The tiny wires and electronic circuits on computer chips are etched into slices of silicon. Miniature motors and engines carved with top-down methods, however, have yet to find practical applications. To break through to the next level of smallness, a new generation of devices will have to be built from the bottom up. By using atoms, molecules, or nanometer-size aggregates as building blocks, scientists hope to exercise the ultimate control over the devices they construct. New nanocomposites, in which nanometer-size particles of one component are mixed into another material, can be vast improvements over their conventionally made counterparts.
Nature abounds with self-assembled objects.
The water molecules in a raindrop automatically aggregate to form a smooth, curved surface. A cell is more complex, but it, too, contains all the information it needs to assemble itself. Then, the right initial components, carefully chosen, will put themselves together while the humans sit back and relax. So far, biologists and biochemists have done much of the work in describing self-assembly, says Whitesides. Long chains of amino acids twist and turn back onto themselves to form three-dimensional proteins.