MIT's new soft robot fish can execute change-of-direction escape maneuvers almost as quickly and efficiently as a real fish darts away from prey. Most robots are built with hard materials. Hard robots must be engineered to avoid collision, which limits their range of motion. But a soft robot -- not just donning a soft exterior, but designed with a soft interior of pulsing liquid tubes -- can replicate more fluid motions, like those of a fish. "We're excited about soft robots for a variety of reasons," said Daniela Rus, director of MIT's Computer Science and Artificial Intelligence Laboratory, who worked on the fish robot project. "As robots penetrate the physical world and start interacting with people more and more, it's much easier to make robots safe if their bodies are so wonderfully soft that there's no danger if they whack you." The self-contained and autonomous robot fish, which is made of rubbery silicone and can also glide slowly through the water, is powered by its tail. The tail features a CO2 canister that blasts air through tubing in the fish's body to affect the angles and movements of the soft structure. The fish was designed by MIT grad student Andrew Marchese, and engineered to actuality with the help of postdoc Cagdas D. Onal and Professor Rus. One weakness of this fish is the battery life. "The fish was designed to explore performance capabilities, not long-term operation," Marchese says. "Next steps for future research are taking that system and building something that's compromised on performance a little bit but increases longevity." Details of the scientists' research was published in the latest edition of the journal Soft Robotics.