Stretchable and highly sensitive polyelectrolyte microgels-enhanced polyacrylamide hydrogel composite for strain sensing

In this study, a stretchable and highly sensitive polyacrylamide hydrogel was synthesized through polyelectrolyte microgels (PMGels) reinforcing strategy. PMGels acted as physical cross-linkers in hydrogels through hydrogen bonding and interpenetrating network interactions, which was conducive to improving the mechanical properties of the hydrogel. The tensile strength, tensile modulus, and fracture elongation of PMGels-9/PAAm-8 could reach 53.2 kPa, 24.6 kPa, and 565%, respectively. The hydrogel exhibited a denser porous structure with the introduction of the PMGels. The hydrogel sensor exhibited graded sensitivity based on the strain range. For example, the gauge factor (GF) was stable at 6.82 in the strain range of 250%–500%. Sensors based on the PMGels-enhanced hydrogel demonstrated the ability to stably detect subtle and large movements of the human body in real-time. The stretchable hydrogels have great potential in developing and applying next-generation wearable electronic devices.