An Interview with John Hart, creator of "nanobama"
(Part 1 of 2, link to Part 2)
When starting off doing research into this article, I realized one of the first things I needed to understand was: exactly how big is a nanometer in imaginable terms. So I did what most intelligent parents across the planet do when they realize their own math lessons are long out-of-date and asked my nearly 9-year-old son to explain it to me.
Well, after a couple of “gosh Dad, you’re so dumb” statements from Ziggy Jr., we were together able to locate various explanations (1, 2, 3) that may or may not help you as well. Kindly note that we have intentionally avoided any descriptive that in any way relates to the sheer scale of bonuses your local bank manager is receiving in relation to said bank’s tax-payer-sponsored bail-out package:
· Nano, a prefix meaning "dwarf" in Greek, also means one billionth. A nanometer is therefore one billionth of a meter;
· One-billionth (10 to the -9 power or 0.000000001 or 1m/1,000,000,000) of a meter is about 25-millionths of an inch;
· Objects that are a few to several hundred nanometers in width are called a nanoparticles, and nanotechnology is the science of manipulating nanoparticles;
· Carbon nanotubes or CNTs are one form of highly organized structures that are included in this area, where you may have also heard of Fullerenes or Bucky Balls or any number of interesting related topics;
· The width of a human hair is about 80,000 – 100’000 nanometers across. In relation to this for example, starting with 1 meter and each time getting 1,000 times SMALLER:
- 1 meter – about the size of a two-year-old child or medium-sized dog, the length of a poster or even a typical Ziggy Nixon blog introduction, etc.;
- 1 millimeter – about the thickness of a dime;
- 1 micrometer – size of pollen, red blood cells, baker's yeast, some bacteria;
- 1 nanometer- the size of some viruses, width of strands of DNA and RNA, thickness of a cell membrane;
· Other comparative examples expressed in nanometers include:
- The period at the end of a sentence is almost 500,000 nanometers in diameter;
- A basketball is about 239,506,000 nanometers wide;
- And while we’re on the topic of basketball, did you know that Shaquille O’Neal is over 2.16 BILLION nanometers tall (which is remarkably enough the same amount of money in billions that he is paid each year);
- And this one we liked a lot: you’d have to move a 3-square-inch Post-It® note a distance equivalent to half-way around the Earth for it to appear 3 nanometers in size, assuming of course that you could still even see it (hint: you couldn’t without a really good telescope).
Now I don’t mean to belittle John Hart’s work at all; in fact, in all of my years of travel and other semi-professional going’s-on (or is it going-on’s?), I doubt that I have seen a more impressive résumé of any type. John’s current work is astounding and also his proposals, for example, along with Neri Oxman and their ‘Construction in Vivo’ work (see also mention of the Holcim Next Generation Award for Sustainable Construction) boggle the mind in terms of what they could mean to everyone of us currently sitting on this greenish-gray ball. And even though said journeys have also led us past the topic of nanotechnology once or twice, John and his team’s recent creative approach to illustrating what can be accomplished with this technology, namely the generation of “nanobamas” found at the site of the same name, only added to our fascination of this topic. And now that our meter worth of introductions is finished, let’s dive right in:
John, how did you get involved in the world of nanotechnology?
I was actually a graduate student at MIT and was reading papers about micro-nano-technology. From here I was very fortunate to receive a fellowship from the Hertz foundation, which is a private foundation here in the United States that funds PhD research in applied science. It’s actually quite a selective program so I was very surprised and honored to be chosen.
This gave me the flexibility along with my advisor to explore a new topic for both of us. It was a complete departure but I was fascinated and intrigued by the properties and potential of carbon nanotubes.
My background at that point was in design manufacturing. We were thinking about how to make design a machine and a manufacturing process to make nanotubes grow really long. Our target was hopefully to make the properties of the individual molecules at the scale that would could essentially hold in our hands and use as macro-scale materials. That part of our work is still a dream, but we have come a long way and have made significant progress in the five years since we started.
Would you say your “youthful aspirations” tended towards art or science or a combination of both?
Like most kids there was a time I wanted to be an architect, a time I wanted to be a surgeon or even a paramedic, etc.. My interests fluctuated.
My dad was an engineer and a scientist. I couldn’t say though that I wanted to follow in his footsteps. The one experience that maybe resonated in my subconscious was that he had a kind of shop in the basement and sometimes I’d go down there with him when he went to work on Saturdays and I liked to tinker around, too. But really there was no long-term aspiration that led me in this direction.
