For the better part of the last decade, producing carbon nanotubes (CNT) in a laboratory wasn't incredibly difficult. Only in the past few years have processes been used to create readily usable masses of science's latest popular, do-it-all wonder child. A new, novel method devised at the University of Warwick may not produce sheets of usable nanotubes, but that is what is so useful about it.
The procedure has allowed the Warwick researchers to create ready-made, highly sensitive ultramicroelectrodes (UME). Rather than being deposited in either a messy mat or a highly ordered line, the CNTs form a somewhat haphazard connection straight across the sensor's disc, establishing what can easily be used as an electric circuit. The group used lithography and chemical vapor deposition, rather than an aqueous solution, to deposit the CNTs on discs of silicon oxide.
One of the most important properties for the use of these UMEs as sensors is that the total surface area of the disc covered by the CNTs is less than one percent. The ultra-low footprint of the circuit on top of the non-conducting disc allows the sensor to more easily screen out noise and interference making them very useful in low signal to noise situations. The Warwick sensor outperforms conventional UMEs with a sensitivity of up to one thousand times greater.
Other possible benefits of the Warwick UME could lie in medical sciences and in research on fuel cell catalysis. Regarding the former, carbon is a much more biologically neutral material than the metals used in current UME sensors and probes, and could have less of an impact on patients' systems. The CNT sensors should be a better candidate for permanent or semi-permanent medical implants.
The team has already used the new UMEs to prove that it is CNTs themselves and not production impurities that make CNTs useful in fuel cell catalysis. In addition, the sensor's nanotubes are easily coated with metals using electrodeposition, and should prove useful to others using CNTs for catalysis research in fuel cells.
The use of fuel cells is expected to grow in the coming years as electronics manufacturers look to use the technology in mobile devices to replace batteries and auto manufacturers use the powerplants to produce highly-efficient, "green" cars and trucks.