Wednesday, July 21, 2010

Spiderman - No more a fiction

Have you ever wondered that you would climb up walls? Have you ever tried grabbing the roof? It's not that tougher as you think. Just give it a try.Yes. Professor Paul Steen and Michael Vogel of Cornell University have paved way for a new world where people climb up walls like lizards! They have invented a new palm-sized device that adheres on all surfaces through electro-osmosis flow process.

They say that they were inspired of Florida beetle which can grab a leaf firmly with a force of 33 mN which is about 60 times its own body weight, yet can detach at any instant.

Thanks to the beetle and another forerunner who's given us a great concept of adhesion to walls and roof. She's none other than Gecko(lizard) which can climb up the walls and stay upright grabbing the roof throughout its life. But there is difference between the adhesion mechanisms followed by the lizards and the beetle. Geckos(lizards) possess millions of minute hair like structures called setae. And each setae contains numerous micro-fibrils which use van der waal's forces to cling to various surfaces.

In 2006, Stanford researchers developed a robot with synthetic setae which enabled it to climb up walls and even to walk on the roof.

But beetles use liquid mechanism to gain the control over adhesion and instantaneous detachment. They use the surface tension and capillarity phenomena of the tiny droplets on their legs to stay attached to leaves for longer time.

Having studied the various mechanisms that enables these creatures to stay grabbed lead the researchers devise a new palm-size instrument that creates a similar effect.

The device consists of flat plate with numerous holes, each of size few micrometer. A bottom plate serves as a fluid reservoir and there is a porous plate in the middle. An electric field is applied by a common nine-volt battery which pumps water through the device causing the water droplets to squeeze through the top layer.
The surface tension of the water droplets enables the device to stick on various surfaces. 

The prototype model with 1000 holes each of 300 microns grabbed 30 gram which is more than 70 paper clips.

This is the same principle why two wet glass plates stick together. But the magnitude of the force is increased in this by increasing the number of pores and decreasing the size of each pore on the plate. For instance, one square inch device with millions of 1 micron holes can hold more than 15 pounds. 

To turn adhesion off, the electric field is simply reversed thereby pulling the water droplets again to the reservoir.

The device can be of great use in the future, where people climb up buildings to reduce on street pedestrian traffic. Also, this can technology can be coupled with robots and other machines which need high rigidity and grabbing capacity. These devices can also be fabricated on shoes and gloves for better performance.

Note: Goal keepers are not to try this on their gloves during their sessions! Strictly!

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