I think my aptitude in school – other than being like the worst kid in gym class – was not an artistic one. I was more into math and the sciences than art, and I did very well in those subjects. But the thing I enjoyed the most in high school was actually debate. I think other than what we’re talking about now, being involved in debate is one of the most valuable things I’ve ever done. It’s still incredibly useful even for what I’m doing now with both my research and teaching at the University of Michigan. It was so valuable to learn how to organize my thoughts, how to write up and outline proposals, and of course, it was excellent experience in learning how to make presentations.
Can we get the “Junior High School demonstration” description of growing nanotube forms?
I think the visuals provided on the nanobama site is a real good accompaniment for a lesson in how we do this, because it makes it easy for all of us to imagine.
The processing parameters of course all depends on the form we want to make. But if we take an image – in this case Shepard Fairey’s famous (ZN: and slightly controversial) picture of President Obama – we then use Adobe illustrator to convert it into a line drawing. Of course, for the more “technical images” we make there are other software programs we can employ to make the starting image.
Then using optical cameras, we print the image via laser at very small scale onto a glass plate which we call the mask. We then shine ultraviolet light through the mask – which is essentially transparent where the shape of Obama’s face appears – and onto a thin layer of polymer on a silicon wafer, thereby patterning the polymer by photolithography with extremely fine detail.
Then the wafer is coated with a very thin layer of catalyst nanoparticle "seeds" which essentially tell the individual nanotubes where to grow. We then remove the remaining polymer that is not needed on the mask, leaving the catalyst seeds in the shape of the image. The resulting wafer that we’ve made is then placed in a furnace with the needed components present which includes a carbon-containing gas.
How does the picture result or appear after the processing?
The carbon nanotubes or CNTs are grown from the catalyst patterns into an organized structure of a “forest” of nanotubes. Each Obama portrait is about 150 million tiny carbon nanotubes in parallel – or approximately equal to how many Americans voted in the 2008 presidential election!
It really can be thought of as if you’re standing in a super super tall forest of trees – of course if you were extremely small yourself. Just imagine though that if each individual nanotube was the size of a real tree – about 1 foot in diameter – then this forest would consist of 100 million super tall trees. Not only that, but these trees would still be growing at the speed of sound or at over 500 feet per second!
The CNTs aren’t “solid” like a tree, however; instead, they are tiny hollow cylinders of highly ordered carbon. (As mentioned in the introduction) their diameter is tens of thousands of times smaller than a human hair or even the period at the end of this sentence. Other properties are that they are several times stronger and stiffer than steel on an equivalent density basis.
(As shown above,) the nanobama faces are approximately 0.5 millimeter wide, or again calculating back, about ten times the width of a human hair. The final images – even the larger ones – are only barely visible to the naked eye (if at all) and are taken using optical and scanning electron microscopes (ZN: for further details into SEM, see the previous report on the work by Martin Oeggerli).
How do you make the “seeds” used to grow the CNTs?
We use a process known as chemical vapor deposition that provides a very thin layer of iron metal onto the surface of our silicon wafer “template” to define the shape of the image.
During the very high temperature heating of the wafers, a carbon dome appears at the site of the catalyst that just continues to grow upwards and perpendicular to the surface until the system runs out of material. That may sound easy but it’s definitely a lot more tricky than that!
How much does one of these images cost from start to finish? For example, would it be practical to start up a portrait company using this technology?
It’s kind of difficult to say exactly. The processing is done on a full scale, that is, we process an entire silicon wafer. The biggest part of the costs comes in processing that whole wafer. In terms of these images we’ve made, for us the real costs come from our time because we put something like this on the same wafer we’re using for our research.
In terms of overall costs, the dedicated costs to make the images is probably only about 50 dollars for use of the SEM to take the pictures. But if we consider the part of the wafer (which is about 4 inches total in diameter) where the pictures are made – about 1 square centimeter – add to that the technicians time, the time as well needed to make the mask and the time on the machines, then it might run about 2,000 – 4,000 dollars for imaging of each section individually.
I guess if you wanted to sell then each image, well, then a lot of the cost will be in creating the image and could run then something like several hundreds of dollars per image. And that’s without color (if you want color in an SEM image, you have to add it later with something like Adobe Illustrator or Photoshop).
Where do you see the most practical future for nanostructure technology for the near or long-term future?
Of course, nano materials and nanotechnology are already in use in many applications. If we focus just on the long-term benefit’s and practicality, I see most of the benefit being in two extremely large and potentially beneficial areas, namely, energy and medicine.
With energy, I see a lot of potential in using nano structures to make solar cells, batteries, capacitors and devices which allow us to better optimize energy conversion.
