Fig. 2: Photocurable hydrogel actuator manipulation.

a The developed model of the stress and the strain for the photocurable hydrogel actuator. b Three-dimensional confocal micrographs of photocurable hydrogel under different stresses, scale bar is 300 μm. c The stress–strain and stress-recovery histograms of the photocurable hydrogel actuator. d The deformation–relaxation fluorescence micrographs of the photocurable hydrogel actuator and the three-dimensional light intensity distribution of the light spot, scale bar is 500 μm. e The light intensity distribution map of the photocurable hydrogel actuator before and after stress. f The inside and lateral spot analysis histograms of the photocurable hydrogel actuator under multiple compression measurements