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EurekAlert! Nanotechnology Portal

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Environmental Impact of Nanotechnology

Nanotechnology and Medicine

The Science of Nanofabrication


 

Dr. Phil Szuromi (moderator):

Good morning, and welcome to EurekAlert!'s online chat on the science of nanofabrication. I'm Phil Szuromi, and I will be moderating our discussion with our experts, Ray Baughman, Jillian Buriak and Ellen Williams.

Ray Baughman serves as the Director of the NanoTech Institute and Robert A. Welch Professor of Chemistry at the University of Texas at Dallas. Dr. Baughman's work in nanofabrication has contributed to advances such as the world's toughest yarns, artificial muscles that generate a hundred times the force of natural muscle, and textiles that store electrical energy.

Jillian Buriak is the Canada Research Chair in Inorganic and Nanoscale Materials at the University of Alberta, and a Senior Research Officer at the University of Alberta's National Institute for Nanotechnology. Her work focuses on the synthesis and characterization of sub-100 nm scale features and objects on semiconductors, which have practical applications in nano and micro fuel cells, metal interconnects, and molecular electronics.

Ellen Williams is a Distinguished University Professor at the University of Maryland and the Director of the University of Maryland Materials Research Science and Engineering Center. Williams' research focuses on the use of experimental surface science tools to explore fundamental issues in statistical mechanics and their practical applications in the growing field of nanotechnology.

Welcome to all.




Dr. Phil Szuromi (moderator):

I'd like to start by asking all of you to discuss briefly some of things you are working on in nanotech that you find particularly exciting.



Dr. Jillian Buriak:

Certainly the field of molecular electronics is very exciting, where the idea is to replace a big chunk of silicon, i.e. a transistor, with a single molecule. So, if you have a molecule that has specific qualities, like switching behavior, or some response to an external stimulus, then this switching could be your bits, your ones and zeroes (1 and 0), which is of course the language in which computers 'think'. So what we work on is coming up with ways that we can attach molecules to technologically important materials like silicon, and gallium arsenide (if you have a cell phone, you have gallium arsenide in there). So this could be extremely important as we reach what people call, however accurately or inaccurately, the end of the road for silicon-based technology - the point at which you can no longer make transistors on silicon any smaller (end of Moore's law). Our disclaimer is, of course, no one is really sure when this 'end of the road' will be reached. But, because we can tailor the behaviour, composition and sizes of molecules much better than we can a solid material, the possibilities are essentially unlimited.



Dr. Ray Baughman:

Another important challenge is to realize in large objects the properties of the nanoscale. Experimental demonstrations have convincingly shown that individual nanoparticles, like carbon nanotubes, have quite exciting and useful electronic, optical, and mechanical properties. The problem is that assemblies of these carbon nanotubes have quite different properties, and ones that are generally less exciting. An important challenge for nanofabrication is to assemble untold trillions of these nanofibers into yarns and sheets that retain the remarkable properties of the individual carbon nanotubes. We are doing this assembly and using the resulting yarns and sheets to make, for example, artificial muscles, yarns that store electrical energy, and devices for thermal energy harvesting.



Dr. Ellen Williams:

What we have been hearing so far is that there are a lot of very important uses for very small structures. So, what I am interested in doing is looking at what the fundamental properties are that will give us special and unique capabilities that come out of nanoscience. Those properties typically fall into three realms of nanoscience, and those are: quantum confinement, large surface-to-volume ratio, and statistical properties of small numbers or small ensembles of molecules. That last one is the one I am most interested in right now. Working with systems where the atoms are moving around and things happen statistically rather than deterministically represents a huge shift from the paradigms of traditional semiconductor electronics, and leads us to think more about the way things are done in the biological world, where there are a lot of things to be corrected for. So, we heard from Jill and Ray about lots of different examples of small systems. If we want to take one example, for instance in molecular electronics, you are going to have an interface between the molecule and some solid state material. At the nanoscale, all the atoms are going to be constantly moving around because of thermal entropy. So, experimentally, we can see those atoms moving around using a scanned probe technique. One of the big challenges we are working on is learning how to understand how those moving atoms affect the performance of the nanodevices, and might result in new ways of doing business. In other words, new ways of creating ensembles of devices that have properties halfway between our traditional semiconductor world and the world of biology.



Dr. Phil Szuromi (moderator):

Thanks! Let's now get to some of the questions that have been submitted, starting with some that clarify the basic ideas in nano.



suresh kumar, bharathair uni., india:

What is the physical definition of nano, and why is the nanoscale so important?



