A team at the Max Planck Institute for Metals Research in Stuttgart has developed a new adhesive material mimicking inflated-pinned microhairs found on the soles of many animals, like many insects, spiders or gecko lizards.

The material's special surface structure allows it to stick to smooth surfaces without any adhesives. This material can be applied from reusable adhesive tape to soles for climbing robots. This kind of hairs allows many animals to climb walls or walk on ceilings. And some geckos can be 35 cm long!

The hair's shape is also important; spatula-shaped ends on the hairs give the strongest adhesion. The first surfaces created were not effective adhesives. Now, the scientists have made big advances in mimicking the biological device. They have developed a new material with excellent adhesive qualities, based on the beetles' sole. Their model presents very small, especially shaped hairs reminiscent of tiny mushrooms. This new model could have hundreds of applications and does not leave any visible marks, and which can be easily cleaned with soap and water.

Five square centimeters of the material can hold objects up to one hundred grams on walls, but this limit is much lower for ceilings. Smooth surfaces, like glass or polished wood, are good bases but woodchip wallpaper is not very suitable. "Insects also find it difficult to travel over slightly roughened surfaces - it's a fundamental problem for adhesion mechanisms," explained Project Leader Stanislav Gorb.

The new material could be used from protective foil for delicate glasses to reusable adhesive fixtures for mirrors, cupboards and windows. It will soon be industrially processed in the manufacture of glass components and it has already performed in higher weight categories: the artificial adhesive fibers on the soles of a 120 gram robot helped it to climb a vertical glass wall. The scientists are still looking for improvements. "However, there's still a lot of work to be done by the Working Group. Something that functions smoothly in the laboratory is a long way away from large-scale production," explained Stanislav Gorb, member of the research team.

Photo credit: Max Planck Institute for Metal Research