GEEKOUT: The Animal Kingdom with David Hu

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Can timing urination of an elephant and a human impact engineering? David Hu talks about animals – more specifically, how we can solve complex human problems by studying animal functions. How exactly do snakes move without legs? How can some spiders seemingly walk on water? These answers can inform how we engineer new technologies.

Hu is an Associate Professor of Mechanical Engineering and Biology (as well as an Adjunct Associate Professor of Physics) in Georgia Tech's George W. Woodruff School of Mechanical Engineering. Hu leads the Hu Biolocomotion Lab at Georgia Tech.


[analog radio tuner scanning stations]
[big band swing rendition of Ramblin' Wreck from Georgia Tech]
[interposed voices of Steve McLaughlin] ...sounds incredibly sounds have abilities that span...I'm really geeking out here.
[applause and laugh track]
[big band swing rendition of Ramblin' Wreck from Georgia Tech]

Steve McLaughlin: You really have this incredible ability to explain complex ideas whether they are biology, whether they’re engineering, how they apply to practice. And that's, you know, one of the things that engineers are often criticized for is we don't do a very good job of communicating to the general public what we do, why we do it, and so on. And I know that that's a passion of yours, you know, in addition to the science is to try to, you know, have engineers, scientists do a much better job of communicating what it is they do, because it's incredibly important and exciting to attract young people to science and engineering. Can you say a little bit about how your interest in engineering evolved, and then how you're so passionate about making sure the public knows what engineers do?

David Hu: I do really like telling the story behind the work. We have the journal articles where we’ll publish the technical aspects of the work. But a lot of times, you know, what I remember is the same kind of story that I'm going to tell my kids and I'll tell my grandkids of, you know, who are the people behind this story and what were the challenges and why was it difficult. And I just really enjoy that process. And one of the reasons that I continue doing it is because it's has actually helped my research quite a bit as well, and that's something a lot of, maybe, scientists and engineers don't know. For example, when we first started studying this urination, we published this article in National Geographic. And this lawyer from New York City sent us an email and it gave us a correction in the article. He said that he used to work in zoos when he was a kid and he said, “Well, elephants actually have a slightly smaller bladder for their body size than according to these evolutionary trends. So you should make this correction in your paper.”

There is no way I could have gotten in touch with this guy unless I had put this out in National Geographic. So he actually influenced our paper, so that we actually when we published the final article in Proceedings of National Academy of Sciences that it was correct. So, and that's just one example of when you reach out to the public, there's a huge, huge number of people out there that are kind of these like citizen scientists that they give feedback, and they just—it's like having a million eyes. They kind of like help you at once. And, I mean, it's just, I think it's a lot of—it's also just fun, it's fun to get to know them and they know there's this huge, huge amount—especially about biology and about nature that the general public knows about. And I really try to use them as experts, too.

Steve McLaughlin: As you were talking about the properties of this kind of ant raft, I was trying to envision the tools that you use to really get this incredibly detailed information. You said you use high-speed cameras. Can you say a little bit, you know, from a technical standpoint what are the kind of tools of the trade for someone who does what you do?

David Hu: The nice thing about being an engineer or scientist, we get to play with really cool devices. The thing that you want to use to study ants is this thing called a rheometer. Now it was actually, this rheometer, it looks like a little merry-go-round except it costs like $60,000. That’s like more than the price of my car, way more. And the rheometer was invented by chemical engineers who wanted to basically engineer food products. For example, M&M’s, they melt in your mouth but not your hand. Yogurt, has this what they call “mouthfeel.” All these products have been engineered by adding different additives to make them taste a different way. And what this rheometer does it has these two spinning plates, and what it does is it can actually measure the properties, the materials, really precisely. And so we are the first ones to actually put sort of living organisms in this rheometer, but we basically treated them as this, you know, alien substance that we kind of wanted to reverse engineer.

Steve McLaughlin: I see. So just, again, using regular tools of the trade that, you know, that engineers use. Like you said, you take take the animals or, in this case, insects, as just another, as another thing that you want to test. So it's totally normal from an engineering standpoint.

David Wu: Yeah. In our lab we borrow the rheometer there. In their lab they have these two rheometers. One of them they call the “clean rheometer,” and my realm is the “dirty rheometer” because we'll put feces and ants in it, and we have to have this vacuum cleaner around in case the ants escape. So yeah it's a—you basically—we make special engineering tools a little bit grosser.

There's this animal that we're studying called the star-nosed mole. No one's ever heard of it, but it's just a mole that can actually sniff underwater with like basically our nose. So if you go scuba diving, you can’t actually smell the underwater. All you smell is that sort of disgusting rubbery mask that you put on. And that's because there's an air water barrier and we can't penetrate that. But a few of these small, sort of small, rodents like the mole, they've actually evolved a way to blow bubbles underwater and inhale those bubbles back in to its own nose. And so it's basically sort of hacked, sort of this system, and made its ability to basically smell under water. And it uses this to sort of catch worms. It's almost completely blind.

Steve McLaughlin: That's what I was gonna say. Why does this mole need to smell underwater? And you're saying it uniquely adapted because it's a better worm hunter than maybe others.

David Wu: Yeah, that's right. It basically has to completely rely on the sense of smell to go in an environment where its nose wouldn't normally work. And so it exhales and inhales these bubbles. And we think we get basically—we're using our grommet, our device that we use on air, and we want to put underwater. And the great thing about this is that we would actually be able to give a whole new regime to sort of above-water sensors because right now there's no solution for sensors underwater.

I was at Auburn a few weeks ago and looked at their aquaculture tanks. The raising of fish is a huge, huge rising industry. But there is no permanent way to actually sense things underwater because of algae, bacteria. The closest device they have is this brush that periodically goes over your sensor underwater, but eventually the brush gets clogged. So we can basically take advantage of this, you know, this star-nosed-mole and we can build this sensor that basically never actually has to touch water, but can actually smell underwater. I think, I think that would be a pretty big deal.

Steve McLaughlin: Now, I mean, again, as you were talking, I’m thinking, why in the world do we need to you know smell things underwater? But that's probably because we've never been able to do it. And if, in fact, we're able to develop the systems or the sensors that might develop from that, it's really, really quite something.

[tribal percussion, birds chirping, monkeys chattering, elephant trumpeting]

[Ramblin' Wreck from Georgia Tech marching band rendition]