LANL researchers Abul Azad, John O'Hara and Tony Chen are developing metamaterials.
Big Advances in Tiny Technologies
October / November 07
Volume 5 Number 5
Invisibility cloaks, gold grown in a matter of seconds, tracking the movement of a single molecule inside a living cell and engineering material stronger than steel—€”these are just a few of the applications nanotechnology could be used for someday in the not-too-distant future.
Nanotechnology at Los Alamos National Laboratory is a broad and deep area of research, especially with the establishment of the Center for Integrated Nanotechnologies Gateway to Los Alamos Facility in May.
In a recent issue of 1663: Los Alamos Science and Technology Magazine, (excerpted here on Page 21) CINT associate director Toni Taylor said:
"CINT's combination of instruments and scientists makes the facility unique. We have complete laboratories where it becomes possible to combine concepts like metamaterials, nanolayered structures, quantum dots, and so on. Bringing these exotic materials together in an integrated form is where we are heading. That's what the —€˜I' in CINT is about—€”integrating different kinds of nanotechnologies to come up with functional devices and systems."
Also, the facility makes possible discussions among scientists working in nanotechnologies in a variety of scientific disciplines. For example, Los Alamos scientist Jim Werner, who works in CINT, specializes in instrumentation and is currently developing a microscope capable of tracking molecules in 3-D. While the biomedical industry will benefit the most from his technology, Werner is no expert in biology, so CINT provides an easy way for him to discuss his experiments with biologists also working in nanotechnology.
Following are descriptions of the multiple technologies being researched and developed at Los Alamos.
Metamaterials
Without a doubt metamaterials is one of the most popular new technology areas being researched. With the promise of invisibility cloaks, lightweight lenses, stealthy antennas, faster computers and more, metamaterials are poised to make major technological contributions in multiple future applications.
Los Alamos scientists John O'Hara and Toni Taylor, post-doctoral researchers Hou-Tong Chen and Abul Azad, and their collaborators Willie Padilla (Boston College) and Richard Averitt (Boston University) have been working together for about two years on metamaterials and have made great progress creating new devices capable of filtering, switching and modulating terahertz wavelength energy.
Metamaterials are basically mimics of nature's atoms but on a much larger scale. Los Alamos scientists create metamaterials by depositing patterns of tiny metal rings on the surface of semiconductor wafers. Like atoms, the rings act like tiny oscillators temporarily storing and then re-emitting energy. The size and shape of the rings determine exactly how the metamaterial will interact with the terahertz wave.
Currently, Los Alamos is one of only a handful of research institutions developing metamaterials for the terahertz wavelengths. While the Los Alamos metamaterials concepts can be scaled to other wavelengths, such as microwaves, O'Hara says by making metamaterials capable of interacting with terahertz waves, a long-standing technology gap may be filled, opening the door to a new class of faster electronics, high-speed communication links and novel imaging techniques.
"Metamaterials are in the discovery stage right now and that's what's so neat about it; you're in an area that nobody's delved into before," O'Hara says. "The implications in the long term will become obvious over time. It's such a powerful concept and it's hard to tell how many manifestations there will be, but we know they could be drastic."
3-D Tracking
Understanding the specific interactions between all the different proteins in a cell is the holy grail of the biomedical industry. Such fundamental knowledge concerning protein-protein interactions has tremendous potential to improve human health, including discovering the causes and cures for cancer.
Jim Werner, Peter Goodwin and post-doctoral researcher Guillaume Lessard have been working on an apparatus for 3-D tracking of single fluorescent molecules for almost four years.
By tracking single molecules inside cells, scientists can get a better understanding of events that occur within cells, such as signal transduction (the conversion, by a cell, of one signal or stimulus to another), crucial for biomedical and pharmaceutical industries. For example, defects in signal transduction can cause diseases such as muscular dystrophy or diabetes, and a better understanding of the proteins involved in these diseases will inevitably lead to better therapeutic strategies.
Recent 2-D tracking studies of single molecules have discovered hidden details concerning the diffusion and transport of receptors on cellular membranes. Werner and his team felt extension from studying 2-D images to 3-D trajectories could greatly expand the utility of single-molecule tracking studies. In particular, using 3-D tracking, proteins inside cells (and not just those on the 2-D cellular membrane) could be followed as a function of time.
"Single-particle tracking in two dimensions has already contributed substantially to our knowledge of organization and transport on complex two-dimensional surfaces, such as cellular membranes," Werner says. "However, most aspects of life, including intracellular transport, are inherently three-dimensional. We are very optimistic our 3-D tracking technology will be useful in exploring many transport processes and protein-protein interactions inside cells, which could lead to the fundamental molecular understanding needed for better therapeutic strategies for many cellular diseases."
To track single molecules in 3-D, the team expanded the capabilities of confocal laser scanning microscopy. In essence, the team built a confocal laser scanning microscope that uses active feedback to keep the molecule under study in the center of the field of view. The team has recently used this instrument to track individual quantum dots, semiconductor nanocrystals, diffusing in three dimensions at rates faster than many intracellular transport processes. These nanocrystals are similar in size and speed to many proteins and are often used as labels for following individual protein motion in two dimensions.
