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Posted on August 16, 2010 by  & 

New way to make energy harvesting nanowires

Nanowires are the basis of some zinc oxide based dye sensitised solar cells DSSC, of piezoelectric and, at the Center for Energy Harvesting Materials and Systems CEHMS, thermoelectric harvesting.
Researchers Florian Mumm and Pawel Sikorski at the Norwegian University of Science and Technology in Trondheim think the shimmering sea mouse, Aphrodita aculeata, may hold a key to a new way of creating this nanoscale electronics, making it possible to produce nanowires 100 times longer than existing methods allow - and for a fraction of the price.
In nature, the fabrication of complex 3D assemblies on the nanometre length scale is a common task, as precisely controlled nanostructures are essential for all living organisms. In this project, Mumm and Sikorski took advantage of this by using naturally produced nanochannel arrays as templates to fabricate nanotubes and nanowires.
The nanochannel structures are part of the bristles of the sea mouse. The bristles are penetrated by long channels as a consequence of their growth process and the sea mouse produces two types of bristles: hairs with a diameter of approximately 10 µm and spines with diameter of up to 500 µm. Both are made of a chitin/protein composite material. The team wondered if the hollow channels struck through each of its setae - the reflective spines which lend the sea mouse its iridescence - might also be useful as a mould for making nanowires.
Nanofabrication-templates could be formed by embedding modified sea mouse spines in poly(dimethylsiloxane) and epoxy in such way, that the opened nanochannels span through the polymer.Conventional nanowires are expensive to produce and specialised facilities are needed. In their more straightforward approach, the pair took setae from dead sea mice, put a charged gold electrode at one end and fired copper or nickel ions into the hollow channels from the other end. These were attracted to the charge plate, filling up the tube and growing into nanowires "Nanowires are at most 0.2 millimeters long, usually. Ours can be grown up to 2 centimeters long," says Mumm.
Credit: Norwegian University of Science and Technology
Top image shows colorful appearance of sea mouse hairs and spines when illuminated with white light - source Norwegian University of Science and Technology
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