Fully physically cross-linked hydrogel as highly stretchable, tough, self-healing and sensitive strain sensors

The development of stretchable materials has aroused immense interests for the applications in flexible wearable electronic devices. However, existing conductor materials can hardly meet all the requirements for use in next-generation wearable devices. In this work, a new type of fully physically cross-linked PVA/PAA/Fe3+ hydrogel with stretchable, tough, conductive, and self-healing property is fabricated by using “one-pot” method under room temperature via free radical polymerization. These hydrogels exhibit unique features, such as high tensile strength (~1.03 MPa), high stretchability (~1370%), high toughness (~6.37 MJ/m3) and excellent self-healing property (the self-healing efficiency could reach 97.34%), as well as rapid self-recovery property (the recovery ratio was 0.83 after waiting 15min). Besides, the conductivity of hydrogel can reach up to 2.67 S/m, and the conductivity of the hydrogel changes accordingly under tension, the hydrogels also have high gauge factor (GF = 3.79) and exhibited high sensitivity in the broad strain window (0–800%), indicating these ionic conductive hydrogels can be used to fabricate excellent high-performance strain sensors.