Sinatra says that a contact pressure (the force created by two objects pushing away from each other) of 1 kilopascals (kPa) or more could potentially squish the fragile jellies. In order to keep the animals safe during capture, the robot needs to apply just the right amount of pressure. But the jellies easily escaped the grasp of the four-appendage device, so the scientists added two additional fingers on the top and bottom of the palm to ensure a firmer grasp. The scientists then ventured over to the New England Aquarium in Boston to test a four-fingered version of the device on three common species of jellyfish: the moon jelly, the blue blubber jelly, and the spotted jelly. Sinatra says it was able to perform 100 grabs before the fingers wore out. The team also tracked the bot’s durability. Speed was an important factor, too: If the arms closed too quickly, they could poke the jelly, but if they closed too slowly, it could slide out and float away. To gauge the bot's success, the researchers wanted to see whether the fingers could withstand the forces of the squirming animals.

Sinatra and her colleagues first practiced using the device on fake jellyfish in their lab. An air channel inside each finger can be pressurized, forcing the appendages to curl inward, and the soft exterior silicone coating of each finger is laced with a web of nanofibers that help direct which way they move. Sinatra's robot has six finger-like appendages that stretch out and delicately close around the fish.

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Harvard origami fish grabber