In the future, the robot that assembles your phone or car might have fingers based on the awesome sticking power of gecko feet.

A team of German researchers has created a microstructured composite that uses UV light to stick and unstick, allowing it to lift delicate equipment without leaving adhesive residue. And if you wanted to build something bigger, the gecko-inspired adhesive can lift things as large as an adult man. Their research, published in Science Robotics on Wednesday takes gecko-inspired transportation to a new level.

The microstructure used by Emre Kizilkan, one of the researchers on the team and an engineer at the Christian-Albrechts-Universität, in this composite is a series of microscopic silicon pillars that are shaped like mushrooms. These mushroom sticky-feet have been used in other adhesives, and several meters of the surface can lift hundreds of pounds — they just didn’t want to let go of the things they stuck to.

“This was the first step in these bio-inspired adhesives and the next step was to control it,” Kizilkan tells Inverse.

The stickiness of gecko toes has inspired an entire field of research.
The stickiness of gecko toes has inspired an entire field of research.

Geckos simply use their muscles to change the structure of their toes to stick and unstick, and so the team looked for a way to imitate this mechanism. This shape change was the key, says Kizilkan. “By controlling the contact areas of the microstructure we can control the adhesion.”

They decided to combine the microstructure with a liquid crystalline elastomer – a structure that is solid most of the time, but can easily change its shape when stimulated. The azobenzene structure the team decided to use actually bends the shape of its molecules when exposed to UV light. This bending action forces the microstructure to peel off from what it’s stuck to, like the molecular equivalent to grabbing both ends of a bath mat and pulling the suction cups up off from the bottom of the tub.

The azobenzene molecule changes shape when it's hit with UV light, bending and releasing the sticky surface.
The azobenzene molecule changes shape when it's hit with UV light, bending and releasing the sticky surface.

With the two layers, the adhesive is easily controlled, as a single UV light source is enough to create a shape change. Removing the UV light restores the gecko-sticky to its original shape, ready to grab on to its next target. Kizilkan says he imagines this technology being of particular importance in robotics, especially in clean room facilities where transporting parts without having to clean them before assembly can be tricky.

Bio-inspired methods of movement can add flexibility to robotics, and over the last ten years, an entire field of gecko-toe inspired research has developed. In the United States, the creation of dry self-cleaning adhesives based on geckos had $30 million of grant funding in 2010 alone.

So these little guys are more than just a cute insurance cartoon — they’re inspiring a movement revolution.

Photos via Stanislav N. Gorb, Emre Kizilkan and Jan Strueben, Getty Images / Carl Court

Dyani Sabin is a science writer from small-town Ohio transplanted to New York City. Former biology researcher and library supervisor, you can also find her writing at Scienceline.

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