9UNP0154SD_Kimberly_Duncan_WordPress 

- Welcome, everybody, to Wednesday Nite at the Lab. I'm Tom Zinnen. I work here at UW-Madison for UW-Extension. We're delighted to have you here. We have Wednesday Nite at the Lab every Wednesday night, 50 times a year. It's co-organized by the Wisconsin Alumni Association and UW-Madison Lifelong Learning Institute. So, happy to have everybody here tonight. Tonight, I'm delighted to have two speakers on nanotechnology. The first is Kimberly Duncan. 

She's a post-doctoral associate with the Interdisciplinary Education Group of the UW-Madison Materials Research Science and Engineering Center, which everybody likes to call MRSEC. The IEG focuses on creating programming and instructional materials on nano-scale science and engineering for a variety of audiences and settings. Prior to coming to UW-Madison, Duncan was the Senior Science Policy Fellow with the American Physical Society's Office of Public Affairs in Washington, D.C. She holds a PhD in chemistry from Princeton University. And Katie Cadwell, who's also a post-doctoral researcher for the Interdisciplinary Research Group of MRSEC. She holds a PhD in chemical engineering from our fair UW-Madison. Please join me in welcoming Kim and Katie to Wednesday Nite at the Lab. 
(applause)
 
- Thanks for that introduction. And thanks for such a great turnout tonight, especially with the new date, doing Thursday night at the lab instead of Wednesday, as the name of the event says. 

As Tom said, tonight we are going to do a brief journey into the nano world. And together, we'll explore what is nanotechnology; what is it doing for us; and where we might we find it in our everyday life. Thankfully, Tom got all the acronyms and the long-winded names of where we work, the Interdisciplinary Education Group of the MRSEC. The role of our group is to do education events like this one, to help get the public informed about nanotechnology. And so, a lot of us may have heard already, the term nanotechnology. And really, it's quite possibly all around us. It's already in the movies you see in Hollywood. Michael Crichton started a big stir about it a few years ago, talking about self-replicating nanobots that were consuming human flesh. We're also seeing it in the cars that we drive and the materials that make up the bumpers and other parts of the car. In our computers, as the silicon chips get smaller and smaller. 

We have it in our clothes, for those of us who are a little bit more messy, like myself. I've got pants that I can spill anything on and it washes right off thanks to nanotechnology. And even one of my favorites is the self-cleaning windows. I know how much it really stinks to get out there in the spring and clean them off. So hopefully, nanotechnology will prevent us from ever having to do that again. So it is all around us. We're already seeing things about it in the media. But what exactly is nanotechnology? If you're out there and you don't know, don't worry. Actually, recent studies show only about 50% of Americans have heard of the word nanotechnology. 

And a very small percentage of those people can actually technically and correctly define it. So I'm just going to put up some formal definitions. One comes from the federal government. It sounds very professional. "Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications." And it says that it's very interdisciplinary. If you look at the MRSEC, you'll notice that the professors that do nanotechnology research span anywhere from chemical engineering, physics, materials research, biology. It really is very interdisciplinary as a science. But for the public, what most of us want to walk away with is that the nanometer is extremely small. And at the nanometer scale, materials behave differently. 

And we're trying to harness these new behaviors as a way to come up with new and novel applications. So exactly how small is a nanometer? We'll just to start off to talk about the metric system. Some of us may remember that from back in school. You're likely more familiar with the English system with the yard and the foot. But when thinking about the metric system, the base unit is the meter. I can then add prefixes to that system to say whether or not it's bigger than a meter or smaller than a meter. And the nanometer is one-billionth of a meter. So if I took a meter stick, it's about the same length as a yard, and I cut it up to a billion pieces, each one of those pieces would be a billionth of a meter in length. Probably, I know for me, that doesn't mean a whole lot. 

It's hard to imagine exactly how big or how many is a billion. So let's try to put this in our own cultural perspective. So if I talk about a kilometer. I've got a picture of the Sears Tower down in Chicago. It's the tallest building in the United States. It stretches 1750 feet into the air. It's only half a kilometer high. So a kilometer, pretty long. It's 1,000 meters. It's also the distance, if you're standing at the edge of the UW campus and looking down State Street, it's approximately a kilometer to the State Capitol. 

So many of you may have already walked that at one point this week, and you'll remember, oh, okay, that's about a kilometer. If I cut the kilometer into a thousand pieces, I get down to the meter. A meter is approximately the height of a bicycle seat for a typical adult bicycle. If I cut that meter into a thousand more pieces, then I'm down to the millimeter scale. It's about the same size as the tip of a pen. So, it's pretty tiny already. If I keep going down-- And remember, these are all things that we can still pretty easily see. If not with our naked eye, with eye glasses or a magnifying glass to see the tip of that pen. If I go even smaller, I get down into the micro scale. So I take that millimeter and cut it, again into a thousand pieces. 

