Lab talk
Jan 28, 2010
Bias-dependent response of CNTs to amino-acid adsorption
Researchers in the nanoelectronics group at UBC, Canada, have recently shown that semi-metallic carbon nanotubes offer a high potential for amino-acid detection.
The work, published in the journal Nanotechnology, demonstrates that semi-metallic carbon nanotubes can be used in a simple two-terminal configuration to detect charged amino acids.
The research reveals that for short semi-metallic nanotubes, the mechanisms of interaction, and consequently the sensing mechanisms, are bias dependent. When the applied bias (in volts) is numerically less than the small bandgap of the tubes (in eV), the transport mechanism in the tube is dominated by intraband carrier flow.
When the bias numerically exceeds the bandgap, however, band-to-band tunneling becomes the dominant transport mechanism. Accordingly, sensing in the former bias range is controlled by quantum-mechanical reflections induced by the adsorbed analyte, while in the latter, tunneling-width modulation primarily determines the sensing current.
About the author
George B Abadir is a PhD student in the Electrical and Computer Engineering Department at the University of British Columbia (UBC), Canada. He is using molecular dynamics and ab initio simulation techniques to model carbon nanotube biosensors. Dr Konrad Walus is an assistant professor in the same department. His research interests cover several areas including bio, gas and physical sensors. Dr David L Pulfrey is a professor and head of the nanoelectronics group at the University of British Columbia. He is active in device modeling, currently: carbon nanotube biosensors, vertical cavity transistor lasers and solar cells. He is a fellow of IEEE and the Canadian Academy of Engineering.
