Charge transfer from metallic single-walled carbon nanotube sensor arrays

This paper explores the possibility of using arrays of metallic carbon nanotubes as sensors. Unlike their semiconducting counterparts, single-walled carbon nanotube arrays or networks that are dominated by metallic conduction pathways have not been investigated for their environmental sensitivity. In this work, we demonstrate transduction of molecular adsorption via charge transfer through predominantly metallic single-walled carbon nanotubes. Raman spectroscopy and electric field dependent transport confirm that signal transduction takes place through primarily large diameter metallic nanotubes. This unique signal transduction mechanism might have implications for novel sensors. The scaling of the signal with array impedance is well described using an irreversible binding model developed previously. The arrays have several advantages including a simple, two-electrode fabrication, rapid regeneration, and a responsivity that scales predictably and linearly with the number of adsorption sites. An array-assisted hydrolysis of reactive analytes is found to regenerate the nanotube surface from hydrolyzable species which include important organophosphate nerve agents.