I'm left with a micron. A human hair, which sort of pushes our eyes to the farthest they can go, to be able to see the diameter of a hair if you held it on end and looked down the small end of it. That's 40 microns. So, similar on a same scale of the micron is a red blood cell. It's about 7 microns. These are still things we can see with a typical light microscope that you might use in a biology class, or that you can buy at a specialty sort of scientific toy store. A nanometer is a thousand times smaller than this. So when we get down to the nano scale, one nanometer, we're on the scale of atoms. So the atoms, the ubiquitous things that make up everything around us. If you've gotten a virus, it's about 3 to 50 nanometers, depending on the virus you look at. 

DNA, the building block of life, the diameter of those helices are about 2.5 nanometers wide. And this iconic picture over here on the right, if you have heard of nanotechnology, you might be familiar with that picture. It's a picture of 49 iron atoms that have been painstakingly placed, atom by atom, on a surface. The diameter of this corral is 14 nanometers. So, nanometer, the take away definition, very, very, very small. So small, you can't see it with your eyes. And so at this point, I'm going to pass it off to my colleague Katie. 
- So Kim mentioned that when you're looking at red blood cells, which are on the micron to 10 micron level, we can still see those using light. And we can't see things like viruses, DNA and molecule that are down on the nano scale. And does anyone know why we might not be able to see those things using light? 

Any volunteers? 
(inaudible)
 Optical length. Sort of. If you could, say, grind a lens fine enough that you could get all the way down to focusing on it. And the reason you can't see things that are down on the nano scale is because they're actually smaller than the wavelength of light. So light is too big of a tool to use to see things on the nano scale. So if we can't see things on a nano scale, how is it that we're able to "see" them? So everyone should have, maybe it was in their seat when they sat down, or on a table in front of them, one of these magnets. And we're going to do a little experiment to kind of demonstrate how it is that we can see things that we can't actually see using light. 

So each one of these magnets has a probe strip on the end. And if you-- 
(inaudible)
 Okay. They're also in the back if you want one. So you can bend the probe strip and break it off from the rest of the magnet. And then what I'd like for everyone to do is to take this probe strip, and along the black side of the magnet, where there's no sticker, draw the end of their probe stick lengthwise across the magnet and then widthwise across the magnet. Does someone want to tell me what they observed when they pulled the strip the long way across the magnet? 
(inaudible)
 It feels smooth. 

And then what happens when you pull the strip across the short end of the magnet? It kind of bumps up and down, right? So the reason it does this is because this magnet has been manufactured to have a pattern of north and south poles in it. Now, when you look at the back of the magnet, can you see where the north and south poles are? No, you can't see them. But I'm going to have you guys vote now on what the pattern of north and south poles would look like on this magnet, if you could see them. So, is it all north or south pole? Is it stripes of north and south poles? Or is it a checkerboard? How many people want to vote for all one pole? 

All right. How about stripes of north and south poles? And how about a checkerboard? So most people think that it's stripes of north and south poles. And the reason you think that is because when you dragged the strip this way, it felt smooth. There was no change in whether your probe was "seeing" a north and south pole. And when you dragged your strip this way, it bumped up and down because it was alternately repelled and attracted to the north and south poles. So even though you couldn't see with your eyes, what the magnetic pattern was on this magnet, you still knew by using this probe. And scientists and engineers use a similar technology. In general, they're called scanning probe microscopies. 

And I've shown one here, specifically, an atomic force microscope. And what this does is it has a very, very, very fine tip. And this tip is attached to the end of a cantilever that's really delicate. And this tip is maybe a few molecules wide at the end. So it's very, very small. And you can drag it across a sample, and just go back and forth in both directions. And as this tip goes across the surface and encounters features on the surface, it moves up and down. As it does that, you can shine a laser on top of this cantilever. And very, very small fluctuations in how that cantilever moves can be projected into much larger movements that can be detected with a laser detector. So, if Kim has a shaky hand today, because maybe she's a little nervous, even though she's not moving her hand very much at all, you can definitely see the movement further away in the laser. 

It's amplified by the distance. And by doing this, you can actually map out surface features down to a very, very small scale. So what I'm showing you here is an AFM image from Professor Max Lagally, here at UW-Madison, of a silicon wafer. And I have a silicon wafer here with me, in a petri dish. And I'll pass it around. When you look at the silicon wafer, it looks very smooth and shiny. It has a mirror-like surface. And so, you can't see with your eye that there's any features there at all. But when you use the atomic force microscope, we can actually have a resolution that's below a nanometer. And these features that you see are actually just one single atom in width. 

And so, using these scanning probe microscopies, we can see what we can't really see. And I'll pass it back to Kim. Mm-hmm? 
(inaudible)
 
- ...the surface, so that you know that your disturbances are caused by molecules, not by, you know, the physical whatever you polished it with. Or the kind of the more things we think of as a physical surface. I think that would have-- I can't imagine something that would be smooth enough so that, you know, that something detecting the surface would be seeing molecules, not artifacts of polishing. 
- So partly, we know that those are atoms or atom vacancies because of the size that they are. 