In medicine as well, there are so many practical uses. Many researchers are already looking at nanotechnology in terms of creating agents to deliver drugs that target specific sites, or to recognize certain molecules or antibodies in the blood, thus making treatments much more effective. This technology can also be used to even target specific organs or tumors without damaging the areas of the body around these that might not be stable to otherwise invasive or damaging treatments.
In addition, there is tremendous potential for nanotube technology to help in diagnoses by acting as “contrast agents” for imaging. For example, you can create nanoparticles that are photoactive or perhaps even coated with a given material so that they bond to the surface of a given abnormality or other defect. The imaging that can then be made enables the analyses and preparation for treatment again much more efficient. The more exact in terms of how we learn to design the individual structures, the more uses we’ll find.
What are the little "hairs" on some of the images, like we see above on the nano-flag?
We start out with a full silicon wafer which is broken up into 1 cm square pieces; when you break it up you scratch it and cleave it with a diamond scribe. This creates silicon dust with catalyst on one side.
This dust then acts as a growth point for these extra nanotubes that are then no longer aligned. These appear then in the SEM images as “hairs”.
Why do the edges in some of the shapes glow?
These are local charging effects in the electron microscope that, along with the intensity of the electron beam and the position of the detector, can create apparent lighting and shadowing effects in the electron microscope image. But it is very fascinating in that it provides a very interesting and natural kind of “lighting effect”.
Plus, working with SEM also enhances what we’re able to illustrate as this process can resolve features much smaller than the wavelength of light, and has a relatively large depth of focus.
How do you obtain such clear order in some images (e.g. Obama’s face) vs. others that appear to be a mix of wild hairs or even less ordered structures?
I think the uniform growth comes from understanding the reaction conditions better. Like how to supply enough carbon to feed all the nanotubes “happily”, how to reproduce the processes better, etc. Today, by controlling the density of the catalyst particles as well as the reaction temperature and chemistry, we can grow these CNT forests to millimeter heights with amazing exactness and detail.
Key is the understanding that the architectures are formed by self-organization of the CNTs as they grow upward from the silicon substrate from the catalyst layer. If we distribute the catalyst uniformly, nanotubes will grow everywhere on the substrate. How the nanotubes organize themselves is defined by how they push and pull each other to produce the architectures shown.
Well, after a couple of “gosh Dad, you’re so dumb” statements from Ziggy Jr., we were together able to locate various explanations (1, 2, 3) that may or may not help you as well. Kindly note that we have intentionally avoided any descriptive that in any way relates to the sheer scale of bonuses your local bank manager is receiving in relation to said bank’s tax-payer-sponsored bail-out package:
· Nano, a prefix meaning "dwarf" in Greek, also means one billionth. A nanometer is therefore one billionth of a meter;
· One-billionth (10 to the -9 power or 0.000000001 or 1m/1,000,000,000) of a meter is about 25-millionths of an inch;
· Objects that are a few to several hundred nanometers in width are called a nanoparticles, and nanotechnology is the science of manipulating nanoparticles;
· Carbon nanotubes or CNTs are one form of highly organized structures that are included in this area, where you may have also heard of Fullerenes or Bucky Balls or any number of interesting related topics;
· The width of a human hair is about 80,000 – 100’000 nanometers across. In relation to this for example, starting with 1 meter and each time getting 1,000 times SMALLER:
- 1 meter – about the size of a two-year-old child or medium-sized dog, the length of a poster or even a typical Ziggy Nixon blog introduction, etc.;
- 1 millimeter – about the thickness of a dime;
- 1 micrometer – size of pollen, red blood cells, baker's yeast, some bacteria;
- 1 nanometer- the size of some viruses, width of strands of DNA and RNA, thickness of a cell membrane;
· Other comparative examples expressed in nanometers include:
- The period at the end of a sentence is almost 500,000 nanometers in diameter;
- A basketball is about 239,506,000 nanometers wide;
- And while we’re on the topic of basketball, did you know that Shaquille O’Neal is over 2.16 BILLION nanometers tall (which is remarkably enough the same amount of money in billions that he is paid each year);
- And this one we liked a lot: you’d have to move a 3-square-inch Post-It® note a distance equivalent to half-way around the Earth for it to appear 3 nanometers in size, assuming of course that you could still even see it (hint: you couldn’t without a really good telescope).
