▎ 摘　　要

Flexible sensors based on conductive hydrogels show great potential in wearable displays and smart devices. However, a water-based hydrogel inevitably freezes or loses its conductivity under extremely cold temperatures, leading to inadequate fulfillment of sensor performance. Herein, a well-designed strategy is proposed for fabricating a low-temperature-tolerant water-based hydrogel for sensor applications. By immersing a multi-crosslinking graphene(GO)/polyacrylic acid (PAA)-Fe3+ hydrogel into a KCl solution, an ion-enhanced conductive (GO/PAA/KCl) hydrogel is obtained with excellent conductivity (24.4 S m(-1) at 20 degrees C; 16.2 S m(-1) at -20 degrees C; 0.8 S m(-1) at -80 degrees C) and outstanding antifreezing properties. The conductive hydrogel also possesses good mechanical properties with a fracture stress of 2.65 MPa and an elongation at break of 1511% and maintains its flexibility even at -35 degrees C. Then, a strain sensor is assembled to monitor the human motion at 20 degrees C and the movement of a wooden mannequin at -20 degrees C. Under both conditions, the sensor presents high sensitivity (GF = 8.66 at 20 degrees C, 7.93 at -20 degrees C) and good durability (300 cycles under 100% strain). Consequently, the anti-freezing ion-enhanced hydrogel will meet the needs of flexible sensors designed for intelligent robots, health monitoring, etc., which have to work in cold regions or extreme climates.