Skin-inspired High-strength, Adhesive, Healable and Smart Thermoregulation Hydrogel Sensor for Multi-Sensing via One-pot PET-RAFT

Currently, smart hydrogel sensors with excellent physicochemical properties and exceptional sensitivity to muliti external stimuli demonstrate considerable potential in various simulation of human skin’s functions. In this study, a poly(N-isopropylacrylamide) (PNIPAM)/polypyrrole (PPy) and para-aramid nanofibers (ANFs) composite hydrogel (NPAH) was synthesized under ultraviolet irradiation using Photoinduced Electron Transfer Reversible Addition-Fragmentation Chain Transfer (PET-RAFT) technology. The incorporation of PPy and ANFs resulted in a substantial enhancement of hydrogel mechanical strength, from 0.1069 MPa for the PNIPAM hydrogel (NH) to 0.9190 MPa for the NP58A4H composite. Furthermore, NP58A4H exhibited remarkable self-healing (91% tentile strength recovery after 6 h healing) and potent adhesive properties (enhanced contact with the material interface) when adhering to various substrates. The NP58A4H sensor demonstrated an effective response to temperature (Relative resistance change is 1.2 %/℃) and strain (GF=1.37) variations, as well as the capacity to detect tension and monitor human movement. Moreover, the photothermal conversion capability of PPy accelerated the lower critical solution temperature (LCST) phase transition of PNIPAM to 31.9 °Cand it possessed selectivity in transmitting light in the visible band of solar radiation and could complete the ‘‘transparent-opaque’’ transition to realize the thermoregulation up to 9.6 °C temperature difference. The proposed NP58A4H with excellent integrated property, especially the highly mechanical strength, self-healing, self-adhesive and sensitive dual-sensing for temperature and strain, shows great potential for simulation of human skin to perception of touch, pressure and ambient temperature simultaneously, indicating promising applications in the fields of wearable healthcare, human-machine interfaces, and intelligent thermal management.