LCN Researchers Develop New Analysis Technique for Carbon Nanotubes

Press Release, 01 July 2008

Carbon nanotubes have outstanding electronic, mechanical and optical properties which make them highly suited to a range of possible future applications in engineering. One big problem with them, however, is that they tend to get tied up in bundles rather like the fibres in a twine of wool. What many applications will require, however, is individual (i.e. not bundled) nanotubes.

It’s therefore important to be able to measure whether any sample of carbon nanotubes consists of bundles or individual nanotubes.  Aki Kumatani and Paul Warburton at the London Centre for Nanotechnology have come up with a new method for determining the extent to which nanotubes are tied up in bundles. Their work was published recently in Applied Physics Letters (volume 92, article no. 243123). [External link]

In this new method nanotubes are first assembled onto a conventional silicon wafer using dielectrophoresis (DEP). The Raman spectrum of these DEP-assembled nanotubes is then measured. The presence of any peaks in the Raman spectrum which correspond to semiconducting nanotubes confirms the existence of bundles in the nanotube sample. The authors show that the new technique is more sensitive than the conventional technique based on spectroscopy in the ultra-violet, visible and near-infrared part of the spectrum. The result is likely to be important in the development of new electronic and photonic devices which rely upon individual carbon nanotubes.


Fig. 1 Scanning electron micrograph of carbon nanotubes assembled between gold electrodes on a silicon substrate using dielectrophoresis


Notes for Editors:

1. About the London Centre for Nanotechnology

The London Centre for Nanotechnology is an interdisciplinary joint enterprise between University College London and Imperial College London. In bringing together world-class infrastructure and leading nanotechnology research activities, the Centre aims to attain the critical mass to compete with the best facilities abroad. Research programmes are aligned to three key areas, namely Planet Care, Healthcare and Information Technology and bridge together biomedical, physical and engineering sciences. Website: