High strength and anti‐swelling hydrogel strain sensors based on amphiphilic polyurethane assemblies for human‐motion detection

Hydrogel sensors are widely used in electronic skin, soft robotics, bioengineering, and medical therapy due to their excellent electrical conductivity, mechanical flexibility, and better biocompatibility. However, the swelling property of hydrogels has been hindering their application in underwater scenarios. Therefore, in this study, to address the anti‐swelling behavior of hydrogels, MXene nanosheets were modified by 1H,1H,2H,2H‐perfluorooctyltrimethoxysilane and then compounded with acrylamide and polyurethane to obtain multifunctional conductive hydrogels (PAM‐WPU/FMX hydrogels). Through the synergistic effect of chemical cross‐linking and hydrogen bonding on the gel network, the hydrogel sensor was characterized by strong resistance to swelling (swelling ratio = 2.22), excellent mechanical properties (strain at break after swelling equilibrium = 418.6%), and high strain sensitivity. For underwater applications, this study offers a model technique for the quick gelation of strong, swelling‐resistant hydrogels. Highlights Amphiphilic polyurethane micelles provided energy dissipation. Modified MXene was hydrophobic and electrically conductive. The strain of the hydrogel obtained after MXene modification was enhanced. The structural recovery capacity of both hydrogels was more than 60%. The modified hydrogel swollen but still had excellent sensing properties. Diagrammatic representation of (A) the preparation of the FMXene(FMX), and (B) the fabrication process of the PAM‐WPU/FMX hydrogels.