Our ability to work at the nanoscale -- using new tools to observe atoms, manipulate molecules, and build structures -- is advancing rapidly. A few days ago, we reported on the success of scientists at Rice University in constructing a nanoscale car. This is an excellent example of building "from the bottom up," precisely combining atoms to make working machines.
Another approach to building nanoscale structures is "from the top down."
The University of Pittsburgh recently became the only institution in the United States and only the second in the world to have a unique nanofabrication capability. . . The eLiNE system allows researchers to create nanometer-scale structures using an electron beam that is focused to less than two nanometers. A unique feature of this instrument is an electron beam-induced deposition and etching capability that allows metals, insulators, and semiconductors to be added or removed, using the electrons as a nanocatalyst.
Using this remarkable tool, Pitt scientists have created the world's smallest chess pieces, approximately 400 nanometers wide.
The device uses five small capillaries — hollow injection needles — to add specific gases and materials to a small surface. Then a small beam of electrons acts to help these gases interact with the object to shape it. . . The electron beam can be focused to a diameter of two nanometers, or about twice the distance between two atoms in a solid object.
"In a sense, it's like having a machine shop, only a million times smaller," said Jeremy Levy, Pitt professor of physics and astronomy.
Levy said that the possibilities of this technology include building incredibly small conductors, since the workstation can 'etch' wires 10 nanometers in diameter onto a surface.
Although this new top-down technology is quite impressive, it is not quite atomically precise, not yet. But it's fascinating to see how quickly the two approaches are coming together. The time when tiny machines will work together inside a nanofactory to make amazing products is not far away.
One final note:
The Rice team has already followed up the nanocar work by designing a light-driven nanocar and a nanotruck that's capable of carrying a payload.
"The synthesis and testing of nanocars and other molecular machines is providing critical insight in our investigations of bottom-up molecular manufacturing," said one of the two lead researchers, James M. Tour, the Chao Professor of Chemistry, professor of mechanical engineering and materials science, and professor of computer science.