Transparent nano-fibre film can be designed to conduct electricity,
repel dirt, attract oil
19 July 2007
A new technique for making a film of tiny plastic fibres
with customisable properties could lead to new products as diverse as
transparent electronic devices, self-cleaning surfaces and biomedical tools
that manipulate strands of DNA.
A scanning electron microscope image of plastic
fibers grown on a sheet of transparent film.
Image courtesy of Ohio State University.
The patent-pending technology developed by researchers at Ohio state
University involves growing a bed of fibres of a specific length, and using
chemical treatments to tailor the fibres' properties. When seen with the
naked eye the surfaces look as flat and transparent as a sheet of glass. But
seen up close, the surfaces are actually carpeted with tiny fibres.
research was published in the June issue of the journal Nature
Arthur J. Epstein, Distinguished University Professor of
chemistry and physics and director of the university's Institute for
Magnetic and Electronic Polymers, said "One of the good things about working
with these polymers is that you're able to structure them in many different
ways. Plus, we found that we can coat almost any surface with these fibres."
For this study, the scientists grew fibres of different heights and
diameters, and were able to modify the fibres' molecular structures by
exposing them to different chemicals.
|A drop of water
balances perfectly on a film of plastic nanofibres. Photo credit; Jo
McCulty, courtesy of Ohio State University.
Different treatments made the fibres repel or attract water or oil.
Depending on the polymer used, the fibres can also be made to conduct
electricity or attract strands of DNA. When the researchers put droplets of
water containing DNA on the fibres, the strands uncoiled and hung suspended
from the fibres like clotheslines.
Epstein said scientists could use the
fibres as a platform to study how DNA interacts with other molecules. They
could also use the spread-out DNA to build new nanostructures.
excited about where this kind of development can take us," said Epstein,
whose research centres on polymers that conduct electricity, and light up or
change colour. Depending on the choice of polymer, the nano-fibre surface
can also conduct electricity. The researchers were able to use the surface
to charge an organic light-emitting device — a find that could pave the way
for transparent plastic electronics.
Finally, they also showed that the
fibres could be used to control the flow of water in microfluidic devices —
a speciality of study co-author L. James Lee, professor of chemical and
biomolecular engineering and head of Ohio State's Center for Affordable
Nanoengineering of Polymeric Biomedical Devices.
The technology is a
merger of two different chemical processes for growing polymer molecules:
one grows tiny dots of polymer 'seeds' on a flat surface, and the other
grows vertical fibres out from the top of the seeds. The fibres grow until
the scientists cut off the chemical reaction, forming a carpet of uniform
The university will license the technology, and Epstein and his
colleagues are looking for new applications for it.
Lee and Epstein are
advisors to former graduate student Nan-Rong Chiou, who developed the
technology to earn his doctorate. Aside from anti-fog windows, self-cleaning
windows, and organic LEDs, Chiou said that he foresees the surfaces working
in glucose sensors, gene therapy devices, artificial muscles, field emission
displays, and electromagnetic interference shielding.
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