Dual-network conductive hydrogel with rapid self-healing ability and great fatigue resistance as strain sensor for human motion monitoring

As the classical soft materials, ionic conductive hydrogels have attracted considerable attention in the field of wearable strain sensors due to their unique stretchability, satisfactory conductivity, and good conformability. However, there remains a challenge in developing ionic conductive hydrogels that possess integrated mechanical strength, self-healing capability, and adhesion performance. Herein, a multifunctional dual-network poly(vinyl alcohol) (PVA)/borax (B)/sodium alginate (SA) ionic conductive hydrogel (PBS) was designed and constructed through a facile one-pot blending method with PVA and SA as the hydrogel matrix and borax as the cross-linker. The dynamic borate ester covalent bonds between PVA, SA and borax and hydrogen bonding between PVA and SA provided the energy dissipated center and endowed PBS hydrogel with favorable stretchability (∼950%), high toughness (122.21 kJ m−3), rapid self-healing ability, good fatigue resistance and robust adhesion performance. It can be assembled into strain sensor for its stable conductivity, high sensing sensitivity (gauge factor (GF) of 6.53), fast response time (280 ms) and excellent durability, which can be directly attached on body to accurately detect diverse human activity signals. This work is expected to provide new ideas for construction of high performance flexible sensor and to expand their application in electronic skin, wearable devices, and soft actuators.