Ultrasensitive and Highly Stretchable Multiple‑Crosslinked Ionic Hydrogel Sensors with Long‑Term Stability

Flexible hydrogels are receiving significant attention for their application in wearable sensors.However,most hydrogel materials exhibit weak and one-time adhesion,low sensitivity,ice crystallization,water evaporation,and poor self-recovery,thereby limiting their application as sensors.These issues are only partly addressed in previous studies.Herein,a multiplecrosslinked poly(2-(methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium hydroxide-co-acrylamide)(P(SBMA-co-AAm))multifunctional hydrogel is prepared via a one-pot synthesis method to overcome the aforementioned limitations.Specifically,ions,glycerol,and 2-(methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium hydroxide are incorporated to reduce the freezing point and improve the moisture retention ability.The proposed hydrogel is superior to existing hydrogels because it exhibits good stretchability(a strain of 2900%),self-healing properties,and transparency through effective energy dissipation in its dynamic crosslinked network.Further,2-(methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium hydroxide as a zwitterion monomer results in an excellent gauge factor of 43.4 at strains of 1300-1600%by improving the ion transportability and achieving a strong adhesion of 20.9 kPa owing to the dipole-dipole moment.The proposed hydrogel is promising for next-generation biomedical applications,such as soft robots,and health monitoring.