Biomimicry

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Biomimicry

Postby proscience » Fri Sep 27, 2013 6:29 am

Can beta keratin bond to unmodified chitin? If so, how?
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Re: Biomimicry

Postby Terik Daly » Fri Sep 27, 2013 7:51 am

Hi Proscience,

A bit more information about your project will help us address your question more effectively. What is your scientific question and hypothesis? Also, when you say "bond" are you referring to bonding of molecules of beta keratin to chitin? Or are you talking about connecting larger pieces of beta keratin to chitin?
All the best,
Terik
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Re: Biomimicry

Postby proscience » Fri Sep 27, 2013 11:49 am

I'm not really sure. I'm working on an Invention Convention project for school. I'm really interested in nanotechnology and biomimicry but I have to make a crude model to explain my invention. I wanted to know if its possible to attach keratin fibers to a chitin scaffold. I read that catapillars bodies are made of unmodified chitin so they are flexible. The exoskeletons of insects are chitin too, but they are hard. I need something flexible from nature.

Keratin is made of strong protein fibers like in hair or feathers. I was thinking about soccer goal nets and basketball nets that are attached to a frame but the nets are strong and flexible and they absorb energy. So is it possible to get the molecules of keratin to bond to a scaffold of chitin that would be flexible like a soccer goal or a basketball net?

I was hoping I could make a model and in my paper explain how it might work at a nano level. I don't know enough about chemistry to know if it will work. I read about hydrogen bonding. I guess sometimes it's strong and sometimes it's weak. I'm stuck and so if you could guide me in any way, that would be great. Thanks.
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Re: Biomimicry

Postby Terik Daly » Fri Sep 27, 2013 1:07 pm

Hi Proscience,

Thank you for posting these additional details - they are very helpful!

I think your idea is clever. A coworker of mine studies nano-structure of iridescent beetle shells as a pattern for photonic crystals; very cool stuff. Based on your project description, I suggest reading up on the Engineering Design Process (http://www.sciencebuddies.org/science-fair-projects/engineering-design-process-guide.shtml). Since you are working on designing something to meet a specific need, following the engineering design process will help clarify what you are doing and why you are doing it. Write everything down in a notebook--all of your thoughts and ideas, what you do as you work on your invention, etc.

With regards to your specific question about bonding keratin to chitin, I'm afraid that I don't have enough of a organic chemistry background to know if (and how) they bond at the molecular level. I will ask another Expert to address that question. So - expect another response within the next day or so with more specifics!
All the best,
Terik
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Re: Biomimicry

Postby proscience » Fri Sep 27, 2013 2:33 pm

The engineering process flow chart is really helpful. I started building my model. I was going to use human hair extensions but switched to feathers. Hair was hard to work with.

Do you know how I can measure shearing of a feather? I also wanted to see if the feather was super hydrophobic like the lotus. I read that you can measure the contact angle but the formula is very complicated and there's a special instrument that does that. My grandfather says there's an app where you can take lots of pictures of dripping water. If I do that can I use a protractor and the picture to measure the contact angle?

I really want to use my idea. My teacher wanted me to come up with a different idea but I don't know what to do. I want to do something different, not some gadget.

Oh, I don't have any lab equipment to use. I have to do this at home.

Thanks for helping.
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Re: Biomimicry

Postby Terik Daly » Fri Sep 27, 2013 3:43 pm

Hi Proscience,

I'm glad the engineering process link was helpful, and it's exciting that you've started your model! I think your idea is an excellent one. If you are passionate about it, then I suggest sticking with it. But, your teacher should approve the project, too! Perhaps it would be helpful to explain to your engineering goal to you teacher. When people invent a gadget of some sort, they do so to fill a need. For example, someone might say "I don't like having a cord connecting my ear buds to my music. I will invent wireless ear buds so people don't have to be tether to their music device." In your case, it sounds like you are trying to invent a whole new material, a material that combines the characteristics of keratin and chitin. Some people's whole job is based on inventing new materials; it's an important branch of science and engineering. Then, other people come along and invent new gadgets, tools, etc. using the new materials. What types of things do you think could be built or improved using <i>your</i> material?

