04/22/2016

Learning to Walk Like a Gecko, See Like a Lobster

17:36 minutes

Gecko hairs. Each tip is only 200 nm wide. Credit: Kellar Autumn
Gecko hairs. Each tip is only 200 nanometers wide. Credit: Kellar Autumn

Have you ever used Velcro to hold two things together? If so, you’ve benefitted from biomimicry, an approach to solving human problems through nature-inspired innovations. The idea behind Velcro, for instance, is famously rooted in one scientist’s observation of the way burrs use small hooks to stick to animals and clothing. The biomimicry field continues to grow as observations of animals and plants spur new ways of tackling challenges like water conservation in desert environments, solar cell efficiency, and more.

Robert Full and Hongrui Jiang are two engineers whose work is inspired by biology; one looks to gecko feet and cockroaches to improve robot movement, while the other has combined certain properties of a lobster eye and an elephantnose fish to improve low-light vision. They discuss how nature has inspired their innovations and where human ingenuity can play a role in improving on what evolution has already produced.

An apparatus combining fish-eye and lobster-eye traits for better low-light vision. Credit: Hongrui Jiang and Hewei Liu
An apparatus combining fish-eye and lobster-eye traits for better low-light vision. Credit: Hongrui Jiang and Hewei Liu

Segment Guests

Robert Full

Robert Full is Editor-in-Chief of the journal Bioinspiration & Biomimetics, and is a Professor of Integrative Biology at U.C. Berkeley in Berkeley, CA.

Hongrui Jiang

Hongrui Jiang is a Professor of Electrical and Computer Engineering at the  University of Wisconsin-Madison.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. If you’ve ever used Velcro, you know, to hold things together like the flaps of your sleeves or camping equipment, you have benefited from the tiny hooks and burrs used to stick and stick and stick to your clothing. You’ve benefited from design inspired by nature, the cocklebur.

That’s how it was discovered. The cocklebur was the inspiration for Velcro. And when you fly on an airplane, you’re benefiting from the structure pigeons wings used to keep themselves aloft.

Japan’s bullet trains are inspired by the drag-resisting bill of the kingfisher. Did you know that? Maybe you’re getting the picture now.

Many engineering feats are really mimicry of successful designs in nature. What if we could make more efficient wind turbines using the fins of humpback whales as a guide or mimic the barnacle-repelling skin of sharks to keep our ships and docks free of pests? What do you think?

What animal or plant characteristic do you think we could benefit from? Give us a call. Our number, 844-724-8255. You can also tweet us @scifri because we’re going to talk with two engineers who work in the world of possibility.

Robert Full is Professor of Integrative Biology at the University of California, Berkeley also Editor in Chief of Bioinspiration & Biomechanics. His work looks at how geckos stick to walls, how cockroaches can run fast while squeezing through tight spaces. I’ve always wondered how they can do that. And who hasn’t? And he thinks about how robots can use these innovations.

And Hongrui Jiang is a Professor of Electrical and Computer Engineering at the University of Wisconsin in Madison. And he has been working on an apparatus that could help people and machines see better in darkness with the help from the eyes of a lobster and a particular African fish. Boy, we want to get in to find out how all of this works.

And as I say, our number again is 844-724-8255. Welcome, gentlemen to Science Friday.

ROBERT FULL: Thank you.

HONGRUI JIANG: Thank you.

IRA FLATOW: Hongrui, you recently published a paper describing a way to make a more light-sensitive lens starting with inspiration from a lobster eye.

HONGRUI JIANG: Correct.

IRA FLATOW: Tell us about that.

HONGRUI JIANG: Well, the idea to improve this light sensitivity of an imaging system. Most of the research right now predominantly focuses on improving the electronics or the material of the imaging sensor. We were interested in a different complementary approach by collecting and guiding more light reaching the imaging sensor. So this will be a great method. And it has a huge benefit because it does not consume electronic power, electrical power. In our exploration, we were inspired by two types of very different natural eyes, those of lobsters and those of elephant-nose fish.

IRA FLATOW: And the lobster eyes, what advantage do they have? Are they multiple many small eyes instead of one big eye? Or is that the idea here?

