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Soft, edible robots that mimic real organisms could be used to deliver drugs to animals. That is just one potential application of a new material made from biodegradable gel.

“The question is, could we develop a material that is, at the same time, very reliable while you use it, but once triggered can completely degrade?” says Martin Kaltenbrunner at Johannes Kepler University Linz in Austria.

Kaltenbrunner and his colleagues created a gel out of ingredients that are safe to eat, including gelatine – which can be fully degraded by the body – citric acid to stop bacterial growth and glycerol for softness and to prevent dehydration.

The biogel is designed to be eaten by bacteria commonly found in waste water, meaning it will break down naturally if it ends up in landfill, for instance, but remain stable otherwise. In lab tests, the researchers found that the gel didn’t dry out or lose any of its properties for more than a year.

The researchers used the gel to make a robot that mimics an elephant’s trunk and found that it could withstand more than 330,000 cycles of non-stop movements without drying out or cracking.

They also integrated sensors to allow for feedback and control, adding a pressure sensor to another robot made from the gel, a toy elephant, that allowed it to grip objects with its trunk.

Since gelatine is edible, the biogel might also be useful in administering drugs to animals through the creation of a robot disguised as prey or food, says Kaltenbrunner. It could also be used to make safer children’s toys, he says. The electronics and sensors aren’t currently edible, however.

“Gelatine stands out for its versatility, ease of manufacturing and low cost compared to other biodegradable elastomers,” says Dario Floreano at the Swiss Federal Institute of Technology in Lausanne, Switzerland. “This work is important because it paves the way for a new generation of wearable sensors and computing devices.”