Now I don’t mean to belittle John Hart’s work at all; in fact, in all of my years of travel and other semi-professional going’s-on (or is it going-on’s?), I doubt that I have seen a more impressive résumé of any type. John’s current work is astounding and also his proposals, for example, along with Neri Oxman and their ‘Construction in Vivo’ work (see also mention of the Holcim Next Generation Award for Sustainable Construction) boggle the mind in terms of what they could mean to everyone of us currently sitting on this greenish-gray ball. And even though said journeys have also led us past the topic of nanotechnology once or twice, John and his team’s recent creative approach to illustrating what can be accomplished with this technology, namely the generation of “nanobamas” found at the site of the same name, only added to our fascination of this topic. And now that our meter worth of introductions is finished, let’s dive right in:
John, how did you get involved in the world of nanotechnology?
I was actually a graduate student at MIT and was reading papers about micro-nano-technology. From here I was very fortunate to receive a fellowship from the Hertz foundation, which is a private foundation here in the United States that funds PhD research in applied science. It’s actually quite a selective program so I was very surprised and honored to be chosen.
This gave me the flexibility along with my advisor to explore a new topic for both of us. It was a complete departure but I was fascinated and intrigued by the properties and potential of carbon nanotubes.
My background at that point was in design manufacturing. We were thinking about how to make design a machine and a manufacturing process to make nanotubes grow really long. Our target was hopefully to make the properties of the individual molecules at the scale that would could essentially hold in our hands and use as macro-scale materials. That part of our work is still a dream, but we have come a long way and have made significant progress in the five years since we started.
Would you say your “youthful aspirations” tended towards art or science or a combination of both?
Like most kids there was a time I wanted to be an architect, a time I wanted to be a surgeon or even a paramedic, etc.. My interests fluctuated.
My dad was an engineer and a scientist. I couldn’t say though that I wanted to follow in his footsteps. The one experience that maybe resonated in my subconscious was that he had a kind of shop in the basement and sometimes I’d go down there with him when he went to work on Saturdays and I liked to tinker around, too. But really there was no long-term aspiration that led me in this direction.
I think my aptitude in school – other than being like the worst kid in gym class – was not an artistic one. I was more into math and the sciences than art, and I did very well in those subjects. But the thing I enjoyed the most in high school was actually debate. I think other than what we’re talking about now, being involved in debate is one of the most valuable things I’ve ever done. It’s still incredibly useful even for what I’m doing now with both my research and teaching at the University of Michigan. It was so valuable to learn how to organize my thoughts, how to write up and outline proposals, and of course, it was excellent experience in learning how to make presentations.
Can we get the “Junior High School demonstration” description of growing nanotube forms?
I think the visuals provided on the nanobama site is a real good accompaniment for a lesson in how we do this, because it makes it easy for all of us to imagine.
The processing parameters of course all depends on the form we want to make. But if we take an image – in this case Shepard Fairey’s famous (ZN: and slightly controversial) picture of President Obama – we then use Adobe illustrator to convert it into a line drawing. Of course, for the more “technical images” we make there are other software programs we can employ to make the starting image.
Then using optical cameras, we print the image via laser at very small scale onto a glass plate which we call the mask. We then shine ultraviolet light through the mask – which is essentially transparent where the shape of Obama’s face appears – and onto a thin layer of polymer on a silicon wafer, thereby patterning the polymer by photolithography with extremely fine detail.
Then the wafer is coated with a very thin layer of catalyst nanoparticle "seeds" which essentially tell the individual nanotubes where to grow. We then remove the remaining polymer that is not needed on the mask, leaving the catalyst seeds in the shape of the image. The resulting wafer that we’ve made is then placed in a furnace with the needed components present which includes a carbon-containing gas.
How does the picture result or appear after the processing?
The carbon nanotubes or CNTs are grown from the catalyst patterns into an organized structure of a “forest” of nanotubes. Each Obama portrait is about 150 million tiny carbon nanotubes in parallel – or approximately equal to how many Americans voted in the 2008 presidential election!
It really can be thought of as if you’re standing in a super super tall forest of trees – of course if you were extremely small yourself. Just imagine though that if each individual nanotube was the size of a real tree – about 1 foot in diameter – then this forest would consist of 100 million super tall trees. Not only that, but these trees would still be growing at the speed of sound or at over 500 feet per second!
The CNTs aren’t “solid” like a tree, however; instead, they are tiny hollow cylinders of highly ordered carbon. (As mentioned in the introduction) their diameter is tens of thousands of times smaller than a human hair or even the period at the end of this sentence. Other properties are that they are several times stronger and stiffer than steel on an equivalent density basis.
