Thursday, March 10, 2005

"NANOTECH: Nanowires corralled for interconnect tasks"

A research group at the University of Delaware has demonstrated a way to precisely position and control the growth of organic nanowires atop a prepatterned substrate, potentially providing a means of interconnecting future nanocircuits. Until now, there has been no way to interconnect such nanoscale devices as carbon nanotube transistors, quantum dots and molecular-memory arrays. In a different approach, researchers at Purdue University have used the self-assembling properties of DNA to create nanowires. University of Delaware professor Thomas Beebe led the team that recently demonstrated nanowires that self-assembled in a thin-film polymer. By stimulating the fledgling wire at one end with a pulse from a scanning-tunneling microscope (STM), the wire self-assembled along the lines of the atomic lattice, yielding nanoscale precision. A barrier, called a corral, stopped the wires' growth at the correct point. This suggests that future devices could be interconnected using self-assembling nanowires that would be stimulated electrically to grow and then terminated with molecular corrals. Separately, researchers at Purdue University attached magnetic nanoparticles to DNA and then cut the strands into DNA wires. Deoxyribonucleic acid-DNA-has an overall negative charge, but when placed in a solution with magnetic particles that have a positive charge, DNA automatically self-assembles into tiny scaffolds that, in effect, create wires. Those wires can be used to self-assemble electronic devices according to a precise program.