Also, silicon itself, the way that it will cleave. It actually makes, you can make very abrupt and clean cuts in silicon. And you still polish it, but it actually likes to kind of splinter along the crystalline faces. And so, it's well-known that you're going to have a very nice, clean and flat surface, at least until you get down to the atomic scale. But even on the atomic scale, this is really flat. 
- It's not a completely uniform pattern. So are they reflections of light? 
- You're not seeing reflections of light. Because light is, you know, a thousand time larger than these features. 
- What are the stripes? 

There are several different ones. 
- These stripes versus the stripes here? 
- Right, it looks like a very regular background, and then there's some black spots and some white. 
- This is an artificially colored image, is the first thing that you have to realize. It's not white, black and turquoise, like it looks up here on the screen. That was how someone decided to map it out using a computer program. There's no color at all, in fact. What they've done is they've used different colors to represent different heights. So, usually the way they do it, I don't know specifically with this image, is they'll have lighter colors representing higher places. So there's just a few more atoms in this spot that's causing that tip to deflect further from the surface. 

So the coloring is completely artificial. 
- We've had a brief introduction to what the nano scale is and how we see there. But what is the big deal? Well, a lot of people are saying that nanotechnology is the next revolution, that nanotechnology will do the same thing for us that the industrial revolution did in the early 1900s. It will do the same thing for us that the Internet did for us in the '80s and '90s. So if we think about life in the 1900s versus life today, very different. The same thing, I imagine. Many of us can't think of going a day without checking our email or looking online for the news. I apologize, I'll scooch out of the way. The news of the day or even doing a little Internet shopping. 

And you'll see that a lot of these revolutions for technology take about 100 years. Railroads came around. There was kind of a quick growth period where a lot of development happened. A steady climb, and then a plateau as railroads became more commonplace. We weren't building as many tracks and such. Well, for nanotech-- Or the same thing goes for the computer taking off. We're starting to probably plateau for computers. But for nanotech, we're pretty early on in this take-off of this next revolution, for nano to be the next big thing. A lot of the proponents of nanotechnology think we're going to follow this curve as it's written. Some of the naysayers say we're going to get to about here, and then just turn over, and nanotechnology is going to prove to be all hype. 

So it's up to you guys out there to start thinking, is it hype or is it really a technological promise. So there are a lot of people saying it's going to be a big deal. Just one quote I wanted to point out. One of the reasons that people think it's going to be a big deal is that it has an amazing possibility for impact on products that are traded on the global market. Mike Roco, who is the director of a government initiative called the National Nanotechnology Initiative, a group that's sort of involved in setting the U.S.'s trajectory for research and development in the field of nanotechnology. He thinks that by 2015, nanotechnology enhanced products will account for $1 trillion, and that in order to reach this, we're going to need two million workers to fill the positions in nanotechnology. So a really huge opportunity for companies, consumer products and other things. And also a huge opportunity for job creation. Supporting Dr. Roco's claim is that the federal government has already started heavily investing in this branch of science. 

You'll see there 13 agencies on the left hand side. Being from D.C., I'm really used to the alphabet soup of the way that the agencies are represented. However, you'll notice at the top, we're talking about the National Science Foundation, the Department of Defense, the Department of Energy. They're sort of the big players when it comes to scientific research. You can see that their investment is much heavier than places maybe like the Department of Justice, or even the Department of Transportation. But the total investment for 2008 is projected to be $1.4 billion. So there are people out there, and certainly a lot of scientists who believe that this is going to be a great place to be investing our money. Why do people think it's such a big idea? It turns out when things get very, very small, that size does actually matter. At the top of this slide you'll see some gold and silver bars. 

Most of us are probably familiar with gold or silver, either through jewelry we own or metal work we've seen. We might not have those gold bars sitting in our closets at home. Maybe just take a look if you have ring or earrings on to remind ourselves that gold is shiny. It's yellow in color. Silver is shiny. It's gray in color. However, when you get down to the nano scale, when you go from bulk all the way down to the nanometer, the silver and gold actually change color. I have a picture up here. The nano particles of silver turn yellow. Whereas nano particles of gold turn red. 

I brought a sample of gold and silver nano particles here that I'll pass around. Please do not open them. Don't try. I've super glued them shut, but don't try to beat the super glue. 
- If they're smaller than the wavelength, how can there be color? 
- That is a great question. And what happens is that the light interacts with the particle in a very different way. So the particle is made up atoms that have electrons that are freely roaming on that particle. And then when the light wave comes in, it causes those electrons to vibrate. Then they're able to emit a color. 

So it is smaller than the wavelength of light. It's the way that the electrons interact with the light. So you might look at these vials and think I just put Kool-Aid in there. There's no particles. But I'm not that sneaky. In addition to the vials I'll pass around, I'll pass around a laser pointer. Please make sure not to shine it in your neighbor's face as you are investigating it. If you take the laser pointer, and you shine it through, I'm going to try not to hit Katie in the eye, shine it through the nanoparticle vial, you'll actually be able to see the laser pointer pass through. The reason you're able to see it is because they're are little itty bitty particles that are interacting with this laser. That's why you see the laser pointer appear. 

