Nano ribbons coil into rings

Researchers from the Georgia Institute of Technology have found a way to coax microscopic zinc oxide ribbons to spontaneously coil, slinky-like, into perfect rings.

The rings are single-crystal material and are 300 nanometers wide, 10 nanometers thick and three microns wide. The rings are a little more than half the girth of a red blood cell.

The tiny rings are potentially useful as parts, including sensors, resonators, transducers and actuators, in nanoscale machines; they could also be used in piezoelectric fluid pumps and as biotech switches, according to the researchers. And they could be placed in the body to monitor blood pressure and blood flow rate in real-time and measure stress at the single-cell level, according to the researchers.

Zinc oxide crystal is piezoelectric, meaning it vibrates when it absorbs electricity, and vibrations cause it to generate small amounts of electricity. The researchers formed the zinc oxide nano ribbons by mixing zinc oxide, indium oxide and lithium carbonate powders with argon gas and heating the mixture to 1,400 degrees Celsius, then dropping the temperature to 400 degrees and adding pressure.

The nanorings could be used in practical applications like blood pressure monitoring within five years, according to the researchers. The work appeared in the February 27, 2004 issue of Science.