Fabrication and application of a stacked carbon electrode set including a suspended mesh made of nanowires and a substrate-bound planar electrode toward for an electrochemical/biosensor platform

Abstract

Herein, we present a novel electrochemical sensing platform that consists of a set of suspended carbon nanowire-based mesh electrode with deliberately controlled shapes (hexagonal or diamond), and a substrate-bound planar carbon electrode. These electrodes overlapped one another with a pre-defined gap which was precisely controlled by using a polymerization-stop layer. By recycling the redox reactions between the electrodes with a 2.1-μm-gap, the redox current of Fe(CN)64−/Fe(CN)63− could be amplified approximately 37 times. This high current amplifying capability enabled dopamine detection down to 5μM using cycling voltammetry. The complex morphology of the stacked carbon structures was obtained by simply using multiple UV-lithography processes and a single pyrolysis process that allowed pre-defined polymer structures to shrink into sub-micrometer-scale carbon structures. The suspended carbon mesh structures confined the mass-transfer near the electrode overlap region, and hence, the electrode set operated as a “sandwich” electrode enclosed within a microchannel. This effect was studied by simulating the mass transfer of the redox species, and confirmed by electrochemical measurements.