Doing things at home is a great option. You can do quite a bit without having too much expensive lab equipment! Speaking of which, let's get to your question about shearing a feather. Am I correct in thinking that you want to measure how strong a feather is when you shear it? Do you want to measure how hard you have to push or pull on a feather to make it shear? Or do you want to measure how much the feather deforms when you push or pull on it? Also, are you thinking of measuring a single feather? Or a group of feathers all together? I think it will probably be easier for you to measure how much the feather deforms in response to a specified stress than to measure how much stress it takes to create a certain amount of deformation. Let me know the answers to these questions, and I will help you think of a way to test it.

Regarding contact angle - your Grandpa's idea of taking pictures of a drop of water on the feather is a good one. With the feather on a flat surface, you could put a drop or two of water on the feather (with an eyedropper or even with a dripping water faucet), take a close-up picture of the droplet, and then use a protractor to measure the contact angle. Sure, the measurement won't be as precise as if you did it in a fancy lab with special instruments. But, you'll get a decent estimate. Creative problem solving is a really important part of a science or engineering project. If your project will be judged when it's done, I know that the judges will be impressed by your thinking about how you could measure the contact angle without special instruments.
All the best,
Terik
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Re: Biomimicry

Postby proscience » Fri Sep 27, 2013 5:40 pm

Well I noticed that flight feathers can stretch in a diagonal direction when I pull on it. My dad says that when the feather separates that's shearing. I'm guessing that a group of feathers can take more stress than a single feather because of surface area. So I wanted the measure how much stretching the group of feathers can take. My research says that flight feathers are very strong. I want to find out how strong. I'm glad that I can measure the contact angle using a protracter :-). The variables I want to measure are hydrophobicity and shearing. Maybe temperature and uv since feathers protect birds from the sun and keeps them warm.
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Re: Biomimicry

Postby proscience » Fri Sep 27, 2013 5:57 pm

Actually, measuring how much the feather deforms would work too since you mentioned that might be easier to measure.

Thanks!
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Re: Biomimicry

Postby Terik Daly » Sat Sep 28, 2013 7:11 am

Hi Proscience,

I can think of a few different ways to measure how strong a feather is. Something shears in response to an applied stress, which is a force per area. But, measuring the force required to deform the feather will give you some idea of how strong the feather is, even if it isn't totally rigorous. So, you'll need some way of measuring force (which is measured in newtons, if you are using SI units, or pounds, if you are using US units). I think a spring scale might work; there are different styles of spring scales out there, but many of them look something like this: http://www.arborsci.com/media/catalog/p ... 1-6970.png. Talk to your teacher and see if your school has one. A friend or neighbor might have one, especially if they like to fish. Different spring scales cover different weight ranges. I suspect you will need a pretty strong one. As a brief note, if you use a SI spring scale, it will probably measure mass in kilograms. To get to newtons, multiple the number of kilograms by the acceleration due to gravity, 9.8 m/(s^2). A newton has units of kg*m/(s^2).

Although I don't have feathers that I can try this with, I think the following procedure will work to get a rough idea for how strong the feathers are under shear. Take a feather and attach two binder clips diagonally across from each other at the two ends of the feather. Then attach one of the binder clips to something very strong and steady. This will be the "anchor" point. Then, loop the hook of the spring scale through the loops on the handle of the other binder clip, and pull on the spring scale until the feather breaks. You'll probably need a helper to watch the spring scale to see what it reads right before the feather breaks. Or, you could video the test and then use the footage to read the spring scale right before the feather breaks. Another option would be hanging the whole setup vertically and then putting a bucket on the other loop of the spring scale and slowing adding weight to the bucket. Then you can weigh the bucket once the test is done to figure out how much load the feather held. The hard part will be making sure that the feather breaks, instead of the binder clip just pulling off the feather. So, depending on how strong the feather is, you may need to glue the binder clips to the feather. If the clips come off, then what you are measuring is the strength of the contact between the feathers and the binder clip (or the strength of the glue, if you glue the clips to the feather). That number will be a lower limit to the strength of the feather--the feather is at least that strong, but it may be stronger.

