Small, Swimming Robots Self-Heal Magnetically After Breaking into Pieces

Living tissue is known to heal itself even after several injuries. However, it has been highly difficult to impart similar abilities to artificial systems like robots.

Scientists have now created small swimming robots with the ability to magnetically heal themselves on-the-fly after getting disintegrated into two or three pieces. They note that someday, this approach could help make more robust devices for industrial or environmental clean-up. The study results have been reported in the Nano Letters journal from ACS.

The researchers have created small robots with the ability to “swim” through fluids and perform useful functions, like cleaning up the environment, performing surgery, and drug delivery. A majority of the experiments have been performed in the lab, but finally, these small machines would be released into hazardous environments, where they might be damaged.

Robots that can swim are usually developed with soft hydrogels or brittle polymers, which can easily tear or crack. Joseph Wang and his team intended to develop swimmers with the ability to self-heal when they move, without any aid from humans or other external triggers.

The researchers created fish-shaped swimmers with a length of 2 cm (about the width of a human finger) and containing a rigid, hydrophobic middle layer; a conductive bottom layer; and an upper strip of powerfully magnetic, aligned microparticles.

Platinum added to the tail reacted with hydrogen peroxide fuel to create oxygen bubbles, which helped propel the robot. When a swimmer was placed by the researchers in a petri dish filled with a weak hydrogen peroxide solution, it travels around the edge of the dish.

They then used a blade to cut the swimmer, and the tail continued to move around until it reached the rest of its body, thus reforming the fish shape through a powerful magnetic interaction.

Moreover, the robots could self-heal themselves upon being cut into three pieces, or even when the magnetic strip was positioned in different configurations. According to the researchers, the fast, flexible, and simple self-healing approach could be a crucial step toward on-the-fly repair for small-scale robots and swimmers.

Small, swimming robots can magnetically heal themselves after breaking into two or three pieces. Video Credit: American Chemical Society.

Journal Reference:

Karshalev, E., et al. (2021) Swimmers Heal on the Move Following Catastrophic Damage. Nano Letters. doi.org/10.1021/acs.nanolett.0c05061.

Source: https://www.acs.org/content/acs/en.html