Ultra-sensitive and wide-dynamic-range sensors based on dense arrays of carbon nanotube tips.

Electrochemical electrodes based on dense and vertically aligned arrays of multi-walled carbon nanotubes (MWCNTs) were produced. The open tips of individual hollow nanotubes are exposed as active sites while the entangled nanotube stems encapsulated in epoxy collectively provide multiplexed and highly conductive pathways for charge transport. This unique structure together with the extraordinary electrical and electrochemical properties of MWCNTs offers a high signal-to-noise ratio (thus high sensitivity) and a large detection range, compared with other carbon-based electrodes. Our electrodes can detect K(3)FeCN(6) and dopamine at concentrations as low as 5 nM and 10 nM, respectively, and are responsive in a large dynamic range that spans almost 5 orders of magnitude.