To test yourself, I have a vial of plain water. You can do the same thing. You can't see the laser pointer go through the water because there's no physical particles. There's molecules, but there's no particles for the light to interact with. You can do it for both the gold and the silver. 
(inaudible)
 The particles are approximately, for the silver, are approximately 50-100 nanometers large. So if you think that an atom is a tenth of a nanometer, there's a considerable number of atoms. The gold is about 25 nanometers in size. It turns out, though, nanotechnology is not really that new. 

Medieval artisans have been using this technique of creating gold and silver nanoparticles, and seeing their color change for a thousand years. They didn't know it at the time. But when the artisans back in the Middle Ages added the metal oxides and the metal chlorides to their hot, molten glass, the process actually caused gold and silver nanoparticles to form. So the way that they got all these different colors was by adding different metals and creating nanoparticles of the metal within the glass. They certainly didn't know that's what they were doing. What they saw was when they added these compounds to the glass, it made this beautiful color. And they put it to good use. Did I hear a question? 
(inaudible)
 They're solid particles. 

And they're embedded in the glass. They're embedded. 
- Are there no particles in water? 
- There are molecules in water. But the nanoparticles are a collection of atoms. Do you have a better way to explain that? 
- When you're talking about particles, we're actually talking about a big chunk of atoms and molecules that are all stuck together. So, as Kim mentioned, your average atom, say, is just going to be on the order of a tenth of a nanometer. And we're talking about particles that are 50 nanometers across. So that's a whole lot of molecules or atoms. 

- Yeah? 
- What about colloids? Wouldn't you call a colloid like nanoparticles? 
- They are called colloidal suspension of nanoparticles. So it does fall under the definition of a colloid. So besides using this nanoparticles of gold back in the Middle Ages, we're also using it today for a very dramatically different application. It turns out that there are researchers at Rice University who are developing ways to treat cancer using nanotechnology. They create something called a gold nanoshell. So they take a piece of glass and they coat the outside of that glass with a very thin layer of gold or, I believe they have also tried silver. And as they change the size or thickness of this gold nanoshell, they get a lot of different colors. 

A lot like the picture I just showed on the last slide, where we had all those different colors in the same glass. Why does this work? Well, it turns out that these nanoparticles or these nanoshells of gold absorb infrared light. And when they absorb the infrared light, the atoms get very excited because they're being irradiated with light. And they get hot. And then the scientists have figured out a way that these nanoshells can be injected into the body, localized into a cancer tumor. And then when the tumor is exposed to infrared light, the nanoshells heat up. They increase in temperature over 30 degrees from where they were, and it causes the cells to die. The great thing is also it's very targeted and the infrared light doesn't affect normal, healthy tissue. We're exposed to infrared light during a regular day and we're not affected. 

However, if we had gold nanoshells within a tumor, it would cause the tumor to heat up, the cells to die. And hopefully they're working towards a way of treating cancer in the future. They're just starting clinical trials. So this won't be a therapy that will be available any time soon. But it's certainly a way that these nanoshells are being utilized for a treatment. Just another example of why size matters. Something we might be more familiar with in our daily life is sunscreens. I know that with my fair skin, I'm constantly slathering white, creamy, goopy stuff all over me. And there's always a spot that I have on my face. It's embarrassing to walk around the beach with a big, white, blotchy spot on you. 

However, the way that the sunscreens work is that there's zinc oxide and titanium dioxide in there. And it's those particles of the zinc oxide and the titanium dioxide that reflect the light and prevent us from getting a sunburn. That's where the white color comes from. If I start to more finely divide those particles until they're the size on the nano scale, again, they interact with the light differently and now the sunscreens are clear. So you can easily buy these sunscreens on the market now. You might have already purchased them this past summer or gearing up for the summer that's coming. Besides color, lots of other things change with the nano scale. I just wanted to point out that there's also reactivity, how reactive something is with its environment. For soda cans, if it's sitting on my desk, I have no worry that it's going to explode or hurt me in any way. But if I take the same aluminum that's in a soda can, and I make it down to the nano scale, it actually turns out to spontaneously combust. 

- All right, so now we're going to take a little break from just the plain old lecture and do a demonstration. I would like two volunteers from the audience. All right, I have one. I need a second, two, all right! So what I have up here is just two plastic tubes. And in the bottom of each tube is a metal cylinder. I have some stainless steel balls. It doesn't matter which one you take. I promise you they are the same. Now, here's what I need you guys to do. 

I'm going to count to three. I'm going to say, "One, two, three, go." And on "go," I want each of you to drop your ball into one of these cylinders. All right. One, two, three, go. You're really good at this. Have you been practicing? 
(light laughter)
 That's amazing. You got that ball to bounce for a long time. 

Let's grab these and try it again. Maybe it was just your superior technique. So maybe we should start over. Let's do it one more time. I'll count to three. One, two, three, go. Okay, so maybe it wasn't your ball bouncing skills that led that one to bounce longer. So what did you guys notice happened between the two trials? Anyone? I switched the two cylinders, right? 

