High-Performance Flexible Sensors of Self-Healing, Reversibly Adhesive, and Stretchable Hydrogels for Monitoring Large and Subtle Strains

Flexible sensors are becoming required in heath monitoring and human-machine interfaces, but it is still a challenge to develop flexible sensors with integrated high performances. Herein, high-performance flexible sensors are fabricated that are self-healing, reversibly adhesive, and utilizing stretchable hydrogels, which are composed of a pluronic F127 diacrylate (F127DA) cross-linked poly(acrylic acid) (PAA) network and polydopamine (PDA), and further cross-linked by Fe3+. The unique structure endows the resulting hydrogels (PAA-PDA-Fe3+ hydrogels) excellent self-healing property, reversible adhesion property, mechanical stretchability, and electrical conductivity. On the basis of the excellent properties of PAA-PDA-Fe3+ hydrogels, flexible sensors with large sensing range (0-575%), high sensitivity (GF = 6.31), low response time (0.25 s), and excellent robustness (>500 cycles) are assembled and further applied in detecting both large and subtle strains induced by human motions and water ripple. Overall, this work not only provides an alternative clue to construct multi-functional hydrogels, but also offers a new kind of high-performance materials for flexible electronic devices, especially those for health monitoring and human-machine interface.