Category Archives: friction

Squid – Arresting device

squidandwhaleLaw enforcement faces the challenge of stopping fleeing vehicles. Non-violent methods include roadblocks and spike strips laid across the pavement. However, neither is entirely successful because drivers sometimes avoid the barriers.

The U.S. Department of Home Security is studying new technologies for stopping vehicles. One promising device is inspired by the squid.

Technical application:

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dolphin-inspired-man-made-fin_1Many sea creatures including dolphins, porpoises, and whales have a tail structure that results in impressive bursts of speed. Their tail fin, called a fluke, is waved back and forth to provide forward motion. Meanwhile, the pectoral and dorsal fins provide directional stability. Dolphins reach speeds of 30-40 miles/hour (48-64 km/hr) and can leap completely out of water. Similarly, massive whales are able to breach or break from the water surface as they churn their tails.

Technical application:

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dog paw inspires for shoes

peaks-sb2.jpg.w300h225In 1935, inventor Paul Sperry sought a solution to a problem encountered in his hobby of sailing off the shore of New England. Whenever the boat deck Maxine20Head.jpg.w180h252became wet, it was slippery and dangerous. One winter day during a walk, he noticed that his cocker spaniel remained surefooted, even on slippery sidewalks. Sperry later examined the dog’s paws closely and noticed wave-like grooves on the pads.
Technical application:

grip on slippery surfaces

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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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stegosaurus plates for innovative wind-turbines

dinotail stegosaurusThousands of wind turbines have been installed worldwide in recent years for the production of clean electric energy. Efforts continue to make the large turbines efficient and quiet. One successful modification of existing turbine blades is inspired by the stegosaur.


Technical application:

improve fluid-turbines

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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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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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