In a laboratory in Connecticut, a palm-sized silicone robot scrunches up its body to inch forward in a caterpillar-like motion. A brick tips over onto its leg, trapping it as it struggles to move on.
A few seconds later, the body wriggles away, leaving one of its legs lying motionless under the brick.
The robot, which can amputate its limbs — just like a gecko can release its tail when it is grabbed by a hungry predator — is the creation of researchers at Yale University.
The main innovation is the robot’s joints. The substance that holds them together has a rubbery consistency at room temperature. When it’s heated up, it becomes more liquidlike, allowing the limb to break off.
The joint works in reverse too. Different pieces can be fused together to create a multi-module machine. In the Yale laboratory, three robots join to cross a gap that’s too wide for one to bridge on its own.
Most modern robots have been made with hard materials, like metals and plastics. But interest is growing in “soft” robots built from pliable materials. Proponents say their flexibility allows them to navigate tight spaces and difficult environments, or to take on delicate tasks better than their rigid counterparts.
Yale’s gecko-inspired robot’s ability to reconfigure itself creates a soft robot that’s even more adaptable. “We can edit the robot’s functionality?on?demand,” said Bilige Yang, a graduate researcher at the Department of Mechanical Engineering and Materials Science, who led the research into the robot that was published in the journal Advanced Materials in late May.
Shape-shifting soft robots
Today, soft robots are used for things like strawberry picking, but they aren’t yet widespread, Yu Jun Tan, an assistant professor at the National University of Singapore (NUS), who is not involved in Yang’s research, told CNN.
But roboticists around the world are working on soft robots, often inspired by nature, to tackle a variety of tasks – from a tiny, starfish-like device for carrying medicine into the twisty human intestine, to a jellyfish-inspired soft machine for underwater exploration.
Tan, who works on materials for soft electronics and soft robotics, says that Yale’s robot is the first self-amputating, self-reconfigurable soft robot she’s seen. “It’s a very, very interesting innovation that can be used across different fields,” she said.
She added that she hopes to see the joint used with robots made with biodegradable materials, for minimum impact in the environment where an amputated part is left.
According to Yang, nature has developed its own solutions “And we can really take inspiration instead of starting from scratch.”
A soft robot that can leave a limb behind could be helpful in search and rescue missions in dangerous rubble, and planetary exploration on treacherous terrain, said Yang.
“What if a soft robot is just minding its own business walking in the wild, but then some part of it is trapped under a rock?” he questioned. “How does the rest of the robot continue on to finish its mission?”
Yang and his colleagues plan to incorporate their innovations into other soft robots they’re working on in the Yale lab, allowing them to become parts in larger modular systems, shapeshifting depending on the task at hand, and adding capabilities as they go.
He gives an example of a robot that doesn’t have enough computational power to process the inputs from the environment it’s working in being able to pick up an extra microprocessor and integrate it. “We can now adapt soft robots … after?the robot is underway for its tasks,” he said.
Next up? Yang and others at Yale are working on a robotic turtle that can transition from land to water smoothly, with legs that can change from the rounded limbs of a tortoise to the flexible, flat legs of a sea turtle.
Additional reporting by Alex Rodway.