Tag Archives: climbing

the hairy feet of the gecko

Have you ever thought about what it would be like to walk on walls? If you’ve ever watched a Spiderman movie or watched a gecko maneuver around its habitat, you probably have. While geckos don’t fight crime, their climbing ability is as fantastic as that of any superhero. Geckos have one of the most unique climbing adaptations of any animal, and scientists are examining the source of this ability to see if human technology could one day achieve something similar.

Geckos are able to cling to almost any surface, no matter how smooth or rough it is. They are also able to detach quickly and easily from these surfaces as they climb. This climbing ability is due to tiny hairs, called setae, on the bottoms of their feet that can only be seen with a microscope. Each hair branches off into even smaller fibers called spatulae. Each gecko has about three million setae, and a billion spatulae! When the gecko places its foot on a surface, these hairs cling to the surface and form intermolecular bonds, called Van der Waals bonds, with the molecules of that surface. These bonds are strong enough to hold the gecko in place, but can be broken easily when the gecko lifts up its foot.

A close-up view of the bottom of a gecko foot, with the microscopic hairs visible.
Close-up of setae on gecko foot. Image by Science Photo Library

In addition to enabling the gecko to attach itself to surfaces, these hairs on the bottom of the gecko’s feet have the ability to clean themselves. If the gecko did not have some sort of ability to clean its feet, dust and dirt would get stuck on the gecko’s feet and break the connection between the feet and the surface. However, the hairs on the gecko’s feet are shaped so that it is difficult for water to stick to the feet. When the gecko gets water on its foot, the water rolls off of it and takes any particles of dirt with it.

Scientists have long been fascinated by the gecko’s ability to stick to surfaces, and many have been working on creating adhesives with fibers similar to the hairs on the bottom of the gecko’s feet. These adhesives are dry, like the gecko’s feet, and can be attached firmly and removed easily. The possibilities for application of adhesives like this are vast in number, and include everyday fasteners as well as use in electronics, robotics, and even outer space technology. One of the areas being explored by scientists is the use of these adhesives in the medical industry. The manufacture of gecko-hair fibers for bandages could mean farewell to the pain of removing a bandage, as well as the sticky residue left behind on your skin. This type of adhesive could even one day replace stitches after surgery.

Polymer fibrillar adhesive based on gecko foot Setae. Image by G.J. Shah, M. Sitti.

Most people probably don’t think about geckos very often apart from what they see in advertisements for car insurance. But for some scientists, these creatures hold the key to a world of possibilities. So next time you’re at the pet store, take a look in the lizard tanks and watch the geckos climb. Someday, thanks to those geckos, humans might be able to do the same thing.

Read more: https://steemit.com/science/@herpetologyguy/what-makes-gecko-feet-so-sticky

Rock on, Dude!

In the rock climbing world, there is not much that people fear more than the sound of a “pop” coming from their fingers. That sound means months of rehab and can keep you off the rock for up to six months [1]. But what exactly is happening when you hear that dreaded sound? The fingers are so small, how can one injury to the fingers be so devastating? Let’s dive in.

As a review of hand anatomy, direct your attention to the graphic on the right. There are two main tendons that run up each finger to allow the fingers to produce the curling motion. In order to keep these tendons close to the bones to provide for maximum torque,

Diagram of the hand showing the tendons and pulleys
Anatomy of the hand [2]
they are held by pulleys. The pulleys are the culprits of the “pop” when grabbing tiny holds. Without these pulleys, the tendons would “bowstring” and pull away from the axis of rotation of the finger and thus decrease the strength of the system [2]. The important pulleys in climbing are the A2 and the A4, as they are fibro-osseous pulleys (connect bone to bone) and are stiffer than the A3 and A5[3].

In climbing, there are two main hand positions when grabbing

The open hand position
The open hand position [2]
holds: Open-hand and crimp. The open-hand grip relies heavily on the forearm muscles, while the crimp puts a significantly higher strain on the skeleton. The crimp is incredibly dangerous, as it puts three times the force being applied to the fingertip on the A2 pulley [4]. A common mistake I have noticed for newer climbers is to crimp everything as the big muscles in the upper arm and back are much stronger than the forearms. Putting all the weight on the skeleton and big muscles allows you to skip over the limiting factor of weaker forearms. This allows climbers to pull on smaller holds and climb harder routes. New climbers are not as aware of the dangers and they get excited

hand in the crimp position
Hand in the crimp position [3]
to send harder and harder routes, but this reinforces the bad habit of crimping which will eventually get you injured. Of course, sometimes crimping is unavoidable when the holds are very small, but it is best to avoid it as much as possible.

 

So how strong are these pulleys? In a study performed with recently deceased cadavers, the A2 pulley resisted up to 408 N, which is 91 pounds [5]. This was determined by removing the bone from the hands and pulling on the pulleys until they broke. Based on another study in live humans, the force applied to the A2 pulley was extrapolated to be around 373 N with 118 N applied to the fingertips [4]. This extrapolation was based on a controlled environment. It is easy to see that a pulley could be loaded with much more force than that if a climber’s foot slips mid- move or if you catch a hold with fewer fingers than you mean to. It was also

Me crimping as hard as I can because I'm weak
Me crimping as hard as I can because I’m weak

found that the bowstringing in the intact A2 increased by 30% throughout a warm-up process [4]. This clearly shows the importance of a good warm-up.

Sources and extra reading:

[1]https://theclimbingdoctor.com/pulley-injuries-explained-part-2/

 

[2]https://theclimbingdoctor.com/pulley-injuries-explained-part-1/

[3]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3371120/

[4]https://www.sciencedirect.com/science/article/pii/S0021929000001846

[5]https://journals-sagepub-com.proxy.library.nd.edu/doi/pdf/10.1016/0266-7681%2890%2990085-I