Always keep in mind your engineering goal. Hydrophobicity and shear strength are two things you can measure, but think about how you can test your material to see if it meets your design criteria. You'll want to make sure you have a specific "test plan". Take a look at http://www.sciencebuddies.org/engineeri ... ents.shtml to help you define design requirements, if you haven't done so already. Also check out http://www.sciencebuddies.org/engineeri ... ment.shtml for info about testing different versions of your material. I suggest that you brainstorm two or three different versions of your material. Be sure to write down why you chose each design--explain your thought process. Then do the same tests on all those materials to see which one best meets your design criteria. You can then iterate, or repeat the process. Use what you learned by doing your tests to design an improved version of your material, and then test that one. Repeat this process until you have a material that meets your design criteria.
All the best,
Terik
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Re: Biomimicry

Postby proscience » Sat Sep 28, 2013 10:17 am

Thanks, I will try it this week and I will let you know what happens.
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Re: Biomimicry

Postby Terik Daly » Sat Sep 28, 2013 10:52 am

Great! I look forward to hearing how things go. I also realized that I wasn't clear about something - testing the feather like this way tells you about their shear strength under tension.
All the best,
Terik
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Re: Biomimicry

Postby proscience » Fri Oct 04, 2013 5:21 am

I did the stress test using a spring scale and small binder clips. Using a group of three flight feathers my result was 0.049 N.
That's pretty weak. I forgot to tell you that I removed the feather from the quill. I need to remove the quill for my invention.

The biggest problem I have is shearing in the vertical direction. How do birds keep their flight feathers together when they fly? Surely there are stronger forces acting on the feathers when they fly. I need to keep the barbules together. Is polyacrylate breathable? Can air pass through a layer of polyacrylate?

Do you think I can use a UV index card to measure how much UV radiation the feather filters out? My project is due at the end of October. :?

Thanks
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Re: Biomimicry

Postby Terik Daly » Fri Oct 04, 2013 2:31 pm

Hi Proscience,

I'm glad you were able to do the stress tests. I'm a bit surprised by your results; I thought the feather would be stronger. But, I haven't done the test and you have! Your comment about "removing the feather from the quill" makes me think that maybe you didn't measure what I thought you were measuring, which may explain the low value. Do you mean that you took the vane off the rachis and shaft and measured the strength of the vane alone, detached from the rachis? (see this page for feather anatomy: http://askabiologist.asu.edu/explore/feather-biology) When the feathers failed, did they break in the middle? Or did they break where they connected to the binder clips? I definitely agree that birds have forces on their feathers greater than 0.049N when they fly. That's part of why I want to know what, precisely, you measured and how the feather broke.

Birds feathers have little interlocking barbules and hooklets that lock together, helping the feathers stay connected and in place. It's a bit like Velcro. They also match the bird's aerodynamic profile, so the way that air passes around the feathers helps them stay together, to some extent. There are also oils and waxes in feathers that might help bind them together. In addition, different types of feathers fill different roles, so flight feathers are quite different from downy feathers.

Can you please describe the vertical shear problem in more detail? One thing to keep in mind is that the strength of materials is often anisotropic, which is a big word that just means they are stronger in one direction than in others. So, you might be able to address the problem by changing the orientation of the feather. Polyacrylate might help the feathers stay together, but I'm not certain of that. You can always test it and see if it works. You can then also test to see if you can blow air through the polyacrylate-coated feathers. That's what the engineering design process is all about. You're showing it in action right here--you built something; you tested it and it didn't work like you had planned. So, you brainstormed possible solutions. Now is the time to test those solutions. It's an iterative process, and it sounds like you are doing it well. Keep track of all your iterations and work; that's what will show your teacher and judges that you didn't just tinker with something. Instead, you applied the engineering design process to invent a material that meets specified design criteria.

Are you referring to a UV indicator card, such as this: http://www.healthedco.com/index.php/uv- ... -card.html? If so, I think that is a neat idea for getting a qualitative sense for how effective your invention is at filtering out UV light. I like how you are thinking. Without knowing more about your invention (its size, shape, opacity, etc.) or seeing a picture of it, I'm not sure how well the card will work, but I think it's a great idea to try. Essentially, if your invention is small compared to the size of the card, then the card won't really be shielded from UV by your invention; light will just go around the invention and hit the card. And, if your invention blocks the light completely then the card won't tell you much about UV filtering specifically. But, these are based on specifics about your invention. From a theoretical point of view, I don't see any reason why the card wouldn't give you qualitative information. From a practical point of view, the card's usefulness will depend on the details of your invention. I suggest trying the card and seeing if it works with your particular invention.

