Fabrication and characterization of gold nanohole electrode arrays

We report a fabrication method for gold nanohole electrodes array using photolithography, deep reactive ion etching, wet etching, and focused ion beam lithography techniques. The electrode arrays were fabricated by drilling of nanoholes on a 100 nm silicon nitride membrane over a large area of titanium/gold thin film, exposing disk-type gold nanoelectrodes at the base of holes. The electrode arrays were characterized using scanning electron microscopy (SEM), cyclic voltammetry (CV), and chronoamperometry (CA). SEM imaging of the arrays showed that the each hole is circular at the mouth and cone recessed disk (truncated cone) at the base. Near “steady-state” voltammetric behavior was achieved for the oxidation of 1 mM ferrocenedicarboxylic acid in 10 mM phosphate buffered saline (PBS) at these electrode arrays. The steady-state responses increase with increasing the number of nanoholes in the array. Because of good reproducibility, high accuracy, and miniaturization compatibility of the proposed fabrication technique, we believe that it has potential applications in developing portable devices for biosensing.