Researchers from City University of Hong Kong have created a caterpillar-inspired robot that folds, rolls, grabs and degrades.

This so-called millirobot, which is composed of a gelatin solution combined with iron oxide microparticles, is being eyed by its developers for drug delivery and other biomedical applications.

When placed above a permanent magnet, the material of the millirobot causes the microparticles to push the gelatin outward in line with the magnetic field, thereby creating insect-like legs. Further, the hydrogel was placed in the cold to solidify it and then soaked in ammonium sulfate to encourage cross-linking in the hydrogel, further fortifying it.

The researchers suggest that altering various factors — the composition of ammonium sulfate, the thickness of the gel or the strength of the magnetic field, for instance — could potentially enable fine tuning properties of the gel and thus the capabilities of the millirobot.

Additionally, the iron oxide microparticles formed magnetic chains within the gel, and when a magnet was moved near the hydrogel, it caused the legs to bend and produce a claw-like grasping motion.

In the lab, the material was used to grip and carry a 3D-printed cylinder and a rubber band. Likewise, the researchers demonstrated that the millirobot could successfully deliver a drug by coating it in a dye solution, then rolling it through a stomach model, eventually reaching its destination, unfurling and releasing the dye via the strategic use of magnets.

Unlike current iterations of millirobots that are composed of silicone and therefore need to be surgically retrieved once released in the body, this new gelatin iteration degrades in just two days, according to its developers, leaving behind only the tiny magnetic particles.

The research is detailed in the article, Soft Tunable Gelatin Robot with Insect-like Claw for Grasping, Transportation, and Delivery, which appears in the journal ACS Applied Polymer Materials.

For more information, watch the accompanying video that appears courtesy of the American Chemical Society.