Ultra-soft robotic grippers are gentle enough to catch jellyfish
If you've had trouble picking up your pet jellyfish with your deep-sea submersible, take heart. Researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and Baruch College at City University of New York have developed ultra-soft, ultra-gentle robotic grippers with fettuccine-like hydraulic fingers that can grasp and release jellyfish and other very soft marine animals without harming them.
With their simple, yet remarkable anatomy and physiology, jellyfish are of great interest to marine biologists and other scientists, but studying them in the deep sea is tricky because, being 95 percent water, they're as fragile as, well, jelly. This makes collecting and handling them difficult because conventional robotic manipulators with their hard, steel claws don't so much grip the jellyfish as shred them.
In recent years, Harvard University and others have developed a series of soft grippers that can be used by deep-diving biologists to collect soft-bodied animals like sea cucumbers or brittle ones like corals. Unfortunately, many species of jellyfish are so fragile they need exceptionally gentle manipulators that don't so much grip as softly cuddle the creature.
According to the Harvard team, the new ultra-soft gripper consists of six fingers made out of flat, pasta-like silicone, which has a hollow channel inside that is bonded to a layer of flexible yet stiff polymer nanofiber. These are attached to a 3D-printed plastic palm that pumps water into them. As the channels fill, each one curls with a pressure of a mere 0.0455 kPA. That's less than 10 percent of the pressure of a human eyelid on the eye and over 22 times less than marine manipulators.
For testing, the team started with artificial silicone jellyfish in a lab tank to study the gripper's basic functions, as well as its precision, positioning, and the best angle and speed at which to capture a jellyfish. This graduated to the New England Aquarium, where they were used to catch and release golf-ball-sized swimming moon jellies, jelly blubbers, and spotted jellies, showing that the animals could be grasped securely and gently without harming or stressing them.
"Marine biologists have been waiting a long time for a tool that replicates the gentleness of human hands in interacting with delicate animals like jellyfish from inaccessible environments," says David Gruber, a professor of biology and environmental science at Baruch College. "This gripper is part of an ever-growing soft robotic toolbox that promises to make underwater species collection easier and safer, which would greatly improve the pace and quality of research on animals that have been under-studied for hundreds of years, giving us a more complete picture of the complex ecosystems that make up our oceans."
The research was published in Science Robotics and the video below discusses the ultra-soft gripper.