Narrow passages speed up worm movement, offering clues for soft-robot design

A study by a physics group investigating active matter discovered that California blackworms travel through narrow channels more rapidly than through wider ones, overturning intuitive expectations. The researchers first created a stripped-down computer model of a flexible, self-propelled chain and noted that it consistently reached the end of a tight corridor faster than a broad one. To verify the simulation, they conducted physical trials using 12-centimeter channels ranging from 1 to 8 millimeters in width, finding that worms took nearly three times longer to exit the widest passages.

The speed advantage arises because confinement aligns the worms with the direction of motion, limiting side-ways turns and pauses that slow progress in spacious channels. These insights could inform the engineering of soft robots that must navigate confined environments, such as medical delivery devices or pipeline inspectors. The work highlights how active, self-moving filaments behave differently from passive polymers like DNA when confined.