So it's not the balls that are different. It's not my two lovely assistants. I'm done. Thank you very much. What's actually different are the two metal cylinders. And I'll go ahead and pass these around. You'll probably notice that they're a little bit different. First of all, this one has something glued to the top. And the reason this one has something glued to the top instead of just being made out of one single metal, is the stuff that's glued to the top is really expensive. I wasn't going to make a big cylinder out of it. 

But what's actually important is the tops of the cylinders, anyway, because that's what the stainless steel balls are bouncing against. So as I pass these around, I kind of want you to look at the surface. And remember that the one that has the extra stuff on top is the one that the ball bounced on for a really long time. And as I pass these around, you'll notice that on that one, the one that the ball bounced a long time on, it's really smooth and shiny. It's gotten a little bit scratched up from sitting around in a container with a bunch of other metal cylinders. But overall, it's smooth. Then if you look at the one where the ball didn't bounce as much, it has a lot of pits in it, dents. And where are those dents coming from? From dropping stainless steel balls on it. So that one dents. 

But the one the ball bounces on a long time doesn't dent. So what's the difference between these two cylinders? Well, the one that's all dented, it's just made out of stainless steel, also. But the one that is not dented, the one that the ball bounced a long time on, is made of something called amorphous metal. So it turns out that not only does size matter in the property of a material, but the arrangement of molecules down on the nano scale also make a difference in the properties that a material exhibits. So in regular metals, regular metal, such as stainless steel, the atoms within that metal tend to form a very regular arrangement. What we call a crystalline lattice. And because these atoms are all arranged nicely, they can kind of move as a group and slide past one another along fault lines. And that's what's happening to the stainless steel cylinder when it's being hit the stainless steel ball. That stainless steel ball is taking some of its kinetic energy, transferring it to the atoms within the stainless steel cylinder, and actually causing those atoms to shift along those fault lines. 

So you get a dent. The ball loses some of its energy to the cylinder. And eventually, it quits bouncing. However, with the amorphous metal, this particular amorphous metal is a mixture of five different atoms. And I'll tell you just off the top of my head, I don't remember what all five of them are right now. And these metals are all mixed together at a very high temperature and then cooled really, really, really fast. This metal is cooled so fast that the atoms don't have time to arrange themselves into a nice, regular crystalline lattice. Instead they get stuck with no particular form or pattern. That's why we call it an amorphous metal. Amorphous means no shape, no form. 

Because these atoms are just all jumbled together and stuck, when the stainless steel ball hits this surface, it's not able to easily dislodge a whole bunch of atoms, because there aren't any clear fault lines in that atomic structure. So, the stainless steel ball doesn't lose kinetic energy to creating dents in the surface, and it bounces for much, much longer. Eventually, it's going to stop. Some energy is lost to acoustics. You heard it as it was bouncing on the surface. That's acoustical energy. Some of the energy is lost just between molecules in the air. But it did bounce a lot longer. And so some of the applications for amorphous metal, it's already being used in sports equipment. So you can't use it in a regulation game, but you can get golf clubs that have amorphous metal, I guess, I'm actually not a golfer. 

But it's on the end of the club where you hit the ball. And because you're not losing energy to deformation within the head of your golf club, you're actually able to, in theory, hit the ball further using one of these golf clubs. If you have a lousy aim, it's not going to help you out any. On a more practical, and less just recreational side, these have been proposed for use in surgical metals. If you want to cut through someone's bone, cartilage or other tissues, you don't want a knife that's going to dull quickly. And so, they can use amorphous materials for these knives and they stay sharp for a lot longer. And Kim's up again. 
- So we talked about what seems like some high-tech applications for nanotechnology. Cancer treatment. I don't know how many stained glass artists we have out there. 

But nanotechnology is actually in your life already. I mentioned a few in the beginning. I mentioned the books, the movies, and some products. We're just going to talk about a few more products that might actually already have turned up in your house. It turns out that silver nanoparticles have an anti-microbial property. So they kill the bacteria that might be building up. So manufacturers are now starting to impregnate materials with these silver nanoparticles so that the material, possibly on the right hand side, like a Tupperware, can kill the bacteria that is starting to form in your Tupperware. Maybe it makes the Tupperware last longer because you don't have things go bad in it. You don't have to throw it away. It's also been showing up in athletic apparel, so you can maybe wear your workout shirt once or twice before you have to wash it and it starts to smell. 

The same thing goes for socks. Your refrigerator. I mentioned Tupperware. There's even a washing machine that was developed that had these silver nanoparticles in the basin, that touted an anti-microbial effect. 
- How does it have an anti-microbial effect? 
- They're pretty secretive about how it works. But what I understand as far as how the silver interacts, is that silver has been used as an anti-microbial before. Sometimes, in previous years and sort of in older days, they would put silver solutions into cuts to kill things. And so the silver causes the cells to die. What they found out with the nanoparticles is the way to get them into materials like socks, and fibers, and other things. 

- They used to use silver nitrates. 
- That's a great example. 
(inaudible)
 
- Unfortunately, what they may do is select for micro organisms that are resistant to the materials, and then become problematic in other ways. 
- That's a great point to realize. There's a lot of these products on the market. And we have to think about how they should be regulated. What happens to the nanoparticles that are in that washing machine when you use it? What happens as you wash the socks? 

