Fig. 9. Dispersion and splitting of the microrobot collective.

a Representative images of a collective transitioning from Y chains to GaSPP to explore the available area. b Collective disperses using the rotation mode (70 Hz) within a quadrotor-shaped object; the collective expands and rotates the object about its center. c transition from rotation mode to GaSPP mode; the collective expands but does not rotate the object. d Collective splits into two groups by forming chains along a boundary and then transitioning to rotation mode. e Demonstration of a collective splitting between two sides through GaSPP and then returning to the same side through gradient-assisted X chain locomotion. The brightness of the images in (a–e) is enhanced using photoshop for better visualization. The symbols on top of the sub-images in (a–e) represent the mode the collective exhibits. These symbols correspond to those shown in Fig. 1a. The sub-images in (b, c) and (e) are labeled at the bottom with the function that the collective performs.