Fabrication of Nanoelectrodes Using Individual Multiwalled Carbon Nanotubes and Their Cyclic Voltammetric Properties

We investigated the applicability of individual multiwalled carbon nanotubes (MWNTs) as nanoelectrodes for high sensitivity electrochemical measurement and device miniaturization. An individual MWNT is split into a pair of nanoelectrodes with a gap between them by reactive ion etching in oxygen. Electrical contacts were provided by nanolithography to the two MWNT sections, which acted as the working and counter electrodes. Using a quasi-Ag/AgCl reference electrode, the nanoelectrodes were subject to cyclic voltammetry inside a droplet of dopamine solution. An excellent electrocatalytic behavior was found: The observed detection limit was as low as 10 pM dopamine. Thus, the proposed MWNT electrode has a significant potential for use in highly integrated, miniaturized devices for electrochemical sensing.