Natural-Scale Snail Robot Is Powered by Light

A soft snail robot, developed by a team at the University of Warsaw with colleagues from Xi'an Jiaotong-Liverpool University, is capable of mimicking the adhesive locomotion of snails and slugs on a natural scale. The bioinspired robot is made from liquid crystalline elastomer (LCE), a smart material that can change its shape under different stimuli, including illumination with visible light. The 10-mm-long robot’s functionality is based on the optomechanical response of an LCE continuous actuator. It harvests energy from a laser beam.

Photo of the snail robot next to a garden banded snail (Cepaea hortensis). Courtesy of UW Physics.

The traveling deformation of the robot’s soft body is generated by a local light-induced phase transition in the LCE and the robot’s interaction with an artificial mucus layer composed of glycerin. The robot’s movement resembles the pedal waves of terrestrial gastropods. It is able to move efficiently in a variety of configurations: on horizontal, vertical, and upside-down surfaces; on smooth and rough surfaces; and through obstacles comparable in size to its dimensions. It can crawl at the speed of a few mm per minute, about 50 times slower than snails of comparable size. Like a biological snail, it can climb up a vertical wall, on a glass ceiling, and across obstacles.

Piotr Wasylczyk, head of the Photonic Nanostructure Facility at the University of Warsaw, said that despite the snail robot’s slow speed, need for constant lubrication, and low energy efficiency, it could offer insight into the application of micromechanics with smart materials and could provide a platform for studying adhesive locomotion. A new generation of smart materials, together with novel fabrication techniques, could further the exploration of small-scale soft robotics.

The research was published in Macromolecular Rapid Communications (https://doi.org/10.1002/marc.201900279).

The snail robot crawling over an obstacle (real time and fast forward). Courtesy of UW Physics.