A der Waals mechanism for gecko foot-hair adhesion.
A new gecko-inspired adhesive using hard plastic microfibers is “switched on” by sliding. One of the things they have tested was the strength on it one article said this “A tape piece with a surface area of 2 cm2 can support a 400-g mass. In contact areas, the synthetic tape achieves onesixth of the adhesion value of the gecko’s foot on smooth glass. The 42 million fibers populating each square centimeter are 15-20 micrometers long (which is one-fifth of the thickness of a sheet of paper) and 0. 6 pm in diameter (1/1 00th the diameter of a human hair).
Each fiber can support a load of 200 nanonewtons. Contact area also increases with higher shear loading, and disappears when shear load is removed, allowing controlled attachment and detachment. “ Found at http://findarticles. com/p/articles/mi_qa3618/is_200907/ai_n32425067/” I also found that they are talking about doctors using it to pack up organs. Other medical use are taking the place of sutures and sealing leaky organs, a surgical adhesive tape could also be infused with drugs to time-release as the material biodegrades.
I found that they are adding the adhesive to the belts of robots so they can climb up surfaces better like a slick glass wall at a ninety degree angle. In 2002, a team of UC Berkeley engineers including Ronald Fearing and Metin Sitti (now at CMU), UC Berkeley biologist Robert Full, Lewis and Clark College biologist Kellar Autumn, UC Santa Barbara engineer Jacob Israelachvili, and Stanford University engineer Thomas Kenny, found that the network of gecko hairs forms intermolecular bonds with the surface by means of van der Waals forces. Link to discussion of 2002 PNAS paper. ) The same research team synthesized gecko hair tips that stick, providing the first direct experimental verification of a van der Waals mechanism for gecko foot-hair adhesion. Those forces only come into play when surfaces get intimately close. When millions of gecko hairs make contact, they collectively create a powerful bond that is a thousand times stronger than the force geckos need to hang onto a wall.