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Posted: November 25, 2008

Researchers create electrical wires made from protein fibers

(Nanowerk News) Researchers at Linköping University in Sweden have succeeded in creating electrical wires consisting of protein fibers encased in plastic. The 10 nanometer thin fibers are self-organizing and compatible with biological systems.
"For the first time, we have created proteins that conduct current extremely well but can also function as semiconductors in transistors, for example," says Mahiar Hamedi, who developed the technique together with Anna Herland and associates at the Division for Biomolecular and Organic Electronics. The technology is described in his doctoral dissertation.
Last year Mahiar Hamedi made headlines with his invention of conductive textile fibers, which can be used to produce electronic cloth. Now he has scaled down that technology by a factor of about a thousand.
These nano fibers are produced in ordinary test tubes. One component is amyloid fibers, long, stable protein fibers that occur naturally in living organisms and can cause, among other things, nerve disorders in humans and animals. The other component is a conjugated polymer (PEDOT-S), a plastic material that conducts current. When the two are mixed in water, the plastic attaches to the fibers and forms a conductive shell that is merely a handful of atoms thick.
"The beauty of the self-assembly process is the ease under which PEDOT-S binds onto the amyloid fibrils directly in water without the need of any heat, and in a matter of a few minutes" Hamedi writes in his dissertation.
By providing the fibers with charged outgrowths, it is possible to get the molecules themselves to form desired structures. This can be an inexpensive and effective way to create extremely tiny three-dimensional electronic circuits.
Using their nano fibers as a channeling material, Mahiar Hamedi and his associates have constructed fully functional electrochemical transistors that work in the area of 0-0.5 volts.
The dissertation also describes a method for creating nano patterns in conductive plastic. As organic material is beginning to be used in more and more advanced electronic circuits, there is a need to fit a huge number of components in a tiny area. The solution is to form the plastic in a mold with structures that are smaller than the wavelength of visible light - and therefore invisible!
The dissertation Organic electronics on micro and nano fibers - from e-textiles to biomolecular nanoelectronics was publicly defended November 21, 2008. External examiner was George Malliaras, Cornell University, USA.
Source: Swedish Research Council