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Electronics, Photonics, Nanotubes, Mechanical Devices, Theoretical Models, Self-Assembly, Networks and Funding
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September 3-7, 2001: I was lucky enough to attend TNT 2001 in Segovia Spain, where 250+ nano scientists and engineers met to discuss the latest Trends in NanoTechnology. While most scientific meetings are held in modern hotels or lecture halls, TNT 2001 took place in the Isabelino-gothic monastery 'Santa Cruz'. The old, yet aesthetically stable surroundings reminded me that mankind has been fabricating remarkable structures on the macroscale for millennia. Thus, the setting seemed an inspiring place to learn how to do that on the nanoscale.
On the more modern side of the conference were the trends, with some of the cooler subjects being Electronics, Photonics, Nanotubes, Mechanical Devices, Theoretical Models, Self-Assembly, Networks and Funding. Here I will briefly describe why each of these trends appears to be in fashion in the world of nanotechnology.
Electronics
There doesn't seem to be any question that our microelectronics industry will soon have to deal with the finite nature of matter found at the nanoscale. This imminent problem (known by the semiconductor industry as "the red brick wall") provides a major motivation for a better understanding of electronic behavior at the nanoscale, for reliable nanofabrication processes, and the development of novel computational architectures. While purely top-down silicon processing can likely continue improving at a steady rate for 5-10 years, nanoelectronics is expected to bring about a new paradigm in computing, and is a very hot application for nanotechnology.
Photonics
Photonic Band Gap (PBG) Materials are similar to semiconductors, where the electrons are replaced by photons (also known as light). By creating periodic structures out of materials with contrast in their dielectric constants, it becomes possible to guide the flow of light through the PBG material in a way similar to how electrons are directed through doped regions of semiconductors. The period of the structure is related to the wavelength of light for which a PBG will exist, for instance a few hundred nanometers for visible light. These materials are a relatively new discovery, with potential applications ranging from efficient light emitting diodes to quantum computers.
Nanotubes
One of the most stylish materials resulting from nanotechnology is the stable phase of carbon known as carbon nanotubes. Discovered ten years ago by Sumio Iijima, one of the participants of TNT 2001, the number of different types of nanotubes (and related materials) is as diverse as their potential applications. A few of those discussed at the conference were for scanning probe microscopy (SPM) tips, field emission displays, nanocircuitry, and even catalysts. With so much potential for utility, nanotubes may just be the wheel of nanotechnology. However, because of their nanoscale diameters there are still plenty of inventions to be made in nanotube research and development.
Mechanical Devices
Macroscale mechanical engineers have already demonstrated the utility of mechanical devices such as cars, assembly lines, plumbing, clocks and other machines. Micromechanics and nanomechanics on the other hand is only now being developed. A typical example of a useful micromechanical system is a cantilever (a miniature diving board). As a key component in many types of SPMs, cantilevers bend in response to forces so small that they enable one to create images of surfaces with nanoscale resolution. While SPM is one success story for micromachines, several others are likely on their way with two realistic applications being very sensitive sensors and intelligent drug delivery. While research involving synthetic (meaning non-biological) nanomechanical devices seems motivated more by curiosity than immediate applications, it's worth remembering that the first microscope was created by a toy-maker.
Theoretical Models
Mathematical and computational modeling of nanoscale systems requires a unique combination of quantum mechanics with classical models. Ab initio (meaning computed from first principles without any empirical input) quantum mechanical models require an immense amount of computational power, which severely limits the size of a system that can be modeled by accurate quantum mechanical models to about 50 atoms with today's best super computers (of course nanotechnology is helping to improve our computers). Classical models, on the other hand can neglect important quantum effects that give nanoscale devices their unique properties. The development of efficient and accurate mathematical models of nano-systems is an essential and rewarding effort.
Self-Assembly
As features decrease in size from micro to nano, they become more expensive to create using conventional fabrication technologies such as photolithography or electron beam lithography. Thus, bottom-up methods that take advantage of the natural tendency for atomically precise devices to self-organize are a highly sought after approach to nanotechnology. Furthermore, conventional lithography is inherently two dimensional, while self-assembly can make full use of three dimensions. An example of a success story for self-assembly is the photonic band gap material known as "inverse opal". This material can be created by filling in the spaces between nanoscale spheres which have been self-assembled into a 3-D hexagonally packed array. As an added bonus, nature provides a plethora of self-assembling molecules to serve not only as inspiration but also as a tool-box for molecular self-assembly.
Networks and Funding
Now that nanotechnology has been accepted by the scientific community, funding interdisciplinary nanotech research and collaborative networks is becoming increasingly trendy. Governments, universities and capitalists are gaining interest in nanotechnology, which means better labs, well defined goals, and more money for nanoscientists and nanoengineers. Nanotechnology in the European Union appears to be a high priority. For instance, the PHANTOMS Network is a European initiative which provides funding to European seniors and young students involved in nanoelectronics. The UK based Institute of Nanotechnology helps to spread the word via the internet. Nanotechnology in the Ibero-American community is facilitated by the CYTED Sub-Program IX: Microelectronics. In the USA, NASA and the National Science Foundation (NSF) help to fund and organize nanotech research. For those considering going commercial, the Joint Venture CMP Cientifica / Spark Inversiones provided tips on how to obtain venture capital.
The utility of interdisciplinary nanotech conferences such as TNT for sparking new ideas was apparent. For instance, on the first day Juan José Sáenz gave a theoretical lecture about how a strong force should be exerted on a neutral particle of nanoscale dimensions inside of a waveguide. Questions about how to measure the effect, and even one about how it might be useful followed. On the next day Christian Joachim gave a talk entitled, "Mono-Molecular Mechanical Machines at the Nanoscale" in which molecules were being pushed around on a surface with a scanning tunneling microscope tip. Changes in the tunneling current could then be correlated to mechanical movements of sub-molecular components. So, the moral of this story is that it might be worth trying to roll nanomachines down a nano-hill by placing neutral nanomachines in a waveguide. Just one idea of many...
Acknowledgements
Thank you Antonio Correia (+Tim, Adriana & Nacho) of CMP Cientifica, Pedro Serena of CSIC, Juan José Sáenz of the Universidad Autónoma de Madrid, and everyone who helped to organize the excellent conference. I'm also grateful to all of the participants and am looking forward to meeting again at TNT2002, or sooner.
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