fig1

Figure 1. Schematic illustration of the design strategies for reversible deformation of hydrogel actuators. Design strategies (purple panel): Oriented structure. Reproduced with permission^[40]. Copyright 2023, Wiley-VCH. Gradient structure. Reproduced with permission^[41]. Copyright 2022, Royal Society of Chemistry. Layered structure. Reproduced with permission^[42]. Copyright 2023, American Chemical Society. Patterned structure. Reproduced with permission^[43]. Copyright 2023, Wiley-VCH. Multifunctional applications (orange panel): Information encryption. Reproduced with permission^[44]. Copyright 2022, Elsevier. Sensor, Reproduced with permission^[45]. Copyright 2023, Elsevier. Gripper, Reproduced with permission^[46]. Copyright 2019, Wiley-VCH. Mechanical arm. Reproduced with permission^[32]. Copyright 2019, Springer Nature Publishing Group.