fig4

From: Hydrogel actuators: from building blocks selection, anisotropic structures design to multifunctional applications

Figure 4. Hydrogel actuators based on pH-sensitive and electric-sensitive polymer matrices. (A) The bilayer hydrogel actuators based on cationic polymer matrices. Reproduced with permission^[62]. Copyright 2022, American Chemical Society; (B) Microfluidic device based on pH-responsive hydrogel actuator. Reproduced with permission^[63]. Copyright 2023, Molecular Diversity Preservation International; (C) The hydrogel actuator switch based on an anionic polymer matrix. Reproduced with permission^[65]. Copyright 2020, American Chemical Society; (D) Hydrogel actuator based on electrically responsive polymer matrix. Reproduced with permission^[70]. Copyright 2022, American Association for the Advancement of Science.