Bioinspired “Root-Soil” Interlocked Micro/Nanostructure Enhanced Hybrid Hydrogels for Robust and Highly Sensitive Strain Sensors

Robust ionic conductive sensors with biocompatibility play a great role in flexible electronics and human–machine interfacing. However, the simultaneous attainment of ionic conductive sensors with high ionic conductivity, outstanding mechanical properties, ambient stability, and skin adhesiveness remains a major challenge. Herein, inspired by “root-soil” interlocked micro/nanostructure, a fiber-reinforced hybrid hydrogel for strain sensor is developed by infiltrating a polyacrylamide (PAM)-grafted sodium alginate (SA) hydrogel precursor into thermoplastic polyurethane (TPU) fibrous membranes and introducing glycerol (GL) and CaCl2. Alongside remarkable mechanical properties (stress up to 5.93 MPa and strain up to 658.32%), the obtained TPU hybrid hydrogel also possesses high ionic conductivity (1.93 S m–1). As a strain sensor, the hybrid hydrogel exhibits excellent sensitivity (gauge factor = 1.95), a large response range (0–658.32%), remarkable cycling stability, and good adhesiveness, suitable for monitoring various human activities, especially pulse monitoring and speech recognition. Moreover, the inclusion of CaCl2 and glycerol provides the hybrid hydrogel with exceptional water-retention and antifreezing properties, enabling practical usage in severe environments. This work provides effective ideas for the design of ionic conductive sensors with high strength, high sensitivity, adhesiveness, and ambient stability, which have potential applications in multifunctional and wearable electronics.