HONGRUI JIANG: Yeah. The lobster eyes, they fall into a category called a superposition compound eyes. Speaking of compound eyes, I think people are more familiar with insect eyes like fly eyes, dragon flies.

IRA FLATOW: Right.

HONGRUI JIANG: These are called apposition compound eyes. To put it simply, one small eye would correspond to one imaging unit, roughly speaking, 1 pixel. In superposition compound eyes, multiple small eyes would correspond to 1 pixel. So there’s more light reaching each pixel. That’s higher light sensitivity.

However, the fabrication to realize such a man-made version of the lobster eye is very challenging. We did succeed a few years ago. But it was very, very hard because the three-dimensional structure and the intrinsic microscale features need to be very precisely arranged and made onto a perfect spherical dome. It’s very intolerant of any imperfection.

IRA FLATOW: Mm-hmm. You also work with the elephant-nose fish together. How did you work them to together to improve the vision?

HONGRUI JIANG: That’s where the elephant-nose fish come in to picture. So scientists discovered a couple of years ago that in the retina of elephant-nose fish, there are some very intriguing microstructures that look like tiny funnels. They found that these structures can effectively collect and the guide the light towards the photoreceptors.

This is, of course, very interesting because optically such design is much more tolerant of imperfection in the structure. So we combined the features of both eyes, the lobster eyes and elephant-nose fish retinas. They’re two very different types of eyes.

And then, we came up with a microscale parabolic mirror array that performs superposition for light sensitivity for the image sensors.

IRA FLATOW: Dr. Jiang, what got you so interested in looking at animal eyes in the first place?

HONGRUI JIANG: I have always been fascinated by animal eyes. I think the natural visual systems have some very interesting, intriguing designs. They are, of course, well suited for the specific animals. But these designs could be very useful for us to improve our man-made systems.

IRA FLATOW: And Robert, do you agree? Why should we look to nature to solve human problems? Because nature may have some of the answers that we’re looking for.

ROBERT FULL: No, absolutely. I think nature can be thought of as sort of a library of wonderful design ideas that can inspire us to design really wonderful new and better things.

IRA FLATOW: And because we don’t have a, you know, a quadcopter that can maneuver like a hummingbird yet. Right? None of our drones can do that.

ROBERT FULL: Not yet.

IRA FLATOW: Not yet.

ROBERT FULL: Not yet. But we’re working on it.

[LAUGHTER]

IRA FLATOW: All right. Let’s go through some of the examples of biomimicry that we might be using without even knowing it. I mentioned Velcro. Right? That was a burr that was discovered. Who was it, George de Mestral or somebody like that, if I remember correctly?

ROBERT FULL: Mm-hmm. Back in 1948, some of the plants got stuck to his dog. And he looked at them and invented Velcro.

IRA FLATOW: And airplanes, the Wright brothers were looking at flying birds.

ROBERT FULL: Yeah. They looked at turkey vultures. And they saw how they turned. And we now have the flaps on the wings called ailerons that help do that.

IRA FLATOW: And Japanese bullet trains were helped by what?

ROBERT FULL: So there’s a the kingfisher bird that dives into the water and has very low drag. And this train was making very loud noises as it was moving 200 miles an hour. And by studying the way that the kingfishers did, they were able to reduce that dragging sound.

IRA FLATOW: I understand that lotus leaves have a connection to paint. Tell me about that.

ROBERT FULL: Lotus leaves are incredible. So they’re naturally self-cleaning, water repellent. And they’ve led to paints and sprays and over 200 patents because they’re superhydrophobic with bumps and hairs. And drops just collect dirt and just roll right off.

IRA FLATOW: What are the limits of biomimicry? You know, there’s got to be a limit. Why isn’t it enough to just copy what nature does?

ROBERT FULL: Well, that’s a really important question. I think that what we first have to realize is we can already do better than nature in many things. There’s been a lot of large birds that have evolved. But none carry, you know, 300 people across the ocean.

No animal can move faster than a rocket or lift a beam to build a skyscraper. So we have to realize that we really want to integrate what the wonderful discoveries we find in nature are with the best human engineering. And after really 3.8 billion years of evolution, the organisms that are here really are not necessarily the best solutions that have been optimized. Organisms are not perfectly designed.