(As shown above,) the nanobama faces are approximately 0.5 millimeter wide, or again calculating back, about ten times the width of a human hair. The final images – even the larger ones – are only barely visible to the naked eye (if at all) and are taken using optical and scanning electron microscopes (ZN: for further details into SEM, see the previous report on the work by Martin Oeggerli).
How do you make the “seeds” used to grow the CNTs?
We use a process known as chemical vapor deposition that provides a very thin layer of iron metal onto the surface of our silicon wafer “template” to define the shape of the image.
During the very high temperature heating of the wafers, a carbon dome appears at the site of the catalyst that just continues to grow upwards and perpendicular to the surface until the system runs out of material. That may sound easy but it’s definitely a lot more tricky than that!
How much does one of these images cost from start to finish? For example, would it be practical to start up a portrait company using this technology?
It’s kind of difficult to say exactly. The processing is done on a full scale, that is, we process an entire silicon wafer. The biggest part of the costs comes in processing that whole wafer. In terms of these images we’ve made, for us the real costs come from our time because we put something like this on the same wafer we’re using for our research.
In terms of overall costs, the dedicated costs to make the images is probably only about 50 dollars for use of the SEM to take the pictures. But if we consider the part of the wafer (which is about 4 inches total in diameter) where the pictures are made – about 1 square centimeter – add to that the technicians time, the time as well needed to make the mask and the time on the machines, then it might run about 2,000 – 4,000 dollars for imaging of each section individually.
I guess if you wanted to sell then each image, well, then a lot of the cost will be in creating the image and could run then something like several hundreds of dollars per image. And that’s without color (if you want color in an SEM image, you have to add it later with something like Adobe Illustrator or Photoshop).
Where do you see the most practical future for nanostructure technology for the near or long-term future?
Of course, nano materials and nanotechnology are already in use in many applications. If we focus just on the long-term benefit’s and practicality, I see most of the benefit being in two extremely large and potentially beneficial areas, namely, energy and medicine.
With energy, I see a lot of potential in using nano structures to make solar cells, batteries, capacitors and devices which allow us to better optimize energy conversion.
In medicine as well, there are so many practical uses. Many researchers are already looking at nanotechnology in terms of creating agents to deliver drugs that target specific sites, or to recognize certain molecules or antibodies in the blood, thus making treatments much more effective. This technology can also be used to even target specific organs or tumors without damaging the areas of the body around these that might not be stable to otherwise invasive or damaging treatments.
In addition, there is tremendous potential for nanotube technology to help in diagnoses by acting as “contrast agents” for imaging. For example, you can create nanoparticles that are photoactive or perhaps even coated with a given material so that they bond to the surface of a given abnormality or other defect. The imaging that can then be made enables the analyses and preparation for treatment again much more efficient. The more exact in terms of how we learn to design the individual structures, the more uses we’ll find.
What are the little "hairs" on some of the images, like we see above on the nano-flag?
We start out with a full silicon wafer which is broken up into 1 cm square pieces; when you break it up you scratch it and cleave it with a diamond scribe. This creates silicon dust with catalyst on one side.
This dust then acts as a growth point for these extra nanotubes that are then no longer aligned. These appear then in the SEM images as “hairs”.
Why do the edges in some of the shapes glow?
These are local charging effects in the electron microscope that, along with the intensity of the electron beam and the position of the detector, can create apparent lighting and shadowing effects in the electron microscope image. But it is very fascinating in that it provides a very interesting and natural kind of “lighting effect”.
Plus, working with SEM also enhances what we’re able to illustrate as this process can resolve features much smaller than the wavelength of light, and has a relatively large depth of focus.
How do you obtain such clear order in some images (e.g. Obama’s face) vs. others that appear to be a mix of wild hairs or even less ordered structures?
I think the uniform growth comes from understanding the reaction conditions better. Like how to supply enough carbon to feed all the nanotubes “happily”, how to reproduce the processes better, etc. Today, by controlling the density of the catalyst particles as well as the reaction temperature and chemistry, we can grow these CNT forests to millimeter heights with amazing exactness and detail.
Key is the understanding that the architectures are formed by self-organization of the CNTs as they grow upward from the silicon substrate from the catalyst layer. If we distribute the catalyst uniformly, nanotubes will grow everywhere on the substrate. How the nanotubes organize themselves is defined by how they push and pull each other to produce the architectures shown.
On the other hand, if the catalyst is only put in certain areas (patterned), again like the Obama portrait, then the nanotubes will grow only from those areas that are coated with catalyst. We’re just continuing to gain a lot more experience and getting better and better at the design processes I guess.
continued in Part 2
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