Self-cleaning adhesive inspired by gecko feet

Researchers at the University of California, Berkeley are in the process of making synthetic adhesives that simulate gecko's ability, they are gradually taking solid steps. Their latest product is the first adhesive that can self-clean after each use without water or chemicals, very similar to the hairs on the gecko's legs.

Ron Fearing, professor of computer science and electrical engineering at the University of California Berkeley, and directed the new material manufacturing team, said: 'The new technology brings us closer to the robots that can works on all terrain. In the future they will be able to walk on walls or ceilings, in every environment, not just for each clean glass sheet '.

The process of making adhesives was published online in Langmuir, a journal published by the American Chemical Society covering many topics, including surface properties, nanostructures and materials. biological simulation.

For many years, scientists have been trying to develop artificial materials that simulate leg hairs to make them easy to reverse. Fearing's team earlier this year built another type of adhesive that mimics the ability of geckos using ultra-small polymers that adhere to and remove easily from clean surfaces.

But scientists say it is very difficult to reproduce geckos on non-clean surfaces but still keep their feet clean enough to walk on the wall. In 2005, the study was co-directed by Associate Professor of Biology Kellar Autumn of Lewis & Clark School (Portland, Ore.), In collaboration with one of the leading US experts in engineering gecko characterization techniques. For the first time, it was revealed that geckos can keep their feet clean and sticky because they release dirt in every step.

Researchers are building a synthetic adhesive that simulates the gecko's ability, it can clean itself after each use without using water or chemicals.This adhesive is very similar to the feathers on the gecko's legs.

Fearing said: 'This is in stark contrast to our understanding of adhesive tape, they are like magnet cleaners and cannot be reused. With our adhesives, we were able to create the first adhesive material but still self-clean it a little after each adhesion. '

In a study funded by the National Science Foundation, scientists at the University of California Berkeley have designed adhesives with a hard polymer made of micro-fibers. Using ultra-fine spheres of 3 to 10 micrometers in diameter to simulate dirt, researchers were able to demonstrate that microfibre is capable of pushing the spheres towards the end of the fiber when the adhesive does not cling. on any surface.

When the fiber is pressed against a smooth surface, the dirt will be more exposed to the surface than the microfiber. Because the adhesive force is equivalent to the contact area, the spheres stick better on the glass surface than the synthetic microfiber. Through each simulation step designed to bring the adhesion force equivalent to the gecko feet, more and more spheres are removed and clung to the surface. After 30 simulation steps, the adhesive removed 60% of smaller sized contaminants on the glass surface.

Jongho Lee, a graduate student at the University of California Berkeley in mechanical engineering and the lead author of the study, said: 'The new material can cling to surfaces but not all dirt. We were able to recover the cohesion of material samples after several steps'.

Larger contaminants are more difficult to remove because they attach to more micro-fibers, they attach to the microfibre more tightly than cling to the glass. According to researchers, to overcome this challenge they need to understand more features of gecko toes; For example, is the size of the distance between the legs of the hairs used in removing dirt.

According to Fearring, the next step of the study will take the ability to stick on rough surfaces as the focus.