Category Archives: surface

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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Pilot Whale for a Self-cleaning Ship Hull and safe of fuel costs

ship Long-finned pilot whales swim in cool regions of the oceans. They grow to 12-16 feet in length and weigh several tons. The whales are characterized by an enlarged forehead and a swimming behavior siwhalemilar to dolphins. The creatures are found to have highly-specialized apparatus for maintaining smooth, clean skin. Countless tiny surface pores produce a slime coating. The gel washes off with movement and is continually replenished. This “skin care” prevents bacteria and algae from gaining a foothold and forming growth colonies. The whale’s surface chemicals also contain enzymes that repel microorganisms. This feature in turn avoids barnacles, tubeworms and other marine life which are otherwise attracted to underwater surfaces.

How can the production of “slime” by pilot whales possibly be useful as a technical application?

Technical application:

clean ships without cleaning

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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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scorpion “skin” for more abrasion resistance

ScorpionA species of North African scorpion does not mind getting sand blasted or whipped by desert winds. While other desert creatures burrow downward for protection, the scorpion scurries in the open and withstands abrasion. Studies reveal that its surface is covered with many hardened, dome-shaped bumps just a few microns in size. This armor coating deflects nearby air flow and reduces the force of wind and sand.

Technical application:

abrasion resistance

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the mystical movement of snakes

Red_milk_snake.JPG.w300h233Snakes have scales on their belly skin which help them move about. On a flat surface, the body weight is continuously redistributed for maximum friction, and the scales provide grip. Researchers at the Georgia Institute of Technology have made detailed studies of the movement of the milk snake. The result, which they call terrestrial lateral undulation, reveals complex motion.

Technical application:

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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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will our lungs help to reduce carbon dioxid emissions on our planet?

lungsOur hard-working lungs clearly show intelligent planning. Within our lungs, countless tiny air sacks called alveoli exchange gases from the bloodstream, supplying fresh oxygen and removing carbon dioxide. The component membranes which allow separation and passage of the gases are about one thousand times thinner than a printed period. The total gas exchange area adds up to at least 70 time an adult’s total body surface area, or the size of a volleyball court. Specialized chemicals, especially carbonic anhydrase, help carry on the continuous gas exchange process.

Technical application:


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Leaves learn us how to produce electricity and harvest water

Transpiration is the evaporation of water from the leaves of plants and trees. The undersidesTranspiration_Xerophyte.jpg of leaves are dotted with hundreds of tiny openings called stoma. Carbon dioxide enters the leaf through these pores, and water escapes.  A mature tree may evaporate hundreds of gallons of water on a warm, dry day. The process cools the vegetation and also allows the internal flow of nutrients. The familiar veins within leaves transmit the water to the stoma. Studies have shown that the branching Tomato_leaf_stomate.jpg.w300h307veins, called a dendrite pattern, are spaced out for maximum water flow. This leaf vein pattern may help design engineers build more efficient irrigation systems.

Tomato leaf stoma


Technical application:

generate  , harvest water

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beaver teeths for sharp cutting-tools

beaver.jpgGerman engineers have applied the tooth sharpening ability of rodents to cutting tools.

Beavers, rats, rabbits and similar rodents depend on their teeth for survival. They are experts at gnawing, and their teeth are designed with a self-sharpening ability. Unlike our own, roSaw_bladedent teeth are covered with enamel on only the front side. Softer dentine is exposed on the back of the front teeth. As the rodent chews and wears down its teeth, it alternates grinding its lower incisors against either the front or the back of the upper incisors. As a result, the hard enamel slowly wears down the softer dentine and the teeth remain sharp. The teeth also continue to grow from the root, maintaining their length. The animals must continue to gnaw or their teeth will outgrow their mouth.

Technical application:

self shaping tools

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