Curcumin-involved self-healing hydrogels as flexible sensors

The rapid development of conductive hydrogels shows great potentials in the field of flexible sensors. Accordingly, the research on the hydrogel sensors with great self-healing property for long-term durability is noticeably essential. In the present study, curcumin (Cur)-involved polyacrylic acid (PAA) and polyethyleneimine (PEI) based hydrogels noted as PAA/PEI-Al-Cur were constructed. The effect of curcumin on the mechanical properties of the hydrogels was firstly studied. The introduction of curcumin could effectively improve the mechanical properties that the tensile strength of the prepared PAA/PEI-Al-Cur hydrogel could reach as high as 119.0 kPa. The existence of Al³⁺ and the porous network structure of the hydrogel entrust to a high conductivity (σ=1.11 S/m). Thus, the hydrogel could be applied as both strain sensor and pressure sensor to detect different deformations and various human activities including large-scale human movements and subtle facial expressions. It is worth noting that the self-healing ability of the hydrogels could be regulated by the amount of introduced curcumin that the optimal dose exhibited ultrafast self-healing ability and the mechanism was illustrated. More to the point, the healed hydrogel could be applied as the sensor to repeatedly and stably perform sensing behavior as the original one. This work provides an effective construction strategy to prepare novel conductive hydrogels for flexible sensors.