The nanoparticles can come off in the wash and get into your water stream. These are all really big questions that scientists and policy makers across the board are trying to figure out how best to address these issues. 
- It seems like it would take an awful lot of them to clog up any system. 
- That's one of the issues. 
- In a washing machine, it would take millions and millions and millions. 
- There are a couple questions. 
- What do we know about nanoparticles being absorbed into our body? 
- It's a relatively new field of study. It is starting to get a lot more attention. They have some studies that point to certain sizes of nanoparticles being cancer causing, causing other issues within cells. 

There's been studies that have shown that carbon nanotubes and other types of nanotechnology, or another form of carbon, can actually cross the blood-brain barrier. So these are all really big questions that people are starting to investigate. And they're doing toxicology studies, of how much nano until a cell dies. Or, how much, at what size are they dangerous. Sometimes the size of one gold particle, it's not toxic. But when you get to another size, it is toxic. So there's a lot of questions that remain unanswered about nanotechnology. 
- Do these particles exist in nature? Are we really exposed to them? 
- In some cases, yes. 

The carbon nanotubes I just mentioned are actually a natural product of combustion. The same thing goes for another carbon molecule called a Bucky Ball. Again, a natural product of combustion. Some of them do occur naturally. 
- Things like for welding, there are things called plumes that come off a weld. Those particles are actually nano-sized, pieces of metal. Another thing on these products, there's many products that say "nano" and it really doesn't have any. 
- Exactly. A great example of that is the iPod Nano. 
(laughter)

 It's pretty big. Another one is there's an Indian company that came out with a car called a Tata Nano. Again, it's a car. It's not nano. But it's very small in comparison to any other car. So in that sense, maybe Apple had it all right. They had the regular iPod and the had the little baby iPod called the Nano. Did you have a question? 
- Well, I've heard about Bucky Balls. 
- Mm-hmm. 

- I've heard that they can trap molecules of gas in them. 
- Oh, I hadn't heard that. But that would be a very cool application. Do you have a question? 
- If carbon nanotubes can cross the blood-brain barrier, couldn't they be used to help treat Tay-Sachs? 
- Maybe. I don't know if it would be possible. But certainly, carbon nanotubes have been investigated as possible therapies for different brain disorders or diseases. 
- So, definitely a lot of the toxicology of nanoparticles is unknown. And a lot of it is because not a lot of people are looking at it. 

So when we talk about the sunscreens that have zinc oxide and titanium dioxide nanoparticles in them, at this point, as far as the FDA is concerned, zinc oxide and titanium dioxide have been established as being safe materials. Of course, when they did all of those studies to establish that, they were using much, much larger particles. And as we talked about earlier, changing the size changes the properties. And when I last read up on it, which has been a few months. But within the last year, they weren't even sure at this point if nanoparticles could be absorbed through your skin or not. So even that level of research was inconclusive. And I think in August, 2007, there was a really good article in Scientific American, kind of on this, you know, we need to be doing some research on the possible impacts of nanotechnology now. And specifically, they were talking about sunscreen. So that would be something that if you were interested in looking kind of where that is now, or at least within the last year, you could look at that article. 
- When you talk about changing the particles, does that mean combining nanoparticles and nano, tiny, tiny, together to make a larger particle? 

What does it mean, to change a nanoparticle? 
- In the example of the sunscreen, the reason that it's white is the particles, the titanium dioxide compound, are big. And so, when you start to make them even smaller, that's when they lose their color. So the change is really taking material that we know on a macro scale, at the sort of visible scale, and making it small. And it's just the size change that makes it behave differently. Does that help to clarify? 
- Are there nanoparticles in vegetable matter? 
- In vegetable matter? 
- So, right now, when we are talking about nanoparticles, we're kind of talking about synthetic, man-made nanoparticles. If you're getting into nature, and you're talking about materials on the nano scale. 

Molecules are on the nano scale. So then it becomes maybe semantics as to what you're going to define as being a nanoparticle or not being a nanoparticle. Kind of what we're talking about now are non-natural nanotechnologies. 
- But they might be in nature as well. 
- There are things in nature that are on the nano scale. For sure. 
- Is-- nanotechnology due to technologies for our generating nanoparticles? Because you said that for a long time that list that we're using. What is the reason for --? 
- I heard that one of the driving factors in nanotechnology is that we constantly want electronics that are smaller. 

And as we build chips made of regular silicon as we showed on this, there's only so small we can really go. So, as chips start to get smaller, we needed to come up with new technologies. And that sort of opened up the door for nanotechnology. 
- Also the development of instrumentation that allows you to work on nano. 
- Right. 
- That allows you to see things at the nano scale. The scanning probe technologies that we were talking about. So, yeah, people have been making nanoparticles since the Medieval Ages, but they weren't able to study them, really. So being able to do that makes a lot of difference. 
- And some of you may have already seen the little vials on the table with the interesting black liquid in it. 

