High-performance ionic conductive double-network hydrogel enabling a long-term flexible strain sensor

Hydrogel sensors have attracted much attention for their promising applications in artificial skin and personal health monitoring. However, developing conductive hydrogel sensors with good self-healing, mechanical strength, fatigue resistance, self-adhesion, high conductivity and sensitivity remains a significant challenge. Herein, a multifunctional ionic conductive double-network (DN) hydrogel was prepared by mixing natural biomolecule, chitosan (CS) and hyaluronic acid (HA) in water. The synergistic physical interactions endowed the hydrogel with rapid self-healing capability and good mechanical flexibility. Benefiting from the abundant hydroxyl groups of CS and HA, the hydrogel exhibited robust adhesion capability to diverse materials surfaces, the maximum peel strength for poly-(tetrafluoroethylene) PTFE was 49.4 kPa and the highest adhesion strength for glass was 38.7 kPa. Moreover, the hydrogel showed high sensing sensitivity [gauge factor (GF) = 4.42], wide strain range (800%), and long-term durability (>300 cycles) to tensile strain, which can be constructed to strain sensor for monitoring large deformation movements and small deformations of human body. It is anticipated that the developed hydrogels provide useful insight and guideline into design and development of high-performance wearable strain sensor and broaden the application field in electronic skin, human-machine interfaces, and personalized health assessment.