We wanted to find out why geckos could walk on walls because we were fascinated when we saw some in Hawaii. We decided to investigate this topic and try to expand on the possibilities of us doing the same thing. 

 

 

We looked at books and websites, watched videos, and   observed  live geckos to find out the way they walked on walls.

Science Fair - Due February 9th

Topic: How do geckos walk upside down? 

Branch Questions:

Do other animals that can walk upside down use the same technique as geckos?

Can Humans do the same?

Are there any inventions that help humans walk upside down?

 

Geckos-What are they:

Geckos are a type of lizard that lives everywhere besides Antarctica. They are nocturnal, unlike lizards. They range in size from 1.5 cm to 60cm. There are 1, 500 species of geckos.

The difference between geckos and lizards is that geckos lay eggs in pairs instead of clusters unlike lizards. They can also make chirps and barking noises. Wild geckos blend into their surroundings. They can be green, orange, yellow, blue, and brown.

Real picture of gecko in Hawaii

Geckos - Van Der Waals forces:

Geckos use Van Der Waals forces to walk on sideways or upside-down surfaces. This is because of sticky hairs on their toes, called setae, that attach to surfaces like glue, but much stronger. If their bodies are close to the wall, it makes it very easy for them to scale it. The atoms and the surfaces either attract or repel each other. The distance also matters in this. The setae generate these forces. Geckos and lizards can change the angle of these hairs, so they can peel their feet away from the surface they are sticking to. The same charges repel, while the opposites attract. The walls and feet are not polarised, and the geckos can still stick, which is why it is proof that Van Der Waals are at work. 

 

Scientists measured how powerful their grip is. The front 2 feet of the largest gecko can carry 2 kilograms.

 

Lipids molecules and Setae:

Geckos have these lipids molecules that repel water, which helps so geckos can climb wet surfaces. Scientists say that they push the water away from beneath the setae, so the geckos can have closer contact with the surface.

Setae are made of a type of keratin, similar to what your hair and fingernails are made of. They are extremely delicate. The keratin is aligned in the direction of the setae, possibly to stop them from wearing down. Scientists studied the setae and found that they are coated in a ultra thin film made of lipids molecules, that repel water. Studies found that geckos can stick underwater, and their feet stay completely dry. The film is only one nanometre thick. The setae are flexible allowing them to stick to the surface.

Smaller things at the ends of the setae are called spatulae. They come so close in contact that the electrons in both the surface and the spatulae interact, creating an attraction called the Van der Waals forces. For a gecko to take its next step, it changes the angle of its setae, interrupting the Van der Waals forces.

 

Van der Waals forces:

Van Der Waals forces are named after Johannes Diderik Van Der Waals, a dutch theoretical physicist in 1873, who discovered the Van Der Waals. 

They are the force that makes geckos stick to the ceiling. Using molecules that have poles, kind of like a magnet.

The changes in charge distribution between close molecules which don't need to be polar. The changes in charge naturally fall into synchronicity, which creates an attractive force.

Scientists tested whether geckos could stick to silicone dioxide (rock or sand) and gallium arsenide. Silicone dioxide is polar, and gallium arsenide is not.

The geckos were equally sticky to both materials, using the Van der Waals forces.

*It is hard to explain, try to find a way to explain it in the simplest way possible*

 

Other Animals (not upside-down) relations:

Most other animals, including humans, can’t stick to walls because they don’t have hairs on their feet. Research also shows that geckos are the biggest sized animals that can stick to walls. If they are any bigger, they won’t be able to stick because of their body weight and their distance from the wall. 

 

Other Animals (upside-down) relations - Lizards (chameleons?):

Chameleons can stick to branches.

Humans - Can we do the same?:

By using very strong magnets - We use magnetic boots to walk around spacecrafts, or cabins of spacecrafts

Why not - We don’t have sticky hairs

If we did- We would be too heavy. Geckos are the biggest thing that can walk upside down

 

Inventions:

• Magnetic boots - We use magnetic boots to walk around spacecrafts, or cabins of spacecrafts
• Scientists studied how geckos climb walls and created a device called Geckskin that can hold 317 kilograms
• Scientists invented an adhesive tape that has little setae.

 

Future Inventions:

• Grappling hook (possibly to latch on to it)
• Suction cups have been used before to scale buildings but ceiling?

If a person is about 90 kilograms it would take two 8”” suction cups

• Carts on the ceiling?

Animals that can walk upside down:

Bugs: by using tiny hairs (that can stick into the walls, because they are so tiny) that make a glue-like substance made from sugars and oils, if you look closely, you might see tiny greasy footprints.

