Getting a grip on tree frog attachment: Structures, mechanisms and biomimetic potential
Tree frogs are versatile climbers that live in elevated habitats. These animals use sticky pads at the tips of their toes to move safely over various substrates, seemingly unaffected by a slippery mucus layer on the skin and by the high mechanical loads that occur during jumping. Julian Langowski, PhD candidate at the Experimental Zoology Group (WUR), had a closer look at the toe pads of tree frogs. He found evidence that the patterned pad surface allows tree frogs to drain the mucus. Consequently, the pads conform closely enough to the substrate to generate intermolecular attachment forces between pad and substrate, so called van der Waals forces. Further, he discovered connective tissue which links the adhesive pad surface to the internal skeleton and strengthens the pads against mechanical loading. The findings of this study may inspire the design of novel biomimetic adhesives that stick as well as tree frogs do.