Biosensing with carbon nanotube devices in solution

Semiconducting carbon nanotubes are extremely sensitive to their electrostatic environment. We use this property to build single-nanotube sensors in liquid environments that detect bio-molecule adsorption in real time via changes in device conductivity. The mechanisms for conductance modulation upon adsorption have been controversial. I will present scanned probe measurements and liquid gating measurements that resolve much of this controversy. We show how modulation of Schottky barrier contacts, together with bulk doping of the nanotubes, lead to gate-dependant changes in conductivity. I will discuss future directions for biosensor research, such as single molecule sensitivity, in which our understanding of electron transport properties will be critical.