Fig. 2: Horsetail-inspired stabilized soft structure.

a A photo of the horsetail. b Unloaded and loaded states of the segment of the horsetail. c Corresponding cross-section of the segment under optical microscope observation reveals that the horsetail’s morphological concave strengthens the structural stability through increased turgor pressure under transverse compression. The deformation of the epicondyle (E) is smaller than that of parenchymatous tissue (PT) shown in the detailed views. The color bar indicates the strain in the parenchymatous tissue, where the warmer the color, the higher the strain the tissue has. The red arrows indicate the direction of pressure inside the horsetail under higher deformation of the parenchyma that strengthens the outer ring. The white arrows show the deformation direction of the shape of the inner ring and the outer ring. The experiment was repeated for 3 different samples. For each sample, the measurement was repeated 10 times. d Schematics of the origami chamber. e The prosthetic knee in the unloaded (left) and loaded (right) states, corresponding to the swing (left) and stance (right) phases during walking, respectively. f Detailed view of the origami chamber in the unloaded (left) and loaded (right) states. The red arrows indicate the direction of pressure inside the chamber that strengthens the knee structure. The black arrows show the deformation direction of the shape of the posterior part and the anterior part.