Researchers at Northwestern University in Illinois have demonstrated the world’s smallest remotely controlled walking robot, just half a millimeter wide. They can spin, crawl, walk, turn, and jump without hydraulics or electricity.

Robots are built using shape memory alloys, which are then deformed into the desired shape. Heating these alloys causes them to return to their original shape, and a thin glass coating can revert them to the deformed shape when heat is released.

The manufacturing process is pretty interesting – the team made the robots as flat structures with a heated state. They then glued the flat structures to the stretched rubber substrate, but at the points of the feet. The rubber was then loosened, reducing the robots’ support area and forcing them to rise from the surface in a controlled bending process, which put the robots in a final, three-dimensional “chilled” position where a glass coating could be applied. Hold the mold until it is heated.