Dr. Ray Baughman:

A nanoscale object is one having a dimension which is between 100 nanometers and one nanometer. A hundred nanometers is about one-thousands the diameter of a human hair. When you get to such small scales, optical, electronic, and magnetic properties can dramatically change. In most cases, these property changes are a result of confinement due to small dimensions. The nanoscale is so important because these obtained properties can be much more exciting and much more useful than those of the bulk material. For example, effectively resistance-less electrical transport and movement of thermal energy without scattering occur on the nanoscale. Another important aspect of the nanoscale is that it enables giant surface-to-volume ratios. As a consequence of these giant surface-to-volume ratios, it is possible to electrochemically inject an enormous amount of charge into nanoparticles. This giant amount of injected electronic charge can be used, for example, for the operation of artificial muscles, super capacitators, and novel sensors.



Washington, DC:

What is nanofabrication, and why is it important?



Dr. Jillian Buriak:

We know now that nanoscale materials have many interesting properties that are very different from bulk materials. Now the question is how do you make these things? Nature is very good at building things in this 1-100 nanometer size regime, but it is quite challenging for us to do the same synthetically. Chemists have centuries of experience making small molecules about one nanometer in size, and physicists and electrical engineers have been working from the macro scale through the micro world into the nano world, in a top down approach. But in between these two worlds, there is a real challenge. The challenge is to make clean, reproducible on a large scale, nanomaterials with the sizes, shapes, and characteristics that you want. It certainly is nice to make a material in the lab on a small scale, and discover its properties, but in order to turn this into a product, to test it for, for instance, its biological properties and its potential effects on the environment, you need to make substantial quantities of materials. So this is requiring chemists, physicists, biologists, and many others to work together to have control over materials of this size.



Dr. Ray Baughman:

I certainly agree with Jillian's comment about the critical importance of synthesis of individual nanoparticles having specific structure. No one can yet synthesize a carbon nanotube having a completely pre-engineered structure, and even subtle structure variations can result in dramatically changed properties. Also, bulk synthesized carbon nanotubes are typically contaminated by major impurities. These contaminants, sometimes over 40% by weight in commercially sold products, can profoundly effect properties, and in some cases provide toxicological effects. Other important aspects of nanofabrication are in combining individual nanoparticles together to make large structures and assembling individual nano-elements to make functional nanosize devices.



olivier dessibourg, scientific journalist LE TEMPS:

Do you think that nanotech, with all the promises that are made, will follow the same way as the GMO among the population, in the sense that the people not knowing what all this stuff is all about, will become more and more afraid, and start the say a big no to something they don't see and even more understand?



Dr. Jillian Buriak:

You can say that nanotechnology has a lot to learn from the experience of biotechnology. In the end, the public simply did not trust corporations making huge profits out of genetically modified organisms. They didn't trust that these products were safe. Because nanotechnology is so young, there is a real opportunity here to do research into the biological and ecological properties in advance and in parallel. It’s very exciting to me to know that there is a great deal of good science being done around the world to address these very problems. For instance, groups around the world are looking at the health effects of nanoscale carbon materials in cells, in living organisms, and in pond water. In my group, we are looking at the stability and long-term behavior of nanoparticles in blood, and others are looking at the effects of inhalation of nanomaterials into the lungs. And this is all very exciting, because people are talking about this, and more importantly they are asking good questions and doing good experiments to test these questions.



Luca Accomazzi, Corriere del Ticino / Switzerland:

The original dream which gave birth to nanotechnology was centered around nanomachines which would build sophisticated materials and more nanomachines -- the "engines of creation." Do you consider these nanomachines feasible? If so, would you care to guess in how many years their development might bear fruit?



Dr. Ellen Williams:

When we talk about the engines of creation, we already have a paradigm for that, and that of course is biology. We already have molecules - DNA that working with RNA can self-replicate, and that can create new molecules such as proteins. What you have to realize is that such replication and creation doesn't come free. You always need a source of energy. In biology, energy is provided most directly to these machines with a chemical reaction, and the process is very complex and very subtle. In nanoscience, we are very, very far from being able to capture the subtlety of biology. On the 10-20 year time scale, people working at the interface of nanoscience and biology may begin to be able to develop synthetic analogs of biological systems. Clearly, when that time comes, we will need to invoke all the standard protocols of safety and biological regulations that we now use in the biotechnology field.