IRA FLATOW: Well, I think that’s an interesting point. That you’re saying basically that nature works just enough for what it needs but not the best that could be. We then–

ROBERT FULL: Exactly.

IRA FLATOW: –take what nature has and try to make it even better.

ROBERT FULL: Exactly. So natural selection is not engineering. Evolution works kind of on the just good enough principle and carries all the baggage of the past. And so you don’t want to compromise things in your design that are a result of the things that organisms do.

They have to grow. Their parts do many things. They evolve from what they have. And engineers, though, can start from scratch.

Biologic evolution is kind of more like a tinkerer than an engineer. And tinkerers never really know kind of what they’ll produce. And they use everything that they have to make something workable.

IRA FLATOW: Hongrui, let’s talk about what else nature has that inspired your work. What inspires you from nature?

HONGRUI JIANG: Sure. Indeed, lots of our work was inspired by nature. I’ll give two examples. The first one, a few years back, we realized the tunable focus, liquid lenses in which a responsive polymer mimics the function of the ciliary muscle in human eyes to adjust the focus of the lens.

In other work, we were inspired by sunflowers. We know that they can orient themselves throughout the day towards the sun to increase the sunlight interception. So we developed the light-sensitive polymers to actuate solar panels to track the sun for more electricity output. So those are just two examples.

IRA FLATOW: And you call your work bioinspiration rather than biomimicry. What is the difference there?

HONGRUI JIANG: Right. I think Dr. Full summarized it very well. I don’t think we have to duplicate the natural systems all the time. A natural system, for example in the eye of an animal, it might be tailored for that specific animal. But it might not necessarily be perfect for our purpose.

And second that we do have many capabilities to make things that animals or plants are not capable of. So again, I think the key is to take advantage of both and combine the merits. I can give you an example.

In the elephant-nosed fish’s eye, the micro funnels work for red light. We don’t necessary have to limit ourselves to red light only. With a parabolic mirror structure that we realized, we can make it work for all visible light.

IRA FLATOW: That’s quite interesting. Let’s go to the phones, 844-724-8255. First up, Reno, Nevada. Felice, hi. Welcome to Science Friday.

FELICE: Hello. How are you?

IRA FLATOW: Fine. How are you? Go ahead.

FELICE: Great. So I’ve always noticed in looking at lacinato kale, the kale that’s commonly used in salads but not the curly kind, it’s incredibly water resistant. And I always had thought it would make really good outside weather gear, rain gear. Has anyone ever looked at the properties in that plant?

IRA FLATOW: Robert, any comment?

ROBERT FULL: I don’t know about that plant, specifically. But there is an enormous amount of work now on plants discovering the very kinds of things you’re suggesting with respect to, particularly new ways to harvest water.

IRA FLATOW: Can you get a little more specific about that?

ROBERT FULL: So hairs, for example, are able to trap water out of the air and then collect them in droplets.

IRA FLATOW: Yeah, because everybody wants to harvest water. It’s in short supply. What could be coming some day to our everyday lives, Robert? Give us an idea.

ROBERT FULL: In terms of–

IRA FLATOW: I mean–

ROBERT FULL: –the– just generally?

IRA FLATOW: Yeah, in generally. You like surfaces, I can see. You talk about fish and things like that, skin.

ROBERT FULL: Well, materials is a huge thing, of course, that we’re able now to make things that we just couldn’t even conceive of before. And so the more our human technologies take on the characteristics of nature, nature becomes a lot better teacher. For example, we can actually begin now to make something like spider silk.

We can go from genes to the behavior. And this material is stronger than steel and more elastic than rubber and softer than wool. And you can make all kinds of clothes or new bulletproof jackets or super durable seats or even artificial tendons.

IRA FLATOW: Now, you’ve got to tell me– now I brought this up at the beginning. You’ve got to tell me the way cockroaches can run fast while pressed to the ground. Could that give new capabilities for rescue robots? Is that what you can use them? Tell me how they do that and how you’ve imitated them.

