/Nano-Carbon Black/Polyacrylamide Conductive Hydrogels With Ultra-Strength and High Toughness Through Multi-Reinforcement for Flexible Strain Sensors

Conductive hydrogels are ideal materials for wearable flexible sensors; however, integrating ultra-high mechanical properties, high sensitivity, and a broad sensing range into a single material remains challenging. Herein, an ultra-strong and tough polyvinyl alcohol/nano-carbon black/polyacrylamide (PVA/CB/PAM) conductive composite hydrogel is fabricated via a multi-reinforcement strategy, which employs nano-carbon black as both a reinforcing agent and conductive filler. The synergy from constructing a double network, nano-carbon black filling, freeze–thaw crystallization, and dehydration-induced contraction endows the hydrogel with outstanding mechanical properties: a tensile strength of 16.06 ± 0.9 MPa, a Young's modulus of 6.33 ± 0.87 MPa, an elongation at break of 610% ± 77%, and a toughness of 46.84 ± 5.21 MJ m −3 . The derived sensor achieves a high gauge factor of 3.81 with low hysteresis over a wide strain range of 0%–600%, and exhibits excellent durability over 500 loading-unloading cycles. It reliably monitors a full spectrum of human activities, from subtle throat movements to high-impact running. This work presents a promising candidate material for high-performance wearable sensors.