Putting a twist on gecko-inspired robot

The subtle adhesive forces that allow geckos to cling to walls and walk across ceilings have inspired researchers to build a robotic device that can pick up and release delicate materials without damage. The research team, based at Kyungpook National University and Dong-A University, has published their research work in Science and Technology of Advanced Materials, an international science journal. The researchers hope it can be applied to the transfer of objects by robotic systems.

A gecko’s foot is sticky because of its coating of tiny hairs, made of protein, called micro setae. These hairs are around 100 micrometres long and 5 micrometres in diameter. Each hair divides into a number of branches that end in flat triangular pads called spatulae, which are so small that their molecules interact with those of the surface the gecko is climbing. This creates weak forces of attraction between these molecules, which holds the gecko in place.

The gecko’s adhesive ability has drawn the attention of many researchers and inspired the use of its adhesion mechanism in robotics. There is an artificial, mushroom-shaped dry adhesive that mimics the mechanism, which has been used to robotically pick up materials. However, the force needed to detach this adhesive from the material’s surface can lead to damage, especially if it is a fragile material.

“In order to exploit these adhesive powers in robotic systems, it is imperative that the robot can not only pick up an object, but also readily detach from it to leave the object in its desired location,” said Seung Hoon Yoo, first author of the research article.

In the study, the team used a vacuum-powered device made of soft silicon rubber to resolve this detachment problem. A new detachment method was introduced, which involves a twisting and lifting motion that pulls the dry adhesive off of the fragile surface without causing any damage. According to the researchers, the addition of this twisting motion caused a tenfold reduction in the force required for detachment, which could be vital when handling delicate materials.

The researchers tested this by attaching their transfer system to a robotic arm, demonstrating that it could pick up a delicate glass disc from a sloping surface, move it to a different location and set it down without causing any damage to it.

Sung Ho Lee, an author of the study, said the researchers expect the method to garner interest from the industry. The team also hopes to serve as a bridge between research and industry by applying it to real industrial applications and developing more advanced models.

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