• Some bugs: use Van Der Waals forces and have hairs that increase the surface area so they can stick more. They also have claws on the end of their feet that also help attach, but also help release. They twist them so it comes off so they can walk.
• Tree frogs: they can grip wet or dry surfaces

Foot is covered in a wet film. Scientists think a tree frog’s foot sticks to things as a damp piece of paper sticks to a window, but it doesn’t work on wet things

Studied the foot and found the film is super thin, in some parts there is no film at all

The foot has little bumps, and because the film is so thin the bumps poke through, helping as traction on slippery surfaces.

The toe pads have fluid flowing through them. On wet surfaces the channels funnel away extra fluid. On dry surfaces they bring more moisture to the pads.

• Small lizards

Using Van der waals forces

Pictures:

Picture of a gecko's foot

 

Links:

https://www.newscientist.com/lastword/mg24632811-600-what-is-the-reptilian-skill-that-allows-lizards-to-walk-upside-down/#:~:text=Geckos%20take%20advantage%20of%20a,feet%20and%20ceiling%20are%20polarised.

https://www.science.org/content/article/how-geckos-stick-der-waals

https://www.snexplores.org/article/not-slippery-when-wet#:~:text=A%20tree%20frog's%20toe%20pads,or%20even%20hang%20upside%20down.

https://byjus.com/chemistry/polarity/#:~:text=Define%20Polarity,melting%20points%2C%20and%20their%20solubilities.

https://www.britannica.com/science/chemistry

https://en.wikipedia.org/wiki/Magnetic_boots#:~:text=Magnetic%20boots%20are%20boots%20that,

the%20cabin%20of%20a%20spacecraft

https://sustainable-nano.com/2019/03/08/spiderman-or-suction-cup-man/#:~:text=According%20to%20Gast%20Manufacturing's%20calculations,used%20before%20to%20scale%20buildings

https://phys.org/news/2012-02-gecko-feet-scientists-super-adhesive-material.html#:~:text=Now%2C%20a%20team%20of%20polymer,pounds%20on%20a%20smooth%20wall

https://www.openaccessgovesrnment.org/whats-the-secret-to-gecko-feet-that-allows-them-to-stick-to-surfaces/139371/

https://www.nsf.gov/news/news_summ.jsp?cntn_id=127499#:~:text=Not%20Slippery%20When%20Wet%3A%20Geckos%20Adhere%20to%20Surfaces%20Submerged%20Underwater,-University%20of%20Akron

https://www.zillarules.com/pet-type/lizards-geckos#:~:text=What%20differentiates%20geckos%20from%20the,enable%20them%20to%20climb%20walls.

https://www.fiercebiotech.com/research/gecko-s-talent-for-re-growing-its-tail-could-help-people-spinal-cord-injuries#:~:text=Like%20many%20lizards%2C%20geckos%20can,any%20other%20type%20of%20lizard.

https://animals.mom.com/geckos-long-tongues-like-frogs-2331.html

https://www.zillarules.com/articles/what-do-geckos-eat#:~:text=Most%20varieties%20of%20geckos%20(including,enjoy%20pinkie%20or%20infant%20mice.

 

We analyzed our findings and tried to expand off our new knowledge. We figured out that the ability to walk on walls is crucial to a gecko's survival. Our suggestion to this theory is because insects, a gecko's essential food, also climbs on walls. Other lizards do not necessarily need this adaptation because they have other dietary options.

Based on our current understanding of geckos and their adaptations, we expanded on inventions to help humans do the same. We looked at the possibility of velcro that can stick onto walls instead of just being used for shoes and anti-gravity spacecrafts. We also looked at suction cups and grappling hooks to see how they could be used to full potential to help us in our daily lives even more.

In conclusion, we answered our overall question, by learning that geckos can walk upside down using a special force called Van Der Waals forces that are triggered by tiny hairs on their feet called setae. We also found out that not all animals need to have little hairs to walk upside down, though they can’t use the Van Der Waals forces without setae.

We did this project because we were interested when we saw a gecko in Hawaii walking upside down. We wanted to see if we as humans can do the same thing, but so far, it's not quite yet possible, except in anti-gravity.

In the future we will build off of our current knowledge about how geckos walk on the ceiling and try to expand our research on a possibility of other animals, mainly humans, to walk upside down.

 

 

We want to acknowledge our parents for organizing meetups for us to work on the project, supplying resources, and encouraging us to do Science Fair. We would also like to thank Heather Lai for hosting Science Club and for giving us this experience. We would also like to acknowledge Britannica, Byjus, New Scientist, NSF, Open Access Government, Phys, Science, Snexplores, Sustainable-Nano, and Wikipedia for the information on this project. Thank you!