Fig. 2: Surface characteristics and magnetic response performance of the JO-robot.

a Images of the JO-robot. The carbonyl iron particles inside the JO-robot are arranged in chains. The chains are perpendicular to the long side of JO-robot, which makes the JO-robot to tumble around the long side. The 3D surface topography image shows the shallow creases on the JO-robot, which can guide the JO-robot to fold when wrapping the droplet. Scale bars are 1 mm (left) and 100 μm (right). b The SEM images and 3D surface topography images of the two surfaces of the JO-robot. The modified surface is rough and covered with microbumps while the unmodified surface is relatively flat. Scale bars are 50 μm. c The lateral adhesion force of the two surfaces of JO-robot (by sliding the droplet horizontally on the surface) d The schematic diagram and front view images of the movement of JO-robot and JO-robot with droplet in a tumbling cycle. Scale bars are 2 mm. e-h The tumbling angle and moving distance of (e), (f) JO-robot and (g), (h) JO-robot with droplet versus magnets array moving distance. The inset schematics show the definition of tumbling angle and moving distance. The error bars in (e), (g) represent the standard deviation of five independent measurements and the error bars in (f), (h) represent the standard deviation of three independent measurements. Source data are provided as a Source Data file.