Vast amounts of data could be stored for a billion years in
carbon nanotubes, claim California researchers.
"We've developed a mechanism for digital memory storage that
consists of a crystalline iron nanoparticle shuttle enclosed within
the hollow of a multiwalled carbon nanotube," said project leader
Alex Zettl. "We've created a memory device that features both
ultra-high density and ultra-long lifetimes, and that can be
written to and read from using the conventional voltages already
available in digital electronics."
The development team is spread across both the Lawrence Berkeley
National Laboratory and the University of California, Berkeley.
"The shuttle memory has information density as high as one
trillion bits per square inch and thermodynamic stability in excess
of one billion years," Zettl said.
"Furthermore, as the system is naturally hermetically sealed, it
provides its own protection against environmental
contamination."
Low voltage current shuttles the iron back and forth inside the
nanotube "with remarkable precision", said Berkley, and the
shuttle's position can be read out directly as electrical
resistance, allowing "potentially hundreds of binary memory
states".
The multiwalled carbon nanotube and enclosed iron nanoparticle
shuttle were synthesised in a single step using pyrolysis of
ferrocene in argon gas at a temperature of 1,000[deg]C.
The memory elements were then ultrasonically dispersed in
isopropanol and deposited on a substrate.
The memory has been seen operating in real time through a
transmission electron microscope:
"In laboratory tests, this device met all the essential
requirements for digital memory storage including the ability to
overwrite old data," said Berkley.
Zettl mused about data durability, pointing out that stone
carvings in the Egyptian temple of Karnak store approximately two
bits of data per square inch and can be read after nearly 4,000
years.
"Interestingly," he said, "the Doomsday Book was written on
vellum and has survived over 900 years, while the 1986 BBC Doomsday
Project, a multimedia survey marking the 900th anniversary of the
original Book, required migration from the original high-density
laserdiscs within two decades because of media failure."