Best of luck as you continue your project. I'm sure the end of October due date feels like it's coming up quickly. But, keep working on your project, step by step, and you'll get there. I'm excited to see how your project turns out! Let me know if I can help in any other way.

All the best,
Terik
All the best,
Terik
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Re: Biomimicry

Postby proscience » Sat Oct 05, 2013 10:12 am

Hi Terik,

Yes, I cut the vane off the rachis because I wanted the feather to be flexible and fabric-like. I put some cut vanes together using a glue that wouldn't make the feather stiff. When I tested the group of vanes they separated at the hooklets. The vanes started to separate in the middle and with more force the rest of the vane would fall apart. I was hoping to find something that would keep the vane flexible but would also make the hooklets stronger so they could take more stress. That's why I asked the question about poly acylates. Yesterday I tried spraying the vanes with hairspray and then a group with liquid bandage because they both have acrylates in them. That's what the label said, but maybe that wasn't the right acrylate. Both products have alcohol in them so all they did was dry out the vane and make it brittle. So that didn't work.
I thought hairsrpay might work because hair is keratin. And I tried liquid bandage because it is flexible. So I guess my idea of spraying the vanes with polyacrylate won't work. I wiah I could tell you my idea, but I don't want someone stealing it.

My challenge is exactly the velcro analogy you mentioned. How do I get the "velcro" on the barb to hang on, but keeping the feather flexible?

To answer your question about the shear problem: If you hold the vane straight up and down with the quill end down and pull perpendicular to the barb, the vane beginns to shear from the center. That's what was 0.049 N, but id you pull the vane in the same direction as the barb it doesn't shear.

UV index card: Yes, I meant the indicator card. I couldn't think of the name. My invention is meant to be temporary. Birds molt their feathers because they can't repair themselves. My invention follows thw same idea, using it for a particular purpose, for a certain length of time, and can be disposed of anywhere without hurting the environment.
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Re: Biomimicry

Postby Terik Daly » Sat Oct 05, 2013 7:13 pm

Hi Proscience,

Thank you for posting those details! They are extremely helpful. Your idea for cutting the vane off the rachis was a good one, and I especially like that you explained why you thought that was a good idea. That's just the kind of thinking you'll want to make clear in your report or presentation.

Your stress test results make sense given what you measured. The Velcro analogy is a really good one for understanding your results. When you put two pieces of Velcro together, it's pretty easy to pull them apart if you pull on them like this:

Image

But, if instead of pulling the two sides of the Velcro strip apart (like in the picture) you pulled parallel to the strips, it would be much, much, much harder to pull them apart. To use a word from my last post, the strength of Velcro could be considered anisotropic--it's much easier to break the "grip" between the strips by applying a force in one direction compared to another. The Velcro works the same way no matter which way you pull on it. But, it can be easier or harder to pull it apart depending on how you pull the strips. In this case, the Velcro is weaker when the applied stress is perpendicular to the “seam” between the two strips. It is much stronger when the applied stress is parallel to the “seam”.

The hooklet bonds between bards in the vane are also anisotropic. The data from your stress tests show this (as with Velcro, it was much easier to pull the barbs apart when they were aligned perpendicular to the applied stress). So, your material may be much stronger in one direction (where the applied stress is parallel to barb) than in the other (where the barbs are perpendicular to the applied stress). The anisotropy of your material might give it interesting (and perhaps useful!) properties, depending on the details of your invention.

That being said, you asked about ways to strengthen the barbs when the applied stress is perpendicular to them. The hairspray and liquid bandage were good ideas, and, as a side note, it's just as important to make note of things that don't work as the things that do. It's all part and parcel of the engineering design process. One idea would be to bond two layers of vanes together, oriented so that they are perpendicular to one another. In that orientation, the "strong" and "weak" directions would add up, giving you a strength that is something in between. You could even try weaving the vanes together, like the lattice top of a pie. The question is what to use to bond the two layers together. One option is cyanoacrylate (Super Glue or a similar brand). You will need to be very careful if you decide to try cyanoacrylate--be sure to read the warning labels, follow the directions carefully, and have an adult supervise you. Use cyanoacrylate in a well-ventilated area and don’t let it get on your fingers.

Let me know how it goes. This sounds like cooler project every time you post how things are going. As always, post back if I can help in any other way.

All the best,
Terik
All the best,
Terik
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