You may notice that the liquid interacts with a magnet. Can anyone think of another liquid that is magnetic? That's because there really isn't any. 
(laughter)
 So I'm just going to show a quick movie. You already have it in front of you. But just another dramatic way that using nanotechnology, we've been able to create these magnetic liquids. And hopefully, technology-- It is liquid. Next slide. Notice that we had a pool of the black liquid at the bottom. 

I brought down the magnet, which is this dark thing. And I think it's much better to see it when you're actually using the vial. The resolution is much better. So we see that the liquid is attracted to that magnet. When the magnet is taken away, the liquid falls down the finger of the apparatus. It turns out this liquid is called Ferrofluid. It's something that NASA invented in the 1960s, as a way to try to control liquids in space. And what it is, it's just tiny particles of magnetite or rust. We make these particles so they're only 10 nanometers in size. We coat them with something special called a surfactant. 

It just keeps the magnetite particles from conglomerating together and losing that nano scale behavior. So you'll see that the magnet interacts with the black Ferrofluid just like any old regular liquid. It's a lot different than maybe those hairy Harry drawing pictures, if you've ever played with iron filings. It looks like a solid when you have even the tiniest of visible iron filings. The current uses for this sort of Ferrofluid is in stereo speakers to help damp the external vibrations, so the music that you listen to sounds a lot better. And even shock absorbers in cars. You can tune, sort of the viscosity of the degree of absorption in that shock absorber by applying a magnetic field and changing the way that the Ferrofluid is interacting there. Some future use that's been suggested is, again, maybe another example of targeted drug delivery. If I can coat these nanoparticles with some sort of drug, and then use a magnet to drag them through my body and concentrate them in the part that I wanted the medication to go. Just a few more examples of other things that might be around. 

Monolayers, which are just very thin layers. Layers that are approximately a few nanometers in thickness can really change the way that a surface interacts. So this is where the self-cleaning windows come in. Possibly being used on bake ware to increase the non-stickiness. If you look at the top picture, you'll see that that bead of water is not splattering out on glass like we're used to. It's beading up and repelling that monolayer that we've laid down. It turns out that these things come from an inspiration in nature. Again, we're still talking about nano sized features, as opposed to special particles. The lotus leaf, or a kale leaf, or a water lily, when you look at it and there's water on it, the water beads up. It enables the leaf to clean itself, because when the water rolls off, it can pick up some dirt as it travels off. 

It turns out that this special beading process comes from tiny, tiny bumps on the leaf. So these tiny bumps prevent the water from being able to spread out on it. It just sits on top of those tiny bumps. And with this inspiration, we've been able to develop coatings that mimic these tiny bumps. So we have buildings, when you put the special Lotusan paint on it, the water beads up and rolls off the dirt. The same thing for water repellent wood. So the wood on your deck isn't being soaked with water. It's repelling the water that's pooling on it. And then lastly, Nanotex fabrics. So, Dockers has khakis, that if you spill wine on them, or get any other dirt, the treatment that's on the fabric changes the surface of the fabric so it doesn't stain. 

But rather, the red wine just rolls right off. And you can see that at the nano scale, these fibers look, they're coated with something. That way, the liquids and other stains interact with them and don't stick. I'll just also make a plug. I know I've mentioned a bunch of consumer products. And while I don't know the technology behind every single consumer product out there, there is an extensive Web site through the Woodrow Wilson Center. I'll put that link up at the end. That site has created a catalog of where nano is in the products around you. So I'll make sure to flash that up. There are people out there looking into it. 

And if you're concerned about it, you can go and look at the catalog they've created. 
- So I thought that in addition to seeing some of the things that are maybe out as consumer products that incorporate nanotechnology, it might be interesting to have at least one example of some nanotechnology research here at UW. And so Professor Tom Keuch, who is in chemical engineering and I think physics, also, and some grad students of his are doing some nanotechnology research that has to do with solar cells. So just to give you a tiny bit of background, the basic way that a solar cell works is that it absorbs energy in the form of light. It uses that energy to create a positive and negative charge within a solar cell. Then, if you can get those positive and negative charges to move to electrodes, you create an electric current. And there's kind of some competing issues in designing an effective solar cell. First off, you want to be able to absorb as much energy as possible. And so to do that, you want to have a thick solar cell, with a lot of whatever material it is that you're using to absorb that sunlight. However, the thicker you make the solar cell, the more difficult you make it for those positive and negative charges to get to the electrodes. 

So in order for those charges to make it to the electrodes efficiently, so that you can get your electrical current, you want to have as thin a solar cell as possible. So you want to simultaneously have a thick and a thin solar cell in order to get good efficiencies. And what they're trying to do is to actually design an electrode where they have an organic solar cell active layer. That's the part that absorbs the sunlight and forms these positive and negative charges. But then they're growing kind of nanopins, nanorods of zinc oxide. And they're using that as the electrode. And because these nanorods of zinc oxide push up into the active layer, they reduce the length that these positive and negative charges have to travel in order to make it to an electrode. So you can have a thicker absorbing layer, but without having to worry about those positive and negative charges having to go all the way through that layer to get to an electrode. So you're kind of having a thick and thin electrode at the same time. And this is just a scanning electron micrograph, one of those scanning probe microscopies we were talking about earlier. 

