A small robotic frog developed at Aarhus University can swim using six artificial muscles activated by light. Behind the achievement is a systematic approach that could help researchers develop muscles for the next generation of soft robots.

It has no motor, batteries or wires. Yet a small frog created using a 3D printer by Ph.D. student Cecilie Ryberg from the Department of Chemistry at Aarhus University can swim across the water’s surface.

It is not particularly fast. In laboratory experiments, it traveled 8 centimeters (3.1 inches) in almost two minutes. But what makes the frog interesting is how it moves.