Interdigitated Nanoelectrode Arrays for Enhanced Sensitivity

Nanoelectrode arrays offer the potential for enhanced performance due to the improved mass transport characteristics offering the potential for faster and more sensitive electroanalysis. The inter-electrode distance can be tailored to optimise the electrochemical response depending upon the requirements.

Diffusion profiles for nanowire electrode arrays with various inter-electrode distances have shown that nanowires sufficiently spatially resolved and diffusionally independent in potential sweep experiments demonstrate superior electrochemical performance by comparison with nanowires that are relatively close to each other (overlapping diffusion profiles). Alternatively, arrays with diffusionally overlapping profiles exhibit enhanced performance (current amplification) when employing step voltammetric techniques such as square wave voltammetry. This has been attributed to operation in the generator-collector (GC) mode.

In this work we demonstrate that interdigitated gold nanowire arrays fabricated on silicon can also operate in the GC mode in simple potential sweep experiments. Collection efficiencies above 90% are achieved for the nanoelectrode designs employed. The use of nanowire arrays in the GC mode led to a 25 times current amplification over that for single nanowires thereby permitting significantly lower detection limits for electroanalysis.

Figure shows a CV of 2 mM FcCOOH in 10 mM PBS solution produced when the second side of the array is held at -0.15V (red), +0.45V (green), and +0.15V (purple).