That Spider-Man ability to climb walls effortlessly is becoming a reality thanks to scientists working with the American military. The study team have now developed a material based on their being inspired by the sticky toes of geckos which enables a human to ascend a vertical glass wall.
They created hand-sized silicone pads which are covered with tiny ridges. These mimic tiny bristles on gecko toes called setae which are capable of adhering to smooth surfaces. Each setae is divided into multiple tiny tips called septulae and weak electrical molecular interactions between these and the surface being crossed provide grip so secure that a gecko can climb upside down without a problem
Stanford University bio-mimetic engineer professor Mark Cutkosky led the team which developed the silicone hand pads that feature rows of microscopic slanting wedges. These temporarily bond to the surface of the glass when weight is applied to the 24 postage-stamp sized tiles on each pad which share the load.
The team had carefully studied the way that a gecko does it before creating adhesive pads from a silicone material called polydimethylsiloxane – PDMS – then building a harness with which Stanford biometric student researcher Elliot Hawkes was able to climb a 3.5 metres tall vertical glass wall with no other form of support despite weighing in at 11 stone.
That said the research team conceded that the technology is far from perfect. Whilst it works admirably on plain surfaces like glass the micro-wedge material simply cannot cope with rough surfaces yet and does not perform well. Hawkes commented that he believed such surfaces could only be overcome through the use of a large number of much smaller tiles as these would increase the grip.
The research was done in developing non-sticky pads, which can be repeatedly reused, as part of the Darpa Z Man project. This is targeted specifically at assisting troops in more easily scaling buildings and other obstacles. The team are hopeful now of developing the technology to allow faster and more smooth climbing generally, perhaps eventually even developing actual spider-man type gloves.
The Team have also commented on speculation that such adhesive properties could find other uses. To this end they are collaborating with NASA for the development of methods of securely grasping space debris. It seems that such controllable dry adhesives – not requiring suction to work effectively – are one of very few technologies that will work without external power in the very low temperature environment of space . Such technology could prove invaluable in coming years to address the mountain of space debris that is currently circling the globe.
Image via http://en.wikipedia.org/wiki/Gecko#mediaviewer/File:Phelsuma_l._laticauda.jpg
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