Highly Stretchable and Self-Healing Strain Sensor Based on Gellan Gum Hybrid Hydrogel for Human Motion Monitoring

Currently, stretchable and conductive hydrogels have attracted considerable attention because of promising applications in the area of flexible electronic skins. However, integrating stretchability, notch-insensitivity, and self-healing property into the hydrogel is still a challenge. Herein, we prepared a stretchable, tough, recoverable, and self-healing hybrid hydrogel by combining a physically cross-linked gellan gum network with a chemically cross-linked polyacrylamide network. The incorporated hydrogen bonding and ionic association in the gellan gum network acting as sacrificial bonds endowed the hybrid hydrogel with superior and tunable mechanical performances. Thermoreversible gelation of gellan gum led to the hybrid hydrogel having excellent recoverability and self-healing capabilities. Furthermore, on the basis of the high strain sensitivity in conductivity, the hybrid hydrogel is able to be used as a flexible conductor to fabricate a flexible strain sensor for detecting both large motions (e.g., joints bending) and tiny activities (e.g., throat vibration). This work provides a prospect for the preparation of a stretchable gellan gum-based hybrid hydrogel and extends its applications to wearable strain-sensing devices.