Edit Braunstein, Lockheed Martin:

I would like to know the opinion of the panelists on the prospects of using buckypapers as potential nanostructures for aerospace applications. So far I have not seen the materialization of the potential mechanical, thermal and electrical properties that characterized the SWNT on to the macrostructures. Why is that? What are the chances to scale up these properties into macro structures?



Dr. Ray Baughman:

The applications of carbon nanotubes for structural applications in aerospace have been hindered for several reasons. First, single wall carbon nanotubes are presently prohibitively expensive. This may change in the near future. Multi-wall nanotubes, on the other hand, are reasonably inexpensive and have been used commercially since about 1992, in over 20 ton quantities per year. The absence of major applications of multi-wall nanotubes for structural applications in aerospace has not yet occurred because of the difficulty of realizing the exciting properties of individual nanotubes in large scale sheets and yarns. Major progress is being made in this area. For example, carbon nanotube fibers have been made that are tougher than any previously know fibers. This toughness, the ability to absorb energy without failing, is very important for aerospace applications.



Mike Glynn, London:

I would like to know what the benefits of nanotechnology are in electrical consumer products -- items such as those that involve sight and sound (audio & visual).



Dr. Jillian Buriak:

A few of the benefits of nanotechnology in electrical consumer products can be seen in LEDs and flat screen displays. These LEDs and flat screens already use nanotechnology and are on the market now. So these are products that have been on the market for a couple of years now. Many people, including the military, are interested in fabric and materials that will respond to the environment. Soldiers are interested in fabrics that can neutralize chemical warfare agents, deliver medicines on demand, and regulate body temperature.



Dr. Ray Baughman:

We might also want to mention here that electronic textiles are already in the marketplace, but at the present time they do not use nanotechnology. The use of nanotechnology will enable increased functionality for electronic textiles. For example, nanotechnology-based clothing textiles could store electrical energy to power communications equipment, provide anti-ballistic protection, sense the health of the wearer, provide woven-in computer circuits and displays, and change textile porosity to optimize comfort.



Jorge Salazar, Earth & Sky Radio Series:

Question for Dr. Williams: Could you relate some of the work that you're doing with these small, noisy groups of molecules with something a little more concrete (for most people) -- say a fuel cell?



Dr. Ellen Williams:

Instead of fuel cells, let me talk about a solar cell. In a solar cell, what we want to have happen is for a bit of light, which we call a photon, to hit the solar cell and break loose an electron, and the electron has to move to one side of an electrical source, and that happens at an interface. So we have to have this interface, and to get good efficiency we need lots of those interfaces. So we are talking about patterning solar cells with interfaces on the 10-20 nanometer separation scale. If each of those interfaces is moving, is not static in its properties, that's going to affect the rate and the noisiness with which the electrical power is delivered. That might just be a problem, or it might be that if we can understand how that interface fluctuates, we can predict the frequencies and correlations and couple them properly into the nanoelectronic devices that we want to drive.



Nicolás Luco, El Mercurio - Chile:

This is a new field. How did it tempt you? In what life road junction did you decide to take up this route, how many years ago and why?



Dr. Jillian Buriak:

I'm a chemist, first and foremost, and chemists, by nature, I think, like to make things, and so for me this was an interesting challenge, but also a natural extension of what I do. So I never really actually decided I'm going to go into nano. For me, it's still chemistry at the root of it all.



Dr. Ray Baughman:

Like many people around the world, I have been doing nanotechnology long before this term was popularized. In fact, the ancient Egyptians were using nanotechnology more than 3000 years ago. The recent cascade of increased skills in playing in nanoscience and nanotechnology has opened a new world. Exploring this nano-world is like visiting a new planet or the depths of the ocean. The exciting new materials seen in this nanoworld excite me both because of the new insights that they provide and the many important new applications that they can enable.



Dr. Ellen Williams:

In the early days, when people first started talking about nanotechnology, a lot of it sounded very crazy. My background is mixed. I trained in physical chemistry, did my graduate work in a chemical engineering department, and moved to physics as a professor to primarily do research in materials science. What I saw in nanoscience were real opportunities that were coming as we broke down interdisciplinary barriers, and started to look at combinations of organic chemistry with solid state physics, biology with inorganic chemistries, electrical engineering with molecular systems, and so on. There really are new opportunities and possibilities because we are putting together things in new combinations that no one has addressed before. So that looks exciting, and everybody in science wants to do what is most exciting. For me, I started calling what I was doing nanoscience about ten years ago.



Dr. Phil Szuromi (moderator):

It looks like we are out of time. Thank you all again for comments and insights.