After benchmarking their instrument on the simple test-bed of quantum dots in glycerol/water, the team is working toward tracking single, quantum-dot-labeled proteins within cells. In addition, the team is also working toward licensing its technology to confocal microscope manufacturers with the end market being clinical and scientific researchers.
Conductive Polymers
Remember the story of King Midas, the king who accidentally turned everything he touched into gold after wishing for the ability to do so? Well, we better tell Los Alamos scientist Hsing-Lin Wang's family to watch out—€”he might just turn them into gold! So maybe everything Wang and his team touch can't be turned to gold, but they have developed a capability to grow gold.
The capability to grow metals is already a commercial product but Wang and his team, scientists Elshan Akhadov and Weiguang Li, former Los Alamos employee James Bailey and collaborator Yuan Gao, have discovered an innovative, inexpensive and less complicated way of growing metals.
There are obvious uses for metals like gold, but the team is targeting a different industry for this capability. Only certain metals, such as gold, silver, platinum and palladium can be grown with special catalytic and optical properties. One of the end-use applications for the metals grown by Los Alamos is in the area of chemical and biological sensors. A phenomenon called SERS, or Surface Enhanced Raman Scattering, enhances the ability to detect the light scattered from a given material at the single molecule level.
While companies are already selling similar surface enhanced substrates, their metals don't compare to the ones grown by Los Alamos scientists. Commercially grown metals are created using complicated chemical vapor deposition methods that are time consuming, very expensive and require lots of attention during the process. Los Alamos' method is simple.
A conductive polymer is first quickly treated with an acidic solution, the polymer is then dipped into an aqueous metal ion solution, and anywhere from a few minutes to a few seconds later a metal is grown on the surface of the conductive polymer. Gold, for example, takes about 20 seconds to grow. Other metals such as silver, platinum and palladium can also be grown.
Not only is this process simple, it's also inexpensive, at least 50 times cheaper than the current commercial product, and produces high quality, homogeneously structured metal nanoparticles, or metals with high-level SERS.
"SERS is a powerful and flexible tool for sensing a broad array of materials," says Russ Hopper, business development executive for LANL's technology transfer division. "SERS has been applied to biochemistry, chemical manufacture, environmental detection and even forensics. Coupled with separations technologies, it is possible to identify single molecules in complex solutions.
The method developed by Dr. Wang to generate SERS substrates is very powerful and should allow the industry to expand well beyond its current boundaries."
This technology is going to have a huge impact on the sensor industry and will eventually expand to areas such as bioassay and disease diagnosis. Wang also said there is huge potential in homeland security and other industries.
CNT Success Story
In April 2006, Los Alamos licensed its carbon nanotube technology to Seattle-based CNT Technologies, Inc. Created by a team of Los Alamos scientists, ultra-strong, lightweight, double-walled carbon nanotubes will be commercially available as one of the strongest engineering materials on Earth in summer 2008.
The ultrastrong, lightweight, carbon nanotube fiber, made from carbon nanotubes spun together and branded SuperThread—„ by the company, can have better properties than steel for many applications and could soon be the primary substance from which airplanes, automobile parts and sports equipment are made.
Initial tests show that SuperThread is one-hundred times stronger than steel and less than one-fortieth the weight.
"Our mission is to produce the highest quality, lightest weight, strongest carbon nanotube fiber at the lowest possible cost for our corporate customers," says Robert O'Leary, CEO of CNT Tech. "If we accomplish that mission—€”and we plan to—€”our corporate customers will change the world in which we live. Aircraft, automobiles, satellites, engines, prosthetics, sporting goods and tens of thousands of other products will be lighter, stronger, safer and more efficient."
Small quantities of SuperThread carbon nanotube fibers are currently being sold for testing by CNT Tech, which is also working together through a Cooperative Research and Development Agreement with Los Alamos. The company has received an order from the. Army Research, Development and Engineering Command.
Additionally, a major U.S. aerospace company and a very large defense contractor have indicated they will purchase substantial portions of the initial pilot plant production to test military and space applications.
In general, these carbon nanotubes will be used mainly to fabricate composite structural components that require low density and high strength. Such components are used in jet and conventional aircraft, helicopters, space shuttles, satellites, rockets, laptop-computer cases and numerous other applications.
While some of these nanotechnologies aren't quite ready for the commercial market, others are. Each of these technologies is new and still being developed. Metamaterials and 3-D tracking might have a way to go on the development side, but their future applications will not only help people but will also be numerous.
"With nanotechnologies, we will be able to do things that have never been done before or that have been extremely difficult to do," says Hopper. "Each of the technologies offers an opportunity to advance the state of the art in their respective fields. While metamaterials offers a chance to alter the basic way matter is used, Wang's SERS nanotechnology is an incremental improvement (albeit a very large increment), to an existing technology. Werner's 3-D molecular tracking offers both incremental improvement and leapfrog improvement for drug design and behavior."
Krystal Zaragoza is a communications specialist at Los Alamos National Laboratory.
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