This is an image of the zinc oxide nanorods. You probably can't see this text from where you're sitting, but this line here is indicating that that distance is one micrometer in length. So these are definitely down on the nano scale. They're very, very tiny. And the hope is that using this technology, we'll be able to make solar cells that are more efficient and eventually cheap enough so that everyone can use them in order to take advantage of solar energy generation within their own homes and businesses. And I think that's about all we have for you tonight. Of course, we would be more than happy to take questions. We've just listed a couple Web sites up here where you can go and find more information on nanotechnology. There's our Web site at the very top. Also, there's a link here for the UW-Madison NSEC. 

And if I try and say what NSEC is, I'll get it wrong. 
- It's the Nano Scale Engineering Center. And the link that I've actually selected to put up there is one of the groups that explicitly deals with risk and societal implications. So that addresses some of the concerns that were coming up regarding the consumer products. 
- And the name of some NanoCafes, that's actually a local group that does kind of science talks, like we're doing tonight, but on different nano topics. The National Nanotechnology Initiative was the group that Kim mentioned at the beginning, the government group that's looking into funding and projections for nanotechnology. And then, the last one is the Woodrow Wilson Center. They have a list of different consumer products that incorporate nanotechnology. So, with that, I think we're done. 
(applause)

 
- Are there any lingering questions? 
- How do you make the nanoparticle sized zinc oxide? 
- How do they make these particular nanotubes? 
- In particular, the sunscreen. How do they pulverize it? 
- They don't pulverize it. There aren't really tools that are small enough that you could easily pulverize things down to the nano scale. At least not and get the size distribution that you wanted. You'd have all different kinds of sizes and dust that you would create. 

They actually create them from, I guess, the bottom up is the way you would put it. I don't know specifically for zinc oxide, because I've never made it. We do make silver and gold nanoparticles ourselves, though. And it's just a chemical reaction that you control the specific amounts of each reactant. And then you usually stop the reaction as they're growing bigger by capping those particles off with something that's non-reactive. 
- Do you start with a solution of ions? 
- Yep, a solution. 
- What would consider the two most important applications that have come out of nanotechnology? 
- Wow, I'm all over the sunscreen. 
- That's a million dollar question. 

I think it's hard to choose. There are so many. One of the reasons-- 
(inaudible)
 I personally find the cancer treatment with gold nanoshells pretty fascinating. And also, there's a lot of research looking into water purification and desalination of ocean water to provide fresh drinking water for people who live in areas that don't have it. So I think that has a tremendous capability to impact a lot of countries who are without clean water. 
- I think also that Kim mentioned that a lot of what's been driving nanotechnology research is the computer industry. And we didn't talk a lot about it tonight. But a lot of the research has been going into making smaller and smaller and smaller circuits. 

And I think, providing that they can make it work, that's going to be pretty important for our everyday lives. 
- What industry? 
- The computer industry. Yeah? 
- Is there, I heard that you could possibly buy the particles. 
- The Ferrofluid? You can. It's available. I think it's called Teacher Innovations. If you email me, or if you have your dad email me, my business cards are out at the table, I can give you the link. 

You can buy them. It's definitely cool. 
- We did. We bought those. 
(laughter)
 
- Any other questions? Yeah? 
- If you're concerned about the safety of some of these things, when you buy a consumer product will you know whether nanotechnology has been used in it? Like for example, fabrics. 

Is there concern that the coating might absorb through your skin? Would you know? 
- At this point, you would, because they're expensive, relatively speaking. And they're generally proud of the fact that it's in the fabric, and it's actively advertised on the tags, or whatever. But no, not necessarily. A lot of cosmetics are using nanotechnology right now. You can get a little more sparkly eye shadow, and stuff like that. And they're really not listing that. 
- It's definitely an interesting regulatory issue. 
(inaudible)

 
- Yes. 
(inaudible)
 
- The situation in Washington is, there's been a lot of talk creating the right definition of nano and what is going to be considered nanotechnology. The FDA, I don't believe is currently regulating it. The only agency that I know that is starting to look into regulation is the EPA. The EPA has recently started a voluntary regulation process for companies who are producing these nanoparticles. Industry is actually anxious to have something in place, probably in response to the asbestos debacle, where companies were making asbestos and it turned out to be very harmful. And now companies are having to pay out a lot of money in lawsuits. 

So the problem, sort of the conundrum is that the materials are generally already tested and shown to be safe. But that's at the macro scale. It's a tricky issue. But there's only one agency I know that's trying at this time. Tom? 
- When you were bouncing the balls, how thin could you slice the amorphous metal before you start to lose that property? You had it really thick. Any idea of how many layers? 
- How many layers you would need? I don't know. 

- Thank you. 
(inaudible)
 
- No, and certainly, just to make another plug for Science Expeditions. We'll be doing a bunch of tables on nanotechnology, and also a science spectacular on stained glass, where you can take home a piece of nano-stained glass if you stop in. Great. All right, well thank you so much. Enjoy your evening. 
(applause)