to the Heavens - Could an incredibly tiny, uniquely strong
structure could make a space elevator? (12/24/02)
Feet - A team of scientists may have discovered a way to take
the fiction out of Spidernamâ€™s sci-fi sticking power. (9/6/02)
Elsewhere on the web
to Nanotechnology and Nanocomputers
Magnificent Seven: Women Faculty Members Cited as Top Scientists
of the Year: Finalists - Angela Belcher (scroll down about half-way)
If you've been lucky enough to spend a day on the beach at this time of year,
you probably came home with a few sea shells as souveniers.
Now, as this ScienCentral News video reports, an imaginative scientist has
figured out how one shell is made.
For the last 25 years, weâ€™ve been able to keep shrinking computer chips
to the point that weâ€™ve doubled their power every 18 months. But weâ€™re
rapidly reaching the
limits of todayâ€™s technology. At Massachusetts
Institute of Technology (MIT), nanotechnologist Angela
M. Belcher, believes our answer begins with sea shells.
To understand how materials work at nanoscale (meaning the size of a few atoms),
many scientists have been studying natural
models. When Angela Belcher was in college and graduate school at the
University of California, Santa Barbara, she frequently found red abalone
shells washed up on beaches. Although abalone shells are made up of calcium
carbonate, the same mineral that makes up chalk and limestone, the shells
are many times stronger than their geological counterparts. Belcher decided
to find out why.
Her answer: the abalone
is a nanotechnologist. To build its shell, it creates a new material,
combining calcium carbonate from the surrounding ocean with its own natural
proteins. Then it creates miniscule plates of only a few hundred molecules,
and stacks them like tiny rows of bricks. An abalone may take as long as 15
years to make a full-size, super-strong shell. Amazingly, Belcher points out,
the abalone accomplishes this feat with natural materials at normal temperatures
To transfer the abaloneâ€™s building skills to nanoscale electronics, Belcher
took advantage of the similar abilities of viruses, called bacteriophages, that
had been genetically engineered. When mixed together, millions of these viruses
can align and stack themselves into orderly layers, creating a new material.
Belcher and her colleagues decided to try linking semiconductor particles to
these harmless, pattern-making viruses. The researchers discovered that
they could employ the viruses as nanoscale construction workers, building new
electronic and magnetic materials.
Because bacteriophages reproduce themselves so quickly, Belcher and her research
group at MIT are able to create a new material every three weeks or so. They
need more time to figure out the materialsâ€™ properties—what they
can and cannot do. But Belcher is confident that her new materials will be useful
in electronics, computing, and medicine.
“Right now,” she says, “Iâ€™m not ruling anything out.”
Her work was funded by the Army Research Office, National
Science Foundation (NSF), Defense
Advanced Research Projects Agency (DARPA), Dupont,
and IBM. It has been
published in the journals
(May 3, 2002), Nature
(four articles, most recently in 2000), and the Proceedings
of the National Academy of Science (March 5, 2000).