Inspired by the movements of a tiny parasitic worm, engineers have created a 5-inch soft robot that can jump as high as a basketball hoop.
Their device, a silicone rod with a carbon-fiber spine, can leap 10 feet high even though it doesn’t have legs. The researchers made it after watching high-speed video of nematodes pinching themselves into odd shapes to fling themselves forward and backward.
The research appears in Science Robotics.
The researchers say their findings could help develop robots capable of jumping across various terrain, at different heights, in multiple directions.
“Nematodes are amazing creatures with bodies thinner than a human hair,” says Sunny Kumar, lead coauthor of the paper and a postdoctoral researcher in the School of Chemical and Biomolecular Engineering (ChBE) at Georgia Tech.
“They don’t have legs but can jump up to 20 times their body length. That’s like me laying down and somehow leaping onto a three-story building.”
Nematodes, also known as round worms, are among the most abundant creatures on Earth. They live in the environment and within humans, other vertebrates, and plants. They can cause illnesses in their host, which sometimes can be beneficial. For instance, farmers and gardeners use nematodes instead of pesticides to kill invasive insects and protect plants.
One way they latch onto their host before entering their bodies is by jumping. Using high-speed cameras, Victor Ortega-Jimenez—a lead author and former Georgia Tech research scientist who’s now a faculty member at the University of California, Berkeley—watched the creatures bend their bodies into different shapes based on where they wanted to go.
“It took me over a year to develop a reliable method to consistently make these tiny worms leap from a piece of paper and film them for the first time in great detail” Ortega-Jimenez says.
To hop backward, nematodes point their head up while tightening the midpoint of their body to create a kink. The shape is similar to a person in a squat position. From there, the worm uses stored energy in its contorted shape to propel backward, end over end, just like a gymnast doing a backflip.
To jump forward, the worm points its head straight and creates a kink on the opposite end of its body, pointed high in the air. The stance is similar to someone preparing for a standing broad jump. But instead of hopping straight, the worm catapults upward.
“Changing their center of mass allows these creatures to control which way they jump. We’re not aware of any other organism at this tiny scale that can effectively leap in both directions at the same height,” Kumar says.
And they do it despite nearly tying their bodies into a knot.
“Kinks are typically dealbreakers,” says Ishant Tiwari, a ChBE postdoctoral fellow and lead coauthor of the study. “Kinked blood vessels can lead to strokes. Kinked straws are worthless. Kinked hoses cut off water. But a kinked nematode stores energy that is used to propel itself in the air.”
After watching their videos, the team created simulations of the jumping nematodes. Then they built soft robots to replicate the leaping worms’ behavior, later reinforcing them with carbon fibers to accelerate the jumps.
Kumar and Tiwari work in Associate Professor Saad Bhamla’s lab. They collaborated on the project with Ortega-Jimenez and researchers at the University of California, Riverside.
The group found that the kinks allow nematodes to store more energy with each jump. They rapidly release it—in a tenth of a millisecond—to leap, and they’re tough enough to repeat the process multiple times.
The study suggests that engineers could create simple elastic systems made of carbon fiber or other materials that could withstand and exploit kinks to hop across various terrain.
“A jumping robot was recently launched to the moon, and other leaping robots are being created to help with search and rescue missions, where they have to traverse unpredictable terrain and obstacles,” Kumar says.
“Our lab continues to find interesting ways that creatures use their unique bodies to do interesting things, then build robots to mimic them.”
Support for the work came from the National Institutes of Health and the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the view of any funding agency.
Source: Georgia Tech
