Self-Propelled Robots Paddle through Water - No Motor, Servo, or Battery Needed

Engineers at Caltech  and ETH Zurich have created robots capable of self-propulsion without using any motors, servos, or power supply. These first-of-their-kind devices paddle through water as the material they are constructed from deforms with temperature changes. The propulsion system relies on strips of a flexible polymer that is curled when cold, and stretches out when warm. The polymer is positioned to activate a switch inside the robot's body, that is in turn attached to a paddle that rows it forward like a rowboat. The switch is made from strips of an elastic material.