November 18, 2014

Spiderman-style gloves let you climb up walls of GLASS (VIDEO)

A climbing system inspired by geckos has turned Spiderman fiction into fact by making it possible for a human to scale vertical glass. During tests, an 11-stone (70kg) volunteer crawled up a 12ft (3.6 metre) pane using just sticky attachments on his hands and feet (pictured)
They employ the same natural molecular forces that allow gecko lizards to scurry around on ceilings.

Geckos climb on a wide variety of surfaces, including smooth surfaces such as glass.

They have adhesive pressures of 15 to 30 pounds (6.8kg to 13.6kg) per square inch for each limb, enabling the creature to hang its entire body by one toe.

A gecko's toe consists of a microscopic hierarchical structure of stalk-like setae - 100 microns in length, 2 microns in radius.

From individual setae, a bundle of hundreds of terminal tips called spatulae - approximately 200 nanometers in diameter at their widest - branch out and contact the climbing surface.

These hairs create an electrostatic force known as Van der Waals. 

It causes neighbouring molecules to be attracted to each other.
Although very weak, the effect is multiplied by thousands of tiny hairs that cover a gecko's toes, allowing them to stick firmly to surfaces.  

Adopting the same principle, scientists created tiny tiles called 'microwedges' to generate Van der Waals forces and produce a dry adhesive even more efficient than the gecko's.

During the experiment, the volunteer testing these microwedge attachments simply peeled them on and off the glass.

The US team led by Dr Elliot Hawkes, from Stanford University, wrote in the Journal of the Royal Society Interface: 'Using this system, a human of mass 70 kilograms (11 stone) successfully ascended a 3.6-metre (11 ft) vertical glass wall with 140 square centimetres of gecko-inspired dry adhesives in each hand.

'We tested hundreds of individual steps on glass with the 70kg (11 stone) climber and 140 square centimetres of adhesive without failure.

As well as the way Tom Cruise clings to the Burj Khalifa in Dubai during Mission Impossible: Ghost Protocol
'The synthetic adhesion system creates a nearly uniform load distribution across the whole adhesive area, improving upon the adhesive-bearing structures of a gecko's toe and enabling a human to climb vertical glass using an area of adhesive no larger than the area of a human hand.'

The research was conducted in collaboration with the US Defence Advanced Research Projects Agency (Darpa), whose 'Z-man' programme is investigating biologically-inspired climbing aids for soldiers.

One application of the technology might be to help astronauts get around in weightless conditions, the authors suggest.

'Recent work has shown that microwedges function in the environment of outer space, so it would be of interest to test this adhesion system in such an environment,' they concluded.

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