Wheels built entirely from soft materials can help robots to roll over tricky terrain and resist damage.

Aaron Mazzeo and his co-workers at Rutgers University in Piscataway, New Jersey, built a squishy wheel inspired by the inching motions of soft creatures such as earthworms. A stretchable ring contains multiple internal chambers, groups of which can be inflated and deflated sequentially around the circle. The pressurized compartments exert torque on a second, outer ring, causing it to turn.

Credit: Wiley

A soft robotic vehicle fitted with four of these wheels (pictured) travelled on a flat surface at 3.7 centimetres per second and kept moving after being dropped from eight times its height. The researchers also drove the robot over a rocky landscape and underwater, and show that their concept can be modified to make winch rotors.

Adv. Mater. http://doi.org/f3qjsh (2016)