Fig. 2. Scale of the semi-aquatic organisms and morphological design of the robotic insect.

a A relationship between the body length and Weber number of animals jumping on water. b A large-scale robotic insect consisting of a shape memory alloy spring actuator and four semi-cylinder feet. The robot is designed large size (Body length = 280 mm) that is ten times larger than a water strider (Body length = 28 mm) for drag propulsion. c Lamination and folding steps of the drag pad. A lateral drag pad for the directional jump is attached to the bottom of the forefoot. Scale bar, 20 mm.