Spatula
Spatulae (singular: Spatula , lat. "Shovels") are spatula-shaped adhesive hairs that help to geckos can stick to smooth surfaces. They form the smallest level of a three-part, hierarchically ordered adhesive system, in which the spatulae are responsible for direct contact with the surface.
Each of the billion hairs per gecko foot is about 200 nanometers wide and long. The thickness is ten to 15 nanometers. This only offers space for five to six keratin molecules next to each other . 100 to 1000 spatulae form the tip of individual setae (lat. Bristles). The setae, which are about 100 micrometers long and 250 nanometers thick, are lined up in a row to form the foot lamellae, which can be seen with the naked eye and are about 400 to 600 micrometers long.
The very small ramifications make the structure very "supple", so that it adapts to even the smallest bumps in the subsurface. Moisture increases the effect of the spatulae, whereby the geckos do not use their own secretions, but naturally occurring surface moisture.
Geckos only need 15 microseconds to detach themselves without effort. They turn their toes upwards so that the setae are at an angle greater than 30 degrees to the ground, with the foot becoming detached. When the foot is raised, the toes are curved to prevent the spatulae from sticking together. When the geckos appear again, the foot is pressed slightly against the direction of movement, so that the setae fold over and their angle to the ground is less than 30 degrees. The tips of the setae are now parallel to the ground, which means that all spatulae are now hermetically attached to the ground. The Van der Waals forces now appearing provide stability.
Web links
- Images of lamellae, setae and spatulae ( Memento from February 28, 2009 in the Internet Archive )
- Gerrit Huber, Hubert Mantz, Ralph Spolenak, Klaus Mecke, Karin Jacobs, Stanislav N. Gorb, Eduard Arzt: Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurement. Proceedings of the National Academy of Sciences 102/45, 16293-16296, doi: 10.1073 / pnas.0506328102
Individual evidence
- ↑ a b c d Gecko's detention apparatus (PDF; 187 kB)
- ↑ a b Dieter M. Humbel: Anatomy of the Geckofusses ( Memento from October 14, 2013 in the Internet Archive )
- ↑ a b c Max Planck Society: Hairy feet stick better to a damp blanket, November 8, 2005 , accessed on August 27, 2013