History of Nanotech
Essay Preview: History of Nanotech
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Meanwhile, a brief mention in Engines of Creation of the dangers of self-replicating systems was proving increasingly troublesome to the field of molecular manufacturing. The idea arose that any molecular manufacturing system would be only one “oops” away from eating the biosphere. The Wired article “Why the Future Doesnt Need Us” by noted computer scientist Bill Joy publicized this concern. Nanoscale technology researchers, fearing-perhaps with justification-that “gray goo” would threaten their funding, increased their efforts to distance their work from molecular manufacturing. One of the easiest ways to do this was to claim that molecular manufacturing was impossible and unscientific. These claims gained force since molecular manufacturing research was (and remains) highly technical, interdisciplinary, theoretical, and mostly undemonstrated.
In the past decade, theorists have begun to flesh out the details of how nanotechnology might be used in manufacturing and medicine, although it is unclear how soon any of this will be possible. Some analysts have estimated that major breakthroughs in molecular manufacturing are at least three decades away; others have suggested that major progress might occur in the next five years.
From atoms, to molecules, to machines, to manufacturing systems that can duplicate themselves using simple molecular feedstocks: this overview has explained only the broadest outline of the approach and its merits, and has not touched on the problems of design, control, and reliability. Those problems appear to be solvable with ordinary research and development. Other problems are somewhat more esoteric and less well understood: for example, it is not yet known exactly how to mechanically manipulate small molecules to make them join into larger functional structures. There are some practical problems that arise at the nanoscale (including many quantum effects and thermal noise) that will complicate the design process. No one has said that developing this technology will be easy.
Fifteen years after the major theoretical work in the field was published, no one has yet identified a factor that would preclude the building of high-performance kilogram-scale products composed of nanometer-scale machinery, using a few hours of time in a kilogram-scale factory. The implications of this capability would be transformative, disruptive–perhaps terrifying–and will be the subject of several future columns.
As skepticism recedes, what is left is a wide-open opportunity. Molecular manufacturing will not replace other forms of nanotechnology–there are too many useful phenomena waiting to be uncovered at the nanoscale. But for straightforward mechanical work, molecular manufacturing may be the most effective approach, with the highest power density and efficiency. Mechanical operations at the nanoscale can implement sensors and computers as well as motors. And the mechanical approach, relegating nanoscale complexities to the lowest levels of structure and preserving precision at all higher levels, should contribute substantially to simplicity of design.
Scientists at Edinburgh, Groningen and Bologna are the first to manipulate tiny nanoscale machines (two millionths of a millimetre high) so that they can move an object that is visible to the naked eye. The team has shifted microlitre drops of diiodomethane not just across a flat surface, but also up a one millimetre, 12 degree slope against the force of gravity. It may be the tiniest of movements, but, in the emerging discipline of nanotechnology, it represents a giant technological leap forward.
Although many scientists are working with so-called “molecular machines” – a process which involves making the parts of molecules move in a controlled fashion – the Edinburgh-led team is the first to make these machines interact with real world objects. Until now, molecular machines have operated in isolation within the laboratory, but this latest piece of research brings them into contact with the everyday world around us.
The research team has developed a Teflon-like surface that is covered with synthetic molecular shuttles, the components of which move up and down by a millionth of a millimetre when exposed to light. The movement of droplets results from the change in surface properties after most of the shuttle molecules change position. The phenomenon is so efficient that it generates enough energy to move the droplet. In terms of scale, the process is mind-boggling: it is the equivalent of a conventional mechanical machine using a millimetre displacement of pistons to lift an object twice the height of the worlds tallest building.
Molecular machines are ubiquitous throughout biology (they make muscles move, for example), but making tiny artificial machines is not easy because the physics that govern how things behave at the molecular level is very different from conventional physics. That means the prospect of large objects being moved around remotely by lasers is still some way off, but this new study, reported in the current issue of Nature Materials journal, may prove useful for some lab-on-a-chip diagnostic techniques, or for performing chemical reactions on a tiny scale without test tubes.
Researchers from the U.S. Department of Energys Argonne National Laboratory and Northern Illinois University have found that very thin materials can still retain an electric polarization, opening the potential for a wide range of tiny devices.
The researchers found that the ferroelectric phase – the phase that has the ability to hold a switchable electric polarization – is stable even for thicknesses as small as six atoms. That is the equivalent of 1.2 nanometers, one-billionth of a meter, or a size several hundred thousand times smaller than the period at the end of this sentence. Previous studies found that as the material became too thin, it quit being a ferroelectric. These results, however, suggest that small thicknesses do not pose a fundamental problem to building very small devices based on these materials.
The research is published in the June 11 issue of Science magazine.
An increasingly wide range of applications are based on ferroelectric thin films, including sensors, microelectromechanical systems, and memories.
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