Carbon nanotube based electronic devices, such as field effect transistors, can be used as very sensitive sensors. We have developed a theoretical model to analyze how the conductivity of a CNT-FET is affected by the electrochemical environment. Colleagues at DuPont have shown that this technique can be used to develop very sensitive biosensors.
Boussaad & Diner (DuPont)
This figure shows an experimental set-up for and electrochemical CNT-FET sensor. 'S' and 'D' are electrodes connected by the CNT's. 'G' is a gate electrode in the plane of the wafer. Other electrodes are relatively massive and allow one to control where the potential drop between the nanotube and the gate electrode occurs.
The figure above represents our model for the CNT-FET device in the presence of redox species in solution around it.
The figure above shows calculated conductance as a function of gate voltage for different ratios of oxidizing and reducing species. It correctly captures the fact that change of this ratio causes a horizontal shift in the response of the device.
“Model for Modulation of Conductance in a Carbon Nanotube Field Effect Transistor by Electrochemical Gating”, Tian Tang and Anand Jagota, Journal of Computational and Theoretical Nanotechnology , submitted (2007).