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 an “ultra-soft, underwater gripper” that could catch and release jellyfish without harm.

According to the researchers, the gripper would help scientists collect and study an animal that has yielded impressive scientific discoveries such as green fluorescent protein that scientists now use to study gene expression, and life-cycle reversal that could play an integral role in combating aging.

“Our ultra-gentle gripper is a clear improvement over existing deep-sea sampling devices for jellies and other soft-bodied creatures that are otherwise nearly impossible to collect intact,” explains Nina Sinatra, a former graduate student in the lab of Robert Wood at the Wyss Institute.

“This technology can also be extended to improve underwater analysis techniques and allow extensive study of the ecological and genetic features of marine organisms without taking them out of the water.”

Using hydraulic pressure, the underwater gripper gently, yet firmly, wraps its fettuccini-like fingers around a single jellyfish, then releases it without causing harm.

The gripper has six “fingers,” which are attached to a rectangular, 3D-printed plastic “palm.” Made up of thin, flat strips of silicone with a hollow channel inside bonded to a layer of flexible but stiffer polymer nanofibers, the fingers curl in the direction of the nanofiber-coated side when their channels are filled with water.

According to the researchers, each finger exerts about 0.0455 kPA—or less than one-tenth of the pressure of a human’s eyelid on their eye—of pressure, which is far less than current state-of-the-art soft marine grippers, which exert about one kPA.

Fitted to a specially created, hand-held device, the gripper’s ability to grasp an artificial silicone jellyfish in a tank of water was tested to determine the positioning and precision, as well as the optimum angle and speed, at which to capture a jellyfish. The grippers were then tested at the New England Aquarium, where they were used to grab several golf ball-sized animals including swimming moon jellies, jelly blubbers, and spotted jellies.

The gripper successfully trapped each jellyfish against the palm of the device. The jellyfish were unable to break free from the fingers’ grasp until the gripper was depressurized, but once they were released, they showed no signs of stress or other adverse effects. Additionally, the fingers were able to open and close approximately 100 times before showing signs of wear and tear.

“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 2017-2018 Radcliffe Fellow, professor of biology and environmental science at Baruch College, and a National Geographic Explorer.

“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 latest innovation in soft robotics for underwater sampling, the underwater gripper is being developed as part of an ongoing collaboration between Gruber and Wood, a Wyss core faculty member, co-lead of the Wyss Institute’s Bioinspired Soft Robotics Platform, the Charles River Professor of Engineering and Applied Sciences at SEAS, and a National Geographic Explorer. Thus far, the collaboration has produced the origami-inspired RAD sampler and multifunctional “squishy fingers” to collect various hard-to-capture organisms such as squids, octopuses, and sponges.

“Soft robotics is an ideal solution to long-standing problems like this one across a wide variety of fields, because it combines the programmability and robustness of traditional robots with unprecedented gentleness thanks to the flexible materials used,” Wood says.

The team is continuing to improve the design of the ultra-soft gripper. To more definitively prove that the gripper does not cause the animals stress, the team plans on conducting studies that evaluate the jellyfishes’ physiological response to being held by the gripper.

During an expedition aboard the research ship Falkorin 2020, Wood and Gruber will conduct more tests of their various underwater robots.

“At the Wyss Institute we are always asking, ‘How can we make this better?’ I am extremely impressed by the ingenuity and out-of-the-box thinking that Rob Wood and his team have applied to solve a real-world problem that exists in the open ocean, rather than in the laboratory. This could help to greatly advance ocean science,” says Wyss Institute Founding Director Donald Ingber, who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and professor of bioengineering at SEAS.

Sinatra served as the first author of a new paper published in Science Robotics that describes the gripper. Gruber was a co-author, and additional authors included Clark Teeple, Daniel Vogt, and Kevin Kit Parker from the Wyss Institute and Harvard SEAS.