Ultrastretchable, Temperature-Responsive, Wearable Ionic Conductive Hydrogel for Multifunctional Sensing Applications

Conductive hydrogels have attracted considerable attention for constructing flexible electronics due to their excellent flexibility, conductivity, and biocompatibility. However, the application scenarios of most hydrogel sensors are hampered by their limited stretchability, weak adhesion, and single-mode strain sensing. Herein, we synthesized a multifunctional ionic conductive PNAS/Fe3+ hydrogel by introducing a thermosensitive P(NIPAM-co-AM) network into homogeneous sodium alginate(SA)/gluconolactone(DGL)/Fe3+ dispersions. The PNAS/Fe3+ hydrogel displayed ultrahigh stretchability (1412%), good repeatable adhesion, high sensitivity (GF = 4.7, ∼1400%), fast response, and cyclic stability, which can accurately detect multiscale human movements, monitor temperature/pressure changes, obtain overall machine learning-assisted gesture recognition accuracy of 98.9%, and acquire tiny electrophysiological signals such as EMG and ECG. More interestingly, the self-sensing hydrogel actuator was fabricated by further unilateral Fe3+ cross-linking of the PNAS/Fe3+ hydrogel to form a double-layer structure with thermosensitive modulus mismatch. This research provides a fresh perspective for developing smart wearable electronic devices.