Category Archives: adhesive

Shark Skin as an bacteria barrier

shark2.jpg.w300h225In the sea, a whale’s skin is home to barnacles, algae, and bacteria. In contrast, shark skin is squeaky clean. Parasites appear unable to attach to the shark skin. It is thought that the many small ridges and bumps on the shark’s skin surface discourage attachment. Bacteria prefer to colonize a smooth surface; a textured surface many require too much energy. The shark skin does not kill bacteria but simply discourages their presence. As a result, there is little chance of bacteria overcoming their resistance to shark skin.

Technical application:

In hospitals nursing call buttons, bed rails, and tray tables.

In restaurant door handles, especially in public restrooms

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Human climbing with efficiently scaled gecko-inspired dry adhesives

spidermanWe present a mechanical concept which improves upon the gecko’s non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive.

Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency.

Technical application:

climb buildings, for cleaning a ships body

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gecko feet sticks by the force of electricity

gecko2 geckoElectronic circuits typically constructed on very thin silicon surfaces. Now, suppose that we want to transfer such a circuit unto a non-flat surface such as cloth or leather. Circuits are fragile and any surface contact during movement can be destructive. Researchers at Northwestern University and the University of Illinois turned to the gecko lizard for the solution. Geckos are masters at sticking and then freeing their feet as they walk across a ceiling. The gecko foot has countless micro-size filaments which adhere to most surfaces by flexible, reversible molecular adhesion.

Technical application:

climb, stick to walls or on street

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tree frog climb wet and dirty surfaces as well as upside down surfaces without falling

TreeFrog_Laubfrosch_cropped.jpg.w300h400Here is an activity to try with a length of adhesive tape. Press the tape against a dusty surface several times. As expected, the tape quickly loses its holding strength as dust particles collect and coat the sticky side. In contrast, consider tree frogs which thrive in dusty, wet, or muddy surroundings. Yet they cling securely to branches and leaves, even hanging upside down. How are they able to hold on without falling?

Technical application:

holding applications

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Dog inspired drying machines

dogshakingPerhaps you have stood near a wet dog as it dries by shaking its fur. Watch out! An impressive amount of water is thrown off in all directions. The shaking technique for furry creatures including mice, dogs, and bears is studied by researchers at the Georgia Institute of Technology in Atlanta. They find that larger animals tend to move their bodies at a frequency of 4-5 shakes per second. Mice and rats move more rapidly, up to 27 shakes per second. Whatever the size, each creature begins the shaking process with its head and then the process moves along the body. Mathematical formulas have been established for the animal shaking process based on size, nature of the fur, water surface tension, and other variables. The animals apparently know these technical details by instinct.

Technical application:

drying machines

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Mussel-Inspired ‘Glue’ for Surgical Repair

sea_shell_glueWhen it comes to sticking power under wet conditions, marine mussels are hard to beat. They can adhere to virtually all inorganic and organic surfaces, sustaining their tenacious bonds in saltwater, including turbulent tidal environments.

Technical application:

unexpected high! Continue reading Mussel-Inspired ‘Glue’ for Surgical Repair