The actuation mechanism of typical soft actuating materials. (A) When subject to high voltage, a strong electrostatic interaction is generated between two electrodes, compressing the film in the thickness direction and expanding it in the area. Reprinted with permission from Ref [6]. (B) After being deformed at a high temperature and fixed into a temporary shape after cooling, shape memory polymer (SMP) can recover to its permanent shape upon heating. Reprinted with permission from Ref [9]. (C) Magnetic soft material (MSM) with programmed magnetic domains exhibits complex shape changes under external magnetic field stimulus. Reprinted with permission from Ref [10]. (D) Thermal stimulated isotropic volumetric change of poly(N-isopropylacrylamide) (PNIPAAm) hydrogel. Reprinted with permission from Ref [14]. (E) Upon thermal stimuli, LCE undergoes the nematic-isotropic phase transition, causing a large contraction in the alignment direction. Reprinted with permission from Ref [15].