src: blog.nationalgeographic.org
The gecko foot has a number of specializations. Their surface can adhere to any type of material with the exception of Teflon (PTFE). This phenomenon can be explained by three elements:
- The foot structure
- The material structure in which the foot adheres
- Ability to attach to the surface and be part of it
Video Gecko feet
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Gecko is a member of the Gekkonidae family. They are reptiles that inhabit temperate and tropical regions. There are over 1,000 different species of gecko. They can be various colors. Gecko is a carnivore, feeding on various foods, including insects and worms. Most geckos species, including the crested gecko ( Rhacodactylus ciliatus ), can climb walls and other surfaces.
Maps Gecko feet
Structure
Chemical structure
The interaction between gecko feet and the climbing surface is stronger than the effect of simple surface area. On its feet, the geckos have many microscopic hairs, or setae (singular seta), which increase the Van der Waals force between the legs and the surface. This setae is a fibrous structural protein that stands out from the epidermis, made of? -keratin, the basic building blocks of human skin.
Physical structure
The -keratin bristles are about 5 m in diameter. The end of each seta consists of about 1,000 spatulas that are shaped like equilateral triangles. The spatula is about 200 nm on one side and 10-30 nm on the other two sides. Setae is parallel to each other but not oriented normally to the toes. When setae contact other surfaces, their load is supported by lateral and vertical components. The lateral load component is limited by spatula peeling, and the vertical load component is limited by shear forces.
src: img00.deviantart.net
Van der Waals Style
Hamaker surface interactions
Persamaan berikut dapat digunakan untuk mengkarakterisasi kekuatan Van der Waals secara kuantitatif, dengan memperkirakan interaksi sebagai antara dua permukaan datar:
-
where F is the power of interaction, A H is the Hamaker constant, and D is the distance between the two surfaces. Gecko setae is much more complicated than flat surfaces, because each leg has about 14,000 setae which each have about 1,000 spatulas. These surface interactions help smooth the surface roughness of the walls, which helps increase the interaction of gecko surfaces into the walls.
Factors affecting adhesion
Many factors affect adhesion, including:
- Surface roughness
- Materials absorbed, such as particles or moisture
- How the gecko's feet touched the surface
- Material gradient properties (dependence of elastic modulus on depth).
src: rsif.royalsocietypublishing.org
Derivation of interaction potential
Van der Waals Interactions
Menggunakan potensi interaksi dipol-dipol gabungan antara molekul A dan B:
-
where W AB is the potential energy between molecules (in joules), C AB (in J m 6 ), and D is the interval between molecules [in meters]. The potential energy of one molecule at perpendicular distance D from the planar surface of an indefinitely expanded material can be estimated as:
-
Interaksi tokek-dinding dapat dianalisis dengan memperkirakan tokek spatula sebagai silinder panjang dengan jari-jari r s . Kemudian interaksi antara spatula tunggal dan permukaan adalah:
-
where A H is the Hamaker constant for ingredients A and B.
Gaya Van der Waals per spatula, F s dapat dihitung dengan membedakan terhadap D dan kami memperoleh:
-
where the typical interatomic spacing of 1.7Ã, ÃÆ'... is used for solids in contact and F s of 40 Ã,ÃμN is used per study by Autumn et al.
src: sites.psu.edu
Experimental verification
The equation for r s can then be used with the calculated Hamaker constant to determine the approximate radius of the estimates. The Hamaker constant through vacuum and water monolayer is used. For those who have a water monolayer, the distance is double to explain water molecules.
-
These values ââare similar to the actual setae fingers on gecko feet (about 2.5 m?).
src: rsta.royalsocietypublishing.org
Synthetic adhesives
Research attempts to simulate gecko adhesive attributes. Projects that have explored the subject include:
- Reproduce the rigid polymer adhesive produced in a microfiber that is approximately the same size as a gecko setae.
- Replicate the self-cleaning attributes that naturally occur when gecko feet accumulate particles from the outer surface between the setae.
- Carbon nanotube arrays are transferred to polymer tape. By 2015, commercial products inspired by this work are released.
src: biotechin.asia
References
Source of the article : Wikipedia