Although many robotic grippers have humanlike fingers, they often do not have the dexterity, flexibility, or affordability needed for industrial applications. Researchers at the Southwest University of Science and Technology and Tsinghua University in China recently took their inspiration from an unlikely source — a doughnut-shaped sea anemone.

The scientists recently demonstrated a robotic gripper that mimics how a sea anemone catches its prey. The bionic torus captures and releases objects by crimping its skin. Not only is is the grasper relatively cheap and easy to produce, but it also can grab a variety of objects of different sizes, shapes, weights, and materials. They discussed their work in last week’s Applied Physics Letters, from AIP Publishing.

“In industries, multi-fingered dexterous hands are widely used to perform grabbing tasks,” said author Weifeng Yuan. “However, these end effectors consist of a large number of components, like joints and sensors, which are difficult to control.”

Rolling skin like that of a sea anemone

The thermoplastic rubber skin that lines the exterior of the liquid-filled ring rolls inward when the inner skin of the gripper experiences a pulling force, sucking in whatever target being grabbed.

Researchers can adjust various features of the torus, such as the rolling direction and length of the skin, to control whether items are engulfed, swallowed or released.

“We found that sea anemones can capture sea creatures with different shapes and sizes, so we decided to investigate the mechanism of the predation strategy, and we believed that the study would be helpful to the design of adaptive soft graspers,” Yuan said.

The group demonstrated the device by latching onto objects, ranging from a piece of cloth to a cellphone to a glass beaker filled with liquid.

A delicate touch for novel applications

Yuan said a flexible gripper has the potential to grasp fragile objects in narrow spaces or extreme, high-pressure environments, such as collecting samples of deep-sea organisms or conveying pipes. What’s more, the grasper can also be built on the nanoscale to manipulate individual cells. Yuan said he sees potential in developing surgical instruments.

“Our grasper can grasp a steel bar from a table one minute and an egg from a basket the next without resetting control parameters,” Yuan said.

The researchers said they hope to continue fleshing out the potential for such a unique device, such as increasing the strength-to-weight ratio by using air instead of liquids.