Comparing the Electrochemical Response of Nanostructured Electrode Arrays

The electrochemical responses from periodic 6 × 6 arrays of recessed gold nanorings were compared to the 6 × 6 recessed gold nanodiscs arrays. The nanostructured arrays were fabricated by focused ion beam milling and their electrochemical response from a reversible redox pair was obtained. Three-dimensional cyclic voltammetry simulations using COMSOL were performed on 6 × 6 periodic arrays of both recessed nanodiscs and nanorings to elucidate the differences in mass transport between these geometries. Specific mass transport properties near the electroactive surface of the electrodes were elucidated by analyzing the calculated concentration profiles of the redox species. Relative contributions from radial diffusion regimes inside the nanoholes play an important role on the electrochemical response of the recessed nanorings. Arrays of nanodiscs are common in different types of applications, particularly in biosensors. The results presented here suggest that the performance and sensitivity of electrochemical nanosensors can be simply improved by implementing electrodes with a geometry which offer greater current density while keeping the overall footprint of the sensor element constant.