Robot made from pig gelatin biodegrades when no longer needed

An origami-inspired robot arm made with material from cotton plants and pigs biodegrades when no longer needed. Such a soft robot could be further developed to carry out medical procedures inside the body and then pass safely through it.

Soft robotics is a growing field because there are a number of applications where a hard, rigid device would be unsafe or unwelcome, such as when working in extremely tight spaces in machinery or in close proximity to – or even inside – people.

Most experimental soft robots are made with synthetic materials such as silicon rubber. Now, Hanqing Jiang at Westlake University in Zhejiang, China, and his colleagues have created a simple version from cellulose derived from cotton and gelatin from pigs, which then biodegrades harmlessly. It can be controlled by a computer and even act as a controller itself.

To make it, the researchers created a Kresling origami shape, forming a tube that can be compressed and bent side-to-side, and joined four of these modules together to make a rudimentary robotic arm 240 millimetres long. By tightening or loosening three equally-spaced threads running inside this arm, they were able to manipulate it in any direction using external motors.

The gelatin also acts as a sensor, changing electrical resistance under bending. By recording these resistance values, the scientists could determine exactly what position the arm was in at any time. They even demonstrated that a smaller construction of modules could be used as a joystick to input signals in a similar way, by passing changing resistance values to a small computer, and these signals could in turn be used to control another soft robotic arm.

“In the future we may have more robots on the planet than human beings, so there’ll be lots of waste,” says Jiang. “In landfill is where we need these robots to disappear.” Jiang says that the robot’s current materials degrade harmlessly in the environment, but slightly different ones would be needed for it to break down entirely within the human body.

Kaspar Althoefer at Queen Mary University of London says that soft robots could be useful in a range of applications, such as squeezing into tight spaces in industrial processes, interacting safely with people or even in medical procedures, particularly surgery. “You could in such a scenario leave your tools behind, so to speak, without a problem,” says Althoefer. “I strongly believe soft robotics can go much further than where we are now. It’s still a fairly new area.”