Carbon nanotubes’ potential as a super material is
blighted by the fact that when first made they often take the form of
an unprepossessing pile of sooty black mess in the bottom of a test
tube. Now researchers in the University of Warwick’s
Department of Chemistry have found a way of producing carbon nanotubes
in which they instantly form a highly sensitive ready made electric
circuit.
The research has just been published in a paper entitled
“Single-Walled Carbon Nanotube Network
Ultramicroelectrodes” by University of Warwick researchers
Ioana Dumitrescu, Professor Julie Macpherson, Professor Patrick Unwin,
and Neil Wilson in Analytical Chemistry, 2008, 10.1021/ac702518g
The researchers used a form of chemical vapour deposition and
lithography to create the ready made disc shaped single walled carbon
nanotube based ultramicroelectrodes. The nanotubes deposit themselves
flat on a surface in a random but relatively even manner. They also all
overlap sufficiently to create a single complete metallic micro-circuit
right across the final disc. What is even more impressive is that they
take up less than one per cent of the surface area of the disc.
This final property makes these instant ultramicroelecrodes
particular useful for the creation of ultra sensitive sensors. The low
surface area of the conducting part of the disc means that they can be
used to screen out background “noise” and cope with
low signal to noise ratios making them up to 1000 times more sensitive
than conventional ultramicroelecrodes sensors. This property also
produces very fast response times allowing them to respond ten times
faster than conventional ultramicroelecrodes.
As these ready made ultramicroelecrodes are carbon based they
also open up a range of new possibilities for use in living systems.
The biocompatibility of carbon is in stark contrast with the obvious
problems that platinum and other metal based probes can pose for living
tissue. The Warwick research team are already beginning to explore how
their single walled carbon nanotube based ultramicroelecrodes can be
used to measure levels of neurotransmitters.
The new ultramicroelecrodes also open up interesting
possibilities for catalysis in fuel cells. Up till now researchers had
been aware that this form of carbon nanotubes appeared to be
particularly useful in the area of catalysis but there was uncertainty
as to whether it was the properties of the carbon nanotubes per se that
provide this benefit or whether it was due to impurities in their
production. The researchers have been able to use this new method of
single walled carbon nanotube assembly to prove that it is actually the
properties of the carbon nanotubes themselves that are useful for
catalysis. The new carbon nanotube assembly technique brings a further
benefit to catalysis applications as the Warwick researchers have been
able to use electrodepoistion to quickly and easily apply specific
metal coatings to the ready formed single walled carbon nanotube
microelectrode networks. This will be of significant benefit to anyone
wanting to use single walled carbon nanotube for catalysis in fuel cell
technology.
Posted 7th May 2008
