Dr Richard Johnston, University of Swansea
Spiderman has become a reality! Taking their inspiration from the feet of geckos - small lizards which can run up walls and stick to ceilings - scientists in the States have created hand-sized pads that enable a 70kg man to climb straight up a vertical pane of glass!
Swansea University materials scientist Richard Johnston has been taking a look at the new invention, which could even prove useful out in space, as he explained to Chris Smith…
Richard - Researchers in the US have developed a pad which can attach to a human’s hands which can allow them to scale a sheet glass building, much like the pads on a gecko’s foot allows it to scale vertical walls. In the past, people have developed something called a gecko tape as a common term, which mimics gecko’s feet in terms of how they adhere to surfaces. But it’s always been difficult to scale those up without significant loss in adhesion or stickiness.
Chris - And how does a gecko’s foot enable it to do that and what this person is now doing, because the paper is quite striking. You see this guy standing there, going vertically up a sheet of glass. How is he doing it?
Richard - It is extremely exciting to see that as well. With gecko’s they have toes covered in millions of tiny hairs. So, these are typically thinner than a human hair. On the tip of each of these hairs – so if you imagine a paintbrush, a paintbrush has a wooden handle and then at the tip of the paintbrush, you have lots and lots, hundreds and thousands of even finer hairs. And so, that’s what a gecko has on its feet – millions of individual hairs which are then tipped with even finer strands.
Chris - How do the hairs actually generate the adhesion with the surface though?
Richard - Each of those tiny hairs utilises something called Van der Waal’s forces. These are tiny electrical forces between the gecko’s hairs and the surface which it’s adhering to. And those billions of tiny forces add up to enough force that holds the gecko onto that surface.
Chris - And the group in America, they’ve managed to recreate a form of that, but in a sufficiently big pad so that you get a sufficiently big force to hold up a person.
Richard - Yes. They’ve come up with an interesting design with slightly different materials, properties for the component parts, whereas the gecko utilises natural materials like collagen. They’ve use nitinol which is a nickel-titanium-based material. So, if you were to look at it, it’s a pad about the size or just larger than a human hand. On that pad, there are a number of separate adhesive pads. This is around 25 and each one of those individually still has those millions of tiny hairs. So, it works on the same principles as the gecko foot in terms of intermolecular forces.
Chris - Are there any applications beyond just Spiderman?
Richard - It’s really interesting actually, because the actual interface material – so all of these fine hairs – that was developed some time ago, it’s just the tendons and the material design behind that that’s new this scale up. But the actual material that they’ve used has been tested in space, and it works. So, you can now imagine you’ve got a scale up that can hold the weight of a human or something the size of a human that could potentially be used in space. So, increasing mobility of astronauts, you can attach and remove these pads in less than a second. So, it’s very fast fastening. Even in our human made built environment, we’ve designed our living spaces to have shiny surfaces, to have vertical flat walls. And so, if we can increase human mobility in terms of inspection, construction, then potentially it has lots of applications.
No references for this story? It would be great to include the name of the researcher or at least the university so we can look up further information. Chuck, Wed, 26th Nov 2014