ROBERT FULL: So, you know, cockroaches are pretty disgusting. But they can tell us a lot of secrets. And so we wondered how they could infest virtually any space by going through these tiny little cracks using their skeleton. And we found that the American cockroach can compress their exoskeleton in half to slip through spaces that are basically the height of two stacked pennies. And they can do it in less than a second.

And what was even more surprising is once we saw them inside the sort of vertically confined space– imagine two plates, one on top of the other– they continued to locomote really rapidly, even though they were compressed so their legs were completely splayed out to the side. They could run at 20 centimeters a second, like 20 body lengths a second, which is equivalent to the human size as fast as any sprinter. Which means they can not only squeeze into those tiny spaces in your house, but they can run at high speeds within your walls and ceilings.

IRA FLATOW: It’s disgusting me more.

[LAUGHTER]

It’s good though.

ROBERT FULL: We also found that you can–

IRA FLATOW: Wait. Let me just give everybody a chance to breathe a little a second. Let me remind everybody that this is Science Friday from PRI, Public Radio International, talking about biomimicry. And Robert Full is here to continue to talk about the wondrous cockroach. Well, go ahead. Finish up that story.

ROBERT FULL: So we found that the cockroaches– we put them in a materials testing machine. And they can withstand a force nearly 900 times their body weight without any injury. So they’re incredibly soft and robust.

And so we looked at this. And from the discoveries on the cockroaches and how they squeeze through crevices, this inspired the design of a origami-like legged robot we called a CRAM for Compressible Robot with Articulated Mechanism. And that in swarms, you could imagine them at some point helping locate survivors that have been trapped in tornadoes or earthquakes or explosions.

IRA FLATOW: So they exist? You’ve made them?

ROBERT FULL: So we’ve made a prototype robot that’s able to go into spaces, compress in half and still run at high speed.

IRA FLATOW: Wow. The size of two coins stacked together?

ROBERT FULL: That’s what the cockroaches can do. So it’s incredibly small spaces.

IRA FLATOW: But yours are just getting to that size.

ROBERT FULL: So ours is about hand size. Because we’re thinking about also adding payload, some sensors that would be needed. But there are other groups working on ones that are just as small as the cockroach.

IRA FLATOW: Hongrui, is there anything you would like to imitate that you haven’t gotten to yet that you liked looking at?

HONGRUI JIANG: In that sense, I have a very long list.

[LAUGHTER]

There are so many things I think. Dr. Full gave a very good example. Another thing that has always intrigued me and actually not just me, I think every researcher, is the brain. And of course, there is a huge initiative to reverse engineer the brain, how the brain processes the information.

Because it has always been fascinating. We take the information in. And our brain can process it and render all this information in a very logical way.

And in some aspects, it easily beats the best computer. And of course on some other hand, the computer obviously can do a much better job than our brain.

IRA FLATOW: Right.

HONGRUI JIANG: That would be one example. I would really love to crack the cold.

IRA FLATOW: Robert, are there ways biomimicry can benefit us, even if we’re not that interested in Velcro or your cockroach feet there?

ROBERT FULL: Well, I think that it really is the only sort of alternative technology to our own. So in a way, looking at nature’s designs can kind of free us from the constraints of our past design thinking and provide true innovation like you’ve heard about.

IRA FLATOW: Well, we’ve got to conserve what we have out there. Right? If we–

ROBERT FULL: I think this is a critically important point. So if we don’t preserve nature’s designs, then these secrets will be lost forever. So if these seemingly useless species disappear, we’ll never know what we’ve lost.

IRA FLATOW: All right, then. There you go. Good words for Earth Day today. I want to thank both of you, Robert Full, Professor at the University of California, Berkeley and Editor in Chief of Bioinspiration & Biomimetics and Hongrui Jiang is a Professor of Electrical and Computer Engineering at University of Wisconsin in Madison.

When we come back, have you ever seen a bullet shatter on impact? We’re going to talk about this new foam made out of steel. It’s amazing. It’s a mind-blower. After this break.

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Christie Taylor is an associate producer for Science Friday. Her day involves diligent research, too many phone calls for an introvert, and asking scientists if they happen to have an audio recording of their research findings.

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