Octopus suckers inspire new technique for grasping objects underwater

For the past few years, Virginia Tech scientists have been looking to octopuses for inspiration to design technologies that can better control a wide range of objects in underwater environments. Their latest breakthrough is a special switchable adhesive modeled after the shape of animal lollipops, according to a new paper published in the journal Advanced Science.

“I’m amazed how an octopus can in one moment grab something so tightly, and then immediately release it. It does this underwater, on rough, curved, irregular objects, and that’s a remarkable achievement.” said co-author and research group leader Michael Bartlett. “We are now closer than ever to replicating the amazing ability of the octopus to precisely grasp and manipulate objects, opening up new possibilities for exploration and manipulation in wet or underwater environments.”

As mentioned previously, there are many natural examples of effective ways to attach to objects in underwater environments, according to the authors. For example, mussels secrete adhesive proteins to attach themselves to wet surfaces, while frogs have uniquely structured finger pads that create capillary and hydrodynamic forces for adhesion. But cephalopods, like octopuses, have an added advantage: the adhesion provided by their grippers can be quickly and easily reversed, so the creatures can adapt to changing conditions, attaching to wet and dry surfaces.

From a mechanical engineering point of view, the octopus has an active pressure-based system for adhesion. The wide outer rim of the straw creates a seal with the body via the pressure difference between the chamber and the surrounding medium. The muscles (which act as actuators) then contract and relax the concave area behind the rim to add or release pressure as needed.

There have been several attempts to imitate cephalopods when designing soft robotic grippers, for example. Returning to 2022, Bartlett and his colleagues wanted to go one step further and recreate not only switchable adhesion but also integrated sensing and control. And the result was Eight glovea wearable system for grasping objects underwater that mimics an octopus’s arm.

Improved Eight Gauntlet

For adhesion, they designed silicone stems covered with a pneumatically controlled membrane, to mimic the structure of octopus suckers. These adhesive elements are then combined with an array of LIDAR optical proximity sensors and microcontrollers to detect objects in real time. When the sensors detect an object, the suction cup is triggered, simulating the nervous and muscular system of an octopus. The team used a neoprene wetsuit glove as the base for the wearable glove, incorporating adhesive elements and sensors into each finger, with flexible air tubes inserted into the base of the adhesive elements.