(MOTHERBOARD) In fishing terms, “catch and release” generally means first impaling with a hook and then nearly suffocating a fish. For engineers at MIT, it means delicately trapping a fish with water itself—albeit in gel form—and then releasing the “quite happy” victim, in the words of Xuanhe Zhao, the mechanical engineering professor that leads a group at MIT studying hydrogel “soft” robots. For the past five years, Zhao and colleagues have been perfecting hydrogel recipes ideal for tough and forceful but also soft and biocompatible robot manipulators.
The results of Zhao’s latest recipe, which are described in the current issue of Nature Communications, can be seen in the video below.
A hydrogel is more than just a soft robot. The soft robots we typically see—and there are a lot of them lately—are fashioned from materials like silicon. But because a hydrogel consists mostly of regular old water, it has the advantage of biocompatibility. A hydrogel might then be safer to use in biomedical settings.
Since hydrogel is basically water jelly, engineers have to prove that it can be useful for tasks like, well, gripping fish, which we might imagine to instead be an internal organ being gripped during surgery. A swimmy fish liver, say. Previous attempts at hydrogel actuators have been limited in this respect, according to Zhao, while the hydrogel gripper seen above is able to achieve up to 1 Newton in force with a response time of less than a second. Add to it the acoustic and optical camouflage that comes with being made out of mostly water—one of the material’s big selling points—and that goldfish didn’t have a chance.