Scientists at Rice University have built molecular vehicles so small that more than 20,000 of them could sit side-by-side on a human hair. Just what we need, in the hands of the same people who designed DU weapons. rkm -------------------------------------------------------- http://www.nytimes.com/2005/10/21/technology/21cnd-nano.html October 21, 2005 Scientists Build Tiny Vehicles for Molecular Passengers By BARNABY J. FEDER Scientists at Rice University have built molecular vehicles so small that more than 20,000 of them could sit side-by-side on a human hair. The fleet consists of nanocars, nanotrucks capable of carrying small-molecule payloads, and trimers that pivot on their three axes. All of them roll on buckyballs, which are 60-atom, soccer-ball-shaped spheres of pure carbon. Each axis pivots up and down independently to allow the vehicles to negotiation atomic potholes and mounds. The work, which was first described earlier this month in the online version of the journal Nano Letters, is the fruit of more than eight years of research led by Prof. James M. Tour into systems that could be used to build structures molecule-by-molecule. "This is it, you can't make anything smaller to transport atoms around," Professor Tour said. The vision of the Rice researchers, like many other specialists working in nanotechnology, is of a world where new materials can be fashioned by armies of tiny machines working in organized ranks. This so-called "bottoms up" version of manufacturing is patterned after biology and, in the view of many researchers, it could be far more efficient than current manufacturing systems. Skeptics have said such molecular manufacturing will prove to be impractical in most cases and may pose unexpected environmental risks. But scientists working in the field almost universally dismiss visions of nanomachines proliferating into a deadly world-choking "gray goo" as popularized in Michael Crichton's novel "Prey." Nanotechnology derives its name from the nanometer, or billionth of a meter. Nanoscale objects are tens to thousands of molecules in size. While they consist of familiar materials, the scale is so small that atomic forces affect their behavior and strange, potentially valuable traits emerge. The nanocars are immune to friction, for example, because the buckyball wheels are a single molecule that cannot be easily pulled apart into its 60 carbon atoms. Professor Tour said the research marked the first time anyone had demonstrated nanoscale structures that roll rather than slide across a surface. The current generation of vehicles can be set in motion by heating the gold surface on which they sit to about 200 degrees Celsius. Absent any outside force, it is unpredictable whether they will move forward or backward, but once they start they will continue in that direction as long as heat is applied. But Rice's researchers have shown that they can control the direction by applying an electrical field. They have also built a tiny light-powered motor for the devices consisting of 30 carbon atoms and a handful of sulfur atoms, Mr. Tour said. But that motor does not capture enough energy to move the devices over the gold surface because the gold molecules absorb most of the light. The nanocars are 95 percent carbon by weight, with a smattering of hydrogen and oxygen atoms to keep them soluble during manufacturing. They are manufactured in a 20-step process similar to the way many drugs are synthesized from small molecules in closed reactors. They are then suspended in toluene gas and spun cast onto the gold surface. Professor Tour said that he had not sought any patents on the work because he believed it would take at least a generation to overcome the many hurdles to molecular manufacturing using the technology Rice has developed. "The patents would have expired long before you could have build a useful business," Professor Tour said. Professor Tour has five graduate students working on the research. He said that the scanning electron microscope imaging necessary to capture the data is managed by his co-author on the Nano Letters paper, Kevin F. Kelly, an assistant professor of electrical and computer engineering, and two other graduate students. The original research was financed by Zyvex, a nanotechnology company based in Richardson, Tex., the Welch Foundation and the National Science Foundation. Professor Tour has recently received an additional research grand from Honda of Japan. 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