How geckos keep firm grip even on wet surfaces
Geckos are known for their sticky adhesive toes that allow them to stick to, climb on, and run along surfaces in any orientation.
Washington: Geckos are known for their sticky adhesive toes that allow them to stick to, climb on, and run along surfaces in any orientation - even upside down - and until recently it was a mystery how they kept their unique ability even on wet surfaces.
A 2012 study in which the reptile slipped on wet glass had perplexed scientists, who were trying to unlock the key to gecko adhesion in climates with plentiful rain and moisture.
The mystery has now been solved with a study showing that wet, water-repellent surfaces, like those of leaves and tree trunks, actually secure a gecko`s grip in a manner similar to dry surfaces.
Researchers from the University of Akron, led by integrated bioscience doctoral candidate Alyssa Stark , tested the lizard on four different surfaces.
The surfaces ranged from hydrophilic - those that liquids spread across when wet, like glass - to hydrophobic - water-repellent surfaces on which liquids bead, such as the one the natural leaves geckos walk on - and intermediate ones, like acrylic sheets.
They were tested on these surfaces both when these surfaces were dry and when they were submerged underwater, and water completely covered the gecko`s feet.
Fitting a small harness around the pelvis, geckos were gently pulled along the surface until their feet began to slip and at this point the maximum force with which a gecko could stick was measured.
On wet glass they slipped and could not maintain adhesion to the surface. However, when tested on more hydrophobic surfaces, they stuck just as well to the wet surface as they did to the dry ones.
They stuck even better to a wet Teflon than they did to the dry one.
The study has been published in the Proceedings of the National Academy of Sciences.